Introduce QGraphicsItem::ItemStopsFocusHandling flag

When set for an item, QGraphicsScene will skip focus handling for this item and
everything underneath it (including focus-out). Allows users to reimplement
custom focus handling.

Use case: touch devices that implement panning. Here, focus-in has to happen
only if no panning was triggered. Analogous, no focus-out should happen when
panning was detected.

Fixes the alternative proposal ("black holes for focus changes") of
QTBUG-16343: QGraphicsView doesn't support focus change on mouse release.

The previous test was only testing one scenario, which didn't give a good idea
whether the flag was actually working as intended.

Task-number: QTBUG-17505
Reviewed-by: Yoann Lopes
Reviewed-by: Jan-Arve Sæther

5 files changed, 84 insertions, 19 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index f463887..4e2d4e2 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -417,6 +417,11 @@
     click focus to items underneath when being clicked on. This flag
     allows you create a non-focusable item that can be clicked on without
     changing the focus. \endomit
+
+    \omitvalue ItemStopsFocusHandling \omit Same as
+    ItemStopsClickFocusPropagation, but also suppresses focus-out. This flag
+    allows you to completely take over focus handling.
+    This flag was introduced in Qt 4.7.
 */
 
 /*!
@@ -11549,6 +11554,9 @@ QDebug operator<<(QDebug debug, QGraphicsItem::GraphicsItemFlag flag)
     case QGraphicsItem::ItemStopsClickFocusPropagation:
         str = "ItemStopsClickFocusPropagation";
         break;
+    case QGraphicsItem::ItemStopsFocusHandling:
+        str = "ItemStopsFocusHandling";
+        break;
     }
     debug << str;
     return debug;
diff --git a/src/gui/graphicsview/qgraphicsitem.h b/src/gui/graphicsview/qgraphicsitem.h
index e59a7c9..67c9cd3 100644
--- a/src/gui/graphicsview/qgraphicsitem.h
+++ b/src/gui/graphicsview/qgraphicsitem.h
@@ -107,7 +107,8 @@ public:
         ItemIsPanel = 0x4000,
         ItemIsFocusScope = 0x8000, // internal
         ItemSendsScenePositionChanges = 0x10000,
-        ItemStopsClickFocusPropagation = 0x20000
+        ItemStopsClickFocusPropagation = 0x20000,
+        ItemStopsFocusHandling = 0x40000
         // NB! Don't forget to increase the d_ptr->flags bit field by 1 when adding a new flag.
     };
     Q_DECLARE_FLAGS(GraphicsItemFlags, GraphicsItemFlag)
diff --git a/src/gui/graphicsview/qgraphicsitem_p.h b/src/gui/graphicsview/qgraphicsitem_p.h
index 5c82116..90ff43f 100644
--- a/src/gui/graphicsview/qgraphicsitem_p.h
+++ b/src/gui/graphicsview/qgraphicsitem_p.h
@@ -559,7 +559,7 @@ public:
     quint32 dirtyChildrenBoundingRect : 1;
 
     // Packed 32 bits
-    quint32 flags : 18;
+    quint32 flags : 19;
     quint32 paintedViewBoundingRectsNeedRepaint : 1;
     quint32 dirtySceneTransform : 1;
     quint32 geometryChanged : 1;
@@ -573,9 +573,9 @@ public:
     quint32 sceneTransformTranslateOnly : 1;
     quint32 notifyBoundingRectChanged : 1;
     quint32 notifyInvalidated : 1;
-    quint32 mouseSetsFocus : 1;
 
     // New 32 bits
+    quint32 mouseSetsFocus : 1;
     quint32 explicitActivate : 1;
     quint32 wantsActive : 1;
     quint32 holesInSiblingIndex : 1;
@@ -586,7 +586,7 @@ public:
     quint32 mayHaveChildWithGraphicsEffect : 1;
     quint32 isDeclarativeItem : 1;
     quint32 sendParentChangeNotification : 1;
-    quint32 padding : 22;
+    quint32 padding : 21;
 
