Merge branch '1.3' into master

Changelog

@@ -7,7 +7,7 @@
     sure to provide a sizeHint.
 
 * v1.3.1 (unreleased)
-  -
+  - Improve dragging across monitors with different dpi scaling
 
 * v1.3.0 (8 February 2021)
   - Experimental QtQuick support (#49)

src/private/DragController.cpp

@@ -255,6 +255,7 @@ void StateDragging::onEntry()
             dw->d->saveLastFloatingGeometry();
     }
 
+    const bool needsUndocking = !q->m_draggable->isWindow();
     q->m_windowBeingDragged = q->m_draggable->makeWindow();
     if (q->m_windowBeingDragged) {
 #if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0) && defined(Q_OS_WIN)
@@ -268,12 +269,17 @@ void StateDragging::onEntry()
 
             QWindow *window = fw->windowHandle();
 
-            // Position the window before the drag start, otherwise if you move mouse too fast there will be an offset
-            window->setPosition(QCursor::pos() - q->m_offset);
+            if (needsUndocking) {
+                // Position the window before the drag start, otherwise if you move mouse too fast there will be an offset
+                // Only required when we've undocked/detached a window.
+                window->setPosition(QCursor::pos() - q->m_offset);
+            }
 
             // Start the native move
             window->startSystemMove();
         }
+#else
+    Q_UNUSED(needsUndocking);
 #endif
 
         qCDebug(state) << "StateDragging entered. m_draggable=" << q->m_draggable->asWidget()

src/private/Draggable_p.h

@@ -79,6 +79,12 @@ public:
     ///@brief Returns whether this draggable is a MDI window, being dragged internally within a main window
     virtual bool isMDI() const = 0;
 
+    /**
+     * @brief Returns whether this draggable is already a window.
+     *
+     * If true, means the drag will simply move the existing window, and no undocking/untabbing is involved.
+     */
+    virtual bool isWindow() const = 0;
 private:
     class Private;
     Private *const d;

src/private/FloatingWindow.cpp

@@ -502,3 +502,8 @@ bool FloatingWindow::isMDI() const
 {
     return false;
 }
+
+bool FloatingWindow::isWindow() const
+{
+    return true;
+}

src/private/FloatingWindow_p.h

@@ -51,6 +51,7 @@ public:
     // Draggable:
     std::unique_ptr<WindowBeingDragged> makeWindow() override;
     DockWidgetBase *singleDockWidget() const override;
+    bool isWindow() const override;
 
     const QVector<DockWidgetBase*> dockWidgets() const;
     const Frame::List frames() const;

src/private/TabWidget.cpp

@@ -94,6 +94,12 @@ std::unique_ptr<WindowBeingDragged> TabBar::makeWindow()
     return std::unique_ptr<WindowBeingDragged>(new WindowBeingDragged(floatingWindow, draggable));
 }
 
+bool TabBar::isWindow() const
+{
+    // Same semantics as tab widget, no need to duplicate logic
+    return m_tabWidget->isWindow();
+}
+
 void TabBar::onMousePress(QPoint localPos)
 {
     m_lastPressedDockWidget = dockWidgetAt(localPos);
@@ -237,6 +243,16 @@ std::unique_ptr<WindowBeingDragged> TabWidget::makeWindow()
     return std::unique_ptr<WindowBeingDragged>(new WindowBeingDragged(floatingWindow, this));
 }
 
+bool TabWidget::isWindow() const
+{
+    if (auto floatingWindow = qobject_cast<FloatingWindow*>(asWidget()->window())) {
+        // Case of dragging via the tab widget when the title bar is hidden
+        return floatingWindow->hasSingleFrame();
+    }
+
+    return false;
+}
+
 DockWidgetBase *TabWidget::singleDockWidget() const
 {
     if (m_frame->hasSingleDockWidget())

src/private/TabWidget_p.h

@@ -57,6 +57,7 @@ public:
 
     // Draggable
     std::unique_ptr<WindowBeingDragged> makeWindow() override;
+    bool isWindow() const override;
 
     void onMousePress(QPoint localPos);
     void onMouseDoubleClick(QPoint localPos);
@@ -175,6 +176,7 @@ public:
     // Draggable interface
     std::unique_ptr<WindowBeingDragged> makeWindow() override;
     DockWidgetBase *singleDockWidget() const override;
+    bool isWindow() const override;
 
     /// @reimp
     bool isMDI() const override;

src/private/TitleBar.cpp

@@ -469,3 +469,8 @@ void TitleBar::updateFloatButton()
     setFloatButtonToolTip(floatingWindow() ? tr("Dock window") : tr("Undock window"));
     setFloatButtonVisible(supportsFloatingButton());
 }
+
+bool TitleBar::isWindow() const
+{
+    return m_floatingWindow != nullptr;
+}

src/private/TitleBar_p.h

@@ -56,6 +56,7 @@ public:
 
     void setIcon(const QIcon &icon);
     std::unique_ptr<WindowBeingDragged> makeWindow() override;
+    bool isWindow() const override;
 
     DockWidgetBase *singleDockWidget() const override;