private void setUpAlphaRect() { if (!mShowAlphaPanel) return; final RectF dRect = mDrawingRect; float left = dRect.left + BORDER_WIDTH_PX; float top = dRect.bottom - ALPHA_PANEL_HEIGHT + BORDER_WIDTH_PX; float bottom = dRect.bottom - BORDER_WIDTH_PX; float right = dRect.right - BORDER_WIDTH_PX; mAlphaRect = new RectF(left, top, right, bottom); mAlphaPattern = new AlphaPatternDrawable((int) (5 * mDensity)); mAlphaPattern.setBounds( Math.round(mAlphaRect.left), Math.round(mAlphaRect.top), Math.round(mAlphaRect.right), Math.round(mAlphaRect.bottom)); }