Avoid flicker when invalidate is propagated in a widget/layout hierarchy

* Do not call invalidate from activateRecursive().
  This resulted in that a layout was invalidated as many times as there
  were items in the layout.

* Several improvements. Do not call resize(size()) too often.
  Calling resize() from the widgetEvent() is not very nice though...

* Remove commented out code

* make sure layout is activated even if the widget does not change size

* activate the layout if the resize is same as size()

* In order to not break existing apps, make this an opt-in feature
  with QGraphicsLayout::setInstantInvalidatePropagation(true);

Reviewed-by: Frederik Gladhorn
Reviewed-by: John Tapsell

3 files changed, 131 insertions, 0 deletions

diff --git a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
index e7c63d540e..447385a7d8 100644
--- a/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
+++ b/tests/auto/qgraphicsanchorlayout/tst_qgraphicsanchorlayout.cpp
@@ -1091,6 +1091,9 @@ void tst_QGraphicsAnchorLayout::setSpacing()
 #ifdef Q_WS_MAC
     QTest::qWait(200);
 #endif
+
+    // 21x21
+    QCOMPARE(p->size(), QSizeF(41, 41));
     QCOMPARE(a->geometry(), QRectF(0, 0, 20, 20));
     QCOMPARE(b->geometry(), QRectF(21, 0, 20, 20));
     QCOMPARE(c->geometry(), QRectF(0, 21, 41, 20));
diff --git a/tests/auto/qgraphicslayout/tst_qgraphicslayout.cpp b/tests/auto/qgraphicslayout/tst_qgraphicslayout.cpp
index 979f03df64..c57392640f 100644
--- a/tests/auto/qgraphicslayout/tst_qgraphicslayout.cpp
+++ b/tests/auto/qgraphicslayout/tst_qgraphicslayout.cpp
@@ -62,6 +62,7 @@ private slots:
     void compressLayoutRequest();
     void automaticReparenting();
     void verifyActivate();
+    void invalidate();
     void constructors();
     void alternativeLayoutItems();
     void ownership();
@@ -218,6 +219,7 @@ class TestLayout : public QGraphicsLinearLayout
         : QGraphicsLinearLayout(parent)
     {
         m_count = 0;
+        m_invalidateCount = 0;
     }
 
     void setGeometry(const QRectF &rect) {
@@ -226,7 +228,12 @@ class TestLayout : public QGraphicsLinearLayout
         QGraphicsLinearLayout::setGeometry(rect);
     }
 
+    void invalidate() {
+        ++m_invalidateCount;
+        QGraphicsLinearLayout::invalidate();
+    }
 
+    int m_invalidateCount;
     int m_count;
 };
 
@@ -251,6 +258,87 @@ void tst_QGraphicsLayout::verifyActivate()
 
