android 两点缩放/移动图片DEMO

package mutl.touch.sample; import android.app.Activity; import android.graphics.Matrix; import android.graphics.PointF; import android.os.Bundle; import android.util.FloatMath; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.widget.ImageView; public class Main extends Activity { private static final int NONE = 0; private static final int DRAG = 1; private static final int ZOOM = 2; private int mode = NONE; private float oldDist; private Matrix matrix = new Matrix(); private Matrix savedMatrix = new Matrix(); private PointF start = new PointF(); private PointF mid = new PointF(); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ImageView view = (ImageView) findViewById(R.id.image_view); view.setOnTouchListener(new OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { ImageView view = (ImageView) v; switch (event.getAction() & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: savedMatrix.set(matrix); start.set(event.getX(), event.getY()); mode = DRAG; break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_POINTER_UP: mode = NONE; break; case MotionEvent.ACTION_POINTER_DOWN: oldDist = spacing(event); if (oldDist > 10f) { savedMatrix.set(matrix); midPoint(mid, event); mode = ZOOM; } break; case MotionEvent.ACTION_MOVE: if (mode == DRAG) { matrix.set(savedMatrix); matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); } else if (mode == ZOOM) { float newDist = spacing(event); if (newDist > 10f) { matrix.set(savedMatrix); float scale = newDist / oldDist; matrix.postScale(scale, scale, mid.x, mid.y); } } break; } view.setImageMatrix(matrix); return true; } private float spacing(MotionEvent event) { float x = event.getX(0) - event.getX(1); float y = event.getY(0) - event.getY(1); return FloatMath.sqrt(x * x + y * y); } private void midPoint(PointF point, MotionEvent event) { float x = event.getX(0) + event.getX(1); float y = event.getY(0) + event.getY(1); point.set(x / 2, y / 2); }}); } }