Android 高清載入巨圖方案 拒絕壓縮圖片

轉自：http://blog.csdn.net/lmj623565791/article/details/49300989

一、概述

距離上一篇部落格有段時間沒更新了，主要是最近有些私事導致的，那麼就先來一篇簡單一點的部落格脈動回來。

對於載入圖片，大家都不陌生，一般為了儘可能避免OOM都會按照如下做法：

1. 對於圖片顯示：根據需要顯示圖片控制元件的大小對圖片進行壓縮顯示。
2. 如果圖片數量非常多：則會使用LruCache等快取機制，將所有圖片佔據的內容維持在一個範圍內。

其實對於圖片載入還有種情況，就是單個圖片非常巨大，並且還不允許壓縮。比如顯示：世界地圖、清明上河圖、微博長圖等。

那麼對於這種需求，該如何做呢？

首先不壓縮，按照原圖尺寸載入，那麼螢幕肯定是不夠大的，並且考慮到記憶體的情況，不可能一次性整圖載入到記憶體中，所以肯定是區域性載入，那麼就需要用到一個類：

• BitmapRegionDecoder

其次，既然螢幕顯示不完，那麼最起碼要新增一個上下左右拖動的手勢，讓使用者可以拖動檢視。

那麼綜上，本篇博文的目的就是去自定義一個顯示巨圖的View，支援使用者去拖動檢視，大概的效果圖如下：

好吧，這清明上河圖太長了，想要觀看全圖，文末下載，圖片在assets目錄。當然如果你的圖，高度也很大，肯定也是可以上下拖動的。

二、初識BitmapRegionDecoder

BitmapRegionDecoder主要用於顯示圖片的某一塊矩形區域，如果你需要顯示某個圖片的指定區域，那麼這個類非常合適。

對於該類的用法，非常簡單，既然是顯示圖片的某一塊區域，那麼至少只需要一個方法去設定圖片；一個方法傳入顯示的區域即可；詳見：

• BitmapRegionDecoder提供了一系列的newInstance方法來構造物件，支援傳入檔案路徑，檔案描述符，檔案的inputstrem等。

  例如：

  <code class="language-java hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> BitmapRegionDecoder bitmapRegionDecoder =
    BitmapRegionDecoder.newInstance(inputStream, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>);
  </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

• 上述解決了傳入我們需要處理的圖片，那麼接下來就是顯示指定的區域。

  <code class="language-java hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">bitmapRegionDecoder.decodeRegion(rect, options);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

  引數一很明顯是一個rect，引數二是BitmapFactory.Options，你可以控制圖片的inSampleSize,inPreferredConfig等。

那麼下面看一個超級簡單的例子：

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.zhy.blogcodes.largeImage;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.Bitmap;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.BitmapFactory;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.BitmapRegionDecoder;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.Rect;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.os.Bundle;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.support.v7.app.AppCompatActivity;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.widget.ImageView;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> com.zhy.blogcodes.R;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.io.IOException;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.io.InputStream;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">LargeImageViewActivity</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">AppCompatActivity</span>
{</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> ImageView mImageView;

    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onCreate</span>(Bundle savedInstanceState)
    {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onCreate(savedInstanceState);
        setContentView(R.layout.activity_large_image_view);

        mImageView = (ImageView) findViewById(R.id.id_imageview);
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span>
        {
            InputStream inputStream = getAssets().open(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"tangyan.jpg"</span>);

            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//獲得圖片的寬、高</span>
            BitmapFactory.Options tmpOptions = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> BitmapFactory.Options();
            tmpOptions.inJustDecodeBounds = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
            BitmapFactory.decodeStream(inputStream, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, tmpOptions);
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> width = tmpOptions.outWidth;
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> height = tmpOptions.outHeight;

