[kwineffects] Pass screen projection matrix to EffectFrame

Exposes the current screen projection matrix in the render pass of
the EffectFrame, so that effects can make use of it.

effects.cpp

@@ -1930,6 +1930,7 @@ void EffectFrameImpl::render(QRegion region, double opacity, double frameOpacity
         return; // Nothing to display
     }
     m_shader = NULL;
+    setScreenProjectionMatrix(static_cast<EffectsHandlerImpl*>(effects)->scene()->screenProjectionMatrix());
     effects->paintEffectFrame(this, region, opacity, frameOpacity);
 }
 

effects.h

@@ -226,6 +226,10 @@ public:
 
     KWayland::Server::Display *waylandDisplay() const override;
 
+    Scene *scene() const {
+        return m_scene;
+    }
+
 public Q_SLOTS:
     void slotCurrentTabAboutToChange(EffectWindow* from, EffectWindow* to);
     void slotTabAdded(EffectWindow* from, EffectWindow* to);

libkwineffects/kwineffects.cpp

@@ -1788,6 +1788,7 @@ public:
 
     bool crossFading;
     qreal crossFadeProgress;
+    QMatrix4x4 screenProjectionMatrix;
 };
 
 EffectFramePrivate::EffectFramePrivate()
@@ -1833,6 +1834,16 @@ void EffectFrame::enableCrossFade(bool enable)
     d->crossFading = enable;
 }
 
+QMatrix4x4 EffectFrame::screenProjectionMatrix() const
+{
+    return d->screenProjectionMatrix;
+}
+
+void EffectFrame::setScreenProjectionMatrix(const QMatrix4x4 &spm)
+{
+    d->screenProjectionMatrix = spm;
+}
+
 } // namespace
 
 #include "kwineffects.moc"

libkwineffects/kwineffects.h

@@ -2937,6 +2937,22 @@ public:
      **/
     qreal crossFadeProgress() const;
 
+    /**
+     * Returns The projection matrix as used by the current screen painting pass
+     * including screen transformations.
+     *
+     * This matrix is only valid during a rendering pass started by render.
+     *
+     * @since 5.6
+     * @see render
+     * @see EffectsHandler::paintEffectFrame
+     * @see Effect::paintEffectFrame
+     **/
+    QMatrix4x4 screenProjectionMatrix() const;
+
+protected:
+    void setScreenProjectionMatrix(const QMatrix4x4 &projection);
+
 private:
     EffectFramePrivate* const d;
 };