Expose GLRenderTarget::virtualScreenGeometry

Summary:
A simple way to get the current per-output geometry. It's also needed by
effects using render targets.

Reviewers: #kwin, #plasma_on_wayland

Subscribers: plasma-devel, kwin

Tags: #plasma_on_wayland, #kwin

Differential Revision: https://phabricator.kde.org/D3100

libkwineffects/kwinglutils.h

@@ -515,12 +515,23 @@ public:
      * Sets the virtual screen geometry to @p g.
      * This is the geometry of the OpenGL window currently being rendered to
      * in the virtual geometry space the rendering geometries use.
+     * @see virtualScreenGeometry
      * @since 5.9
      **/
     static void setVirtualScreenGeometry(const QRect &g) {
         s_virtualScreenGeometry = g;
     }
 
+    /**
+     * The geometry of the OpenGL window currently being rendered to
+     * in the virtual geometry space the rendering system uses.
+     * @see setVirtualScreenGeometry
+     * @since 5.9
+     **/
+    static QRect virtualScreenGeometry() {
+        return s_virtualScreenGeometry;
+    }
+
 
 protected:
     void initFBO();