Implement QDesktopWidget::screenCountChanged signal on desktop platforms,

and add manual testcase.

Provide replacement "screenCount" for numScreens and document numScreens
as obsolete to be more consistent with other APIs.

10 files changed, 323 insertions, 81 deletions

diff --git a/dist/changes-4.6.0 b/dist/changes-4.6.0
index 4c7bf52..5e211ff 100644
--- a/dist/changes-4.6.0
+++ b/dist/changes-4.6.0
@@ -68,3 +68,7 @@ information about a particular change.
       to the item's position and transformation, you can set the flag
       QGraphicsItem::ItemSendsGeometryChanges (which is enabled by default by
       QGraphicsWidget and QGraphicsProxyWidget).
+
+- QDesktopWidget on X11 no longer emits the resized(int) signal when screens
+  are added or removed. This was not done on other platforms. Use the 
+  screenCountChanged signal instead
diff --git a/doc/src/qdesktopwidget.qdoc b/doc/src/qdesktopwidget.qdoc
index 1158904..383ccfc 100644
--- a/doc/src/qdesktopwidget.qdoc
+++ b/doc/src/qdesktopwidget.qdoc
@@ -54,9 +54,9 @@
     Systems with more than one graphics card and monitor can manage the
     physical screen space available either as multiple desktops, or as a
     large virtual desktop, which usually has the size of the bounding
-    rectangle of all the screens (see isVirtualDesktop()). For an
+    rectangle of all the screens (see virtualDesktop). For an
     application, one of the available screens is the primary screen, i.e.
-    the screen where the main widget resides (see primaryScreen()). All
+    the screen where the main widget resides (see primaryScreen). All
     windows opened in the context of the application should be
     constrained to the boundaries of the primary screen; for example,
     it would be inconvenient if a dialog box popped up on a different
@@ -64,16 +64,16 @@
 
     The QDesktopWidget provides information about the geometry of the
     available screens with screenGeometry(). The number of screens
-    available is returned by numScreens(). The screen number that a
-    particular point or widget is located in is returned by
-    screenNumber().
+    available is returned by screenCount, and the screenCountChanged
+    signal is emitted when screens are added or removed during runtime.
+    The screen number that a particular point or widget is located in
+    is returned by screenNumber().
 
     Widgets provided by Qt use this class, for example, to place
     tooltips, menus and dialog boxes according to the parent or
-    application widget.
-
-    Applications can use this class to save window positions, or to place
-    child widgets on one screen.
+    application widget. Applications can use this class to save window
+    positions, or to place child widgets and dialogs on one particular
+    screen.
 
     \img qdesktopwidget.png Managing Multiple Screens
 
@@ -115,30 +115,15 @@
 */
 
 /*!
-    \fn bool QDesktopWidget::isVirtualDesktop() const
-
-    Returns true if the system manages the available screens in a
-    virtual desktop; otherwise returns false.
-
-    For virtual desktops, screen() will always return the same widget.
-    The size of the virtual desktop is the size of this desktop
-    widget.
-*/
-
-/*!
-    \fn int QDesktopWidget::primaryScreen() const
-
-    Returns the index of the primary screen.
-
-    \sa numScreens()
-*/
-
-/*!
     \fn int QDesktopWidget::numScreens() const
-
+    
     Returns the number of available screens.
+    
+    \obsolete
+
+    This function is deprecated. Use screenCount instead.
 
-    \sa primaryScreen()
+    \sa primaryScreen
 */
 
 /*!
@@ -146,13 +131,12 @@
 
     Returns a widget that represents the screen with index \a screen
     (a value of -1 means the default screen).
-    
 
     If the system uses a virtual desktop, the returned widget will
     have the geometry of the entire virtual desktop; i.e., bounding
     every \a screen.
 
