Android開發之TextView文字水平滾動效果實現

       在網路上搜集了很多關於這方面的文章和實現方法，最終經過實踐驗證和部分調整，完全可用，包括不依賴焦點和選中TextView便可實現水平滾動效果。

      現將主要程式碼羅列如下，希望對看到的人有幫助。

第一步：編寫MarqueeText.java類，繼承自TextView

package cn.superyouth.www.itools;


import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.widget.TextView;


public class MarqueeText extends TextView {
	 /** 是否停止滾動 */
    private boolean mStopMarquee;
    private String mText;
    private float mCoordinateX;
    private float mTextWidth;


    public MarqueeText(Context context, AttributeSet attrs) {
        super(context, attrs);
    }


    public void setText(String text) {
        this.mText = text;
        mTextWidth = getPaint().measureText(mText);
        if (mHandler.hasMessages(0))
            mHandler.removeMessages(0);
        mHandler.sendEmptyMessageDelayed(0, 2000);
    }


    @SuppressLint("NewApi")
	@Override
    protected void onAttachedToWindow() {
        mStopMarquee = false;
        if (!(mText == null || mText.isEmpty()))
            mHandler.sendEmptyMessageDelayed(0, 2000);
        super.onAttachedToWindow();
    }


    @Override
    protected void onDetachedFromWindow() {
        mStopMarquee = true;
        if (mHandler.hasMessages(0))
            mHandler.removeMessages(0);
        super.onDetachedFromWindow();
    }


    @SuppressLint("NewApi")
	@Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (!(mText == null || mText.isEmpty()))
            canvas.drawText(mText, mCoordinateX, 30, getPaint());
    }


    @SuppressLint("HandlerLeak")
	private Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 0:
                if (Math.abs(mCoordinateX) > (mTextWidth + 5)) {
                    mCoordinateX = 0;
                    invalidate();
                    if (!mStopMarquee) {
                        sendEmptyMessageDelayed(0,500);
                    }
                } else {
                    mCoordinateX -= 1;
                    invalidate();
                    if (!mStopMarquee) {
                        sendEmptyMessageDelayed(0, 30);
                    }
                }
                break;
            }
            super.handleMessage(msg);
        }
    };
}

第二步：編寫佈局檔案main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/backsmall"
    android:orientation="vertical" >
    <cn.superyouth.www.itools.MarqueeText
          android:id="@+id/textMsg" 
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"        
          android:layout_marginTop="115dp"         
          android:textColor="@android:color/black" 
          android:lines="1"
          android:focusable="true"
          android:focusableInTouchMode="true"
          android:scrollHorizontally="true"  
          android:marqueeRepeatLimit="marquee_forever"  
          android:ellipsize="marquee" 
    />
</LinearLayout>

第三步：編寫SYIT_Index.java繼承自Activity類

package cn.superyouth.www;


import java.io.IOException;
import cn.superyouth.www.itools.MarqueeText;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Intent;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.method.ScrollingMovementMethod;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;


public class SYIT_Index extends Activity {
	MarqueeText autoScrollTextView;


	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);


		autoScrollTextView = (MarqueeText) findViewById(R.id.textMsg);
		autoScrollTextView.setTextSize(30);
		
        autoScrollTextView.setTextColor(Color.BLUE);
		autoScrollTextView.setText("暫無任何預警資訊!");
        // 點選預警提示資訊
		autoScrollTextView.setOnClickListener(new OnClickListener() {
			public void onClick(View arg0) {
				// 進入預警資訊頁面
				Intent intent = new Intent(SYIT_Index.this, SYIT_Warning.class);
				startActivity(intent);
			}
		});
     }
}