Use Qt's High-DPI scaling on Windows

CHANGELOG.md

@@ -3,8 +3,10 @@
 ## Unversioned
 
 - Major: Release plugins alpha. (#5288)
+- Major: Improve high-DPI support on Windows. (#4868)
 - Minor: Add option to customise Moderation buttons with images. (#5369)
 - Bugfix: If a network request errors with 200 OK, Qt's error code is now reported instead of the HTTP status. (#5378)
+- Dev: Use Qt's high DPI scaling. (#4868)
 - Dev: Add doxygen build target. (#5377)
 - Dev: Make printing of strings in tests easier. (#5379)
 - Dev: Refactor and document `Scrollbar`. (#5334)

resources/qss/settings.qss

@@ -1,11 +1,11 @@
 * {
-    font-size: <font-size>px;
+    font-size: 14px;
     font-family: "Segoe UI";
 }
 
 QCheckBox::indicator {
-    width: <checkbox-size>px;
-    height: <checkbox-size>px;
+    width: 14px;
+    height: 14px;
 }
 
 chatterino--ComboBox {

src/RunGui.cpp

@@ -86,10 +86,6 @@ namespace {
         QApplication::setAttribute(Qt::AA_DontCreateNativeWidgetSiblings);
 #endif
 
-#if defined(Q_OS_WIN32) && QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-        QApplication::setAttribute(Qt::AA_DisableHighDpiScaling, true);
-#endif
-
         QApplication::setStyle(QStyleFactory::create("Fusion"));
 
 #ifndef Q_OS_MAC

src/main.cpp

@@ -26,11 +26,6 @@ using namespace chatterino;
 
 int main(int argc, char **argv)
 {
-    // TODO: This is a temporary fix (see #4552).
-#if defined(Q_OS_WINDOWS) && QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    qputenv("QT_ENABLE_HIGHDPI_SCALING", "0");
-#endif
-
     QApplication a(argc, argv);
 
     QCoreApplication::setApplicationName("chatterino");

src/messages/MessageElement.cpp

@@ -155,8 +155,8 @@ void EmoteElement::addToContainer(MessageLayoutContainer &container,
     {
         if (flags.has(MessageElementFlag::EmoteImages))
         {
-            auto image =
-                this->emote_->images.getImageOrLoaded(container.getScale());
+            auto image = this->emote_->images.getImageOrLoaded(
+                container.getImageScale());
             if (image->isEmpty())
             {
                 return;
@@ -210,7 +210,7 @@ void LayeredEmoteElement::addToContainer(MessageLayoutContainer &container,
     {
         if (flags.has(MessageElementFlag::EmoteImages))
         {
-            auto images = this->getLoadedImages(container.getScale());
+            auto images = this->getLoadedImages(container.getImageScale());
             if (images.empty())
             {
                 return;
@@ -364,7 +364,7 @@ void BadgeElement::addToContainer(MessageLayoutContainer &container,
     if (flags.hasAny(this->getFlags()))
     {
         auto image =
-            this->emote_->images.getImageOrLoaded(container.getScale());
+            this->emote_->images.getImageOrLoaded(container.getImageScale());
         if (image->isEmpty())
         {
             return;
@@ -798,7 +798,7 @@ void ScalingImageElement::addToContainer(MessageLayoutContainer &container,
     if (flags.hasAny(this->getFlags()))
     {
         const auto &image =
-            this->images_.getImageOrLoaded(container.getScale());
+            this->images_.getImageOrLoaded(container.getImageScale());
         if (image->isEmpty())
         {
             return;

src/messages/layouts/MessageLayout.cpp

@@ -74,7 +74,8 @@ int MessageLayout::getWidth() const
 
 // Layout
 // return true if redraw is required
-bool MessageLayout::layout(int width, float scale, MessageElementFlags flags,
+bool MessageLayout::layout(int width, float scale, float imageScale,
+                           MessageElementFlags flags,
                            bool shouldInvalidateBuffer)
 {
     //    BenchmarkGuard benchmark("MessageLayout::layout()");
@@ -106,6 +107,8 @@ bool MessageLayout::layout(int width, float scale, MessageElementFlags flags,
     // check if dpi changed
     layoutRequired |= this->scale_ != scale;
     this->scale_ = scale;
+    layoutRequired |= this->imageScale_ != imageScale;
+    this->imageScale_ = imageScale;
 
     if (!layoutRequired)
     {
@@ -148,7 +151,8 @@ void MessageLayout::actuallyLayout(int width, MessageElementFlags flags)
     bool hideSimilar = getSettings()->hideSimilar;
     bool hideReplies = !flags.has(MessageElementFlag::RepliedMessage);
 
-    this->container_.beginLayout(width, this->scale_, messageFlags);
+    this->container_.beginLayout(width, this->scale_, this->imageScale_,
+                                 messageFlags);
 
     for (const auto &element : this->message_->elements)
     {
@@ -288,16 +292,11 @@ QPixmap *MessageLayout::ensureBuffer(QPainter &painter, int width)
     }
 
