Scaling support in ColorPicker effect
Summary:
glReadPixels needs the correct location relative to the
framebuffer so we need to factor in the scale as well as translation
when going from compositor space.
Test Plan:
Ran the plasma colour picker plasmoid in windowed mode
Clicked on multiple parts of a window
It was right every time
Reviewers: Plasma
Subscribers: plasma-devel, kwin, KWin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D4950