Floating windows now support a minimize button

Introduced Flag_TitleBarHasMinimizeButton for it.
It implies Flag_DontUseUtilityFloatingWindows too, since Qt::Tool
don't appear in the task bar.

example: kddockwidgets_example -k

examples/dockwidgets/main.cpp

@@ -78,8 +78,11 @@ int main(int argc, char **argv)
     QCommandLineOption nonDockable("d", QCoreApplication::translate("main", "DockWidget #9 will be non-dockable"));
     parser.addOption(nonDockable);
 
-    QCommandLineOption maximizeButton("b", QCoreApplication::translate("main", "DockWidgets have maximize/restore buttons instead of float/dock button"));
-    parser.addOption(maximizeButton);
+    QCommandLineOption maximizeButtonOption("b", QCoreApplication::translate("main", "Floating dockWidgets have maximize/restore buttons instead of float/dock button"));
+    parser.addOption(maximizeButtonOption);
+
+    QCommandLineOption minimizeButtonOption("k", QCoreApplication::translate("main", "Floating dockWidgets have a minimize button. Implies not being an utility window (~Qt::Tool)"));
+    parser.addOption(minimizeButtonOption);
 
     QCommandLineOption segmentedIndicators("y", QCoreApplication::translate("main", "Use segmented indicators instead of classical"));
     parser.addOption(segmentedIndicators);
@@ -169,9 +172,12 @@ int main(int argc, char **argv)
     if (parser.isSet(reorderTabsOption))
         flags |= KDDockWidgets::Config::Flag_AllowReorderTabs;
 
-    if (parser.isSet(maximizeButton))
+    if (parser.isSet(maximizeButtonOption))
         flags |= KDDockWidgets::Config::Flag_TitleBarHasMaximizeButton;
 
+    if (parser.isSet(minimizeButtonOption))
+        flags |= KDDockWidgets::Config::Flag_TitleBarHasMinimizeButton;
+
     if (parser.isSet(lazyResizeOption))
         flags |= KDDockWidgets::Config::Flag_LazyResize;
 

src/Config.h

@@ -71,6 +71,7 @@ public:
         Flag_internal_DontUseParentForFloatingWindows = 0x1000, ///> FloatingWindows won't have a parent top-level. Internal, use Flag_DontUseUtilityFloatingWindows instead.
 
         Flag_DontUseUtilityFloatingWindows = Flag_internal_DontUseQtToolWindowsForFloatingWindows | Flag_internal_DontUseParentForFloatingWindows,
+        Flag_TitleBarHasMinimizeButton = 0x2000 | Flag_DontUseUtilityFloatingWindows, ///> The title bar will have a minimize button when floating. This implies Flag_DontUseUtilityFloatingWindows too, otherwise they wouldn't appear in the task bar.
         Flag_Default = Flag_AeroSnapWithClientDecos ///> The defaults
     };
     Q_DECLARE_FLAGS(Flags, Flag)

src/private/TitleBar.cpp

@@ -45,6 +45,7 @@ TitleBar::TitleBar(FloatingWindow *parent)
     connect(m_floatingWindow, &FloatingWindow::numFramesChanged, this, &TitleBar::updateCloseButton);
     connect(m_floatingWindow, &FloatingWindow::numFramesChanged, this, &TitleBar::updateFloatButton);
     connect(m_floatingWindow, &FloatingWindow::numFramesChanged, this, &TitleBar::updateMaximizeButton);
+    connect(m_floatingWindow, &FloatingWindow::numFramesChanged, this, &TitleBar::updateMinimizeButton);
     connect(m_floatingWindow, &FloatingWindow::windowStateChanged, this, &TitleBar::updateMaximizeButton);
     connect(m_floatingWindow, &FloatingWindow::activatedChanged , this, &TitleBar::isFocusedChanged);
     init();
@@ -190,6 +191,14 @@ bool TitleBar::supportsMaximizeButton() const
     return m_floatingWindow != nullptr;
 }
 
+bool TitleBar::supportsMinimizeButton() const
+{
+    if ((Config::self().flags() & Config::Flag_TitleBarHasMinimizeButton) != Config::Flag_TitleBarHasMinimizeButton) // this specific flag is not base^2
+        return false;
+
+    return m_floatingWindow != nullptr;
+}
+
 bool TitleBar::hasIcon() const
 {
     return !m_icon.isNull();
@@ -293,3 +302,17 @@ void TitleBar::onMaximizeClicked()
 {
     toggleMaximized();
 }
+
+void TitleBar::onMinimizeClicked()
+{
+    if (!m_floatingWindow)
+        return;
+
+    if (!(Config::self().flags() & Config::Flag_DontUseUtilityFloatingWindows)) {
+        // Qt::Tool windows don't appear in the task bar.
+        // Unless someone tells me a good reason to allow this situation.
+        return;
+    }
+
+    m_floatingWindow->showMinimized();
+}

src/private/TitleBar_p.h

@@ -66,6 +66,9 @@ public:
     ///@brief returns whether this title bar supports a maximize/restore button
     bool supportsMaximizeButton() const;
 
