如何在图像上绘制封装边框?

我已经重写了要在其上绘制边框的图像绘制方法 AppCompatImageView .

对于某些图像,它工作良好,但对于某些图像,它在图像的上方和下方有一些空白,如下图所示。我想在图像尺寸上精确地画出边框。

下面是代码

private static final int PADDING = 8;
    private static final float STROKE_WIDTH = 8.0f;

    private Paint mBorderPaint;

   private void initBorderPaint() {
        mBorderPaint = new Paint();
        mBorderPaint.setAntiAlias(true);
        mBorderPaint.setStyle(Paint.Style.STROKE);
        mBorderPaint.setColor(Color.WHITE);
        mBorderPaint.setStrokeWidth(STROKE_WIDTH);
    }

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.drawRect(PADDING, PADDING, getWidth() - PADDING, getHeight() - PADDING, mBorderPaint);
}