Calculate effect bounds when drawing widget graphics effect

Calculate effect bounds for the updated region when drawing the effect
so that the whole affected area gets updated. The effect bounds have
already been added to the region so it doesn't need to be handled in
the drawing function.

Pick-to: 6.2 5.15
Fixes: QTBUG-96240
Change-Id: I0c317311622e6299fb1a3015541408d1d83c93de
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 153 insertions, 0 deletions

diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index 27cf884fd5..9e676556de 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -376,6 +376,8 @@ private slots:
     void focusWidget_task254563();
     void rectOutsideCoordinatesLimit_task144779();
     void setGraphicsEffect();
+    void render_graphicsEffect_data();
+    void render_graphicsEffect();
 
 #ifdef QT_BUILD_INTERNAL
     void destroyBackingStore();
@@ -10380,6 +10382,157 @@ void tst_QWidget::setGraphicsEffect()
     QVERIFY(!blurEffect);
 }
 
+
+class TestGraphicsEffect : public QGraphicsEffect
+{
+public:
+    TestGraphicsEffect(QObject *parent = nullptr)
+        : QGraphicsEffect(parent)
+    {
+        m_pattern = QPixmap(10, 10);
+        m_pattern.fill(Qt::lightGray);
+        QPainter p(&m_pattern);
+        p.fillRect(QRectF(0, 0, 5, 5), QBrush(Qt::darkGray));
+        p.fillRect(QRectF(5, 5, 5, 5), QBrush(Qt::darkGray));
+    }
+    void setExtent(int extent)
+    {
+        m_extent = extent;
+    }
+    QRectF boundingRectFor(const QRectF &sr) const override
+    {
+        return QRectF(sr.x() - m_extent, sr.y() - m_extent,
+                      sr.width() + 2 * m_extent, sr.height() + 2 * m_extent);
+    }
+protected:
+    void draw(QPainter *painter) override
+    {
+        QBrush brush;
+        brush.setTexture(m_pattern);
+        brush.setStyle(Qt::TexturePattern);
+        QPaintDevice *p = painter->device();
+        painter->fillRect(QRect(-m_extent, -m_extent,
+                                p->width() + m_extent, p->height() + m_extent), brush);
+    }
+    QPixmap m_pattern;
+    int m_extent = 0;
+};
+
+static QImage fillExpected1()
+{
+    QImage expected(QSize(40, 40), QImage::Format_RGB32);
+    QPainter p(&expected);
+    p.fillRect(QRect{{0, 0}, expected.size()}, QBrush(Qt::gray));
+    p.fillRect(QRect(10, 10, 10, 10), QBrush(Qt::red));
+    p.fillRect(QRect(20, 20, 10, 10), QBrush(Qt::blue));
+    return expected;
+}
+static QImage fillExpected2()
+{
+    QImage expected = fillExpected1();
+    QPainter p(&expected);
+    p.fillRect(QRect(10, 10, 5, 5), QBrush(Qt::darkGray));
+    p.fillRect(QRect(15, 15, 5, 5), QBrush(Qt::darkGray));
+    p.fillRect(QRect(15, 10, 5, 5), QBrush(Qt::lightGray));
+    p.fillRect(QRect(10, 15, 5, 5), QBrush(Qt::lightGray));
+    return expected;
+}
+static QImage fillExpected3()
+{
+    QImage expected(QSize(40, 40), QImage::Format_RGB32);
+    QPixmap pattern;
+    pattern = QPixmap(10, 10);
+    pattern.fill(Qt::lightGray);
+    QPainter p(&pattern);
+    p.fillRect(QRectF(0, 0, 5, 5), QBrush(Qt::darkGray));
+    p.fillRect(QRectF(5, 5, 5, 5), QBrush(Qt::darkGray));
+    QBrush brush;
+    brush.setTexture(pattern);
+    brush.setStyle(Qt::TexturePattern);
+    QPainter p2(&expected);
+    p2.fillRect(QRect{{0, 0}, expected.size()}, brush);
+    return expected;
+}
+static QImage fillExpected4()
+{
+    QImage expected = fillExpected1();
+    QPixmap pattern;
+    pattern = QPixmap(10, 10);
+    pattern.fill(Qt::lightGray);
+    QPainter p(&pattern);
+    p.fillRect(QRectF(0, 0, 5, 5), QBrush(Qt::darkGray));
+    p.fillRect(QRectF(5, 5, 5, 5), QBrush(Qt::darkGray));
+    QBrush brush;
+    brush.setTexture(pattern);
+    brush.setStyle(Qt::TexturePattern);
+    QPainter p2(&expected);
+    p2.fillRect(QRect{{15, 15}, QSize{20, 20}}, brush);
+    return expected;
+}
+
+void tst_QWidget::render_graphicsEffect_data()
+{
+    QTest::addColumn<QImage>("expected");
+    QTest::addColumn<bool>("topLevelEffect");
+    QTest::addColumn<bool>("child1Effect");
+    QTest::addColumn<bool>("child2Effect");
+    QTest::addColumn<int>("extent");
+
+    QTest::addRow("no_effect") << fillExpected1() << false << false << false << 0;
+    QTest::addRow("first_child_effect") << fillExpected2() << false << true << false << 0;
+    QTest::addRow("top_level_effect") << fillExpected3() << true << false << false << 0;
+    QTest::addRow("effect_with_extent") << fillExpected4() << false << false << true << 5;
+}
+
+void tst_QWidget::render_graphicsEffect()
+{
+    QFETCH(QImage, expected);
+    QFETCH(bool, topLevelEffect);
+    QFETCH(bool, child1Effect);
+    QFETCH(bool, child2Effect);
+    QFETCH(int, extent);
+
+    QScopedPointer<QWidget> topLevel(new QWidget);
+    topLevel->setPalette(Qt::gray);
+    topLevel->resize(40, 40);
+    topLevel->setWindowTitle(QLatin1String(QTest::currentTestFunction()) + QLatin1String("::")
+                             + QLatin1String(QTest::currentDataTag()));
+
+    // Render widget with 2 child widgets
+    QImage image(topLevel->size(), QImage::Format_RGB32);
+    image.fill(QColor(Qt::gray).rgb());
+
+    QPainter painter(&image);
+
+    QWidget *childWidget1(new QWidget(topLevel.data()));
+    childWidget1->setAutoFillBackground(true);
+    childWidget1->setPalette(Qt::red);
+    childWidget1->resize(10, 10);
+    childWidget1->move(10, 10);
+    QWidget *childWidget2(new QWidget(topLevel.data()));
+    childWidget2->setAutoFillBackground(true);
+    childWidget2->setPalette(Qt::blue);
+    childWidget2->resize(10, 10);
+    childWidget2->move(20, 20);
+
+    TestGraphicsEffect *graphicsEffect(new TestGraphicsEffect(topLevel.data()));
+    if (topLevelEffect)
+        topLevel->setGraphicsEffect(graphicsEffect);
+    if (child1Effect)
+        childWidget1->setGraphicsEffect(graphicsEffect);
+    if (child2Effect)
+        childWidget2->setGraphicsEffect(graphicsEffect);
+    graphicsEffect->setExtent(extent);
+
+    // Render without effect
+    topLevel->render(&painter);
+#ifdef RENDER_DEBUG
+    image.save("render_GraphicsEffect" + QTest::currentDataTag() + ".png");
+    expected.save("render_GraphicsEffect_expected" + QTest::currentDataTag() + ".png");
+#endif
+    QCOMPARE(image, expected);
+}
+
 void tst_QWidget::activateWindow()
 {
     if (!QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::WindowActivation))