-    \sa primaryScreen(), numScreens(), isVirtualDesktop()
+    \sa primaryScreen, screenCount, virtualDesktop
 */
 
 /*!
@@ -216,7 +200,7 @@
     Returns the index of the screen that contains the largest
     part of \a widget, or -1 if the widget not on a screen.
 
-    \sa primaryScreen()
+    \sa primaryScreen
 */
 
 /*!
@@ -226,7 +210,7 @@
     Returns the index of the screen that contains the \a point, or the
     screen which is the shortest distance from the \a point.
 
-    \sa primaryScreen()
+    \sa primaryScreen
 */
 
 /*!
@@ -245,3 +229,34 @@
 
     This signal is emitted when the work area available on \a screen changes.
 */
+
+/*!
+    \property QDesktopWidget::screenCount
+    \brief the number of screens currently available on the system.
+    
+    \sa screenCountChanged()
+*/
+
+/*!
+    \property QDesktopWidget::primaryScreen
+    \brief the index of the screen that is configured to be the primary screen
+    on the system.
+*/
+
+/*!
+    \property QDesktopWidget::virtualDesktop
+
+    \brief if the system manages the available screens in a virtual desktop.
+
+    For virtual desktops, screen() will always return the same widget.
+    The size of the virtual desktop is the size of this desktop
+    widget.
+*/
+
+/*!
+    \fn void QDesktopWidget::screenCountChanged(int newCount)
+
+    This signal is emitted when the number of screens changes to \a newCount.
+    
+    \sa screenCount
+*/
diff --git a/src/gui/kernel/qapplication_x11.cpp b/src/gui/kernel/qapplication_x11.cpp
index cc41299..a07ccdd 100644
--- a/src/gui/kernel/qapplication_x11.cpp
+++ b/src/gui/kernel/qapplication_x11.cpp
@@ -3441,19 +3441,10 @@ int QApplication::x11ProcessEvent(XEvent* event)
         QSize oldSize(w->size());
         w->data->crect.setWidth(DisplayWidth(X11->display, scr));
         w->data->crect.setHeight(DisplayHeight(X11->display, scr));
-        QVarLengthArray<QRect> oldSizes(desktop->numScreens());
-        for (int i = 0; i < desktop->numScreens(); ++i)
-            oldSizes[i] = desktop->screenGeometry(i);
         QResizeEvent e(w->size(), oldSize);
         QApplication::sendEvent(w, &e);
-        for (int i = 0; i < qMin(oldSizes.count(), desktop->numScreens()); ++i) {
-            if (oldSizes[i] != desktop->screenGeometry(i))
-                emit desktop->resized(i);
-        }
-        for (int i = oldSizes.count(); i < desktop->numScreens(); ++i)
-            emit desktop->resized(i); // added
-        for (int i = desktop->numScreens(); i < oldSizes.count(); ++i)
-            emit desktop->resized(i); // removed
+        if (w != desktop)
+            QApplication::sendEvent(desktop, &e);
     }
 #endif // QT_NO_XRANDR
 
diff --git a/src/gui/kernel/qdesktopwidget.h b/src/gui/kernel/qdesktopwidget.h
index 470f10a..5ac953c 100644
--- a/src/gui/kernel/qdesktopwidget.h
+++ b/src/gui/kernel/qdesktopwidget.h
@@ -85,6 +85,7 @@ public:
 Q_SIGNALS:
     void resized(int);
     void workAreaResized(int);
+    void screenCountChanged(int);
 
 protected:
     void resizeEvent(QResizeEvent *e);
@@ -97,6 +98,9 @@ private:
     friend class QApplicationPrivate;
 };
 
+inline int QDesktopWidget::screenCount() const
+{ return numScreens(); }
+
 QT_END_NAMESPACE
 
