Don't use deprecated QDesktopWidget

Summary:
QApplication::desktop() is deprecated. It is advised to use
QGuiApplication::screens() instead.

Reviewers: #kwin, apol

Reviewed By: apol

Subscribers: apol, davidedmundson, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D22379

kcmkwin/kwinoptions/windows.cpp

@@ -119,7 +119,7 @@ KFocusConfig::KFocusConfig(bool _standAlone, KConfig *_config, QWidget * parent)
 
 void KFocusConfig::updateMultiScreen()
 {
-    m_ui->multiscreenBox->setVisible(QApplication::desktop()->screenCount() > 1);
+    m_ui->multiscreenBox->setVisible(QApplication::screens().count() > 1);
 }
 
 

kcmkwin/kwinscreenedges/monitor.cpp

@@ -26,20 +26,45 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <QApplication>
 #include <QDebug>
-#include <QDesktopWidget>
 #include <QGraphicsView>
 #include <QGraphicsScene>
 #include <QGraphicsSceneEvent>
 #include <QMenu>
+#include <QScreen>
+#include <QWindow>
 
 namespace KWin
 {
 
+static QWindow *windowFromWidget(const QWidget *widget)
+{
+    QWindow *windowHandle = widget->windowHandle();
+    if (windowHandle) {
+        return windowHandle;
+    }
+
+    const QWidget *nativeParent = widget->nativeParentWidget();
+    if (nativeParent) {
+        return nativeParent->windowHandle();
+    }
+
+    return nullptr;
+}
+
+static QScreen *screenFromWidget(const QWidget *widget)
+{
+    const QWindow *windowHandle = windowFromWidget(widget);
+    if (windowHandle && windowHandle->screen()) {
+        return windowHandle->screen();
+    }
+
+    return QGuiApplication::primaryScreen();
+}
+
 Monitor::Monitor(QWidget* parent)
     : ScreenPreviewWidget(parent)
 {
-    QDesktopWidget *desktop = QApplication::desktop();
-    QRect avail = desktop->availableGeometry(desktop->screenNumber(this));
+    QRect avail = screenFromWidget(this)->geometry();
     setRatio((qreal)avail.width() / (qreal)avail.height());
     for (int i = 0;
             i < 8;

kcmkwin/kwintabbox/layoutpreview.cpp

@@ -25,6 +25,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QDesktopWidget>
 #include <QQmlEngine>
 #include <QQmlContext>
+#include <QScreen>
 #include <QStandardPaths>
 #include <KConfigGroup>
 #include <KDesktopFile>
@@ -243,7 +244,8 @@ void SwitcherItem::setCurrentIndex(int index)
 
 QRect SwitcherItem::screenGeometry() const
 {
-    return qApp->desktop()->screenGeometry(qApp->desktop()->primaryScreen());
+    const QScreen *primaryScreen = qApp->primaryScreen();
+    return primaryScreen->geometry();
 }
 
 void SwitcherItem::incrementIndex()

kcmkwin/kwintabbox/main.cpp

@@ -145,7 +145,7 @@ KWinTabBoxConfig::KWinTabBoxConfig(QWidget* parent, const QVariantList& args)
         connect(ui[i]->otherActivities, SIGNAL(clicked(bool)), SLOT(changed()));
 
         connect(ui[i]->filterScreens, SIGNAL(clicked(bool)), SLOT(changed()));
-        if (QApplication::desktop()->screenCount() < 2) {
+        if (QApplication::screens().count() < 2) {
             ui[i]->filterScreens->hide();
             ui[i]->screenFilter->hide();
         } else {