动画画布错误：无法从void转换为可绘制的位图

Question

我为项目的画布制作了动画，但是出现错误：“无法从void转换为可绘制的位图”。 哪里错了？

BitmapDrawable circle = (BitmapDrawable) canvas.drawCircle(canvas.getWidth()/2, (float) (canvas.getHeight()/1.8), 13, black);

对于上下文，这是代码的完整摘录

protected void onDraw(Canvas canvas) {  

        Paint black = new Paint(Color.BLACK);

        BitmapDrawable circle = (BitmapDrawable) canvas.drawCircle(canvas.getWidth()/2, (float) (canvas.getHeight()/1.8), 13, black);
        if (x<0 && y <0) {
            x = this.getWidth()/2;
            y = this.getHeight()/2;
        } else {
            x += xVelocity;
            y += yVelocity;
            if ((x > this.getWidth() - circle.getBitmap().getWidth()) || (x < 0)) {
                xVelocity = xVelocity*-1;
            }
            if ((y > this.getHeight() - circle.getBitmap().getHeight()) || (y < 0)) {
                yVelocity = yVelocity*-1;
            }
        }
        canvas.drawBitmap(circle.getBitmap(), x, y, null);  

        h.postDelayed(r, FRAME_RATE);


    } 

Answer 1

您的Radius参数必须为浮点数，请尝试将其更改为13f

drawCircle(float cx, float cy, float radius, Paint paint)

BitmapDrawable circle = (BitmapDrawable) canvas.drawCircle(canvas.getWidth()/2, (float) (canvas.getHeight()/1.8), 13f, black);