java - Canvas 中的背景(图像)，同时在顶部绘制路径

Question

@Override protected void onDraw(Canvas canvas) {

        if (mBitmap != null) {

            canvas.drawColor(0xFFAAAAAA);

            canvas.drawBitmap(background,0,0,mBitmapPaint);

            if(isRelevant){
                canvas.drawBitmap(mBitmapLast, 0,0, mBitmapLastPaint);
            }

            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
                canvas.drawPath(mPath, mPaint);
        }
    }

我尝试过换行

canvas.drawColor(0xFFAAAAAA);
                canvas.drawBitmap(background,0,0,mBitmapPaint);

当 canvas.drawColor(0xFFAAAAAA); 是第二个时，当我在屏幕上绘制路径时，它们会显示出来。有没有办法使背景(位图)显示在 Canvas 路径下方？

Answer 1

尝试设置Xfermode在你的路径的油漆中:

mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OVER));  // or DST_OVER

并查看PorterDuff.Mode解释了。