Android多点触摸测试类

package org.wch.gesture;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.SurfaceHolder.Callback;   import android.view.SurfaceView;   public class MySurfaceView extends SurfaceView implements 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 MySurfaceView(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();     }   public 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]);   }   }   @Override  public boolean onTouchEvent(MotionEvent event) {   int pointerCount=event.getPointerCount();   if(pointerCount>MAX_TOUCHPOINTS){   pointerCount=MAX_TOUCHPOINTS;   }   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   c.drawColor(Color.BLACK);   }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);   }   }   getHolder().unlockCanvasAndPost(c);   }   return true;   }   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);      }     private void drawCircle(int x, int y, Paint paint, Canvas c) {   c.drawCircle(x, y, 40 * scale, paint);         }     @Override  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);             }     }   @Override  public void surfaceCreated(SurfaceHolder holder) {   // TODO Auto-generated method stub   }   @Override  public void surfaceDestroyed(SurfaceHolder holder) {   // TODO Auto-generated method stub   }    }
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