     // Optional stacking order
     int globalStackingOrder;
diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index f997fc2..2d85de6 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -1317,8 +1317,10 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
 
     // Set focus on the topmost enabled item that can take focus.
     bool setFocus = false;
+
     foreach (QGraphicsItem *item, cachedItemsUnderMouse) {
-        if (item->isBlockedByModalPanel()) {
+        if (item->isBlockedByModalPanel()
+            || (item->d_ptr->flags & QGraphicsItem::ItemStopsFocusHandling)) {
             // Make sure we don't clear focus.
             setFocus = true;
             break;
@@ -1331,10 +1333,10 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
                 break;
             }
         }
-        if (item->d_ptr->flags & QGraphicsItem::ItemStopsClickFocusPropagation)
-            break;
         if (item->isPanel())
             break;
+        if (item->d_ptr->flags & QGraphicsItem::ItemStopsClickFocusPropagation)
+            break;
     }
 
     // Check for scene modality.
@@ -5925,6 +5927,7 @@ bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QTouchEve
 
     // Set focus on the topmost enabled item that can take focus.
     bool setFocus = false;
+
     foreach (QGraphicsItem *item, cachedItemsUnderMouse) {
         if (item->isEnabled() && ((item->flags() & QGraphicsItem::ItemIsFocusable) && item->d_ptr->mouseSetsFocus)) {
             if (!item->isWidget() || ((QGraphicsWidget *)item)->focusPolicy() & Qt::ClickFocus) {
@@ -5938,6 +5941,11 @@ bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QTouchEve
             break;
         if (item->d_ptr->flags & QGraphicsItem::ItemStopsClickFocusPropagation)
             break;
+        if (item->d_ptr->flags & QGraphicsItem::ItemStopsFocusHandling) {
+            // Make sure we don't clear focus.
+            setFocus = true;
+            break;
+        }
     }
 
     // If nobody could take focus, clear it.
@@ -5970,7 +5978,8 @@ bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QTouchEve
         }
         if (item && item->isPanel())
             break;
-        if (item && (item->d_ptr->flags & QGraphicsItem::ItemStopsClickFocusPropagation))
+        if (item && (item->d_ptr->flags
+                     & (QGraphicsItem::ItemStopsClickFocusPropagation | QGraphicsItem::ItemStopsFocusHandling)))
             break;
     }
 
diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index dacb61e..168f75e 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -447,7 +447,8 @@ private slots:
     void updateMicroFocus();
     void textItem_shortcuts();
     void scroll();
-    void stopClickFocusPropagation();
+    void focusHandling_data();
+    void focusHandling();
     void deviceCoordinateCache_simpleRotations();
 
     // task specific tests below me
@@ -10537,8 +10538,39 @@ void tst_QGraphicsItem::scroll()
     QCOMPARE(item2->lastExposedRect, expectedItem2Expose);
 }
 
