QWidget::mapTo/FromGlobal(): Rewrite using a QTransform.

Introduce a function going up the widget hierarchy determining a QTransform
for mapping the coordinates applying the transformations of any QGraphicsView
instances found. In mapFromGlobal(), use the inverse of it. This fixes the
case of widget hierarchies embedded into QGraphicsView with transformations.

Increase fuzz in the tests due to float rounding errors.

Task-number: QTBUG-41135
Task-number: QTBUG-50030
Task-number: QTBUG-50136
Task-number: QTBUG-52507
Change-Id: I507e0bccd546250fe9c2d1b74ef38657d61490b4
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

1 files changed, 53 insertions, 46 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 48334cd169..0376ab88ac 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -12346,6 +12346,53 @@ static inline bool canMapPosition(QWindow *window)
     return window->handle() && !qt_window_private(window)->resizeEventPending;
 }
 
+#ifndef QT_NO_GRAPHICSVIEW
+static inline QGraphicsProxyWidget *graphicsProxyWidget(const QWidget *w)
+{
+    QGraphicsProxyWidget *result = Q_NULLPTR;
+    const QWidgetPrivate *d = qt_widget_private(const_cast<QWidget *>(w));
+    if (d->extra)
+        result = d->extra->proxyWidget;
+    return result;
+}
+#endif // !QT_NO_GRAPHICSVIEW
+
+struct MapToGlobalTransformResult {
+    QTransform transform;
+    QWindow *window;
+};
+
+static MapToGlobalTransformResult mapToGlobalTransform(const QWidget *w)
+{
+    MapToGlobalTransformResult result;
+    result.window = Q_NULLPTR;
+    for ( ; w ; w = w->parentWidget()) {
+#ifndef QT_NO_GRAPHICSVIEW
+        if (QGraphicsProxyWidget *qgpw = graphicsProxyWidget(w)) {
+            if (const QGraphicsScene *scene = qgpw->scene()) {
+                const QList <QGraphicsView *> views = scene->views();
+                if (!views.isEmpty()) {
+                    result.transform *= qgpw->sceneTransform();
+                    result.transform *= views.first()->viewportTransform();
+                    w = views.first()->viewport();
+                }
+            }
+        }
+#endif // !QT_NO_GRAPHICSVIEW
+        QWindow *window = w->windowHandle();
+        if (window && canMapPosition(window)) {
+            result.window = window;
+            break;
+        }
+
+        const QPoint topLeft = w->geometry().topLeft();
+        result.transform.translate(topLeft.x(), topLeft.y());
+        if (w->isWindow())
+            break;
+    }
+    return result;
+}
+
 /*!
     \fn QPoint QWidget::mapToGlobal(const QPoint &pos) const
 
@@ -12357,29 +12404,9 @@ static inline bool canMapPosition(QWindow *window)
 */
 QPoint QWidget::mapToGlobal(const QPoint &pos) const
 {
-#ifndef QT_NO_GRAPHICSVIEW
-    Q_D(const QWidget);
-    if (d->extra && d->extra->proxyWidget && d->extra->proxyWidget->scene()) {
-        const QList <QGraphicsView *> views = d->extra->proxyWidget->scene()->views();
-        if (!views.isEmpty()) {
-            const QPointF scenePos = d->extra->proxyWidget->mapToScene(pos);
-            const QPoint viewPortPos = views.first()->mapFromScene(scenePos);
-            return views.first()->viewport()->mapToGlobal(viewPortPos);
-        }
-    }
-#endif // !QT_NO_GRAPHICSVIEW
-    int x = pos.x(), y = pos.y();
-    const QWidget *w = this;
-    while (w) {
-        QWindow *window = w->windowHandle();
-        if (window && canMapPosition(window))
-            return window->mapToGlobal(QPoint(x, y));
-
-        x += w->data->crect.x();
-        y += w->data->crect.y();
-        w = w->isWindow() ? 0 : w->parentWidget();
-    }
-    return QPoint(x, y);
+    const MapToGlobalTransformResult t = mapToGlobalTransform(this);
+    const QPoint g = t.transform.map(pos);
+    return t.window ? t.window->mapToGlobal(g) : g;
 }
 
 /*!
@@ -12392,29 +12419,9 @@ QPoint QWidget::mapToGlobal(const QPoint &pos) const
 */
 QPoint QWidget::mapFromGlobal(const QPoint &pos) const
 {
-#ifndef QT_NO_GRAPHICSVIEW
-    Q_D(const QWidget);
-    if (d->extra && d->extra->proxyWidget && d->extra->proxyWidget->scene()) {
-        const QList <QGraphicsView *> views = d->extra->proxyWidget->scene()->views();
-        if (!views.isEmpty()) {
-            const QPoint viewPortPos = views.first()->viewport()->mapFromGlobal(pos);
-            const QPointF scenePos = views.first()->mapToScene(viewPortPos);
-            return d->extra->proxyWidget->mapFromScene(scenePos).toPoint();
-        }
-    }
-#endif // !QT_NO_GRAPHICSVIEW
-    int x = pos.x(), y = pos.y();
-    const QWidget *w = this;
-    while (w) {
-        QWindow *window = w->windowHandle();
-        if (window && canMapPosition(window))
-            return window->mapFromGlobal(QPoint(x, y));
-
-        x -= w->data->crect.x();
-        y -= w->data->crect.y();
-        w = w->isWindow() ? 0 : w->parentWidget();
-    }
-    return QPoint(x, y);
+   const MapToGlobalTransformResult t = mapToGlobalTransform(this);
+   const QPoint windowLocal = t.window ? t.window->mapFromGlobal(pos) : pos;
+   return t.transform.inverted().map(windowLocal);
 }
 
 QWidget *qt_pressGrab = 0;