Implement zoom on pointer instead of the viewport center with Ctrl + Wheel
First commit:
Rearrange PageView::wheelEvent to separate Ctrl+Wheel handling from scrolling
This commit changes the "if / else" into "if return" so most of the scrolling implementation is not indented and the Ctrl+Wheel case is handled as a special case at the beginning of the function.
This commit doesn't have functionnality changes.
Second commit: When doing Ctrl+Wheel, zoom on pointer instead of the center of the screen
The zoom is implemented using zoomWithFixedCenter so it zooms into the current mouse pointer location instead of zooming on the viewport center.
Edited by Alexis Murzeau