add basic multi screen support

--the user can change the dock's screen
from the configuration window... Optimizations
must be made of course in the future...

app/dockcorona.cpp

@@ -382,8 +382,26 @@ void DockCorona::addDock(Plasma::Containment *containment)
             return;
     }
 
+    QScreen *nextScreen{qGuiApp->primaryScreen()};
+
+    if (containment->screen() >= 0) {
+        QString connector = m_screenPool->connector(containment->screen());
+        bool found{false};
+        foreach(auto scr, qGuiApp->screens()){
+            if (scr && scr->name() == connector){
+                found=true;
+                nextScreen = scr;
+                break;
+            }
+        }
+
+        if (!found)
+            return;
+    }
+
     qDebug() << "Adding dock for container...";
-    auto dockView = new DockView(this);
+    qDebug() << "screen!!! :" << containment->screen() << " - "<<m_screenPool->connector(containment->screen());
+    auto dockView = new DockView(this, nextScreen);
     dockView->init();
     dockView->setContainment(containment);
     connect(containment, &QObject::destroyed, this, &DockCorona::dockContainmentDestroyed);

app/dockview.cpp

@@ -59,9 +59,9 @@ DockView::DockView(Plasma::Corona *corona, QScreen *targetScreen)
                      | Qt::WindowDoesNotAcceptFocus);
 
     if (targetScreen)
-        adaptToScreen(targetScreen);
+        setScreenToFollow(targetScreen);
     else
-        adaptToScreen(qGuiApp->primaryScreen());
+        setScreenToFollow(qGuiApp->primaryScreen());
 
     connect(this, &DockView::containmentChanged
     , this, [&]() {
@@ -112,7 +112,8 @@ DockView::~DockView()
 
 void DockView::init()
 {
-    //connect(this, &DockView::screenChanged, this, &DockView::syncGeometry);
+    connect(this, &QQuickWindow::screenChanged, this, &DockView::screenChanged);
+
     connect(qGuiApp, &QGuiApplication::primaryScreenChanged, this, &DockView::syncGeometry, Qt::UniqueConnection);
     connect(this, &DockView::screenGeometryChanged, this, &DockView::syncGeometry);
     connect(this, &QQuickWindow::widthChanged, this, &DockView::widthChanged);
@@ -139,7 +140,7 @@ void DockView::init()
 
 void DockView::adaptToScreen(QScreen *screen)
 {
-    if (!screen) {
+/*    if (!screen) {
         return;
     }
 
@@ -150,12 +151,63 @@ void DockView::adaptToScreen(QScreen *screen)
     //FIXME:: This code in a multi-screen environment that
     //primary screen is not set to 0 it creates an endless
     //showing loop at startup (catch-up race) between screen:0 and primaryScreen
+    if (this->containment())
+        this->containment()->reactToScreenChange();
+
+    syncGeometry(); */
+}
+
+void DockView::setCurrentScreen(const QString id)
+{
+    if (!m_screenToFollow || m_screenToFollow->name() == id){
+        return;
+    }
+
+    QScreen *nextScreen{nullptr};
+
+    foreach(auto scr, qGuiApp->screens()){
+        if (scr && scr->name() == id){
+            nextScreen = scr;
+            break;
+        }
+    }
+
+    if (nextScreen)
+        setScreenToFollow(nextScreen);
+}
+
+void DockView::setScreenToFollow(QScreen *screen)
+{
+    if (!screen || m_screenToFollow == screen) {
+        return;
+    }
+
+    m_screenToFollow = screen;
+
+    qDebug() << "adapting to screen...";
+
+    setScreen(screen);
+
     if (this->containment())
         this->containment()->reactToScreenChange();
 
     syncGeometry();
 }
 
+void DockView::screenChanged(QScreen *scr)
+{
+    if (!scr || m_screenToFollow == scr) {
+        return;
+    }
+
+    emit docksCountChanged();
+
+   //IMPORTAT!!! this code creates crashes when changing plasma
+   //layouts it needs inverstigation!!!
+   // setScreen(m_screenToFollow);
+   // syncGeometry();
+}
+
 void DockView::addNewDock()
 {
     auto *dockCorona = qobject_cast<DockCorona *>(this->corona());
@@ -193,6 +245,14 @@ QScreen *DockView::atScreens(QQmlListProperty<QScreen> *property, int index)
     return qGuiApp->screens().at(index);
 }
 
+QString DockView::currentScreen() const
+{
+    if (m_screenToFollow)
+        return m_screenToFollow->name();
+
+    return "";
+}
+
 void DockView::showConfigurationInterface(Plasma::Applet *applet)
 {
     if (!applet || !applet->containment())
@@ -365,8 +425,11 @@ inline void DockView::syncGeometry()
     if (!(this->screen() && this->containment()))
         return;
 