-void tst_QGraphicsItem::stopClickFocusPropagation()
+Q_DECLARE_METATYPE(QGraphicsItem::GraphicsItemFlag);
+
+void tst_QGraphicsItem::focusHandling_data()
 {
+    QTest::addColumn<QGraphicsItem::GraphicsItemFlag>("focusFlag");
+    QTest::addColumn<bool>("useStickyFocus");
+    QTest::addColumn<int>("expectedFocusItem"); // 0: none, 1: focusableUnder, 2: itemWithFocus
+
+    QTest::newRow("Focus goes through.")
+        << static_cast<QGraphicsItem::GraphicsItemFlag>(0x0) << false << 1;
+
+    QTest::newRow("Focus goes through, even with sticky scene.")
+        << static_cast<QGraphicsItem::GraphicsItemFlag>(0x0) << true  << 1;
+
+    QTest::newRow("With ItemStopsClickFocusPropagation, we cannot focus the item beneath the flagged one (but can still focus-out).")
+        << QGraphicsItem::ItemStopsClickFocusPropagation << false << 0;
+
+    QTest::newRow("With ItemStopsClickFocusPropagation, we cannot focus the item beneath the flagged one (and cannot focus-out if scene is sticky).")
+        << QGraphicsItem::ItemStopsClickFocusPropagation << true << 2;
+
+    QTest::newRow("With ItemStopsFocusHandling, focus cannot be changed by presses.")
+        << QGraphicsItem::ItemStopsFocusHandling << false << 2;
+
+    QTest::newRow("With ItemStopsFocusHandling, focus cannot be changed by presses (even if scene is sticky).")
+        << QGraphicsItem::ItemStopsFocusHandling << true << 2;
+}
+
+void tst_QGraphicsItem::focusHandling()
+{
+    QFETCH(QGraphicsItem::GraphicsItemFlag, focusFlag);
+    QFETCH(bool, useStickyFocus);
+    QFETCH(int, expectedFocusItem);
+
     class MyItem : public QGraphicsRectItem
     {
     public:
@@ -10549,12 +10581,9 @@ void tst_QGraphicsItem::stopClickFocusPropagation()
         }
     };
 
-    QGraphicsScene scene(-50, -50, 400, 400);
-    scene.setStickyFocus(true);
-
     QGraphicsRectItem *noFocusOnTop = new MyItem;
+    noFocusOnTop->setFlag(QGraphicsItem::ItemIsFocusable, false);
     noFocusOnTop->setBrush(Qt::yellow);
-    noFocusOnTop->setFlag(QGraphicsItem::ItemStopsClickFocusPropagation);
 
     QGraphicsRectItem *focusableUnder = new MyItem;
     focusableUnder->setBrush(Qt::blue);
@@ -10566,9 +10595,13 @@ void tst_QGraphicsItem::stopClickFocusPropagation()
     itemWithFocus->setFlag(QGraphicsItem::ItemIsFocusable);
     itemWithFocus->setPos(250, 10);
 
+    QGraphicsScene scene(-50, -50, 400, 400);
     scene.addItem(noFocusOnTop);
     scene.addItem(focusableUnder);
     scene.addItem(itemWithFocus);
+    scene.setStickyFocus(useStickyFocus);
+
+    noFocusOnTop->setFlag(focusFlag);
     focusableUnder->stackBefore(noFocusOnTop);
     itemWithFocus->setFocus();
 
@@ -10580,14 +10613,28 @@ void tst_QGraphicsItem::stopClickFocusPropagation()
     QTRY_COMPARE(QApplication::activeWindow(), static_cast<QWidget *>(&view));
     QVERIFY(itemWithFocus->hasFocus());
 
-    QPointF mousePressPoint = noFocusOnTop->mapToScene(QPointF());
-    mousePressPoint.rx() += 60;
-    mousePressPoint.ry() += 60;
+    const QPointF mousePressPoint = noFocusOnTop->mapToScene(noFocusOnTop->boundingRect().center());
     const QList<QGraphicsItem *> itemsAtMousePressPosition = scene.items(mousePressPoint);
-    QVERIFY(itemsAtMousePressPosition.contains(focusableUnder));
+    QVERIFY(itemsAtMousePressPosition.contains(noFocusOnTop));
 
     sendMousePress(&scene, mousePressPoint);
-    QVERIFY(itemWithFocus->hasFocus());
+
+    switch (expectedFocusItem) {
+    case 0:
+        QCOMPARE(scene.focusItem(), static_cast<QGraphicsRectItem *>(0));
+        break;
+    case 1:
+        QCOMPARE(scene.focusItem(), focusableUnder);
+        break;
+    case 2:
+        QCOMPARE(scene.focusItem(), itemWithFocus);
+        break;
+    }
+
+    // Sanity check - manually setting the focus must work regardless of our
+    // focus handling flags:
+    focusableUnder->setFocus();
+    QCOMPARE(scene.focusItem(), focusableUnder);
 }
 
 void tst_QGraphicsItem::deviceCoordinateCache_simpleRotations()