            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//設定顯示圖片的中心區域</span>
            BitmapRegionDecoder bitmapRegionDecoder = BitmapRegionDecoder.newInstance(inputStream, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>);
            BitmapFactory.Options options = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> BitmapFactory.Options();
            options.inPreferredConfig = Bitmap.Config.RGB_565;
            Bitmap bitmap = bitmapRegionDecoder.decodeRegion(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Rect(width / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> - <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>, height / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> - <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>, width / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>, height / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>), options);
            mImageView.setImageBitmap(bitmap);


        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IOException e)
        {
            e.printStackTrace();
        }


    }

}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li></ul>

上述程式碼，就是使用BitmapRegionDecoder去載入assets中的圖片，呼叫bitmapRegionDecoder.decodeRegion解析圖片的中間矩形區域，返回bitmap，最終顯示在ImageView上。

效果圖：

上面的小圖顯示的即為下面的大圖的中間區域。

ok，那麼目前我們已經瞭解了BitmapRegionDecoder的基本使用者，那麼往外擴散，我們需要自定義一個控制元件去顯示巨圖就很簡單了，首先Rect的範圍就是我們View的大小，然後根據使用者的移動手勢，不斷去更新我們的Rect的引數即可。

三、自定義顯示大圖控制元件

根據上面的分析呢，我們這個自定義控制元件思路就非常清晰了：

• 提供一個設定圖片的入口
• 重寫onTouchEvent，在裡面根據使用者移動的手勢，去更新顯示區域的引數
• 每次更新區域引數後，呼叫invalidate，onDraw裡面去regionDecoder.decodeRegion拿到bitmap，去draw

理清了，發現so easy，下面上程式碼：

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.zhy.blogcodes.largeImage.view;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.content.Context;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.Bitmap;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.BitmapFactory;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.BitmapRegionDecoder;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.Canvas;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.Rect;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.util.AttributeSet;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.view.MotionEvent;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.view.View;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.io.IOException;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.io.InputStream;

<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
 * Created by zhy on 15/5/16.
 */</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">LargeImageView</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">View</span>
{</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> BitmapRegionDecoder mDecoder;
    <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
     * 圖片的寬度和高度
     */</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> mImageWidth, mImageHeight;
    <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
     * 繪製的區域
     */</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">volatile</span> Rect mRect = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Rect();

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> MoveGestureDetector mDetector;


    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> BitmapFactory.Options options = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> BitmapFactory.Options();

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span>
    {
        options.inPreferredConfig = Bitmap.Config.RGB_565;
    }

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">setInputStream</span>(InputStream is)
    {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span>
        {
            mDecoder = BitmapRegionDecoder.newInstance(is, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>);
            BitmapFactory.Options tmpOptions = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> BitmapFactory.Options();
            <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// Grab the bounds for the scene dimensions</span>
            tmpOptions.inJustDecodeBounds = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
            BitmapFactory.decodeStream(is, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, tmpOptions);
            mImageWidth = tmpOptions.outWidth;
            mImageHeight = tmpOptions.outHeight;

            requestLayout();
            invalidate();
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IOException e)
        {
            e.printStackTrace();
        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">finally</span>
        {

            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span>
            {
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (is != <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>) is.close();
            } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (Exception e)
            {
            }
        }
    }


    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">init</span>()
    {
        mDetector = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> MoveGestureDetector(getContext(), <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> MoveGestureDetector.SimpleMoveGestureDetector()
        {
            <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onMove</span>(MoveGestureDetector detector)
            {
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> moveX = (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>) detector.getMoveX();
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> moveY = (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>) detector.getMoveY();

                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mImageWidth > getWidth())
                {
                    mRect.offset(-moveX, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>);
                    checkWidth();
                    invalidate();
                }
                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mImageHeight > getHeight())
                {
                    mRect.offset(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, -moveY);
                    checkHeight();
                    invalidate();
                }

                <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
            }
        });
    }


    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">checkWidth</span>()
    {


        Rect rect = mRect;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> imageWidth = mImageWidth;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> imageHeight = mImageHeight;

