Drawing a rectangle behind a custom non-animated ImageView

Question

I need a custom Image View that first draws some shapes behind the image before it draws the image itself, using the same “Scaling” that applies to the actual bitmap itself. Everything works fine, except that I have AlphaAnimation to fade out a custom ImageView. It reduces part of BitmapDrawable, but not my form. The shape is always drawn in full opacity. I tried setting the alpha of the paint that I use for the getAlpha view, but no luck. Here is my onDraw function inside my own ImageView class:

@Override
protected void onDraw(Canvas canvas) {
    float[] f = new float[9];
    getImageMatrix().getValues(f);

    final float scaleX = f[Matrix.MSCALE_X];
    final float scaleY = f[Matrix.MSCALE_Y];

    final Drawable d = getDrawable();
    final int origW = d.getIntrinsicWidth();
    final int origH = d.getIntrinsicHeight();

    final int actW = Math.round(origW * scaleX);
    final int actH = Math.round(origH * scaleY);

    canvas.drawRect(Math.max((getWidth() - actW) / 2, 0) + 1, Math.max((getHeight() - actH) / 2, 0) + 1, Math.max((getWidth() - actW) / 2, 0) + actW - 1, Math.max((getHeight() - actH) / 2, 0) + actH - 1, paint);
    super.onDraw(canvas);
}

Answer 1

, - , .

Answer 2

, : 5.0.0_r1, onDraw imageView

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    if (mDrawable == null) {
        return; // couldn't resolve the URI
    }

    if (mDrawableWidth == 0 || mDrawableHeight == 0) {
        return;     // nothing to draw (empty bounds)
    }

    if (mDrawMatrix == null && mPaddingTop == 0 && mPaddingLeft == 0) {
        mDrawable.draw(canvas);
    } else {
        int saveCount = canvas.getSaveCount();
        canvas.save();

        if (mCropToPadding) {
            final int scrollX = mScrollX;
            final int scrollY = mScrollY;
            canvas.clipRect(scrollX + mPaddingLeft, scrollY + mPaddingTop,
                    scrollX + mRight - mLeft - mPaddingRight,
                    scrollY + mBottom - mTop - mPaddingBottom);
        }

        canvas.translate(mPaddingLeft, mPaddingTop);

        if (mDrawMatrix != null) {
            canvas.concat(mDrawMatrix);
        }
        mDrawable.draw(canvas);
        canvas.restoreToCount(saveCount);
    }
}

, Paint, , . Paint Drawable.getAlpha()

Drawable.getAlpha() API 19, Drawable :

class MyDrawable extends Drawable {

    final Drawable originalDrawable;
    private int mAlpha = 1;

    @Override
    public int getAlpha() {
        return mAlpha;
    }

    public MyDrawable(Drawable drawable){
        originalDrawable = drawable;
    }

    @Override
    public void draw(Canvas canvas) {
        originalDrawable.draw(canvas);
    }

    @Override
    public void setAlpha(int alpha) {
        mAlpha = alpha;
        originalDrawable.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        originalDrawable.setColorFilter(cf);
    }

    @Override
    public int getOpacity() {
        return originalDrawable.getOpacity();
    }
}