Help: Add option for disabling antialising of fonts

For the backends that we can do it for (litehtml, QTextBrowser).

Fixes: QTCREATORBUG-12177
Change-Id: If64a279f74f878b6797bf43d8129058c6183919b
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Kai Köhne <kai.koehne@qt.io>

src/plugins/help/generalsettingspage.cpp

@@ -18,6 +18,7 @@
 
 #include <utils/algorithm.h>
 #include <utils/fileutils.h>
+#include <utils/layoutbuilder.h>
 
 #include <QCheckBox>
 #include <QComboBox>
@@ -76,6 +77,7 @@ private:
     QFontComboBox *familyComboBox;
     QComboBox *styleComboBox;
     QComboBox *sizeComboBox;
+    QCheckBox *antialiasCheckBox;
     QLineEdit *homePageLineEdit;
     QComboBox *helpStartComboBox;
     QComboBox *contextHelpComboBox;
@@ -92,49 +94,31 @@ private:
 
 GeneralSettingsPageWidget::GeneralSettingsPageWidget()
 {
+    using namespace Layouting;
+
     // font group box
-    auto fontGroupBox = new QGroupBox(Tr::tr("Font"));
-    auto familyLabel = new QLabel(Tr::tr("Family:"));
-
     familyComboBox = new QFontComboBox;
-    auto styleLabel = new QLabel(Tr::tr("Style:"));
     styleComboBox = new QComboBox;
-    auto sizeLabel = new QLabel(Tr::tr("Size:"));
     sizeComboBox = new QComboBox;
-
-    auto fontLayout = new QHBoxLayout();
-    fontLayout->addWidget(familyComboBox);
-    fontLayout->addSpacing(20);
-    fontLayout->addWidget(styleLabel);
-    fontLayout->addWidget(styleComboBox);
-    fontLayout->addSpacing(20);
-    fontLayout->addWidget(sizeLabel);
-    fontLayout->addWidget(sizeComboBox);
-    fontLayout->addStretch();
-
-    auto noteLabel = new QLabel(Tr::tr(
-        "Note: The above setting takes effect only if the HTML file does not use a style sheet."));
-    noteLabel->setWordWrap(true);
-    auto zoomLabel = new QLabel(Tr::tr("Zoom:"));
-
     zoomSpinBox = new QSpinBox;
     zoomSpinBox->setMinimum(10);
     zoomSpinBox->setMaximum(3000);
     zoomSpinBox->setSingleStep(10);
     zoomSpinBox->setValue(100);
     zoomSpinBox->setSuffix(Tr::tr("%"));
+    antialiasCheckBox = new QCheckBox(Tr::tr("Antialias"));
 
-    auto zoomLayout = new QHBoxLayout();
-    zoomLayout->addWidget(zoomSpinBox);
-    zoomLayout->addStretch();
-
-    auto fontGroupBoxLayout = new QGridLayout;
-    fontGroupBox->setLayout(fontGroupBoxLayout);
-    fontGroupBoxLayout->addWidget(familyLabel, 0, 0);
-    fontGroupBoxLayout->addLayout(fontLayout, 0, 1);
-    fontGroupBoxLayout->addWidget(noteLabel, 1, 0, 1, 2);
-    fontGroupBoxLayout->addWidget(zoomLabel, 2, 0);
-    fontGroupBoxLayout->addLayout(zoomLayout, 2, 1);
+    auto fontGroupBox = new QGroupBox(Tr::tr("Font"));
+    // clang-format off
+    Column {
+        Row { Tr::tr("Family:"), familyComboBox,
+              Tr::tr("Style:"), styleComboBox,
+              Tr::tr("Size:"), sizeComboBox, st },
+        Row { Tr::tr("Note: The above setting takes effect only if the "
+                     "HTML file does not use a style sheet.") },
+        Row { Tr::tr("Zoom:"), zoomSpinBox, antialiasCheckBox, st }
+    }.attachTo(fontGroupBox);
+    // clang-format on
 
     // startup group box
     auto startupGroupBox = new QGroupBox(Tr::tr("Startup"));
@@ -231,6 +215,7 @@ GeneralSettingsPageWidget::GeneralSettingsPageWidget()
     m_font = LocalHelpManager::fallbackFont();
     m_fontZoom = LocalHelpManager::fontZoom();
     zoomSpinBox->setValue(m_fontZoom);
+    antialiasCheckBox->setChecked(LocalHelpManager::antialias());
 
     updateFontSizeSelector();
     updateFontStyleSelector();
@@ -309,6 +294,8 @@ void GeneralSettingsPageWidget::apply()
     if (m_fontZoom != LocalHelpManager::fontZoom())
         LocalHelpManager::setFontZoom(m_fontZoom);
 