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (rect.right > imageWidth)
        {
            rect.right = imageWidth;
            rect.left = imageWidth - getWidth();
        }

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (rect.left < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)
        {
            rect.left = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
            rect.right = getWidth();
        }
    }


    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">checkHeight</span>()
    {

        Rect rect = mRect;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> imageWidth = mImageWidth;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> imageHeight = mImageHeight;

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (rect.bottom > imageHeight)
        {
            rect.bottom = imageHeight;
            rect.top = imageHeight - getHeight();
        }

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (rect.top < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)
        {
            rect.top = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
            rect.bottom = getHeight();
        }
    }


    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">LargeImageView</span>(Context context, AttributeSet attrs)
    {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context, attrs);
        init();
    }

    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onTouchEvent</span>(MotionEvent event)
    {
        mDetector.onToucEvent(event);
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
    }

    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onDraw</span>(Canvas canvas)
    {
        Bitmap bm = mDecoder.decodeRegion(mRect, options);
        canvas.drawBitmap(bm, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);
    }

    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onMeasure</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> widthMeasureSpec, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> heightMeasureSpec)
    {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> width = getMeasuredWidth();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> height = getMeasuredHeight();

        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> imageWidth = mImageWidth;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> imageHeight = mImageHeight;

         <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//預設直接顯示圖片的中心區域，可以自己去調節</span>
        mRect.left = imageWidth / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> - width / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;
        mRect.top = imageHeight / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span> - height / <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>;
        mRect.right = mRect.left + width;
        mRect.bottom = mRect.top + height;

