Add detachable tabs for the log windows.

src/QDetachTabWidget.cpp

@@ -0,0 +1,187 @@
+#include "QDetachTabWidget.h"
+#include <QtWidgets/QTabBar>
+#include <QtWidgets/QMenu>
+#include <QtWidgets/QAction>
+#include <QtGui/QCursor>
+#include <QtCore/QDebug>
+
+QDetachTabWidget::QDetachTabWidget(QWidget* parent) : QTabWidget(parent) {
+
+    QObject::connect(tabBar(), &QTabBar::tabBarDoubleClicked,           this, &QDetachTabWidget::handleShowContextMenu);
+    QObject::connect(this,     &QTabWidget::tabCloseRequested,          this, &QDetachTabWidget::handleTabClosedRequested);
+}
+
+void QDetachTabWidget::closeEvent (QCloseEvent* e) {
+
+    auto it = _tabInfo.begin();
+
+    while (it != _tabInfo.end()) {
+
+        delete it->_widget;
+
+        it = _tabInfo.erase(it); // Erase current tab and point to the next one.
+    }
+
+    QTabWidget::closeEvent(e);
+}
+
+void QDetachTabWidget::handleShowContextMenu(int tabIndex) {
+
+    QMenu menu("Window Action", this);
+
+    QAction* detachAction   = menu.addAction(tr("Detach"));
+    QAction* reattachAction = menu.addAction(tr("Reattach"));
+
+    QAction* action = menu.exec(QCursor::pos());
+
+    //
+    // Handle detaching a tab.
+    //
+    if (action == detachAction) {
+
+        // Get the tab the user selected.
+        QWidget* w = widget(tabIndex);
+
+        // It can't be a 'placeholder' as it was already detached.
+        if (w->objectName() == "QDetachTabWidgetPlaceholder") {
+            return;
+        }
+
+        // Create a blank 'placeholder' tab.
+        QWidget* placeholder = new QWidget;
+        placeholder->setObjectName("QDetachTabWidgetPlaceholder");
+
+        // Create an entry for the tab cache. Remember the real tab and the 'placeholder' tab. Plus the tab title.
+        QDetachTabInfo tabinfo(tabText(tabIndex), w, placeholder);
+        _tabInfo.append(tabinfo);
+
+        // Remove the real tab.
+        removeTab(tabIndex);
+
+        // Insert the 'placeholder' in the same position.
+        insertTab(tabIndex, placeholder, tabinfo._title);
+
+        // Tweak the detached tab to make sure it can't be destroyed as it is now a normal window.
+        w->setParent(0);
+        Qt::WindowFlags flags     = w->windowFlags();
+        Qt::WindowFlags closeFlag = Qt::WindowCloseButtonHint;
+        flags = flags & (~closeFlag);
+        w->setWindowFlags(flags);
+        w->setWindowTitle(tabinfo._title);
+        w->show();
+
+        // Set the tabwidget to the placeholder tab.
+        setCurrentIndex(tabIndex);
+    }
+
+    //
+    // Handle reattaching a tab.
+    //
+    if (action == reattachAction) {
+
+        // Get the tab the user selected to re-attach.
+        QWidget* w = widget(tabIndex);
+
+        // It must be a 'placeholder'
+        if (w->objectName() != "QDetachTabWidgetPlaceholder") {
+            return;
+        }
+
+        // Look for the 'placeholder' tab in the tab cache.
+        // Note, we do a scan of the cache because a QTabWidget can have isMovable() enabled.
+        // Using 'tabindex' is not always reliable.
+        QList<QDetachTabInfo>::iterator it = findPlaceholderWidget(w);
+        if (it == _tabInfo.end()) {
+            return;
+        }
+
+        // Remove the 'placeholder' tab.
+        removeTab(tabIndex); delete w;
+
+        // Insert the real tab in the same position.
+        insertTab(tabIndex, it->_widget, it->_title);
+
+        // Set the tabwidget to the real tab.
+        setCurrentIndex(tabIndex);
+
+        // Delete the entry from the tab cache.
+        _tabInfo.erase(it);
+    }
+}
+
+//
+// The QDetachTabWidget listens for 'tabCloseRequests'. Only to
+// reattach the widget, if necessary. Normally, you derive from
+// QDetachTabWidget and add signal/connect to do the same. I'm
+// counting on mine happening first.
+//
+void QDetachTabWidget::handleTabClosedRequested (int tabIndex) {
+
+    // Get the widget to be closed.
+    QWidget* w = widget(tabIndex);
+
+    //qDebug() << "QDetachTabWidget::handleTabClosedRequested:" << tabIndex << w->objectName();
+
+    // If the widget is a 'placeholder', reattach the real widget and delete the 'placeholder'.
+    if (w->objectName() == "QDetachTabWidgetPlaceholder") {
+
+        //qDebug() << "Reattaching detached tab.";
+
+        // Look for the 'placeholder' tab in the tab cache.
+        // Note, we do a scan of the cache because a QTabWidget can have isMovable() enabled.
+        // Using 'tabindex' is not always reliable.
+        QList<QDetachTabInfo>::iterator it = findPlaceholderWidget(w);
+        if (it == _tabInfo.end()) {
+            return;
+        }
+
+        // Remove the 'placeholder' tab.
+        removeTab(tabIndex); delete w;
+
+        // Insert the real tab in the same position.
+        insertTab(tabIndex, it->_widget, it->_title);
+
+        // Set the tabwidget to the real tab.
+        setCurrentIndex(tabIndex);
+
+        // Delete the entry from the tab cache.
+        _tabInfo.erase(it);
+    }
+}
+
+//
+// Look for the real widget in the tab cache.
+//
+QList<QDetachTabInfo>::iterator QDetachTabWidget::findWidget (QWidget* widget) {
+
+    QList<QDetachTabInfo>::iterator it = _tabInfo.begin();
+
+    while (it != _tabInfo.end()) {
+        if (it->_widget == widget) {
+            return it;
+        }
+
+        it++;
+    }
+
+    return it;
+}
+
+//
+// Look for the 'placeholder' widget in the tab cache.
+//
+QList<QDetachTabInfo>::iterator QDetachTabWidget::findPlaceholderWidget (QWidget* widget) {
+
+    QList<QDetachTabInfo>::iterator it = _tabInfo.begin();
+
+    while (it != _tabInfo.end()) {
+        if (it->_placeholderWidget == widget) {
+            return it;
+        }
+
+        it++;
+    }
+
+    return it;
+}
+