public void setPadding(int left, int top, int right, int bottom) {
        if ((left | top | right | bottom) == 0) {
            mState.mPadding = null;
        } else {
            if (mState.mPadding == null) {
                mState.mPadding = new Rect();
            }
            mState.mPadding.set(left, top, right, bottom);
        }
        invalidateSelf();
    }
Sets padding for the shape.

@param left   padding for the left side (in pixels)
@param top    padding for the top (in pixels)
@param right  padding for the right side (in pixels)
@param bottom padding for the bottom (in pixels)
caprice/ui/src/main/java/net/qiujuer/genius/ui/drawable/TouchEffectDrawable.java