 QT_END_HEADER
diff --git a/src/gui/kernel/qdesktopwidget_mac.mm b/src/gui/kernel/qdesktopwidget_mac.mm
index 2489fe4..7dd74da 100644
--- a/src/gui/kernel/qdesktopwidget_mac.mm
+++ b/src/gui/kernel/qdesktopwidget_mac.mm
@@ -97,15 +97,13 @@ QT_USE_NAMESPACE
 Q_GLOBAL_STATIC(QDesktopWidgetImplementation, qdesktopWidgetImplementation)
 
 QDesktopWidgetImplementation::QDesktopWidgetImplementation()
-    : appScreen(0), displays(0)
+    : appScreen(0)
 {
     onResize();
 }
 
 QDesktopWidgetImplementation::~QDesktopWidgetImplementation()
 {
-    if (displays)
-        [displays release];
 }
 
 QDesktopWidgetImplementation *QDesktopWidgetImplementation::instance()
@@ -118,13 +116,7 @@ QRect QDesktopWidgetImplementation::availableRect(int screenIndex) const
     if (screenIndex < 0 || screenIndex >= screenCount)
         screenIndex = appScreen;
 
-    NSRect r = [[displays objectAtIndex:screenIndex] visibleFrame];
-    NSRect primaryRect = [[displays objectAtIndex:0] frame];
-
-    const int flippedY = - r.origin.y +                // account for position offset and
-              primaryRect.size.height - r.size.height; // height difference.
-    return QRectF(r.origin.x, flippedY,
-            r.size.width, r.size.height).toRect();
+	return availableRects[screenIndex].toRect(); 
 }
 
 QRect QDesktopWidgetImplementation::screenRect(int screenIndex) const
@@ -132,22 +124,28 @@ QRect QDesktopWidgetImplementation::screenRect(int screenIndex) const
     if (screenIndex < 0 || screenIndex >= screenCount)
         screenIndex = appScreen;
 
-    NSRect r = [[displays objectAtIndex:screenIndex] frame];
-    NSRect primaryRect = [[displays objectAtIndex:0] frame];
-
-    const int flippedY = - r.origin.y +                // account for position offset and
-              primaryRect.size.height - r.size.height; // height difference.
-    return QRectF(r.origin.x, flippedY,
-            r.size.width, r.size.height).toRect();
+    return screenRects[screenIndex].toRect();
 }
 
 void QDesktopWidgetImplementation::onResize()
 {
-    if (displays)
-        [displays release];
-
-    displays = [[NSScreen screens] retain];
-    screenCount = [displays count];
+    QMacCocoaAutoReleasePool pool; 
+    NSArray *displays = [NSScreen screens]; 
+    screenCount = [displays count]; 
+ 
+    screenRects.clear(); 
+    availableRects.clear(); 
+    NSRect primaryRect = [[displays objectAtIndex:0] frame]; 
+    for (int i = 0; i<screenCount; i++) { 
+        NSRect r = [[displays objectAtIndex:i] frame]; 
+        const int flippedY = - r.origin.y +            // account for position offset and 
+              primaryRect.size.height - r.size.height; // height difference. 
+        screenRects.append(QRectF(r.origin.x, flippedY, 
+            r.size.width, r.size.height)); 
+        r = [[displays objectAtIndex:i] visibleFrame]; 
+        availableRects.append(QRectF(r.origin.x, flippedY, 
+                r.size.width, r.size.height)); 
+    } 
 }
 
 
@@ -195,7 +193,7 @@ const QRect QDesktopWidget::screenGeometry(int screen) const
 
 int QDesktopWidget::screenNumber(const QWidget *widget) const
 {
-   QDesktopWidgetImplementation *d = qdesktopWidgetImplementation();
+    QDesktopWidgetImplementation *d = qdesktopWidgetImplementation();
     if (!widget)
         return d->appScreen;
     QRect frame = widget->frameGeometry();
@@ -216,7 +214,7 @@ int QDesktopWidget::screenNumber(const QWidget *widget) const
 
