Android手势缩放图片以及图片黏贴在手指随手势移动

﹏ヽ暗。殇╰゛Y 2022-08-07 02:36 224阅读 0赞

一个Android手势缩放图片的工具类；同时，此类还实现另外一个功能：当手指按在触屏上移动时候，图片“黏贴”在手指上随手指移动而整体移动。

具体使用方法可以是这样：先new一个此类的实例，然后在ImageView的方法setOnTouchListener(new ImageViewOnMultiTouchListener());

例如：

ImageViewOnMultiTouchListener listener=new ImageViewOnMultiTouchListener();
    		ImageView mImageView=(ImageView)findViewById(R.id.imageView);
    		mImageView.setOnTouchListener(listener);

ImageViewOnMultiTouchListener.java全部源代码：

public class ImageViewOnMultiTouchListener implements View.OnTouchListener {
    
    		private final int NONE = 0;
    		private final int MOVE = 1;
    		private final int ZOOM = 2;
    		private final int DRAG = 3;
    
    		private int mode = NONE;
    		private Matrix matrix = new Matrix();
    		private Matrix savedMatrix = new Matrix();
    		private PointF start = new PointF();
    		private PointF mid = new PointF();
    		private float oldDistance = 0;
    
    		@Override
    		public boolean onTouch(View v, MotionEvent event) {
    
    			ImageView view = (ImageView) v;
    
    			switch (event.getAction() & MotionEvent.ACTION_MASK) {
    			case MotionEvent.ACTION_DOWN:
    				matrix.set(view.getImageMatrix());
    				savedMatrix.set(matrix);
    				start.set(event.getX(), event.getY());
    
    				mode = DRAG;
    
    				break;
    
    			case MotionEvent.ACTION_POINTER_DOWN:
    				oldDistance = spacing(event);
    				if (oldDistance > 5f) {
    					savedMatrix.set(matrix);
    					midPoint(mid, event);
    
    					mode = ZOOM;
    				}
    
    				break;
    
    			case MotionEvent.ACTION_UP:
    			case MotionEvent.ACTION_POINTER_UP:
    				mode = NONE;
    
    				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 > 5f) {
    						matrix.set(savedMatrix);
    						float scale = newDist / oldDistance;
    						matrix.postScale(scale, scale, mid.x, mid.y);
    					}
    				}
    
    				break;
    			}
    
    			view.setImageMatrix(matrix);
    			view.setScaleType(ImageView.ScaleType.MATRIX);
    			view.setPadding(3, 5, 3, 5);
    
    			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);
    		}
    	}