android拖动图片移动效果(2)

                int dy = (int) event.getRawY() - lastY; 
 
                int left = v.getLeft() + dx; 
                int top = v.getTop() + dy; 
                int right = v.getRight() + dx; 
                int bottom = v.getBottom() + dy; 
                // 设置不能出界 
                if (left < 0) { 
                    left = 0; 
                    right = left + v.getWidth(); 
                } 
 
                if (right > screenWidth) { 
                    right = screenWidth; 
                    left = right - v.getWidth(); 
                } 
 
                if (top < 0) { 
                    top = 0; 
                    bottom = top + v.getHeight(); 
                } 
 
                if (bottom > screenHeight) { 
                    bottom = screenHeight; 
                    top = bottom - v.getHeight(); 
                } 
 
                v.layout(left, top, right, bottom);