From 97c100b9c1b436d16d7bba45b0c3814c80879949 Mon Sep 17 00:00:00 2001
From: ed <eddavies95@gmail.com>
Date: Mon, 15 Oct 2018 15:54:29 +0100
Subject: [PATCH] Windows:  Added a workaround for non-DPI aware windows having
 an incorrect scale factor when using the OpenGL renderer

---
 .../juce_gui_basics/native/juce_win32_Windowing.cpp |  5 +++++
 modules/juce_opengl/native/juce_OpenGL_win32.h      |  9 +++++++++
 modules/juce_opengl/opengl/juce_OpenGLContext.cpp   | 13 ++++++-------
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/modules/juce_gui_basics/native/juce_win32_Windowing.cpp b/modules/juce_gui_basics/native/juce_win32_Windowing.cpp
index 91fe905e32..cf7a1ed834 100644
--- a/modules/juce_gui_basics/native/juce_win32_Windowing.cpp
+++ b/modules/juce_gui_basics/native/juce_win32_Windowing.cpp
@@ -4020,6 +4020,11 @@ JUCE_API ComponentPeer* createNonRepaintingEmbeddedWindowsPeer (Component& compo
                                   (HWND) parentHWND, true);
 }
 
+JUCE_API bool shouldScaleGLWindow (void* hwnd)
+{
+    return isPerMonitorDPIAwareWindow ((HWND) hwnd);
+}
+
 JUCE_IMPLEMENT_SINGLETON (HWNDComponentPeer::WindowClassHolder)
 
 //==============================================================================
diff --git a/modules/juce_opengl/native/juce_OpenGL_win32.h b/modules/juce_opengl/native/juce_OpenGL_win32.h
index 3f3f5c31be..15ed2154ba 100644
--- a/modules/juce_opengl/native/juce_OpenGL_win32.h
+++ b/modules/juce_opengl/native/juce_OpenGL_win32.h
@@ -28,6 +28,7 @@ namespace juce
 {
 
 extern ComponentPeer* createNonRepaintingEmbeddedWindowsPeer (Component&, void* parent);
+extern bool shouldScaleGLWindow (void* hwnd);
 
 //==============================================================================
 class OpenGLContext::NativeContext
@@ -160,6 +161,14 @@ public:
     }
    #endif
 
+    double getWindowScaleFactor (const Rectangle<int>& screenBounds)
+    {
+        if (nativeWindow != nullptr && shouldScaleGLWindow (nativeWindow->getNativeHandle()))
+            return Desktop::getInstance().getDisplays().findDisplayForRect (screenBounds).scale;
+
+        return 1.0;
+    }
+
 private:
     struct DummyComponent  : public Component
     {
diff --git a/modules/juce_opengl/opengl/juce_OpenGLContext.cpp b/modules/juce_opengl/opengl/juce_OpenGLContext.cpp
index aef2086e1e..a45d714d35 100644
--- a/modules/juce_opengl/opengl/juce_OpenGLContext.cpp
+++ b/modules/juce_opengl/opengl/juce_OpenGLContext.cpp
@@ -280,15 +280,14 @@ public:
     {
         if (auto* peer = component.getPeer())
         {
-            lastScreenBounds = component.getTopLevelComponent()->getScreenBounds();
-
-            auto newScale = Desktop::getInstance().getDisplays().findDisplayForRect (lastScreenBounds).scale;
+           #if JUCE_WINDOWS
+            auto newScale = nativeContext->getWindowScaleFactor (component.getTopLevelComponent()->getScreenBounds());
+           #else
+            auto newScale = Desktop::getInstance().getDisplays().findDisplayForRect (component.getTopLevelComponent()->getScreenBounds()).scale;
+           #endif
 
             auto localBounds = component.getLocalBounds();
-
-            auto newArea = peer->getComponent().getLocalArea (&component, localBounds)
-                                               .withZeroOrigin()
-                             * newScale;
+            auto newArea = peer->getComponent().getLocalArea (&component, localBounds).withZeroOrigin() * newScale;
 
             if (scale != newScale || viewportArea != newArea)
             {