BitmapShader 實現圓型圖片
我們在寫UI的時候經常會碰到要求將一個方形的圖片變成一個圓形或者圓角的圖片。如果設計師能給一個圓形的圖片那當然是最好的。但是有時候為了減少app的大小,往往就一個方形的圖片,怎麼辦能?該如何實現,今天我就來講講使用BitmapShader實現圓形圖片。
首先獲得邊框的寬度和顏色
public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0);
mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_border_width, DEFAULT_BORDER_WIDTH);
mBorderColor = a.getColor(R.styleable.CircleImageView_border_color, DEFAULT_BORDER_COLOR);
a.recycle();
init();
}
接著在attr.xml檔案中配置
<declare-styleable name="CircleImageView">
<attr name="border_width" format="dimension" />
<attr name="border_color" format="color" />
</declare-styleable>
然後初始化畫筆和著色器
private void setup() {
if (mBitmap == null) {
return;
}
//將mBitmap作為著色器,就是在指定區域內繪製mBitmap
mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
//將mBitmapPaint圖片畫筆設定mBitmapShader
mBitmapPaint.setAntiAlias(true);
mBitmapPaint.setShader(mBitmapShader);
//初始化邊框畫筆mBorderPaint
mBorderPaint.setStyle(Paint.Style.STROKE);
mBorderPaint.setAntiAlias(true);
mBorderPaint.setColor(mBorderColor);
mBorderPaint.setStrokeWidth(mBorderWidth);
//獲得圖片的長寬
mBitmapHeight = mBitmap.getHeight();
mBitmapWidth = mBitmap.getWidth();
//初始化邊框矩形
mBorderRect.set(0, 0, getWidth(), getHeight());
//獲得圖片的半徑
mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2);
//初始化繪製矩形
mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width() - mBorderWidth, mBorderRect.height() - mBorderWidth);
mDrawableRadius = Math.min(mDrawableRect.height() / 2, mDrawableRect.width() / 2);
updateShaderMatrix();
invalidate();
}
再更新Shader矩陣
private void updateShaderMatrix() {
float scale;
float dx = 0;
float dy = 0;
mShaderMatrix.set(null);
if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width() * mBitmapHeight) {
scale = mDrawableRect.height() / (float) mBitmapHeight;
//圖片放大或者縮小後x軸的偏移
dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f;
} else {
scale = mDrawableRect.width() / (float) mBitmapWidth;
//圖片放大或者縮小後y軸的偏移
dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f;
}
// shader的變換矩陣,我們這裡主要用於放大或者縮小
mShaderMatrix.setScale(scale, scale);
//ShaderMatrix調整座標軸
mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth, (int) (dy + 0.5f) + mBorderWidth);
//著色器設定變換矩陣
mBitmapShader.setLocalMatrix(mShaderMatrix);
}
偏移量dx、dy的計算, 圖片放大或者縮小後x軸的偏移,ImageView的座標原點是在左上角,所以放大或者縮小後右下角已經和邊距間距,為了讓圖片居中移動1/2間距。dy的偏移量也是如此。
最後就是繪製了,在onDraw方法中繪製圖片和邊框
@Override
protected void onDraw(Canvas canvas) {
if (getDrawable() == null) {
return;
}
canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint);
if (mBorderWidth != 0) {
canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint);
}
}
全部程式碼如下:
package com.jijin.driver.weidgets;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.net.Uri;
import android.util.AttributeSet;
import android.widget.ImageView;
import com.jijin.driver.R;
public class CircleImageView extends ImageView {
private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP;
private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888;
private static final int COLORDRAWABLE_DIMENSION = 2;
private static final int DEFAULT_BORDER_WIDTH = 0;
private static final int DEFAULT_BORDER_COLOR = Color.BLACK;
private final RectF mDrawableRect = new RectF();
private final RectF mBorderRect = new RectF();
private final Matrix mShaderMatrix = new Matrix();
private final Paint mBitmapPaint = new Paint();
private final Paint mBorderPaint = new Paint();
private int mBorderColor = DEFAULT_BORDER_COLOR;
private int mBorderWidth = DEFAULT_BORDER_WIDTH;
private Bitmap mBitmap;
private BitmapShader mBitmapShader;
private int mBitmapWidth;
private int mBitmapHeight;
private float mDrawableRadius;
private float mBorderRadius;
private ColorFilter mColorFilter;
private boolean mReady;
private boolean mSetupPending;
public CircleImageView(Context context) {
super(context);
init();
}
public CircleImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0);
mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_border_width, DEFAULT_BORDER_WIDTH);
mBorderColor = a.getColor(R.styleable.CircleImageView_border_color, DEFAULT_BORDER_COLOR);
a.recycle();
init();
}
private void init() {
super.setScaleType(SCALE_TYPE);
mReady = true;
