android多点触摸缩放图片
16lz
2021-12-04
/** * 自定义触摸事件 * @author tian * */private class TouchListener implements OnTouchListener{ private PointF startPoint = new PointF(); private Matrix matrix = new Matrix(); private Matrix currentMaritx = new Matrix(); private int mode = 0;//用于标记模式 private static final int DRAG = 1;//拖动 private static final int ZOOM = 2;//放大 private float startDis = 0; private PointF midPoint;//中心点@Overridepublic boolean onTouch(View v, MotionEvent event) {// TODO Auto-generated method stubswitch (event.getAction() & MotionEvent.ACTION_MASK){case MotionEvent.ACTION_DOWN:mode = DRAG;currentMaritx.set(imageView.getImageMatrix());//记录ImageView当期的移动位置startPoint.set(event.getX(),event.getY());//开始点break;case MotionEvent.ACTION_MOVE://移动事件if (mode == DRAG) {//图片拖动事件float dx = event.getX() - startPoint.x;//x轴移动距离float dy = event.getY() - startPoint.y;matrix.set(currentMaritx);//在当前的位置基础上移动matrix.postTranslate(dx, dy);} else if(mode == ZOOM){//图片放大事件float endDis = distance(event);//结束距离if(endDis > 10f){float scale = endDis / startDis;//放大倍数matrix.set(currentMaritx);matrix.postScale(scale, scale, midPoint.x, midPoint.y);}}break; case MotionEvent.ACTION_UP: mode = 0; break; //有手指离开屏幕,但屏幕还有触点(手指) case MotionEvent.ACTION_POINTER_UP: mode = 0; break; //当屏幕上已经有触点(手指),再有一个手指压下屏幕 case MotionEvent.ACTION_POINTER_DOWN: mode = ZOOM; startDis = distance(event); if(startDis > 10f){//避免手指上有两个茧 midPoint = mid(event); currentMaritx.set(imageView.getImageMatrix());//记录当前的缩放倍数 } break; }imageView.setImageMatrix(matrix);return true; }} /** * 两点之间的距离 * @param event * @return */ private static float distance(MotionEvent event){ //两根线的距离 float dx = event.getX(1) - event.getX(0); float dy = event.getY(1) - event.getY(0); return FloatMath.sqrt(dx*dx + dy*dy); } /** * 计算两点之间中心点的距离 * @param event * @return */ private static PointF mid(MotionEvent event){ float midx = event.getX(1) + event.getX(0); float midy = event.getY(1) - event.getY(0); return new PointF(midx/2, midy/2); }
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