QMainWindow: move the separator handling in another class

So it will be re-used by QDockWidgetGroupWindow

The Layout template argument can be the QMainWindowLayout,
or the QDockWidgetGroupLayout. They have a function
dockAreaLayoutInfo which return a QDockAreaLayout* or a
QDockAreaLayoutInfo*, respectively. These two class
have the same interface as far as QMainWindowLayoutSeparatorHelper
is concerned. (QDockAreaLayout forward most of its call to
the relevant QDockAreaLayoutInfo)

The code is mostly moved without modification, but there is a change in
startSeparatorMove, because we don't have access to the layoutState to
set the fallbackToSizeHints variable, so instead, we do that from
QMainWindowLayout::hover.

Change-Id: Ic5fa3ee2def3d0155195f751d4770b207732139f
Reviewed-by: Sérgio Martins <sergio.martins@kdab.com>

1 files changed, 251 insertions, 12 deletions

diff --git a/src/widgets/widgets/qmainwindowlayout_p.h b/src/widgets/widgets/qmainwindowlayout_p.h
index 507759fe96..dcd94e3617 100644
--- a/src/widgets/widgets/qmainwindowlayout_p.h
+++ b/src/widgets/widgets/qmainwindowlayout_p.h
@@ -58,6 +58,8 @@
 
 #include "QtWidgets/qlayout.h"
 #include "QtWidgets/qtabbar.h"
+#include "QtGui/qpainter.h"
+#include "QtGui/qevent.h"
 #include "QtCore/qvector.h"
 #include "QtCore/qset.h"
 #include "QtCore/qbasictimer.h"
@@ -72,6 +74,251 @@ QT_BEGIN_NAMESPACE
 class QToolBar;
 class QRubberBand;
 