 int QDesktopWidget::screenNumber(const QPoint &point) const
 {
-   QDesktopWidgetImplementation *d = qdesktopWidgetImplementation();
+    QDesktopWidgetImplementation *d = qdesktopWidgetImplementation();
     int closestScreen = -1;
     int shortestDistance = INT_MAX;
     for (int i = 0; i < d->screenCount; ++i) {
@@ -232,13 +230,25 @@ int QDesktopWidget::screenNumber(const QPoint &point) const
 
 void QDesktopWidget::resizeEvent(QResizeEvent *)
 {
-   QDesktopWidgetImplementation *d = qdesktopWidgetImplementation();
+    QDesktopWidgetImplementation *d = qdesktopWidgetImplementation();
+
+    const int oldScreenCount = d->screenCount;
+    const QVector<QRect> oldRects(d->screenRects);
+    const QVector<QRect> oldWorks(d->availableRects);
 
     d->onResize();
 
-    for (int i = 0; i < d->screenCount; ++i) {
-        emit resized(i);
+    for (int i = 0; i < qMin(oldScreenCount, d->screenCount); ++i) {
+        if (oldRects.at(i) != d->screenRects.at(i))
+            emit resized(i);
+    }
+    for (int i = 0; i < qMin(oldScreenCount, d->screenCount); ++i) {
+        if (oldWorks.at(i) != d->availableRects.at(i))
+            emit workAreaResized(i);
     }
+
+    if (oldscreencount != d->screenCount)
+        emit screenCountChanged(d->screenCount);
 }
 
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qdesktopwidget_mac_p.h b/src/gui/kernel/qdesktopwidget_mac_p.h
index 0fdc455..e9d5d9f 100644
--- a/src/gui/kernel/qdesktopwidget_mac_p.h
+++ b/src/gui/kernel/qdesktopwidget_mac_p.h
@@ -64,7 +64,8 @@ public:
     int appScreen;
     int screenCount;
 
-    NSArray *displays;
+    QVector<QRectF> availableRects; 
+    QVector<QRectF> screenRects; 
 
     QRect availableRect(int screenIndex) const;
     QRect screenRect(int screenIndex) const;
diff --git a/src/gui/kernel/qdesktopwidget_win.cpp b/src/gui/kernel/qdesktopwidget_win.cpp
index fb176b7..a89e08f 100644
--- a/src/gui/kernel/qdesktopwidget_win.cpp
+++ b/src/gui/kernel/qdesktopwidget_win.cpp
@@ -354,10 +354,8 @@ int QDesktopWidget::screenNumber(const QPoint &point) const
 void QDesktopWidget::resizeEvent(QResizeEvent *)
 {
     Q_D(QDesktopWidget);
-    QVector<QRect> oldrects;
-    oldrects = *d->rects;
-    QVector<QRect> oldworkrects;
-    oldworkrects = *d->workrects;
+    const QVector<QRect> oldrects(*d->rects);
+    const QVector<QRect> oldworkrects(*d->workrects);
     int oldscreencount = d->screenCount;
 
     QDesktopWidgetPrivate::cleanup();
@@ -368,18 +366,22 @@ void QDesktopWidget::resizeEvent(QResizeEvent *)
 #endif
 
     for (int i = 0; i < qMin(oldscreencount, d->screenCount); ++i) {
-        QRect oldrect = oldrects[i];
-        QRect newrect = d->rects->at(i);
+        const QRect oldrect = oldrects[i];
+        const QRect newrect = d->rects->at(i);
         if (oldrect != newrect)
             emit resized(i);
     }
 
     for (int j = 0; j < qMin(oldscreencount, d->screenCount); ++j) {
-        QRect oldrect = oldworkrects[j];
-        QRect newrect = d->workrects->at(j);
+        const QRect oldrect = oldworkrects[j];
+        const QRect newrect = d->workrects->at(j);
         if (oldrect != newrect)
             emit workAreaResized(j);
     }
+
+    if (oldscreencount != d->screenCount) {
+        emit screenCountChanged(d->screenCount);
+    }
 }
 
