1、机顶盒应用中经常用到跑马灯效果，而自己绘制跑马灯效果的关键在于步长和刷新频率的控制，一般情况下，刷新频率不要大于16ms,因为16ms是保证不掉帧的关键时间点，所以就不会出现卡顿的现象，具体实现代码如下：
package com.example.marquee;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.RectF;import android.os.Handler;import android.text.TextPaint;import android.text.TextUtils;import android.util.AttributeSet;import android.view.View;public class CustomTextView extends View { /** * 界面刷新时间(ms) */ public static final int INVALIDATE_TIME = 15; /** * 每次移动的像素点(px) */ public static final int INVALIDATE_STEP = 4; /** * 一次移动完成后等待的时间(ms) */ public static final int WAIT_TIME = 1500; /** * 滚动文字前后的间隔 */ private String space = " "; private String drawingText = ""; private TextPaint paint; public boolean exitFlag; private float textWidth; private String _mText; private int posX = 0; private float posY; private int width; private RectF rf; private Handler mHandler = new Handler(); public CustomTextView(Context context) { this(context, null); } public CustomTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public CustomTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initView(); } private void initView() { paint = new TextPaint(); paint.setAntiAlias(true); paint.setColor(Color.WHITE); paint.setTextSize(30F); rf = new RectF(0, 0, 0, 0); } public void setText(String text) { this._mText = text; this.drawingText = _mText; layoutView(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(widthMeasureSpec, heightMeasureSpec); layoutView(); } private void layoutView() { width = getWidth(); rf.right = width; rf.bottom = getHeight(); textWidth = paint.measureText(_mText, 0, _mText.length()); posY = getTextDrawingBaseline(paint, rf); } @Override protected void onDraw(Canvas canvas) { if (getVisibility() != View.VISIBLE || TextUtils.isEmpty(drawingText)) { return; } canvas.save(); canvas.drawText(drawingText, 0, drawingText.length(), posX, posY, paint); canvas.restore(); } private Runnable moveRun = new Runnable() { @Override public void run() { if(width >= textWidth){ return; } drawingText = _mText + space + _mText; posX -= INVALIDATE_STEP; if(posX >= -1 * INVALIDATE_STEP / 2 && posX <= INVALIDATE_STEP / 2){ mHandler.postDelayed(this, WAIT_TIME); invalidate(); return; } if (posX < -1 * textWidth - paint.measureText(space, 0, space.length())) { posX = INVALIDATE_STEP; } invalidate(); if(!exitFlag){ mHandler.postDelayed(this, INVALIDATE_TIME); return; } posX = 0; } }; @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); stopMove(); } @Override public void onWindowFocusChanged(boolean hasWindowFocus) { super.onWindowFocusChanged(hasWindowFocus); layoutView(); startMove(); } private void stopMove() { exitFlag = true; mHandler.removeCallbacksAndMessages(null); } public void startMove() { exitFlag = false; mHandler.post(moveRun); } /** * 获取绘制文字的baseline * * @param paint * @param targetRect * @return */ public static float getTextDrawingBaseline(Paint paint, RectF targetRect) { if (paint == null || targetRect == null) { return 0; } Paint.FontMetrics fontMetric = paint.getFontMetrics(); return targetRect.top + (targetRect.height() - fontMetric.bottom + fontMetric.top) / 2.0f - fontMetric.top; }}调用代码：
package com.example.marquee;import android.app.Activity;import android.graphics.Color;import android.os.Bundle;import android.widget.RelativeLayout;public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); RelativeLayout rl = new RelativeLayout(MainActivity.this); setContentView(rl); CustomTextView view = new CustomTextView(MainActivity.this); view.setBackgroundColor(Color.GRAY); view.setText("1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"); rl.addView(view, 300, 100); }}大家可以根据自己的需要去调整步长，建议不要修改刷新间隔时间。
附件是Demo工程，可以在上面调整出需要的速度