From 9ce5832e11bcecd125c2ef2cc200a586bdacb12e Mon Sep 17 00:00:00 2001
From: David Edmundson <kde@davidedmundson.co.uk>
Date: Mon, 6 Mar 2017 00:38:37 +0000
Subject: [PATCH] Store GLRenderTarget::scale

Summary:
GLRenderTarget already stores the translation from global compositor
space to the render target co-ordinates, we also need a scale factor for
the exact same reasons.

Test Plan: Used in various effects after this patch and it works there.

Reviewers: #plasma

Subscribers: plasma-devel, kwin, #kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D4948
---
 libkwineffects/kwinglutils.cpp |  1 +
 libkwineffects/kwinglutils.h   | 16 ++++++++++++++++
 scene_opengl.cpp               |  2 ++
 3 files changed, 19 insertions(+)

diff --git a/libkwineffects/kwinglutils.cpp b/libkwineffects/kwinglutils.cpp
index 06a49de3e2..36f219cbfb 100644
--- a/libkwineffects/kwinglutils.cpp
+++ b/libkwineffects/kwinglutils.cpp
@@ -1037,6 +1037,7 @@ bool GLRenderTarget::s_blitSupported = false;
 QStack<GLRenderTarget*> GLRenderTarget::s_renderTargets = QStack<GLRenderTarget*>();
 QSize GLRenderTarget::s_virtualScreenSize;
 QRect GLRenderTarget::s_virtualScreenGeometry;
+qreal GLRenderTarget::s_virtualScreenScale = 1.0;
 
 void GLRenderTarget::initStatic()
 {
diff --git a/libkwineffects/kwinglutils.h b/libkwineffects/kwinglutils.h
index 95bf5c57ee..9d1935544e 100644
--- a/libkwineffects/kwinglutils.h
+++ b/libkwineffects/kwinglutils.h
@@ -505,6 +505,21 @@ public:
         return s_virtualScreenGeometry;
     }
 
+    /**
+     * The scale of the OpenGL window currently being rendered to
+     *
+     * @returns the ratio between the virtual geometry space the rendering
+     * system uses and the target
+     * @since 5.10
+     */
+    static void setVirtualScreenScale(qreal scale) {
+        s_virtualScreenScale = scale;
+    }
+
+    static qreal virtualScreenScale() {
+        return s_virtualScreenScale;
+    }
+
 
 protected:
     void initFBO();
@@ -518,6 +533,7 @@ private:
     static QStack<GLRenderTarget*> s_renderTargets;
     static QSize s_virtualScreenSize;
     static QRect s_virtualScreenGeometry;
+    static qreal s_virtualScreenScale;
 
     GLTexture mTexture;
     bool mValid;
diff --git a/scene_opengl.cpp b/scene_opengl.cpp
index 8ebebae451..22debbd9f9 100644
--- a/scene_opengl.cpp
+++ b/scene_opengl.cpp
@@ -700,6 +700,7 @@ qint64 SceneOpenGL::paint(QRegion damage, ToplevelList toplevels)
             QRegion repaint = m_backend->prepareRenderingForScreen(i);
             GLVertexBuffer::setVirtualScreenGeometry(geo);
             GLRenderTarget::setVirtualScreenGeometry(geo);
+            GLRenderTarget::setVirtualScreenScale(screens()->scale(i));
 
             const GLenum status = glGetGraphicsResetStatus();
             if (status != GL_NO_ERROR) {
@@ -728,6 +729,7 @@ qint64 SceneOpenGL::paint(QRegion damage, ToplevelList toplevels)
         }
         GLVertexBuffer::setVirtualScreenGeometry(screens()->geometry());
         GLRenderTarget::setVirtualScreenGeometry(screens()->geometry());
+        GLRenderTarget::setVirtualScreenScale(1);
 
         int mask = 0;
         updateProjectionMatrix();