     // Create new buffer
-#if defined(Q_OS_MACOS) || defined(Q_OS_LINUX)
     this->buffer_ = std::make_unique<QPixmap>(
         int(width * painter.device()->devicePixelRatioF()),
         int(this->container_.getHeight() *
             painter.device()->devicePixelRatioF()));
     this->buffer_->setDevicePixelRatio(painter.device()->devicePixelRatioF());
-#else
-    this->buffer_ = std::make_unique<QPixmap>(
-        width, std::max(16, this->container_.getHeight()));
-#endif
 
     this->bufferValid_ = false;
     DebugCount::increase("message drawing buffers");

src/messages/layouts/MessageLayout.hpp

@@ -56,8 +56,8 @@ class MessageLayout
 
     MessageLayoutFlags flags;
 
-    bool layout(int width, float scale_, MessageElementFlags flags,
-                bool shouldInvalidateBuffer);
+    bool layout(int width, float scale_, float imageScale,
+                MessageElementFlags flags, bool shouldInvalidateBuffer);
 
     // Painting
     MessagePaintResult paint(const MessagePaintContext &ctx);
@@ -128,6 +128,7 @@ class MessageLayout
     int currentLayoutWidth_ = -1;
     int layoutState_ = -1;
     float scale_ = -1;
+    float imageScale_ = -1.F;
     MessageElementFlags currentWordFlags_;
 
 #ifdef FOURTF

src/messages/layouts/MessageLayoutContainer.cpp

@@ -30,7 +30,7 @@ constexpr const QMargins MARGIN{8, 4, 8, 4};
 namespace chatterino {
 
 void MessageLayoutContainer::beginLayout(int width, float scale,
-                                         MessageFlags flags)
+                                         float imageScale, MessageFlags flags)
 {
     this->elements_.clear();
     this->lines_.clear();
@@ -45,6 +45,7 @@ void MessageLayoutContainer::beginLayout(int width, float scale,
     this->width_ = width;
     this->height_ = 0;
     this->scale_ = scale;
+    this->imageScale_ = imageScale;
     this->flags_ = flags;
     auto mediumFontMetrics =
         getIApp()->getFonts()->getFontMetrics(FontStyle::ChatMedium, scale);
@@ -526,6 +527,11 @@ float MessageLayoutContainer::getScale() const
     return this->scale_;
 }
 
+float MessageLayoutContainer::getImageScale() const
+{
+    return this->imageScale_;
+}
+
 bool MessageLayoutContainer::isCollapsed() const
 {
     return this->isCollapsed_;

src/messages/layouts/MessageLayoutContainer.hpp

@@ -32,7 +32,8 @@ struct MessageLayoutContainer {
      * This will reset all line calculations, and will be considered incomplete
      * until the accompanying end function has been called
      */
-    void beginLayout(int width_, float scale_, MessageFlags flags_);
+    void beginLayout(int width, float scale, float imageScale,
+                     MessageFlags flags);
 
     /**
      * Finish the layout process of this message
@@ -146,6 +147,11 @@ struct MessageLayoutContainer {
      */
     float getScale() const;
 
+    /**
+     * Returns the image scale
+     */
+    float getImageScale() const;
+
     /**
      * Returns true if this message is collapsed
      */
@@ -270,6 +276,10 @@ struct MessageLayoutContainer {
 
     // variables
     float scale_ = 1.F;
+    /**
+     * Scale factor for images
+     */
+    float imageScale_ = 1.F;
     int width_ = 0;
     MessageFlags flags_{};
     /**

src/widgets/AttachedWindow.cpp

@@ -270,20 +270,22 @@ void AttachedWindow::updateWindowRect(void *_attachedPtr)
     }
 
     float scale = 1.f;
+    float ourScale = 1.F;
     if (auto dpi = getWindowDpi(attached))
     {
         scale = *dpi / 96.f;
+        ourScale = scale / this->devicePixelRatio();
 
         for (auto w : this->ui_.split->findChildren<BaseWidget *>())
         {
-            w->setOverrideScale(scale);
+            w->setOverrideScale(ourScale);
         }
-        this->ui_.split->setOverrideScale(scale);
+        this->ui_.split->setOverrideScale(ourScale);
     }
 
     if (this->height_ != -1)
     {
-        this->ui_.split->setFixedWidth(int(this->width_ * scale));
+        this->ui_.split->setFixedWidth(int(this->width_ * ourScale));
 
         // offset
         int o = this->fullscreen_ ? 0 : 8;

src/widgets/BaseWidget.cpp

@@ -120,19 +120,6 @@ void BaseWidget::setScaleIndependantHeight(int value)
         QSize(this->scaleIndependantSize_.width(), value));
 }
 
-float BaseWidget::qtFontScale() const
-{
-    if (auto *window = dynamic_cast<BaseWindow *>(this->window()))
-    {
-        // ensure no div by 0
-        return this->scale() / std::max<float>(0.01f, window->nativeScale_);
-    }
-    else
-    {
-        return this->scale();
-    }
-}
-
 void BaseWidget::childEvent(QChildEvent *event)
 {
     if (event->added())

src/widgets/BaseWidget.hpp

@@ -34,8 +34,6 @@ class BaseWidget : public QWidget
     void setScaleIndependantWidth(int value);
     void setScaleIndependantHeight(int value);
 
-    float qtFontScale() const;
-
 protected:
     void childEvent(QChildEvent *) override;
     void showEvent(QShowEvent *) override;