wayland: implement scaling

This involves many subsystems:

- config:
    - allow setting the connector scale
    - allow setting the cursor size
- cursors:
    - load server cursors for all requested sizes and scales
- wl_surface:
    - track the output the surface belongs to
    - send wl_surface.enter/leave
- wl_output:
    - implement wl_output.scale
- text:
    - pre-render texts for all used scales
- renderer:
    - properly align scale textures and rectangles
- wp_fractional_scale:
    - new interface for fractional scaling

jay-config/src/video.rs

@@ -79,6 +79,23 @@ impl Connector {
         get!(false).connector_connected(self)
     }
 
+    /// Returns the scale of the currently connected monitor.
+    pub fn scale(self) -> f64 {
+        if !self.exists() {
+            return 1.0;
+        }
+        get!(1.0).connector_get_scale(self)
+    }
+
+    /// Sets the scale to use for the currently connected monitor.
+    pub fn set_scale(self, scale: f64) {
+        if !self.exists() {
+            return;
+        }
+        log::info!("setting scale to {}", scale);
+        get!().connector_set_scale(self, scale);
+    }
+
     /// Returns the connector type.
     pub fn ty(self) -> ConnectorType {
         if !self.exists() {
@@ -95,18 +112,18 @@ impl Connector {
         get!(Mode::zeroed()).connector_mode(self)
     }
 
-    /// Returns the width of the current mode of the connector.
+    /// Returns the logical width of the connector.
     ///
-    /// This is a shortcut for `mode().width()`.
+    /// The returned value will be different from `mode().width()` if the scale is not 1.
     pub fn width(self) -> i32 {
-        self.mode().width
+        get!().connector_size(self).0
     }
 
-    /// Returns the height of the current mode of the connector.
+    /// Returns the logical height of the connector.
     ///
-    /// This is a shortcut for `mode().height()`.
+    /// The returned value will be different from `mode().height()` if the scale is not 1.
     pub fn height(self) -> i32 {
-        self.mode().height
+        get!().connector_size(self).1
     }
 
     /// Returns the refresh rate in mhz of the current mode of the connector.