動畫畫布錯誤：無法從void轉換為可繪制的位圖

Question

我為項目的畫布制作了動畫，但是出現錯誤：“無法從void轉換為可繪制的位圖”。 哪里錯了？

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

對於上下文，這是代碼的完整摘錄

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參數必須為浮點數，請嘗試將其更改為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);