    }


}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li><li style="box-sizing: border-box; padding: 0px 5px;">83</li><li style="box-sizing: border-box; padding: 0px 5px;">84</li><li style="box-sizing: border-box; padding: 0px 5px;">85</li><li style="box-sizing: border-box; padding: 0px 5px;">86</li><li style="box-sizing: border-box; padding: 0px 5px;">87</li><li style="box-sizing: border-box; padding: 0px 5px;">88</li><li style="box-sizing: border-box; padding: 0px 5px;">89</li><li style="box-sizing: border-box; padding: 0px 5px;">90</li><li style="box-sizing: border-box; padding: 0px 5px;">91</li><li style="box-sizing: border-box; padding: 0px 5px;">92</li><li style="box-sizing: border-box; padding: 0px 5px;">93</li><li style="box-sizing: border-box; padding: 0px 5px;">94</li><li style="box-sizing: border-box; padding: 0px 5px;">95</li><li style="box-sizing: border-box; padding: 0px 5px;">96</li><li style="box-sizing: border-box; padding: 0px 5px;">97</li><li style="box-sizing: border-box; padding: 0px 5px;">98</li><li style="box-sizing: border-box; padding: 0px 5px;">99</li><li style="box-sizing: border-box; padding: 0px 5px;">100</li><li style="box-sizing: border-box; padding: 0px 5px;">101</li><li style="box-sizing: border-box; padding: 0px 5px;">102</li><li style="box-sizing: border-box; padding: 0px 5px;">103</li><li style="box-sizing: border-box; padding: 0px 5px;">104</li><li style="box-sizing: border-box; padding: 0px 5px;">105</li><li style="box-sizing: border-box; padding: 0px 5px;">106</li><li style="box-sizing: border-box; padding: 0px 5px;">107</li><li style="box-sizing: border-box; padding: 0px 5px;">108</li><li style="box-sizing: border-box; padding: 0px 5px;">109</li><li style="box-sizing: border-box; padding: 0px 5px;">110</li><li style="box-sizing: border-box; padding: 0px 5px;">111</li><li style="box-sizing: border-box; padding: 0px 5px;">112</li><li style="box-sizing: border-box; padding: 0px 5px;">113</li><li style="box-sizing: border-box; padding: 0px 5px;">114</li><li style="box-sizing: border-box; padding: 0px 5px;">115</li><li style="box-sizing: border-box; padding: 0px 5px;">116</li><li style="box-sizing: border-box; padding: 0px 5px;">117</li><li style="box-sizing: border-box; padding: 0px 5px;">118</li><li style="box-sizing: border-box; padding: 0px 5px;">119</li><li style="box-sizing: border-box; padding: 0px 5px;">120</li><li style="box-sizing: border-box; padding: 0px 5px;">121</li><li style="box-sizing: border-box; padding: 0px 5px;">122</li><li style="box-sizing: border-box; padding: 0px 5px;">123</li><li style="box-sizing: border-box; padding: 0px 5px;">124</li><li style="box-sizing: border-box; padding: 0px 5px;">125</li><li style="box-sizing: border-box; padding: 0px 5px;">126</li><li style="box-sizing: border-box; padding: 0px 5px;">127</li><li style="box-sizing: border-box; padding: 0px 5px;">128</li><li style="box-sizing: border-box; padding: 0px 5px;">129</li><li style="box-sizing: border-box; padding: 0px 5px;">130</li><li style="box-sizing: border-box; padding: 0px 5px;">131</li><li style="box-sizing: border-box; padding: 0px 5px;">132</li><li style="box-sizing: border-box; padding: 0px 5px;">133</li><li style="box-sizing: border-box; padding: 0px 5px;">134</li><li style="box-sizing: border-box; padding: 0px 5px;">135</li><li style="box-sizing: border-box; padding: 0px 5px;">136</li><li style="box-sizing: border-box; padding: 0px 5px;">137</li><li style="box-sizing: border-box; padding: 0px 5px;">138</li><li style="box-sizing: border-box; padding: 0px 5px;">139</li><li style="box-sizing: border-box; padding: 0px 5px;">140</li><li style="box-sizing: border-box; padding: 0px 5px;">141</li><li style="box-sizing: border-box; padding: 0px 5px;">142</li><li style="box-sizing: border-box; padding: 0px 5px;">143</li><li style="box-sizing: border-box; padding: 0px 5px;">144</li><li style="box-sizing: border-box; padding: 0px 5px;">145</li><li style="box-sizing: border-box; padding: 0px 5px;">146</li><li style="box-sizing: border-box; padding: 0px 5px;">147</li><li style="box-sizing: border-box; padding: 0px 5px;">148</li><li style="box-sizing: border-box; padding: 0px 5px;">149</li><li style="box-sizing: border-box; padding: 0px 5px;">150</li><li style="box-sizing: border-box; padding: 0px 5px;">151</li><li style="box-sizing: border-box; padding: 0px 5px;">152</li><li style="box-sizing: border-box; padding: 0px 5px;">153</li><li style="box-sizing: border-box; padding: 0px 5px;">154</li><li style="box-sizing: border-box; padding: 0px 5px;">155</li><li style="box-sizing: border-box; padding: 0px 5px;">156</li><li style="box-sizing: border-box; padding: 0px 5px;">157</li><li style="box-sizing: border-box; padding: 0px 5px;">158</li><li style="box-sizing: border-box; padding: 0px 5px;">159</li><li style="box-sizing: border-box; padding: 0px 5px;">160</li><li style="box-sizing: border-box; padding: 0px 5px;">161</li><li style="box-sizing: border-box; padding: 0px 5px;">162</li><li style="box-sizing: border-box; padding: 0px 5px;">163</li><li style="box-sizing: border-box; padding: 0px 5px;">164</li><li style="box-sizing: border-box; padding: 0px 5px;">165</li><li style="box-sizing: border-box; padding: 0px 5px;">166</li><li style="box-sizing: border-box; padding: 0px 5px;">167</li><li style="box-sizing: border-box; padding: 0px 5px;">168</li><li style="box-sizing: border-box; padding: 0px 5px;">169</li><li style="box-sizing: border-box; padding: 0px 5px;">170</li><li style="box-sizing: border-box; padding: 0px 5px;">171</li><li style="box-sizing: border-box; padding: 0px 5px;">172</li><li style="box-sizing: border-box; padding: 0px 5px;">173</li><li style="box-sizing: border-box; padding: 0px 5px;">174</li><li style="box-sizing: border-box; padding: 0px 5px;">175</li><li style="box-sizing: border-box; padding: 0px 5px;">176</li><li style="box-sizing: border-box; padding: 0px 5px;">177</li><li style="box-sizing: border-box; padding: 0px 5px;">178</li><li style="box-sizing: border-box; padding: 0px 5px;">179</li><li style="box-sizing: border-box; padding: 0px 5px;">180</li><li style="box-sizing: border-box; padding: 0px 5px;">181</li><li style="box-sizing: border-box; padding: 0px 5px;">182</li><li style="box-sizing: border-box; padding: 0px 5px;">183</li><li style="box-sizing: border-box; padding: 0px 5px;">184</li></ul>

