android中画布上的意外缩放行为

Question

我有一个视图，我在其中绘制矩形和 10 条线。我正在使用捏缩放来缩放视图，但我得到了意想不到的行为。线条正在缩放，但矩形不是。

谁能指出我的错误。

视图的onDraw()方法是：

    onDraw() method of the view is:

                Rect r =new Rect(0, 0, 700, 40);

        public void onDraw(Canvas canvas) {

            float kk=mScaleFactor;    //this variable will be set by pinch zoom event and represent how much to scale
            sf*=kk;                   // this view must scale according to previous scaling  


            canvas.save();
            makeLinesinRangetwo(10, canvas); // this will make l0 lines within the width of rectangle

            float cX = canvas.getWidth()/2.0f; //Width/2 gives the horizontal centre
            float cY = canvas.getHeight()/2.0f; //Height/2 gives the vertical centre
            canvas.scale(sf , 1,cX,cY);
            paint.setStyle(Paint.Style.FILL);
            paint.setColor(Color.BLUE); 
            canvas.drawRect(r, paint);
            canvas.restore();
            requestLayout();                               //this will change view width to fit the expanded rectangle 
            }

当我缩放 (0,0) 时也是如此。矩形和线条都在缩放。我没有得到这种行为。

    public void onDraw(Canvas canvas) {

            float kk=mScaleFactor;    //this variable will be set by pinch zoom event and represent how much to scale
            sf*=kk;                   // this view must scale according to previous scaling  


            canvas.save();
            makeLinesinRangetwo(10, canvas); // this will make l0 lines within the width of rectangle

            canvas.scale(sf , 1);
            paint.setStyle(Paint.Style.FILL);
            paint.setColor(Color.BLUE); 
            canvas.drawRect(r, paint);
            canvas.restore();
            requestLayout();                               //this will change view width to fit the expanded rectangle 
            }

Answer 1

我认为问题在于您在中心缩放画布，但您应该将 pivotX 和 pivotY 指定为矩形的中心。