From 62f904b6988942b3e4e03ca99e5d2cbc27a1bae0 Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Tue, 21 Nov 2023 17:17:17 +0200
Subject: [PATCH] Drop EffectsHandler::renderScreen()

It's no longer relevant after merging libkwin and libkwineffects. By
dropping EffectsHandler::renderScreen() and making the screen transform
use the Scene API directly, we can clean up some OpenGL context handling
code.
---
 src/effect/effecthandler.cpp                  | 17 ---------
 src/effect/effecthandler.h                    |  5 ---
 .../screentransform/screentransform.cpp       | 38 ++++++++++++-------
 3 files changed, 24 insertions(+), 36 deletions(-)

diff --git a/src/effect/effecthandler.cpp b/src/effect/effecthandler.cpp
index 53e8ee5bf5..a81ca0f284 100644
--- a/src/effect/effecthandler.cpp
+++ b/src/effect/effecthandler.cpp
@@ -1569,23 +1569,6 @@ Output *EffectsHandler::findScreen(int screenId) const
     return Workspace::self()->outputs().value(screenId);
 }
 
-void EffectsHandler::renderScreen(Output *output)
-{
-    Q_ASSERT(effects->isOpenGLCompositing());
-
-    RenderLayer layer(output->renderLoop());
-    SceneDelegate delegate(m_scene, output);
-    delegate.setLayer(&layer);
-
-    m_scene->prePaint(&delegate);
-
-    effects->makeOpenGLContextCurrent(); // TODO: doesn't belong here, but there's no better place atm either
-    RenderTarget renderTarget(GLFramebuffer::currentFramebuffer());
-    m_scene->paint(renderTarget, output->geometry());
-
-    m_scene->postPaint();
-}
-
 bool EffectsHandler::isCursorHidden() const
 {
     return Cursors::self()->isCursorHidden();
diff --git a/src/effect/effecthandler.h b/src/effect/effecthandler.h
index be95540897..76ac1b697e 100644
--- a/src/effect/effecthandler.h
+++ b/src/effect/effecthandler.h
@@ -718,11 +718,6 @@ public:
     Output *findScreen(const QString &name) const;
     Output *findScreen(int screenId) const;
 
-    /**
-     * Renders @p screen in the current render target
-     */
-    void renderScreen(Output *screen);
-
     KWin::EffectWindow *inputPanel() const;
     bool isInputPanelOverlay() const;
 
diff --git a/src/plugins/screentransform/screentransform.cpp b/src/plugins/screentransform/screentransform.cpp
index 51516e4619..067edf4c00 100644
--- a/src/plugins/screentransform/screentransform.cpp
+++ b/src/plugins/screentransform/screentransform.cpp
@@ -8,10 +8,12 @@
 */
 // own
 #include "screentransform.h"
+#include "core/renderlayer.h"
 #include "core/rendertarget.h"
 #include "core/renderviewport.h"
 #include "effect/effecthandler.h"
 #include "opengl/glutils.h"
+#include "scene/workspacescene.h"
 
 #include <QDebug>
 
@@ -81,24 +83,32 @@ void ScreenTransformEffect::addScreen(Output *screen)
         effects->addRepaintFull();
     });
     connect(screen, &Output::aboutToChange, this, [this, screen] {
+        Scene *scene = effects->scene();
+
+        RenderLayer layer(screen->renderLoop());
+        SceneDelegate delegate(scene, screen);
+        delegate.setLayer(&layer);
+
+        scene->prePaint(&delegate);
+
         effects->makeOpenGLContextCurrent();
-        auto &state = m_states[screen];
-        state.m_oldTransform = screen->transform();
-        state.m_oldGeometry = screen->geometry();
-        state.m_prev.texture = GLTexture::allocate(GL_RGBA8, screen->geometry().size() * screen->scale());
-        if (!state.m_prev.texture) {
+        if (auto texture = GLTexture::allocate(GL_RGBA8, screen->geometry().size() * screen->scale())) {
+            auto &state = m_states[screen];
+            state.m_oldTransform = screen->transform();
+            state.m_oldGeometry = screen->geometry();
+            state.m_prev.texture = std::move(texture);
+            state.m_prev.framebuffer = std::make_unique<GLFramebuffer>(state.m_prev.texture.get());
+
+            RenderTarget renderTarget(state.m_prev.framebuffer.get());
+            scene->paint(renderTarget, screen->geometry());
+
+            // Now, the effect can cross-fade between current and previous state.
+            state.m_captured = true;
+        } else {
             m_states.remove(screen);
-            return;
         }
-        state.m_prev.framebuffer = std::make_unique<GLFramebuffer>(state.m_prev.texture.get());
 
-        // Rendering the current scene into a texture
-        GLFramebuffer::pushFramebuffer(state.m_prev.framebuffer.get());
-        effects->renderScreen(screen);
-        GLFramebuffer::popFramebuffer();
-
-        // Now, the effect can cross-fade between current and previous state.
-        state.m_captured = true;
+        scene->postPaint();
     });
 }