QScreen manual test: add MouseMonitor to test multi-screen scenarios

- QMouseEvent::screenPos() should be global desktop position
- QDesktopWidget::screenNumber() should tell the correct screen
- QGuiApplication::topLevelAt(screenPos) should find the window where
  the mouse is clicked

Change-Id: I9a63ab3ee1944b7246551d0f3d5e37f0d2aa5457
Reviewed-by: Błażej Szczygieł <spaz16@wp.pl>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

tests/manual/qscreen/main.cpp

@@ -45,6 +45,61 @@
 #include <QStatusBar>
 #include <QLineEdit>
 #include <QDesktopWidget>
+#include <QPushButton>
+#include <QLabel>
+#include <QMouseEvent>
+
+
+class MouseMonitor : public QLabel {
+    Q_OBJECT
+public:
+    MouseMonitor() : m_grabbed(false) {
+        setMinimumSize(540, 240);
+        setAlignment(Qt::AlignCenter);
+        setMouseTracking(true);
+        setWindowTitle(QLatin1String("Mouse Monitor"));
+        updateText();
+    }
+
+    void updateText() {
+        QString txt = m_grabbed ?
+                QLatin1String("Left-click to test QGuiApplication::topLevelAt(click pos)\nRight-click to ungrab\n") :
+                QLatin1String("Left-click to grab mouse\n");
+        if (!m_cursorPos.isNull()) {
+            txt += QString(QLatin1String("Current mouse position: %1, %2 on screen %3\n"))
+                    .arg(m_cursorPos.x()).arg(m_cursorPos.y()).arg(QApplication::desktop()->screenNumber(m_cursorPos));
+            if (QGuiApplication::mouseButtons() & Qt::LeftButton) {
+                QWindow *win = QGuiApplication::topLevelAt(m_cursorPos);
+                txt += QString(QLatin1String("Top-level window found? %1\n"))
+                        .arg(win ? (win->title().isEmpty() ? "no title" : win->title()) : "none");
+            }
+        }
+        setText(txt);
+    }
+
+protected:
+    void mouseMoveEvent(QMouseEvent *ev) Q_DECL_OVERRIDE {
+        m_cursorPos = ev->screenPos().toPoint();
+        updateText();
+    }
+
+    void mousePressEvent(QMouseEvent *ev) Q_DECL_OVERRIDE {
+        m_cursorPos = ev->screenPos().toPoint();
+        qDebug() << "top level @" << m_cursorPos << ":" << QGuiApplication::topLevelAt(m_cursorPos);
+        updateText();
+        if (!m_grabbed) {
+            grabMouse(Qt::CrossCursor);
+            m_grabbed = true;
+        } else if (ev->button() == Qt::RightButton) {
+            setVisible(false);
+            deleteLater();
+        }
+    }
+
+private:
+    QPoint m_cursorPos;
+    bool m_grabbed;
+};
 
 class ScreenPropertyWatcher : public PropertyWatcher
 {
@@ -101,6 +156,7 @@ public:
 
 protected:
     bool event(QEvent *event) Q_DECL_OVERRIDE;
+    void startMouseMonitor();
 
 private:
     const QString m_annotation;
@@ -124,6 +180,11 @@ ScreenWatcherMainWindow::ScreenWatcherMainWindow(QScreen *screen)
     a = fileMenu->addAction(QLatin1String("Quit"));
     a->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_Q));
     connect(a, SIGNAL(triggered()), qApp, SLOT(quit()));
+
+    QMenu *toolsMenu = menuBar()->addMenu(QLatin1String("&Tools"));
+    a = toolsMenu->addAction(QLatin1String("Mouse Monitor"));
+    a->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_M));
+    connect(a, &QAction::triggered, this, &ScreenWatcherMainWindow::startMouseMonitor);
 }
 
 static inline QString msgScreenChange(const QWidget *w, const QScreen *oldScreen, const QScreen *newScreen)
@@ -159,6 +220,12 @@ bool ScreenWatcherMainWindow::event(QEvent *event)
     return QMainWindow::event(event);
 }
 
+void ScreenWatcherMainWindow::startMouseMonitor()
+{
+    MouseMonitor *mm = new MouseMonitor();
+    mm->show();
+}
+
 void screenAdded(QScreen* screen)
 {
     screen->setOrientationUpdateMask((Qt::ScreenOrientations)0x0F);