 #ifdef Q_CC_MSVC
diff --git a/src/gui/kernel/qdesktopwidget_x11.cpp b/src/gui/kernel/qdesktopwidget_x11.cpp
index 59d3239..1555fc0 100644
--- a/src/gui/kernel/qdesktopwidget_x11.cpp
+++ b/src/gui/kernel/qdesktopwidget_x11.cpp
@@ -372,7 +372,32 @@ int QDesktopWidget::screenNumber(const QPoint &point) const
 void QDesktopWidget::resizeEvent(QResizeEvent *event)
 {
     Q_D(QDesktopWidget);
+    int oldScreenCount = d->screenCount;
+    QVector<QRect> oldRects(oldScreenCount);
+    QVector<QRect> oldWorks(oldScreenCount);
+    for (int i = 0; i < oldScreenCount; ++i) {
+        oldRects[i] = d->rects[i];
+        oldWorks[i] = d->workareas[i];
+    }
+
     d->init();
+
+    for (int i = 0; i < qMin(oldScreenCount, d->screenCount); ++i) {
+        if (oldRects.at(i) != d->rects[i])
+            emit resized(i);
+    }
+
+    // ### workareas are just reset by init, not filled with new values
+    // ### so this will not work correctly
+    for (int j = 0; j < qMin(oldScreenCount, d->screenCount); ++j) {
+        if (oldWorks.at(j) != d->workareas[j])
+            emit workAreaResized(j);
+    }
+
+    if (oldScreenCount != d->screenCount) {
+        emit screenCountChanged(d->screenCount);
+    }
+
     qt_desktopwidget_workarea_dirty = true;
     QWidget::resizeEvent(event);
 }
diff --git a/tests/manual/qdesktopwidget/main.cpp b/tests/manual/qdesktopwidget/main.cpp
new file mode 100644
index 0000000..1afc82e
--- /dev/null
+++ b/tests/manual/qdesktopwidget/main.cpp
@@ -0,0 +1,188 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at http://www.qtsoftware.com/contact.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtGui>
+
+class DesktopView : public QGraphicsView
+{
+    Q_OBJECT
+public:
+    DesktopView()
+        : that(0)
+    {
+        scene = new QGraphicsScene;
+        setScene(scene);
+
+        QDesktopWidget *desktop = QApplication::desktop();
+        connect(desktop, SIGNAL(resized(int)), this, SLOT(updateScene()));
+        connect(desktop, SIGNAL(workAreaResized(int)), this, SLOT(updateScene()));
+        connect(desktop, SIGNAL(screenCountChanged(int)), this, SLOT(updateScene()));
+
+        updateScene();
+
+        QTransform transform;
+        transform.scale(0.25, 0.25);
+        setTransform(transform);
+
+        setBackgroundBrush(Qt::darkGray);
+    }
+
+protected:
+    void moveEvent(QMoveEvent *e)
+    {
+        if (that) {
+            that->setRect(appRect());
+            scene->update();
+        }
+        QGraphicsView::moveEvent(e);
+    }
+    void resizeEvent(QResizeEvent *e)
+    {
+        if (that) {
+            that->setRect(appRect());
+        }
+        QGraphicsView::resizeEvent(e);
+    }
+
+private slots:
+    void updateScene()
+    {
+        scene->clear();
+
+        const QDesktopWidget *desktop = QApplication::desktop();
+        const bool isVirtualDesktop = desktop->isVirtualDesktop();
+        const int homeScreen = desktop->screenNumber(this);
+
+        QRect sceneRect;
+        int screenCount = desktop->screenCount();
+        for (int s = 0; s < screenCount; ++s) {
+            const bool isPrimary = desktop->primaryScreen() == s;
+            const QRect screenRect = desktop->screenGeometry(s);
+            const QRect workRect = desktop->availableGeometry(s);
+            const QBrush fillBrush = palette().brush(isPrimary ? QPalette::Active : QPalette::Inactive, QPalette::Highlight);