+template <typename Layout> // Make use of the "Curiously recurring template pattern"
+class QMainWindowLayoutSeparatorHelper
+{
+    Layout *layout() { return static_cast<Layout *>(this); }
+    const Layout *layout() const { return static_cast<const Layout *>(this); }
+    QWidget *window() { return layout()->parentWidget(); }
+
+public:
+    QList<int> hoverSeparator;
+    QPoint hoverPos;
+
+#if !defined(QT_NO_DOCKWIDGET) && !defined(QT_NO_CURSOR)
+    QCursor separatorCursor(const QList<int> &path);
+    void adjustCursor(const QPoint &pos);
+    QCursor oldCursor;
+    QCursor adjustedCursor;
+    bool hasOldCursor = false;
+    bool cursorAdjusted = false;
+
+    QList<int> movingSeparator;
+    QPoint movingSeparatorOrigin, movingSeparatorPos;
+    QBasicTimer separatorMoveTimer;
+
+    bool startSeparatorMove(const QPoint &pos);
+    bool separatorMove(const QPoint &pos);
+    bool endSeparatorMove(const QPoint &pos);
+
+#endif
+
+    bool windowEvent(QEvent *e);
+};
+
+#if !defined(QT_NO_DOCKWIDGET) && !defined(QT_NO_CURSOR)
+template <typename Layout>
+QCursor QMainWindowLayoutSeparatorHelper<Layout>::separatorCursor(const QList<int> &path)
+{
+    const QDockAreaLayoutInfo *info = layout()->dockAreaLayoutInfo()->info(path);
+    Q_ASSERT(info != 0);
+    if (path.size() == 1) { // is this the "top-level" separator which separates a dock area
+                            // from the central widget?
+        switch (path.first()) {
+        case QInternal::LeftDock:
+        case QInternal::RightDock:
+            return Qt::SplitHCursor;
+        case QInternal::TopDock:
+        case QInternal::BottomDock:
+            return Qt::SplitVCursor;
+        default:
+            break;
+        }
+    }
+
+    // no, it's a splitter inside a dock area, separating two dock widgets
+
+    return info->o == Qt::Horizontal ? Qt::SplitHCursor : Qt::SplitVCursor;
+}
+
+template <typename Layout>
+void QMainWindowLayoutSeparatorHelper<Layout>::adjustCursor(const QPoint &pos)
+{
+    QWidget *w = layout()->window();
+    hoverPos = pos;
+
+    if (pos == QPoint(0, 0)) {
+        if (!hoverSeparator.isEmpty())
+            w->update(layout()->dockAreaLayoutInfo()->separatorRect(hoverSeparator));
+        hoverSeparator.clear();
+
+        if (cursorAdjusted) {
+            cursorAdjusted = false;
+            if (hasOldCursor)
+                w->setCursor(oldCursor);
+            else
+                w->unsetCursor();
+        }
+    } else if (movingSeparator.isEmpty()) { // Don't change cursor when moving separator
+        QList<int> pathToSeparator = layout()->dockAreaLayoutInfo()->findSeparator(pos);
+
+        if (pathToSeparator != hoverSeparator) {
+            if (!hoverSeparator.isEmpty())
+                w->update(layout()->dockAreaLayoutInfo()->separatorRect(hoverSeparator));
+
+            hoverSeparator = pathToSeparator;
+
+            if (hoverSeparator.isEmpty()) {
+                if (cursorAdjusted) {
+                    cursorAdjusted = false;
+                    if (hasOldCursor)
+                        w->setCursor(oldCursor);
+                    else
+                        w->unsetCursor();
+                }
+            } else {
+                w->update(layout()->dockAreaLayoutInfo()->separatorRect(hoverSeparator));
+                if (!cursorAdjusted) {
+                    oldCursor = w->cursor();
+                    hasOldCursor = w->testAttribute(Qt::WA_SetCursor);
+                }
+                adjustedCursor = separatorCursor(hoverSeparator);
+                w->setCursor(adjustedCursor);
+                cursorAdjusted = true;
+            }
+        }
+    }
+}
+
+template <typename Layout>
+bool QMainWindowLayoutSeparatorHelper<Layout>::windowEvent(QEvent *event)
+{
+    QWidget *w = window();
+    switch (event->type()) {
+    case QEvent::Paint: {
+        QPainter p(w);
+        QRegion r = static_cast<QPaintEvent *>(event)->region();
+        layout()->dockAreaLayoutInfo()->paintSeparators(&p, w, r, hoverPos);
+        break;
+    }
+
+#ifndef QT_NO_CURSOR
+    case QEvent::HoverMove: {
+        adjustCursor(static_cast<QHoverEvent *>(event)->pos());
+        break;
+    }
+
+    // We don't want QWidget to call update() on the entire QMainWindow
+    // on HoverEnter and HoverLeave, hence accept the event (return true).
+    case QEvent::HoverEnter:
+        return true;
+    case QEvent::HoverLeave:
+        adjustCursor(QPoint(0, 0));
+        return true;
+    case QEvent::ShortcutOverride: // when a menu pops up
+        adjustCursor(QPoint(0, 0));
+        break;
+#endif // QT_NO_CURSOR
+
+    case QEvent::MouseButtonPress: {
+        QMouseEvent *e = static_cast<QMouseEvent *>(event);
+        if (e->button() == Qt::LeftButton && startSeparatorMove(e->pos())) {
+            // The click was on a separator, eat this event
+            e->accept();
+            return true;
+        }
+        break;
+    }
+
+    case QEvent::MouseMove: {
+        QMouseEvent *e = static_cast<QMouseEvent *>(event);
+
+#ifndef QT_NO_CURSOR
+        adjustCursor(e->pos());
+#endif
+        if (e->buttons() & Qt::LeftButton) {
+            if (separatorMove(e->pos())) {
+                // We're moving a separator, eat this event
+                e->accept();
+                return true;
+            }
+        }
+
+        break;
+    }
+
+    case QEvent::MouseButtonRelease: {
+        QMouseEvent *e = static_cast<QMouseEvent *>(event);
+        if (endSeparatorMove(e->pos())) {
+            // We've released a separator, eat this event
+            e->accept();
+            return true;
+        }
+        break;
+    }
+
+#if !defined(QT_NO_CURSOR)
+    case QEvent::CursorChange:
+        // CursorChange events are triggered as mouse moves to new widgets even
+        // if the cursor doesn't actually change, so do not change oldCursor if
+        // the "changed" cursor has same shape as adjusted cursor.
+        if (cursorAdjusted && adjustedCursor.shape() != w->cursor().shape()) {
+            oldCursor = w->cursor();
+            hasOldCursor = w->testAttribute(Qt::WA_SetCursor);
+
+            // Ensure our adjusted cursor stays visible
+            w->setCursor(adjustedCursor);
+        }
+        break;
+#endif
+    case QEvent::Timer:
+        if (static_cast<QTimerEvent *>(event)->timerId() == separatorMoveTimer.timerId()) {
+            // let's move the separators
+            separatorMoveTimer.stop();
+            if (movingSeparator.isEmpty())
+                return true;
+            if (movingSeparatorOrigin == movingSeparatorPos)
+                return true;
+
+            // when moving the separator, we need to update the previous position
+            window()->update(layout()->dockAreaLayoutInfo()->separatorRegion());
+
+            layout()->layoutState = layout()->savedState;
+            layout()->dockAreaLayoutInfo()->separatorMove(movingSeparator, movingSeparatorOrigin,
+                                                          movingSeparatorPos);
+            movingSeparatorPos = movingSeparatorOrigin;
+            return true;
+        }
+        break;
+    default:
+        break;
+    }
+    return false;
+}
+
+template <typename Layout>
+bool QMainWindowLayoutSeparatorHelper<Layout>::startSeparatorMove(const QPoint &pos)
+{
+    movingSeparator = layout()->dockAreaLayoutInfo()->findSeparator(pos);
+
+    if (movingSeparator.isEmpty())
+        return false;
+
+    layout()->savedState = layout()->layoutState;
+    movingSeparatorPos = movingSeparatorOrigin = pos;
+
+    return true;
+}
+template <typename Layout>
+bool QMainWindowLayoutSeparatorHelper<Layout>::separatorMove(const QPoint &pos)
+{
+    if (movingSeparator.isEmpty())
+        return false;
+    movingSeparatorPos = pos;
+    separatorMoveTimer.start(0, window());
+    return true;
+}
+template <typename Layout>
+bool QMainWindowLayoutSeparatorHelper<Layout>::endSeparatorMove(const QPoint &)
+{
+    if (movingSeparator.isEmpty())
+        return false;
+    movingSeparator.clear();
+    layout()->savedState.clear();
+    return true;
+}
+#endif
+
 #ifndef QT_NO_DOCKWIDGET
 class QDockWidgetGroupWindow : public QWidget
 {
@@ -168,7 +415,9 @@ public:
     bool restoreState(QDataStream &stream, const QMainWindowLayoutState &oldState);
 };
 