if (mSetupPending) {
setup();
mSetupPending = false;
}
}
@Override
public ScaleType getScaleType() {
return SCALE_TYPE;
}
@Override
public void setScaleType(ScaleType scaleType) {
if (scaleType != SCALE_TYPE) {
throw new IllegalArgumentException(String.format("ScaleType %s not supported.", scaleType));
}
}
@Override
public void setAdjustViewBounds(boolean adjustViewBounds) {
if (adjustViewBounds) {
throw new IllegalArgumentException("adjustViewBounds not supported.");
}
}
@Override
protected void onDraw(Canvas canvas) {
if (getDrawable() == null) {
return;
}
canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint);
if (mBorderWidth != 0) {
canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint);
}
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
setup();
}
public int getBorderColor() {
return mBorderColor;
}
public void setBorderColor(int borderColor) {
if (borderColor == mBorderColor) {
return;
}
mBorderColor = borderColor;
mBorderPaint.setColor(mBorderColor);
invalidate();
}
public int getBorderWidth() {
return mBorderWidth;
}
public void setBorderWidth(int borderWidth) {
if (borderWidth == mBorderWidth) {
return;
}
mBorderWidth = borderWidth;
setup();
}
@Override
public void setImageBitmap(Bitmap bm) {
super.setImageBitmap(bm);
mBitmap = bm;
setup();
}
@Override
public void setImageDrawable(Drawable drawable) {
super.setImageDrawable(drawable);
mBitmap = getBitmapFromDrawable(drawable);
setup();
}
public Bitmap getImage(){
return mBitmap;
}
@Override
public void setImageResource(int resId) {
super.setImageResource(resId);
mBitmap = getBitmapFromDrawable(getDrawable());
setup();
}
@Override
public void setImageURI(Uri uri) {
super.setImageURI(uri);
mBitmap = getBitmapFromDrawable(getDrawable());
setup();
}
@Override
public void setColorFilter(ColorFilter cf) {
if (cf == mColorFilter) {
return;
}
mColorFilter = cf;
mBitmapPaint.setColorFilter(mColorFilter);
invalidate();
}
private Bitmap getBitmapFromDrawable(Drawable drawable) {
if (drawable == null) {
return null;
}
if (drawable instanceof BitmapDrawable) {
return ((BitmapDrawable) drawable).getBitmap();
}
try {
Bitmap bitmap;
if (drawable instanceof ColorDrawable) {
bitmap = Bitmap.createBitmap(COLORDRAWABLE_DIMENSION, COLORDRAWABLE_DIMENSION, BITMAP_CONFIG);
} else {
bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), BITMAP_CONFIG);
}
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
drawable.draw(canvas);
return bitmap;
} catch (OutOfMemoryError e) {
return null;
}
}
private void setup() {
if (!mReady) {
mSetupPending = true;
return;
}
if (mBitmap == null) {
return;
}
//將mBitmap作為著色器,就是在指定區域內繪製mBitmap
mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
//將mBitmapPaint圖片畫筆設定mBitmapShader
mBitmapPaint.setAntiAlias(true);
mBitmapPaint.setShader(mBitmapShader);
//初始化邊框畫筆mBorderPaint
mBorderPaint.setStyle(Paint.Style.STROKE);
mBorderPaint.setAntiAlias(true);
mBorderPaint.setColor(mBorderColor);
mBorderPaint.setStrokeWidth(mBorderWidth);
//獲得圖片的長寬
mBitmapHeight = mBitmap.getHeight();
mBitmapWidth = mBitmap.getWidth();
//初始化邊框矩形
mBorderRect.set(0, 0, getWidth(), getHeight());
//獲得圖片的半徑
mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2);
//初始化繪製矩形
mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width() - mBorderWidth, mBorderRect.height() - mBorderWidth);
mDrawableRadius = Math.min(mDrawableRect.height() / 2, mDrawableRect.width() / 2);
updateShaderMatrix();
invalidate();
}
private void updateShaderMatrix() {
float scale;
float dx = 0;
float dy = 0;
mShaderMatrix.set(null);
if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width() * mBitmapHeight) {
scale = mDrawableRect.height() / (float) mBitmapHeight;
dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f;
} else {
scale = mDrawableRect.width() / (float) mBitmapWidth;
dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f;
}
// shader的變換矩陣,我們這裡主要用於放大或者縮小
mShaderMatrix.setScale(scale, scale);
mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth, (int) (dy + 0.5f) + mBorderWidth);
//著色器設定變換矩陣
mBitmapShader.setLocalMatrix(mShaderMatrix);
}
}
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