原文地址：http://mobile.51cto.com/hot-235078.htm
我们曾就《Android手势识别ViewFlipper触摸动画》做过详细的讲解，其实，Android应用程序开发中，多点触摸（Multitouch）不是那么遥不可及，实现起来也很简单。如果您对开发多点触摸程序感兴趣的话，那么本文将是一个很好的开始，本例只需要两个类就能实现多点触摸。
首先来看看我们的视图类MTView.java:
package com.ideasandroid.demo; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; public class MTView extends SurfaceView implements SurfaceHolder.Callback { private static final int MAX_TOUCHPOINTS = 10; private static final String START_TEXT = "请随便触摸屏幕进行测试"; private Paint textPaint = new Paint(); private Paint touchPaints[] = new Paint[MAX_TOUCHPOINTS]; private int colors[] = new int[MAX_TOUCHPOINTS]; private int width, height; private float scale = 1.0f; public MTView(Context context) { super(context); SurfaceHolder holder = getHolder(); holder.addCallback(this); setFocusable(true); // 确保我们的View能获得输入焦点 setFocusableInTouchMode(true); // 确保能接收到触屏事件 init(); } private void init() { // 初始化10个不同颜色的画笔 textPaint.setColor(Color.WHITE); colors[0] = Color.BLUE; colors[1] = Color.RED; colors[2] = Color.GREEN; colors[3] = Color.YELLOW; colors[4] = Color.CYAN; colors[5] = Color.MAGENTA; colors[6] = Color.DKGRAY; colors[7] = Color.WHITE; colors[8] = Color.LTGRAY; colors[9] = Color.GRAY; for (int i = 0; i < MAX_TOUCHPOINTS; i++) { touchPaints[i] = new Paint(); touchPaints[i].setColor(colors[i]); } } /* * 处理触屏事件 */ @Override public boolean onTouchEvent(MotionEvent event) { // 获得屏幕触点数量 int pointerCount = event.getPointerCount(); if (pointerCount > MAX_TOUCHPOINTS) { pointerCount = MAX_TOUCHPOINTS; } // 锁定Canvas,开始进行相应的界面处理 Canvas c = getHolder().lockCanvas(); if (c != null) { c.drawColor(Color.BLACK); if (event.getAction() == MotionEvent.ACTION_UP) { // 当手离开屏幕时，清屏 } else { // 先在屏幕上画一个十字，然后画一个圆 for (int i = 0; i < pointerCount; i++) { // 获取一个触点的坐标，然后开始绘制 int id = event.getPointerId(i); int x = (int) event.getX(i); int y = (int) event.getY(i); drawCrosshairsAndText(x, y, touchPaints[id], i, id, c); } for (int i = 0; i < pointerCount; i++) { int id = event.getPointerId(i); int x = (int) event.getX(i); int y = (int) event.getY(i); drawCircle(x, y, touchPaints[id], c); } } // 画完后，unlock getHolder().unlockCanvasAndPost(c); } return true; } /** * 画十字及坐标信息 * * @param x * @param y * @param paint * @param ptr * @param id * @param c */ private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr, int id, Canvas c) { c.drawLine(0, y, width, y, paint); c.drawLine(x, 0, x, height, paint); int textY = (int) ((15 + 20 * ptr) * scale); c.drawText("x" + ptr + "=" + x, 10 * scale, textY, textPaint); c.drawText("y" + ptr + "=" + y, 70 * scale, textY, textPaint); c.drawText("id" + ptr + "=" + id, width - 55 * scale, textY, textPaint); } /** * 画圆 * * @param x * @param y * @param paint * @param c */ private void drawCircle(int x, int y, Paint paint, Canvas c) { c.drawCircle(x, y, 40 * scale, paint); } /* * 进入程序时背景画成黑色，然后把“START_TEXT”写到屏幕 */ public void surfaceChanged(SurfaceHolder holder, int format, intwidth, int height) { this.width = width; this.height = height; if (width > height) { this.scale = width / 480f; } else { this.scale = height / 480f; } textPaint.setTextSize(14 * scale); Canvas c = getHolder().lockCanvas(); if (c != null) { // 背景黑色 c.drawColor(Color.BLACK); float tWidth = textPaint.measureText(START_TEXT); c.drawText(START_TEXT, width / 2 - tWidth / 2, height / 2, textPaint); getHolder().unlockCanvasAndPost(c); } } public void surfaceCreated(SurfaceHolder holder) { } public void surfaceDestroyed(SurfaceHolder holder) { } } 接下来看看我们的Activity，MultitouchVisible.java
package com.ideasandroid.demo; import android.app.Activity; import android.os.Bundle; import android.view.Window; import android.view.WindowManager; public class MultitouchVisible extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //隐藏标题栏 requestWindowFeature(Window.FEATURE_NO_TITLE); //设置成全屏 getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); //设置为上面的MTView setContentView(new MTView(this)); } }