Expand description
This protocol allows a compositor to suggest for surfaces to render at fractional scales.
A client can submit scaled content by utilizing wp_viewport. This is done by creating a wp_viewport object for the surface and setting the destination rectangle to the surface size before the scale factor is applied.
The buffer size is calculated by multiplying the surface size by the intended scale.
The wl_surface buffer scale should remain set to 1.
If a surface has a surface-local size of 100 px by 50 px and wishes to submit buffers with a scale of 1.5, then a buffer of 150px by 75 px should be used and the wp_viewport destination rectangle should be 100 px by 50 px.
For toplevel surfaces, the size is rounded halfway away from zero. The rounding algorithm for subsurface position and size is not defined.