Android开发之多点触摸（Multitouch）

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，android应用程序开发中，多点触摸不是那么遥不可及，实现起来也很简单，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 */@Overridepublic 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，unlockgetHolder().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, int width,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) {}}

代码中都做了相应的注释，这里就不多说。

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));    }}

Android : 多点触摸（1，2，3）
http://blog.csdn.net/tsiannian/article/details/6636463
http://blog.csdn.net/tsiannian/article/details/6636480
http://blog.csdn.net/tsiannian/article/details/6638929

Muilti-touch 双指缩放的实现探索
http://blog.csdn.net/barryhappy/article/details/7392326

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