+    LocalHelpManager::setAntialias(antialiasCheckBox->isChecked());
+
     QString homePage = QUrl::fromUserInput(homePageLineEdit->text()).toString();
     if (homePage.isEmpty())
         homePage = Help::Constants::AboutBlank;

src/plugins/help/helpplugin.cpp

@@ -374,6 +374,13 @@ HelpViewer *HelpPlugin::createHelpViewer()
     connect(LocalHelpManager::instance(), &LocalHelpManager::fontZoomChanged,
             viewer, &HelpViewer::setFontZoom);
 
+    // initialize antialias
+    viewer->setAntialias(LocalHelpManager::antialias());
+    connect(LocalHelpManager::instance(),
+            &LocalHelpManager::antialiasChanged,
+            viewer,
+            &HelpViewer::setAntialias);
+
     viewer->setScrollWheelZoomingEnabled(LocalHelpManager::isScrollWheelZoomingEnabled());
     connect(LocalHelpManager::instance(), &LocalHelpManager::scrollWheelZoomingEnabledChanged,
             viewer, &HelpViewer::setScrollWheelZoomingEnabled);

src/plugins/help/helpviewer.cpp

@@ -71,6 +71,8 @@ HelpViewer::~HelpViewer()
     restoreOverrideCursor();
 }
 
+void HelpViewer::setAntialias(bool) {}
+
 void HelpViewer::setFontZoom(int percentage)
 {
     setScale(percentage / 100.0);

src/plugins/help/helpviewer.h

@@ -32,6 +32,7 @@ public:
     ~HelpViewer() override;
 
     virtual void setViewerFont(const QFont &font) = 0;
+    virtual void setAntialias(bool on);
 
     virtual void setScale(qreal scale) = 0;
 

src/plugins/help/litehtmlhelpviewer.cpp

@@ -134,6 +134,11 @@ void LiteHtmlHelpViewer::setScale(qreal scale)
     m_viewer->setZoomFactor(scale == 0 ? qreal(1) : scale);
 }
 
+void LiteHtmlHelpViewer::setAntialias(bool on)
+{
+    m_viewer->setAntialias(on);
+}
+
 QString LiteHtmlHelpViewer::title() const
 {
     return m_viewer->title();

src/plugins/help/litehtmlhelpviewer.h

@@ -24,8 +24,8 @@ public:
     ~LiteHtmlHelpViewer() override;
 
     void setViewerFont(const QFont &font) override;
-
     void setScale(qreal scale) override;
+    void setAntialias(bool on) final;
 
     QString title() const override;
 

src/plugins/help/localhelpmanager.cpp

@@ -52,21 +52,23 @@ QHelpEngine* LocalHelpManager::m_guiEngine = nullptr;
 QMutex LocalHelpManager::m_bkmarkMutex;
 BookmarkManager* LocalHelpManager::m_bookmarkManager = nullptr;
 
-static const char kHelpHomePageKey[] = "Help/HomePage";
-static const char kFontFamilyKey[] = "Help/FallbackFontFamily";
-static const char kFontStyleNameKey[] = "Help/FallbackFontStyleName";
-static const char kFontSizeKey[] = "Help/FallbackFontSize";
-static const char kFontZoomKey[] = "Help/FontZoom";
-static const char kStartOptionKey[] = "Help/StartOption";
-static const char kContextHelpOptionKey[] = "Help/ContextHelpOption";
-static const char kReturnOnCloseKey[] = "Help/ReturnOnClose";
-static const char kUseScrollWheelZooming[] = "Help/UseScrollWheelZooming";
-static const char kLastShownPagesKey[] = "Help/LastShownPages";
-static const char kLastSelectedTabKey[] = "Help/LastSelectedTab";
-static const char kViewerBackend[] = "Help/ViewerBackend";
+const char kHelpHomePageKey[] = "Help/HomePage";
+const char kFontFamilyKey[] = "Help/FallbackFontFamily";
+const char kFontStyleNameKey[] = "Help/FallbackFontStyleName";
+const char kFontSizeKey[] = "Help/FallbackFontSize";
+const char kFontZoomKey[] = "Help/FontZoom";
+const char kAntialiasKey[] = "Help/FontAntialias";
+const char kStartOptionKey[] = "Help/StartOption";
+const char kContextHelpOptionKey[] = "Help/ContextHelpOption";
+const char kReturnOnCloseKey[] = "Help/ReturnOnClose";
+const char kUseScrollWheelZooming[] = "Help/UseScrollWheelZooming";
+const char kLastShownPagesKey[] = "Help/LastShownPages";
+const char kLastSelectedTabKey[] = "Help/LastSelectedTab";
+const char kViewerBackend[] = "Help/ViewerBackend";
 
