Add support for DPI aware applications on Windows

modules/juce_gui_basics/juce_gui_basics.h

@@ -111,6 +111,13 @@
  #define JUCE_USE_XCURSOR 1
 #endif
 
+/** Config: JUCE_WIN_PER_MONITOR_DPI_AWARE
+    Enables per-monitor DPI awareness on Windows 8.1 and above.
+*/
+#ifndef JUCE_WIN_PER_MONITOR_DPI_AWARE
+ #define JUCE_WIN_PER_MONITOR_DPI_AWARE 1
+#endif
+
 //==============================================================================
 namespace juce
 {

modules/juce_gui_extra/embedding/juce_ScopedDPIAwarenessDisabler.h

@@ -0,0 +1,56 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE library.
+   Copyright (c) 2017 - ROLI Ltd.
+
+   JUCE is an open source library subject to commercial or open-source
+   licensing.
+
+   By using JUCE, you agree to the terms of both the JUCE 5 End-User License
+   Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
+   27th April 2017).
+
+   End User License Agreement: www.juce.com/juce-5-licence
+   Privacy Policy: www.juce.com/juce-5-privacy-policy
+
+   Or: You may also use this code under the terms of the GPL v3 (see
+   www.gnu.org/licenses).
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+
+#if (JUCE_WINDOWS && JUCE_WIN_PER_MONITOR_DPI_AWARE) || DOXYGEN
+
+//==============================================================================
+/**
+    A Windows-specific class that temporarily sets the DPI awareness context of
+    the current thread to be DPI unaware and resets it to the previous context
+    when it goes out of scope.
+
+    If you create one of these before creating a top-level window, the window
+    will be DPI unaware and bitmap strectched by the OS on a display with >100%
+    scaling.
+
+    You shouldn't use this unless you really know what you are doing and
+    are dealing with native HWNDs.
+*/
+class JUCE_API  ScopedDPIAwarenessDisabler
+{
+public:
+    ScopedDPIAwarenessDisabler();
+    ~ScopedDPIAwarenessDisabler();
+
+private:
+    void* previousContext = nullptr;
+};
+#endif
+
+} // namespace juce

modules/juce_gui_extra/juce_gui_extra.h

@@ -88,6 +88,7 @@
 #include "embedding/juce_NSViewComponent.h"
 #include "embedding/juce_UIViewComponent.h"
 #include "embedding/juce_XEmbedComponent.h"
+#include "embedding/juce_ScopedDPIAwarenessDisabler.h"
 #include "misc/juce_AppleRemote.h"
 #include "misc/juce_BubbleMessageComponent.h"
 #include "misc/juce_ColourSelector.h"

modules/juce_gui_extra/native/juce_win32_ActiveXComponent.cpp

@@ -231,6 +231,9 @@ namespace ActiveXHelpers
 
 //==============================================================================
 class ActiveXControlComponent::Pimpl  : public ComponentMovementWatcher
+                                     #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+                                      , public ComponentPeer::ScaleFactorListener
+                                     #endif
 {
 public:
     Pimpl (HWND hwnd, ActiveXControlComponent& activeXComp)
@@ -251,12 +254,26 @@ public:
 
         clientSite->Release();
         storage->Release();
+
+       #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+        for (int i = 0; i < ComponentPeer::getNumPeers(); ++i)
+            if (auto* peer = ComponentPeer::getPeer (i))
+                peer->removeScaleFactorListener (this);
+        #endif
     }
 
     void setControlBounds (Rectangle<int> newBounds) const
     {
         if (controlHWND != 0)
+        {
+           #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+            if (auto* peer = owner.getTopLevelComponent()->getPeer())
+                newBounds = (newBounds.toDouble() * peer->getPlatformScaleFactor()).toNearestInt();
+           #endif
+
             MoveWindow (controlHWND, newBounds.getX(), newBounds.getY(), newBounds.getWidth(), newBounds.getHeight(), TRUE);
+        }
+
     }
 
     void setControlVisible (bool shouldBeVisible) const
@@ -269,12 +286,17 @@ public:
     void componentMovedOrResized (bool /*wasMoved*/, bool /*wasResized*/) override
     {
         if (auto* peer = owner.getTopLevelComponent()->getPeer())
-            setControlBounds (peer->getAreaCoveredBy(owner));
+            setControlBounds (peer->getAreaCoveredBy (owner));
     }
 
     void componentPeerChanged() override
     {
         componentMovedOrResized (true, true);
+
+       #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+        if (auto* peer = owner.getTopLevelComponent()->getPeer())
+            peer->addScaleFactorListener (this);
+       #endif
     }
 
     void componentVisibilityChanged() override
@@ -283,6 +305,13 @@ public:
         componentPeerChanged();
     }
 
+   #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+    void nativeScaleFactorChanged (double /*newScaleFactor*/) override
+    {
+        componentMovedOrResized (true, true);
+    }
+   #endif
+
     // intercepts events going to an activeX control, so we can sneakily use the mouse events
     static LRESULT CALLBACK activeXHookWndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
     {

modules/juce_opengl/native/juce_OpenGL_win32.h

@@ -31,6 +31,9 @@ extern ComponentPeer* createNonRepaintingEmbeddedWindowsPeer (Component&, void*
 
