Android编程开发之多点触摸(Multitouch)实现方法

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, 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) {  }}

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));  }}