android 基于surfaceview 的多点触控实现

       hello，各位朋友。最近接到一个功能需要实现多点触控，也就是我们通常所看到的把手指放在屏幕上，可以放大和缩小图片的 操作。在google上查找了一些资料，发现很多都是使用imageView在实现的。但是在游戏的开发过程中，使用surfaceview效率会更高一些，所以就尝试使用surfaceview来实现。

看代码：

public class DisplayActivity extends Activity {
	private SurfaceView videoView;
	private SurfaceHolder sfh;
	private Canvas canvas;
	private Paint paint;
	private boolean flag = true;
	private int screenW, screenH;
	private Bitmap bmpIcon;
	//记录两个触屏点的坐标
	private int x1, x2, y1, y2;
	//倍率
	private float rate = 1;
	//记录上次的�?�?
	private float oldRate = 1;
	//记录第一次触屏时线段的长�?
	private float oldLineDistance;
	//判定是否头次多指触点屏幕
	private boolean isFirst = true;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.media_play);
		videoView = (SurfaceView)findViewById(R.id.videoView);
		sfh = videoView.getHolder();
		sfh.addCallback(new DisplaySurfaceView());
		DisplayMetrics dm = new DisplayMetrics(); 
		getWindowManager().getDefaultDisplay().getMetrics(dm); 
		screenW = dm.widthPixels; 
		screenH = (dm.heightPixels)/2;

	}

	class DisplaySurfaceView implements SurfaceHolder.Callback{
		@Override
		public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
			
		}

		@Override
		public void surfaceCreated(SurfaceHolder arg0) {
			new ImageThread().start();
		}

		@Override
		public void surfaceDestroyed(SurfaceHolder arg0) {
			flag = false;
		}
		
	}
	
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		if (event.getAction() == MotionEvent.ACTION_UP) {
			isFirst = true;
			oldRate = rate;
		} else {
			if (event.getPointerCount() > 1) { 
				x1 = (int) event.getX(0);
				y1 = (int) event.getY(0);
				x2 = (int) event.getX(1);
				y2 = (int) event.getY(1);
				if (event.getPointerCount() == 2) {
					if (isFirst) {
						//得到第一次触屏时线段的长�?
						oldLineDistance = (float) Math.sqrt(Math.pow(event.getX(1) - event.getX(0), 2) + Math.pow(event.getY(1) - event.getY(0), 2));
						isFirst = false;
					} else {
						//得到非第�?��触屏时线段的长度
						float newLineDistance = (float) Math.sqrt(Math.pow(event.getX(1) - event.getX(0), 2) + Math.pow(event.getY(1) - event.getY(0), 2));
						//获取本次的缩放比�?
						rate = oldRate * newLineDistance / oldLineDistance;
					}
				}
			}
		}
		return true;
	}
	
	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		return super.onKeyDown(keyCode, event);
	}
	
	class ImageThread extends Thread{
		@Override
		public void run() {
			while (flag) {
				long start = System.currentTimeMillis();
				myDraw();
				long end = System.currentTimeMillis();
				try {
					if (end - start < 50) {
						Thread.sleep(50 - (end - start));
					}
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
	}

	public void myDraw() {
		try {
			canvas = sfh.lockCanvas();
			if (canvas != null) {
				canvas.drawColor(Color.BLACK);
				canvas.save();
				//缩放画布(以图片中心点进行缩放，XY轴缩放比例相�?
				bmpIcon = BitmapFactory.decodeResource(this.getResources(), R.drawable.aa);
				canvas.scale(rate, rate, screenW / 2, screenH / 2);
				int width = screenW / 2 - bmpIcon.getWidth() / 2;
				int height = screenH / 2 - bmpIcon.getHeight() / 2;
				//绘制位图icon
				canvas.drawBitmap(bmpIcon, width, height, paint);
				canvas.restore();
				//便于观察，这里绘制两个触点时形成的线�?
//				canvas.drawLine(x1, y1, x2, y2, paint);
				sfh.unlockCanvasAndPost(canvas);
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
		}
	}
	
	@Override
	public void onConfigurationChanged(Configuration newConfig) {
		super.onConfigurationChanged(newConfig);
	}
}

 

media_play.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/displayName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="left"
        android:text="321321321"
        android:textColor="#AA1122" />

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="400dp" >

        <SurfaceView
            android:id="@+id/videoView"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:scaleType="matrix" />
    </LinearLayout>

    <Button
        android:id="@+id/aaaBtn"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="123321" />

</LinearLayout>

 这样就实现了多点触控，放大和缩小图片的效果了，aa这个图片是自己随便找的一个，可以根据实际情况修改。

评论

1 楼 ZSRTFAT 2013-09-08  

学习了，谢谢分享