-class Q_AUTOTEST_EXPORT QMainWindowLayout : public QLayout
+class Q_AUTOTEST_EXPORT QMainWindowLayout
+    : public QLayout,
+      public QMainWindowLayoutSeparatorHelper<QMainWindowLayout>
 {
     Q_OBJECT
 
@@ -181,8 +430,6 @@ public:
     QMainWindow::DockOptions dockOptions;
     void setDockOptions(QMainWindow::DockOptions opts);
 
-    void timerEvent(QTimerEvent *e) Q_DECL_OVERRIDE;
-
     // status bar
 
     QLayoutItem *statusbar;
@@ -260,15 +507,7 @@ public:
 #endif // QT_NO_TABWIDGET
 #endif // QT_NO_TABBAR
 
-    // separators
-
-    QList<int> movingSeparator;
-    QPoint movingSeparatorOrigin, movingSeparatorPos;
-    QBasicTimer separatorMoveTimer;
-
-    bool startSeparatorMove(const QPoint &pos);
-    bool separatorMove(const QPoint &pos);
-    bool endSeparatorMove(const QPoint &pos);
+    QDockAreaLayout *dockAreaLayoutInfo() { return &layoutState.dockAreaLayout; }
     void keepSize(QDockWidget *w);
 #endif // QT_NO_DOCKWIDGET