 }
 
+void tst_QGraphicsLayout::invalidate()
+{
+    QGraphicsLayout::setInstantInvalidatePropagation(true);
+    QGraphicsScene scene;
+    QGraphicsView view(&scene);
+
+    TestGraphicsWidget *a = new TestGraphicsWidget;
+    scene.addItem(a);
+    TestLayout *alay = new TestLayout(a);
+    TestGraphicsWidget *b = new TestGraphicsWidget;
+    alay->addItem(b);
+    TestLayout *blay = new TestLayout(b);
+    TestGraphicsWidget *e = new TestGraphicsWidget;
+    blay->addItem(e);
+
+
+    TestGraphicsWidget *c = new TestGraphicsWidget;
+    alay->addItem(c);
+    TestLayout *clay = new TestLayout(c);
+    TestGraphicsWidget *f = new TestGraphicsWidget;
+    clay->addItem(f);
+
+    TestGraphicsWidget *d = new TestGraphicsWidget;
+    alay->addItem(d);
+    TestLayout *dlay = new TestLayout(d);
+    TestGraphicsWidget *g = new TestGraphicsWidget;
+    dlay->addItem(g);
+
+    view.show();
+
+    alay->m_invalidateCount = 0;
+    blay->m_invalidateCount = 0;
+    clay->m_invalidateCount = 0;
+    dlay->m_invalidateCount = 0;
+
+    QCoreApplication::sendPostedEvents();
+    QCoreApplication::processEvents();
+
+    alay->activate();
+    QCOMPARE(alay->isActivated(), true);
+    QCOMPARE(blay->isActivated(), true);
+    QCOMPARE(clay->isActivated(), true);
+    qDebug() << "alay->m_invalidateCount:" << alay->m_invalidateCount;
+    qDebug() << "blay->m_invalidateCount:" << blay->m_invalidateCount;
+    qDebug() << "clay->m_invalidateCount:" << clay->m_invalidateCount;
+    qDebug() << "dlay->m_invalidateCount:" << dlay->m_invalidateCount;
+
+    a->clearEventCount();
+    b->clearEventCount();
+    c->clearEventCount();
+
+    blay->invalidate();
+    QCOMPARE(alay->isActivated(), false);
+    QCOMPARE(blay->isActivated(), false);
+    QCOMPARE(clay->isActivated(), true);
+    QCOMPARE(a->eventCount(QEvent::LayoutRequest), 0);
+    QCOMPARE(b->eventCount(QEvent::LayoutRequest), 0);
+    QCOMPARE(c->eventCount(QEvent::LayoutRequest), 0);
+
+
+    alay->m_invalidateCount = 0;
+    blay->m_invalidateCount = 0;
+    clay->m_invalidateCount = 0;
+    dlay->m_invalidateCount = 0;
+    clay->invalidate();
+    QCOMPARE(alay->isActivated(), false);
+    QCOMPARE(blay->isActivated(), false);
+    QCOMPARE(clay->isActivated(), false);
+
+    QCoreApplication::sendPostedEvents();
+    QCOMPARE(a->eventCount(QEvent::LayoutRequest), 1);
+    QCOMPARE(b->eventCount(QEvent::LayoutRequest), 0);
+    QCOMPARE(c->eventCount(QEvent::LayoutRequest), 0);
+    qDebug() << "alay->m_invalidateCount:" << alay->m_invalidateCount;
+    qDebug() << "blay->m_invalidateCount:" << blay->m_invalidateCount;
+    qDebug() << "clay->m_invalidateCount:" << clay->m_invalidateCount;
+    qDebug() << "dlay->m_invalidateCount:" << dlay->m_invalidateCount;
+
+    QGraphicsLayout::setInstantInvalidatePropagation(false);
+}
+
 class Layout : public QGraphicsLayout
 {
 public:
diff --git a/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp b/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
index 62ba1b4981..8f8ac67d09 100644
--- a/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
+++ b/tests/auto/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp
@@ -94,6 +94,7 @@ private slots:
     void itemSpacing();
     void setStretchFactor_data();
     void setStretchFactor();
+    void testStretch();
     void defaultStretchFactors_data();
     void defaultStretchFactors();
     void sizeHint_data();
@@ -667,6 +668,10 @@ void tst_QGraphicsLinearLayout::invalidate()
     layout.setContentsMargins(0, 0, 0, 0);
     view.show();
     widget->show();
+    //QTest::qWait(1000);
+    QTest::qWaitForWindowShown(&view);
+    qApp->processEvents();
+    layout.layoutRequest = 0;
 
     layout.setContentsMargins(1, 2, 3, 4);
     QApplication::sendPostedEvents(0, 0);
@@ -1130,6 +1135,41 @@ void tst_QGraphicsLinearLayout::setStretchFactor()
     delete widget;
 }
 
+void tst_QGraphicsLinearLayout::testStretch()
+{
+    QGraphicsScene scene;
+    QGraphicsView *view = new QGraphicsView(&scene);
+    QGraphicsWidget *form = new QGraphicsWidget(0, Qt::Window);
+
+    scene.addItem(form);
+    form->setMinimumSize(600, 600);
+    form->setMaximumSize(600, 600);
+    QGraphicsLinearLayout *layout = new QGraphicsLinearLayout(Qt::Horizontal, form);
+    QGraphicsWidget *w1 = new RectWidget;
+    w1->setPreferredSize(100,100);
+    w1->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+    QGraphicsWidget *w2 = new RectWidget;
+    w2->setPreferredSize(200,200);
+    w2->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+    layout->setSpacing(0);
+    layout->setContentsMargins(0, 0, 0, 0);
+    layout->addItem(w1);
+    layout->addStretch(2);
+    layout->addItem(w2);
+    QCOMPARE(layout->count(), 2);
+    QVERIFY(layout->itemAt(0) == w1);
+    QVERIFY(layout->itemAt(1) == w2);
+    layout->activate();
+
+    //view->setSceneRect(-50, -50, 800, 800);
+    //view->show();
+    //QTest::qWaitForWindowShown(view);
+    //QTest::qWait(5000);
+    QCOMPARE(form->geometry().size(), QSizeF(600,600));
+    QCOMPARE(w1->geometry(), QRectF(0, 0, 100, 100));
+    QCOMPARE(w2->geometry(), QRectF(400, 0, 200, 200));
+}
+
 void tst_QGraphicsLinearLayout::defaultStretchFactors_data()
 {
     QTest::addColumn<Qt::Orientation>("orientation");