 //==============================================================================
 class OpenGLContext::NativeContext
+   #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+    : public ComponentPeer::ScaleFactorListener
+   #endif
 {
 public:
     NativeContext (Component& component,
@@ -87,6 +90,12 @@ public:
     {
         deleteRenderContext();
         releaseDC();
+
+       #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+        for (int i = 0; i < ComponentPeer::getNumPeers(); ++i)
+            if (auto* peer = ComponentPeer::getPeer (i))
+                peer->removeScaleFactorListener (this);
+       #endif
     }
 
     bool initialiseOnRenderThread (OpenGLContext& c)
@@ -117,9 +126,17 @@ public:
     void updateWindowPosition (Rectangle<int> bounds)
     {
         if (nativeWindow != nullptr)
+        {
+           #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+            if (safeComponent != nullptr)
+                if (auto* peer = safeComponent->getTopLevelComponent()->getPeer())
+                    bounds = (bounds.toDouble() * peer->getPlatformScaleFactor()).toNearestInt();
+           #endif
+
             SetWindowPos ((HWND) nativeWindow->getNativeHandle(), 0,
                           bounds.getX(), bounds.getY(), bounds.getWidth(), bounds.getHeight(),
                           SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOOWNERZORDER);
+        }
     }
 
     bool createdOk() const noexcept                 { return getRawContext() != nullptr; }
@@ -134,6 +151,15 @@ public:
 
     struct Locker { Locker (NativeContext&) {} };
 
+   #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+    void nativeScaleFactorChanged (double /*newScaleFactor*/) override
+    {
+        if (safeComponent != nullptr)
+            if (auto peer = safeComponent->getTopLevelComponent()->getPeer())
+                updateWindowPosition (peer->getAreaCoveredBy (*safeComponent));
+    }
+   #endif
+
 private:
     struct DummyComponent  : public Component
     {
@@ -150,6 +176,9 @@ private:
     HGLRC renderContext;
     HDC dc;
     OpenGLContext* context = {};
+   #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+    Component::SafePointer<Component> safeComponent;
+   #endif
 
     #define JUCE_DECLARE_WGL_EXTENSION_FUNCTION(name, returnType, params) \
         typedef returnType (__stdcall *type_ ## name) params; type_ ## name name;
@@ -174,8 +203,15 @@ private:
         nativeWindow.reset (createNonRepaintingEmbeddedWindowsPeer (*dummyComponent, topComp->getWindowHandle()));
 
         if (auto* peer = topComp->getPeer())
+        {
             updateWindowPosition (peer->getAreaCoveredBy (component));
 
+           #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+            peer->addScaleFactorListener (this);
+            safeComponent = Component::SafePointer<Component> (&component);
+           #endif
+        }
+
         nativeWindow->setVisible (true);
         dc = GetDC ((HWND) nativeWindow->getNativeHandle());
     }

modules/juce_video/native/juce_win32_Video.h

@@ -159,6 +159,9 @@ namespace VideoRenderers
 
 //==============================================================================
 struct VideoComponent::Pimpl  : public Component
+                             #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+                              , public ComponentPeer::ScaleFactorListener
+                             #endif
 {
     Pimpl (VideoComponent& ownerToUse, bool)
         : owner (ownerToUse),
@@ -174,6 +177,12 @@ struct VideoComponent::Pimpl  : public Component
         close();
         context = nullptr;
         componentWatcher = nullptr;
+
+       #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+        for (int i = 0; i < ComponentPeer::getNumPeers(); ++i)
+            if (auto* peer = ComponentPeer::getPeer (i))
+                peer->removeScaleFactorListener (this);
+       #endif
     }
 
     Result loadFromString (const String& fileOrURLPath)
@@ -300,7 +309,7 @@ struct VideoComponent::Pimpl  : public Component
 
         if (getWidth() > 0 && getHeight() > 0)
             if (auto* peer = getTopLevelComponent()->getPeer())
-                context->updateWindowPosition (peer->getAreaCoveredBy (*this));
+                context->updateWindowPosition ((peer->getAreaCoveredBy (*this).toDouble() * peer->getPlatformScaleFactor()).toNearestInt());
     }
 
     void updateContextVisibility()
@@ -332,6 +341,14 @@ struct VideoComponent::Pimpl  : public Component
             owner.onErrorOccurred (errorMessage);
     }
 
+   #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+    void nativeScaleFactorChanged (double /*newScaleFactor*/) override
+    {
+        if (videoLoaded)
+            updateContextPosition();
+    }
+   #endif
+
     File currentFile;
     URL currentURL;
 
@@ -755,6 +772,10 @@ private:
 
                 hwnd = nativeWindow->hwnd;
 
+               #if JUCE_WIN_PER_MONITOR_DPI_AWARE
+                topLevelPeer->addScaleFactorListener (&component);
+               #endif
+
                 if (hwnd != 0)
                 {
                     hdc = GetDC (hwnd);