QQuickTextNodeEngine: don't create background when its alpha is 0

If the alpha value for the background color of a text element is 0,
we don't need to create a rectangle node to represent it, as the
rectangle will be invisible anyway.

[ChangeLog][QtQuick][QQuickTextNodeEngine] don't create a new
rectangle node as the background of text, when the alpha of it is
0

Fixes: QTBUG-76137
Change-Id: I40c624ee8f61740fd07e7d3751a78b6224882913
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

3 files changed, 40 insertions, 2 deletions

diff --git a/src/quick/items/qquicktextnodeengine.cpp b/src/quick/items/qquicktextnodeengine.cpp
index 5a4ef2b686..f407de84cb 100644
--- a/src/quick/items/qquicktextnodeengine.cpp
+++ b/src/quick/items/qquicktextnodeengine.cpp
@@ -781,8 +781,8 @@ void  QQuickTextNodeEngine::addToSceneGraph(QQuickTextNode *parentNode,
     for (int i = 0; i < m_backgrounds.size(); ++i) {
         const QRectF &rect = m_backgrounds.at(i).first;
         const QColor &color = m_backgrounds.at(i).second;
-
-        parentNode->addRectangleNode(rect, color);
+        if (color.alpha() != 0)
+            parentNode->addRectangleNode(rect, color);
     }
 
     // Add all text with unselected color first
diff --git a/tests/auto/quick/qquicktext/data/transparentBackground.qml b/tests/auto/quick/qquicktext/data/transparentBackground.qml
new file mode 100644
index 0000000000..a10a1779bb
--- /dev/null
+++ b/tests/auto/quick/qquicktext/data/transparentBackground.qml
@@ -0,0 +1,16 @@
+import QtQuick 2.0
+
+Rectangle {
+    width: 200
+    height: 200
+    color: "white"
+    Text {
+        objectName: "text"
+        textFormat: Text.RichText
+        anchors.fill: parent
+        color: "black"
+        text: "<h1 style=\"background-color:rgba(255,255,255,0.00)\">foo</h1>"
+        verticalAlignment: Text.AlignTop
+        horizontalAlignment: Text.AlignLeft
+    }
+}
diff --git a/tests/auto/quick/qquicktext/tst_qquicktext.cpp b/tests/auto/quick/qquicktext/tst_qquicktext.cpp
index eafa6cb052..3414bec4a6 100644
--- a/tests/auto/quick/qquicktext/tst_qquicktext.cpp
+++ b/tests/auto/quick/qquicktext/tst_qquicktext.cpp
@@ -163,6 +163,8 @@ private slots:
 
     void verticallyAlignedImageInTable();
 
+    void transparentBackground();
+
 private:
     QStringList standard;
     QStringList richText;
@@ -4428,6 +4430,26 @@ void tst_qquicktext::verticallyAlignedImageInTable()
     // Don't crash
 }
 
+void tst_qquicktext::transparentBackground()
+{
+    if ((QGuiApplication::platformName() == QLatin1String("offscreen"))
+        || (QGuiApplication::platformName() == QLatin1String("minimal")))
+        QSKIP("Skipping due to grabToImage not functional on offscreen/minimimal platforms");
+
+    QScopedPointer<QQuickView> window(new QQuickView);
+    window->setSource(testFileUrl("transparentBackground.qml"));
+    QTRY_COMPARE(window->status(), QQuickView::Ready);
+
+    window->show();
+    QVERIFY(QTest::qWaitForWindowExposed(window.data()));
+    QImage img = window->grabWindow();
+    QCOMPARE(img.isNull(), false);
+
+    QColor color = img.pixelColor(0, 0);
+    QCOMPARE(color.red(), 255);
+    QCOMPARE(color.blue(), 255);
+    QCOMPARE(color.green(), 255);
+}
 QTEST_MAIN(tst_qquicktext)
 
 #include "tst_qquicktext.moc"