-    if (qGuiApp->primaryScreen() && screen() != qGuiApp->primaryScreen()){
-        setScreen(qGuiApp->primaryScreen());
+    //if (qGuiApp->primaryScreen() && screen() != qGuiApp->primaryScreen()){
+    //    setScreen(qGuiApp->primaryScreen());
+    //}
+    if (screen() != m_screenToFollow) {
+        setScreenToFollow(m_screenToFollow);
     }
 
     updateEnabledBorders();

app/dockview.h

@@ -53,6 +53,8 @@ class DockView : public PlasmaQuick::ContainmentView {
     Q_PROPERTY(int normalThickness READ normalThickness WRITE setNormalThickness NOTIFY normalThicknessChanged)
     Q_PROPERTY(int shadow READ shadow WRITE setShadow NOTIFY shadowChanged)
 
+    Q_PROPERTY(QString currentScreen READ currentScreen NOTIFY currentScreenChanged)
+
     Q_PROPERTY(float maxLength READ maxLength WRITE setMaxLength NOTIFY maxLengthChanged)
 
     Q_PROPERTY(Plasma::FrameSvg::EnabledBorders enabledBorders READ enabledBorders NOTIFY enabledBordersChanged)
@@ -68,6 +70,7 @@ public:
     void init();
 
     void adaptToScreen(QScreen *screen);
+    void setScreenToFollow(QScreen *screen);
 
     void resizeWindow();
     void syncGeometry();
@@ -102,6 +105,8 @@ public:
 
     Plasma::FrameSvg::EnabledBorders enabledBorders() const;
 
+    QString currentScreen() const;
+
     VisibilityManager * visibility() const;
 
     QQmlListProperty<QScreen> screens();
@@ -115,6 +120,7 @@ public slots:
     Q_INVOKABLE QList<int> freeEdges() const;
     Q_INVOKABLE QVariantList containmentActions();
     Q_INVOKABLE void setLocalDockGeometry(const QRect &geometry);
+    Q_INVOKABLE void setCurrentScreen(const QString id);
     Q_INVOKABLE bool tasksPresent();
     Q_INVOKABLE void updateEnabledBorders();
 
@@ -134,6 +140,7 @@ signals:
     void eventTriggered(QEvent *ev);
 
     void alignmentChanged();
+    void currentScreenChanged();
     void dockLocationChanged();
     void docksCountChanged();
     void drawShadowsChanged();
@@ -152,6 +159,7 @@ signals:
 private slots:
     void menuAboutToHide();
     void statusChanged(Plasma::Types::ItemStatus);
+    void screenChanged(QScreen *screen);
 
 private:
     void addAppletActions(QMenu *desktopMenu, Plasma::Applet *applet, QEvent *event);
@@ -175,6 +183,7 @@ private:
     QMenu *m_contextMenu;
     QPointer<PlasmaQuick::ConfigView> m_configView;
     QPointer<VisibilityManager> m_visibility;
+    QPointer<QScreen> m_screenToFollow;
 
     //only for the mask, not to actually paint
     Plasma::FrameSvg::EnabledBorders m_enabledBorders = Plasma::FrameSvg::AllBorders;

shell/contents/configuration/BehaviorConfig.qml

@@ -45,12 +45,58 @@ PlasmaComponents.Page {
         //! BEGIN: Location
         ColumnLayout {
             Layout.fillWidth: true
-            spacing: units.smallSpacing
+            spacing: units.largeSpacing
 
             Header {
                 text: i18n("Location")
             }
 
+            RowLayout {
+                Layout.fillWidth: true
+                Layout.leftMargin: units.smallSpacing * 2
+                Layout.rightMargin: units.smallSpacing * 2
+                spacing: 1
+
+                Component.onCompleted: {
+                    if (dock.screens.length > 1)
+                        visible = true;
+                    else
+                        visible = false;
+                }
+
+                PlasmaComponents.Label {
+                    text: i18n("Screen:")
+                    Layout.alignment: Qt.AlignRight
+                }
+
+                PlasmaComponents.ComboBox {
+                    id: screenCmb
+                    Layout.fillWidth: true
+                    Component.onCompleted: {
+                        var screens = []
+
+                       // screens.push(i18n("On Primary"));
+
+                        for (var i = 0; i < dock.screens.length; i++) {
+                            screens.push(dock.screens[i].name)
+                        }
+
+                        model = screens;
+
+                        currentIndex = find(dock.currentScreen);
+                        console.log(dock.currentScreen);
+                    }
+
+                    onCurrentIndexChanged: {
+                        console.log("current index changed!!! :"+ currentIndex);
+                        if (currentIndex !== find(dock.currentScreen)) {
+                            console.log("screen must be changed...");
+                            dock.setCurrentScreen(currentText);
+                        }
+                    }
+                }
+            }
+
             RowLayout {
                 id: locationLayout
                 Layout.fillWidth: true