根據上述原始碼:

1. setInputStream裡面去獲得圖片的真實的寬度和高度，以及初始化我們的mDecoder
2. onMeasure裡面為我們的顯示區域的rect賦值，大小為view的尺寸
3. onTouchEvent裡面我們監聽move的手勢，在監聽的回撥裡面去改變rect的引數，以及做邊界檢查，最後invalidate
4. 在onDraw裡面就是根據rect拿到bitmap，然後draw了

ok，上面並不複雜，不過大家有沒有注意到，這個監聽使用者move手勢的程式碼寫的有點奇怪，恩，這裡模仿了系統的ScaleGestureDetector，編寫了MoveGestureDetector，程式碼如下：

• MoveGestureDetector

  <code class="language-java hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">
  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.zhy.blogcodes.largeImage.view;
  
  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.content.Context;
  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.graphics.PointF;
  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.view.MotionEvent;
  
  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">MoveGestureDetector</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">BaseGestureDetector</span>
  {</span>
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> PointF mCurrentPointer;
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> PointF mPrePointer;
      <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//僅僅為了減少建立記憶體</span>
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> PointF mDeltaPointer = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> PointF();
  
      <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//用於記錄最終結果，並返回</span>
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> PointF mExtenalPointer = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> PointF();
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> OnMoveGestureListener mListenter;
  
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">MoveGestureDetector</span>(Context context, OnMoveGestureListener listener)
      {
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context);
          mListenter = listener;
      }
  
      <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">handleInProgressEvent</span>(MotionEvent event)
      {
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> actionCode = event.getAction() & MotionEvent.ACTION_MASK;
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">switch</span> (actionCode)
          {
              <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_CANCEL:
              <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_UP:
                  mListenter.onMoveEnd(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>);
                  resetState();
                  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;
              <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_MOVE:
                  updateStateByEvent(event);
                  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> update = mListenter.onMove(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>);
                  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (update)
                  {
                      mPreMotionEvent.recycle();
                      mPreMotionEvent = MotionEvent.obtain(event);
                  }
                  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;
  
          }
      }
  
      <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">handleStartProgressEvent</span>(MotionEvent event)
      {
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> actionCode = event.getAction() & MotionEvent.ACTION_MASK;
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">switch</span> (actionCode)
          {
              <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_DOWN:
                  resetState();<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//防止沒有接收到CANCEL or UP ,保險起見</span>
                  mPreMotionEvent = MotionEvent.obtain(event);
                  updateStateByEvent(event);
                  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;
              <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> MotionEvent.ACTION_MOVE:
                  mGestureInProgress = mListenter.onMoveBegin(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>);
                  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;
          }
  
      }
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">updateStateByEvent</span>(MotionEvent event)
      {
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> MotionEvent prev = mPreMotionEvent;
  
          mPrePointer = caculateFocalPointer(prev);
          mCurrentPointer = caculateFocalPointer(event);
  
          <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//Log.e("TAG", mPrePointer.toString() + " ,  " + mCurrentPointer);</span>
  