-static const int kDefaultFallbackFontSize = 14;
-static const int kDefaultFontZoom = 100;
+const int kDefaultFallbackFontSize = 14;
+const int kDefaultFontZoom = 100;
+const bool kDefaultAntialias = true;
 const int kDefaultStartOption = LocalHelpManager::ShowLastPages;
 const int kDefaultContextHelpOption = Core::HelpManager::SideBySideIfPossible;
 const bool kDefaultReturnOnClose = false;
@@ -175,6 +177,19 @@ int LocalHelpManager::setFontZoom(int percentage)
     return newZoom;
 }
 
+bool LocalHelpManager::antialias()
+{
+    return Core::ICore::settings()->value(kAntialiasKey, kDefaultAntialias).toBool();
+}
+
+void LocalHelpManager::setAntialias(bool on)
+{
+    if (on != antialias()) {
+        Core::ICore::settings()->setValueWithDefault(kAntialiasKey, on, kDefaultAntialias);
+        emit m_instance->antialiasChanged(on);
+    }
+}
+
 LocalHelpManager::StartOption LocalHelpManager::startOption()
 {
     const QVariant value = Core::ICore::settings()->value(kStartOptionKey, kDefaultStartOption);

src/plugins/help/localhelpmanager.h

@@ -61,6 +61,9 @@ public:
     static int fontZoom();
     static int setFontZoom(int percentage);
 
+    static bool antialias();
+    static void setAntialias(bool on);
+
     static StartOption startOption();
     static void setStartOption(StartOption option);
 
@@ -104,6 +107,7 @@ public:
 signals:
     void fallbackFontChanged(const QFont &font);
     void fontZoomChanged(int percentage);
+    void antialiasChanged(bool on);
     void returnOnCloseChanged();
     void scrollWheelZoomingEnabledChanged(bool enabled);
     void contextHelpOptionChanged(Core::HelpManager::HelpViewerLocation option);

src/plugins/help/textbrowserhelpviewer.cpp

@@ -55,22 +55,28 @@ TextBrowserHelpViewer::~TextBrowserHelpViewer() = default;
 
 void TextBrowserHelpViewer::setViewerFont(const QFont &newFont)
 {
-    setFontAndScale(newFont, LocalHelpManager::fontZoom() / 100.0);
+    setFontAndScale(newFont, LocalHelpManager::fontZoom() / 100.0, LocalHelpManager::antialias());
 }
 
-void TextBrowserHelpViewer::setFontAndScale(const QFont &font, qreal scale)
+void TextBrowserHelpViewer::setFontAndScale(const QFont &font, qreal scale, bool antialias)
 {
-    m_textBrowser->withFixedTopPosition([this, &font, scale] {
+    m_textBrowser->withFixedTopPosition([this, &font, scale, antialias] {
         QFont newFont = font;
         const float newSize = font.pointSizeF() * scale;
         newFont.setPointSizeF(newSize);
+        newFont.setStyleStrategy(antialias ? QFont::PreferAntialias : QFont::NoAntialias);
         m_textBrowser->setFont(newFont);
     });
 }
 
 void TextBrowserHelpViewer::setScale(qreal scale)
 {
-    setFontAndScale(LocalHelpManager::fallbackFont(), scale);
+    setFontAndScale(LocalHelpManager::fallbackFont(), scale, LocalHelpManager::antialias());
+}
+
+void TextBrowserHelpViewer::setAntialias(bool on)
+{
+    setFontAndScale(LocalHelpManager::fallbackFont(), LocalHelpManager::fontZoom() / 100.0, on);
 }
 
 QString TextBrowserHelpViewer::title() const

src/plugins/help/textbrowserhelpviewer.h

@@ -22,8 +22,8 @@ public:
     ~TextBrowserHelpViewer() override;
 
     void setViewerFont(const QFont &font) override;
-
     void setScale(qreal scale) override;
+    void setAntialias(bool on) final;
 
     QString title() const override;
 
@@ -48,7 +48,7 @@ public:
     void print(QPrinter *printer) override;
 
 private:
-    void setFontAndScale(const QFont &font, qreal scale);
+    void setFontAndScale(const QFont &font, qreal scale, bool antialias);
 
     TextBrowserHelpWidget *m_textBrowser;
 };