+    ///@brief returns whether this title bar supports a minimize button
+    bool supportsMinimizeButton() const;
+
     ///@brief returns whether this title bar has an icon
     bool hasIcon() const;
 
@@ -97,10 +100,12 @@ protected:
     Q_INVOKABLE void onCloseClicked();
     Q_INVOKABLE void onFloatClicked();
     Q_INVOKABLE void onMaximizeClicked();
+    Q_INVOKABLE void onMinimizeClicked();
     Q_INVOKABLE void toggleMaximized();
 
     virtual void updateFloatButton() {}
     virtual void updateMaximizeButton() {}
+    virtual void updateMinimizeButton() {}
 
     // The following are needed for the unit-tests
     virtual bool isCloseButtonVisible() const { return true; }

src/private/widgets/TitleBarWidget.cpp

@@ -50,8 +50,11 @@ void TitleBarWidget::init()
     m_layout->setSpacing(2);
 
     m_maximizeButton = TitleBarWidget::createButton(this, style()->standardIcon(QStyle::SP_TitleBarMaxButton));
+    m_minimizeButton = TitleBarWidget::createButton(this, style()->standardIcon(QStyle::SP_TitleBarMinButton));
     m_floatButton = TitleBarWidget::createButton(this, style()->standardIcon(QStyle::SP_TitleBarNormalButton));
     m_closeButton = TitleBarWidget::createButton(this, style()->standardIcon(QStyle::SP_TitleBarCloseButton));
+
+    m_layout->addWidget(m_minimizeButton);
     m_layout->addWidget(m_maximizeButton);
     m_layout->addWidget(m_floatButton);
     m_layout->addWidget(m_closeButton);
@@ -59,10 +62,12 @@ void TitleBarWidget::init()
     connect(m_floatButton, &QAbstractButton::clicked, this, &TitleBarWidget::onFloatClicked);
     connect(m_closeButton, &QAbstractButton::clicked, this, &TitleBarWidget::onCloseClicked);
     connect(m_maximizeButton, &QAbstractButton::clicked, this, &TitleBarWidget::onMaximizeClicked);
+    connect(m_minimizeButton, &QAbstractButton::clicked, this, &TitleBarWidget::onMinimizeClicked);
 
     updateCloseButton();
     updateFloatButton();
     updateMaximizeButton();
+    updateMinimizeButton();
 
     connect(this, &TitleBar::titleChanged, this, [this] {
         update();
@@ -99,7 +104,7 @@ int TitleBarWidget::buttonAreaWidth() const
 TitleBarWidget::~TitleBarWidget()
 {
     // To avoid a crash
-    for (auto button : { m_floatButton, m_maximizeButton, m_closeButton }) {
+    for (auto button : { m_minimizeButton, m_floatButton, m_maximizeButton, m_closeButton }) {
         button->setParent(nullptr);
         button->deleteLater();
     }
@@ -143,6 +148,11 @@ void TitleBarWidget::updateCloseButton()
     m_closeButton->setEnabled(!anyNonClosable);
 }
 
+void TitleBarWidget::updateMinimizeButton()
+{
+    m_minimizeButton->setVisible(supportsMinimizeButton());
+}
+
 void TitleBarWidget::updateMaximizeButton()
 {
     if (auto fw = floatingWindow()) {

src/private/widgets/TitleBarWidget_p.h

@@ -51,6 +51,7 @@ protected:
     void updateFloatButton() override;
     void updateCloseButton() override;
     void updateMaximizeButton() override;
+    void updateMinimizeButton() override;
 
      // The following are needed for the unit-tests
     bool isCloseButtonVisible() const override;
@@ -68,6 +69,7 @@ private:
     QAbstractButton *m_closeButton = nullptr;
     QAbstractButton *m_floatButton = nullptr;
     QAbstractButton *m_maximizeButton = nullptr;
+    QAbstractButton *m_minimizeButton = nullptr;
     QLabel *m_dockWidgetIcon = nullptr;
 };