GdkMonitor: Add support orientation/angle information
Actually some platforms get/support monitor's orientation information.
- Wayland: transform of display geometry (
WL_OUTPUT_TRANSFORM_*
). - Windows:
dmDisplayOrientation
inDEVMODE
(DMDO_*
). - Android:
android.view.Display.getRotation()
.
This also requires to support Screen Orientation API (https://w3c.github.io/screen-orientation/), So I would like to request to add angle information in GdkMonitor
.