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> mSkipThisMoveEvent = prev.getPointerCount() != event.getPointerCount();
  
          <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//Log.e("TAG", "mSkipThisMoveEvent = " + mSkipThisMoveEvent);</span>
          mExtenalPointer.x = mSkipThisMoveEvent ? <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> : mCurrentPointer.x - mPrePointer.x;
          mExtenalPointer.y = mSkipThisMoveEvent ? <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span> : mCurrentPointer.y - mPrePointer.y;
  
      }
  
      <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
       * 根據event計算多指中心點
       *
       *<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> event
       *<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @return</span>
       */</span>
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> PointF <span class="hljs-title" style="box-sizing: border-box;">caculateFocalPointer</span>(MotionEvent event)
      {
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> count = event.getPointerCount();
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> x = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, y = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i < count; i++)
          {
              x += event.getX(i);
              y += event.getY(i);
          }
  
          x /= count;
          y /= count;
  
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> PointF(x, y);
      }
  
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> <span class="hljs-title" style="box-sizing: border-box;">getMoveX</span>()
      {
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> mExtenalPointer.x;
  
      }
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> <span class="hljs-title" style="box-sizing: border-box;">getMoveY</span>()
      {
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> mExtenalPointer.y;
      }
  
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">interface</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">OnMoveGestureListener</span>
      {</span>
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onMoveBegin</span>(MoveGestureDetector detector);
  
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onMove</span>(MoveGestureDetector detector);
  
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onMoveEnd</span>(MoveGestureDetector detector);
      }
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">SimpleMoveGestureDetector</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">implements</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">OnMoveGestureListener</span>
      {</span>
  
          <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onMoveBegin</span>(MoveGestureDetector detector)
          {
              <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
          }
  
          <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onMove</span>(MoveGestureDetector detector)
          {
              <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
          }
  
          <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onMoveEnd</span>(MoveGestureDetector detector)
          {
          }
      }
  