+            QGraphicsRectItem *screen = new QGraphicsRectItem(0, 0, screenRect.width(), screenRect.height());
+
+            if (isVirtualDesktop) {
+                thatRoot = QPoint();
+                screen->setPos(screenRect.x(), screenRect.y());
+            } else {
+               // for non-virtual desktops we assume that screens are
+               // simply next to each other
+                if (s)
+                    screen->setPos(sceneRect.right(), 0);
+                if (s == homeScreen)
+                    thatRoot = screen->pos().toPoint();
+            }
+
+            screen->setBrush(fillBrush);
+            scene->addItem(screen);
+            sceneRect.setLeft(qMin(sceneRect.left(), screenRect.left()));
+            sceneRect.setRight(qMax(sceneRect.right(), screenRect.right()));
+            sceneRect.setTop(qMin(sceneRect.top(), screenRect.top()));
+            sceneRect.setBottom(qMax(sceneRect.bottom(), screenRect.bottom()));
+
+            QGraphicsRectItem *workArea = new QGraphicsRectItem(screen);
+            workArea->setRect(0, 0, workRect.width(), workRect.height());
+            workArea->setPos(workRect.x() - screenRect.x(), workRect.y() - screenRect.y());
+            workArea->setBrush(Qt::white);
+
+            QGraphicsSimpleTextItem *screenNumber = new QGraphicsSimpleTextItem(workArea);
+            screenNumber->setText(QString::number(s));
+            screenNumber->setPen(QPen(Qt::black, 1));
+            screenNumber->setBrush(fillBrush);
+            screenNumber->setFont(QFont("Arial Black", 18));
+            screenNumber->setTransform(QTransform().scale(10, 10));
+            screenNumber->setTransformOrigin(screenNumber->boundingRect().center());
+            QSizeF center = (workRect.size() - screenNumber->boundingRect().size()) / 2;
+            screenNumber->setPos(center.width(), center.height());
+
+            screen->show();
+            screen->setZValue(1);
+        }
+
+        if (isVirtualDesktop) {
+            QGraphicsRectItem *virtualDesktop = new QGraphicsRectItem;
+            virtualDesktop->setRect(sceneRect);
+            virtualDesktop->setPen(QPen(Qt::black));
+            virtualDesktop->setBrush(Qt::DiagCrossPattern);
+            scene->addItem(virtualDesktop);
+            virtualDesktop->setZValue(-1);
+            virtualDesktop->show();
+        }
+
+        that = new QGraphicsRectItem;
+        that->setBrush(Qt::red);
+        that->setOpacity(0.5);
+        that->setZValue(2);
+        that->setRect(appRect());
+        that->show();
+        scene->addItem(that);
+
+        scene->setSceneRect(sceneRect);
+        scene->update();
+    }
+
+    QRect appRect() const
+    {
+        QRect rect = frameGeometry();
+        if (!QApplication::desktop()->isVirtualDesktop()) {
+            rect.translate(thatRoot);
+        }
+        return rect;
+    }
+
+private:
+    QGraphicsScene *scene;
+    QGraphicsRectItem *that;
+    QPoint thatRoot;
+};
+
+#include "main.moc"
+
+int main(int argc, char **argv)
+{
+    QApplication app(argc, argv);
+
+    DesktopView view;
+    view.show();
+
+    return app.exec();
+}
diff --git a/tests/manual/qdesktopwidget/qdesktopwidget.pro b/tests/manual/qdesktopwidget/qdesktopwidget.pro
new file mode 100644
index 0000000..93d56eb
--- /dev/null
+++ b/tests/manual/qdesktopwidget/qdesktopwidget.pro
@@ -0,0 +1,2 @@
+TEMPLATE = app
+SOURCES += main.cpp