Add shadow rendering helper functions
Summary:
This patch makes other helper functions reuse more code by calling these shadow rendering functions instead of defining their own shadows.
The shadows are perfectly shaped, tested up to 8x scaling.
Without this patch, the radius of the shadows for checkboxes is slighly too wide and there is a gap between the inside edge of the radio button shadow and the outside edge of the radio button.
Shadow rendering performance has also been improved a bit.
Test Plan:
run QT_SCALE_FACTOR=8 oxygen-demo5 and examine the shadows. You can try higher scaling levels, but that's overkill.
8x scaling
before:
after:
Reviewers: Breeze, hpereiradacosta, Plasma
Reviewed By: hpereiradacosta
Subscribers: ngraham, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D26094