  }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li><li style="box-sizing: border-box; padding: 0px 5px;">83</li><li style="box-sizing: border-box; padding: 0px 5px;">84</li><li style="box-sizing: border-box; padding: 0px 5px;">85</li><li style="box-sizing: border-box; padding: 0px 5px;">86</li><li style="box-sizing: border-box; padding: 0px 5px;">87</li><li style="box-sizing: border-box; padding: 0px 5px;">88</li><li style="box-sizing: border-box; padding: 0px 5px;">89</li><li style="box-sizing: border-box; padding: 0px 5px;">90</li><li style="box-sizing: border-box; padding: 0px 5px;">91</li><li style="box-sizing: border-box; padding: 0px 5px;">92</li><li style="box-sizing: border-box; padding: 0px 5px;">93</li><li style="box-sizing: border-box; padding: 0px 5px;">94</li><li style="box-sizing: border-box; padding: 0px 5px;">95</li><li style="box-sizing: border-box; padding: 0px 5px;">96</li><li style="box-sizing: border-box; padding: 0px 5px;">97</li><li style="box-sizing: border-box; padding: 0px 5px;">98</li><li style="box-sizing: border-box; padding: 0px 5px;">99</li><li style="box-sizing: border-box; padding: 0px 5px;">100</li><li style="box-sizing: border-box; padding: 0px 5px;">101</li><li style="box-sizing: border-box; padding: 0px 5px;">102</li><li style="box-sizing: border-box; padding: 0px 5px;">103</li><li style="box-sizing: border-box; padding: 0px 5px;">104</li><li style="box-sizing: border-box; padding: 0px 5px;">105</li><li style="box-sizing: border-box; padding: 0px 5px;">106</li><li style="box-sizing: border-box; padding: 0px 5px;">107</li><li style="box-sizing: border-box; padding: 0px 5px;">108</li><li style="box-sizing: border-box; padding: 0px 5px;">109</li><li style="box-sizing: border-box; padding: 0px 5px;">110</li><li style="box-sizing: border-box; padding: 0px 5px;">111</li><li style="box-sizing: border-box; padding: 0px 5px;">112</li><li style="box-sizing: border-box; padding: 0px 5px;">113</li><li style="box-sizing: border-box; padding: 0px 5px;">114</li><li style="box-sizing: border-box; padding: 0px 5px;">115</li><li style="box-sizing: border-box; padding: 0px 5px;">116</li><li style="box-sizing: border-box; padding: 0px 5px;">117</li><li style="box-sizing: border-box; padding: 0px 5px;">118</li><li style="box-sizing: border-box; padding: 0px 5px;">119</li><li style="box-sizing: border-box; padding: 0px 5px;">120</li><li style="box-sizing: border-box; padding: 0px 5px;">121</li><li style="box-sizing: border-box; padding: 0px 5px;">122</li><li style="box-sizing: border-box; padding: 0px 5px;">123</li><li style="box-sizing: border-box; padding: 0px 5px;">124</li><li style="box-sizing: border-box; padding: 0px 5px;">125</li><li style="box-sizing: border-box; padding: 0px 5px;">126</li><li style="box-sizing: border-box; padding: 0px 5px;">127</li><li style="box-sizing: border-box; padding: 0px 5px;">128</li><li style="box-sizing: border-box; padding: 0px 5px;">129</li><li style="box-sizing: border-box; padding: 0px 5px;">130</li><li style="box-sizing: border-box; padding: 0px 5px;">131</li><li style="box-sizing: border-box; padding: 0px 5px;">132</li><li style="box-sizing: border-box; padding: 0px 5px;">133</li><li style="box-sizing: border-box; padding: 0px 5px;">134</li><li style="box-sizing: border-box; padding: 0px 5px;">135</li><li style="box-sizing: border-box; padding: 0px 5px;">136</li><li style="box-sizing: border-box; padding: 0px 5px;">137</li><li style="box-sizing: border-box; padding: 0px 5px;">138</li><li style="box-sizing: border-box; padding: 0px 5px;">139</li><li style="box-sizing: border-box; padding: 0px 5px;">140</li><li style="box-sizing: border-box; padding: 0px 5px;">141</li><li style="box-sizing: border-box; padding: 0px 5px;">142</li><li style="box-sizing: border-box; padding: 0px 5px;">143</li><li style="box-sizing: border-box; padding: 0px 5px;">144</li><li style="box-sizing: border-box; padding: 0px 5px;">145</li><li style="box-sizing: border-box; padding: 0px 5px;">146</li><li style="box-sizing: border-box; padding: 0px 5px;">147</li><li style="box-sizing: border-box; padding: 0px 5px;">148</li><li style="box-sizing: border-box; padding: 0px 5px;">149</li><li style="box-sizing: border-box; padding: 0px 5px;">150</li><li style="box-sizing: border-box; padding: 0px 5px;">151</li><li style="box-sizing: border-box; padding: 0px 5px;">152</li></ul>

• BaseGestureDetector

  <code class="hljs cs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">package com.zhy.blogcodes.largeImage.view;
  
  import android.content.Context;
  import android.view.MotionEvent;
  
  
  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">abstract</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> BaseGestureDetector
  {
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> boolean mGestureInProgress;
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> MotionEvent mPreMotionEvent;
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> MotionEvent mCurrentMotionEvent;
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> Context mContext;
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">BaseGestureDetector</span>(Context context)
      {
          mContext = context;
      }
  
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> boolean <span class="hljs-title" style="box-sizing: border-box;">onToucEvent</span>(MotionEvent <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>)
      {
  
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (!mGestureInProgress)
          {
              handleStartProgressEvent(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>);
          } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>
          {
              handleInProgressEvent(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>);
          }
  
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;
  
      }
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">abstract</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">handleInProgressEvent</span>(MotionEvent <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>);
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">abstract</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">handleStartProgressEvent</span>(MotionEvent <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>);
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">abstract</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">updateStateByEvent</span>(MotionEvent <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">event</span>);
  
      <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">resetState</span>()
      {
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mPreMotionEvent != <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>)
          {
              mPreMotionEvent.recycle();
              mPreMotionEvent = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;
          }
          <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mCurrentMotionEvent != <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>)
          {
              mCurrentMotionEvent.recycle();
              mCurrentMotionEvent = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;
          }
          mGestureInProgress = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>;
      }
  
  
  }
  </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li></ul>

  你可能會說，一個move手勢搞這麼多程式碼，太麻煩了。的確是的，move手勢的檢測非常簡單，那麼之所以這麼寫呢，主要是為了可以複用，比如現在有一堆的XXXGestureDetector，當我們需要監聽什麼手勢，就直接拿個detector來檢測多方便。我相信大家肯定也鬱悶過Google，為什麼只有ScaleGestureDetector而沒有RotateGestureDetector呢。

根據上述，大家應該理解了為什麼要這麼做，當時不強制，每個人都有個性。

不過值得一提的是：上面這個手勢檢測的寫法，不是我想的，而是一個開源的專案https://github.com/rharter/android-gesture-detectors，裡面包含很多的手勢檢測。對應的博文是：http://code.almeros.com/android-multitouch-gesture-detectors#.VibzzhArJXg那面上面兩個類就是我偷學了的~ 哈

四、測試

測試其實沒撒好說的了，就是把我們的LargeImageView放入佈局檔案，然後Activity裡面去設定inputstream了。

<code class="language-xml hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">RelativeLayout</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xmlns:android</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"http://schemas.android.com/apk/res/android"</span>
                <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">xmlns:tools</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"http://schemas.android.com/tools"</span>
                <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>
                <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>></span>


    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">com.zhy.blogcodes.largeImage.view.LargeImageView
</span>        <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/id_largetImageview"</span>
        <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>
        <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>/></span>

<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">RelativeLayout</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

然後在Activity裡面去設定圖片：

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">package</span> com.zhy.blogcodes.largeImage;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.os.Bundle;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> android.support.v7.app.AppCompatActivity;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> com.zhy.blogcodes.R;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> com.zhy.blogcodes.largeImage.view.LargeImageView;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.io.IOException;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">import</span> java.io.InputStream;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">LargeImageViewActivity</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">AppCompatActivity</span>
{</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> LargeImageView mLargeImageView;

    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onCreate</span>(Bundle savedInstanceState)
    {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onCreate(savedInstanceState);
        setContentView(R.layout.activity_large_image_view);

        mLargeImageView = (LargeImageView) findViewById(R.id.id_largetImageview);
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span>
        {
            InputStream inputStream = getAssets().open(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"world.jpg"</span>);
            mLargeImageView.setInputStream(inputStream);

        } <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (IOException e)
        {
            e.printStackTrace();
        }


    }

}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li></ul>

效果圖：

ok，那麼到此，顯示巨圖的方案以及詳細的程式碼就描述完成了，總體還是非常簡單的。 
但是，在實際的專案中，可能會有更多的需求，比如增加放大、縮小；增加快滑手勢等等，那麼大家可以去參考這個庫：https://github.com/johnnylambada/WorldMap，該庫基本實現了絕大多數的需求，大家根據本文這個思路再去看這個庫，也會簡單很多，定製起來也容易。我這個地圖的圖就是該庫裡面提供的。

哈，掌握了這個，以後面試過程中也可以悄悄的裝一把了，當你優雅的答完android載入圖片的方案以後，然後接一句，其實還有一種情況，就是高清顯示巨圖，那麼我們應該…相信面試官對你的印象會好很多~ have a nice day ~

原始碼點選下載

參考連結

• http://code.almeros.com/android-multitouch-gesture-detectors#.VibzzhArJXg
• https://github.com/rharter/android-gesture-detectors
• https://github.com/johnnylambada/WorldMap