QDistanceFieldGlyphCache: make sure the arbiter of atlas can be set

When using QText2DEntity to display text, the node of QTextureAtlas
will be create when traversing the node tree, and it will use root
node as its parent node. However, since the children node of root
node is being traversed in this moment, QTextureAtlas will not be
traversed, that means the change arbiter won't be set, and the change
in frontend cannot notify backend.

[ChangeLog][Qt3DExtras][QDistanceFieldGlyphCache] make sure the change
arbiter of atlas for QText2DEntity can be set when traversing node tree,
and add new auto test for this.

Fixes: QTBUG-77084
Change-Id: Iad09efe4376ba61f54624965118358a160be42a2
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

1 files changed, 98 insertions, 0 deletions

diff --git a/tests/auto/extras/qtext2dentity/tst_qtext2dentity.cpp b/tests/auto/extras/qtext2dentity/tst_qtext2dentity.cpp
new file mode 100644
index 000000000..6fcc2e637
--- /dev/null
+++ b/tests/auto/extras/qtext2dentity/tst_qtext2dentity.cpp
@@ -0,0 +1,98 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
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+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
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+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
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+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
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+** modification, are permitted provided that the following conditions are
+** met:
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+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtTest/QTest>
+#include <Qt3DExtras/QText2DEntity>
+#include <Qt3DQuickExtras/qt3dquickwindow.h>
+#include <Qt3DQuick/QQmlAspectEngine>
+#include <Qt3DCore/private/qnode_p.h>
+
+QVector<Qt3DCore::QNode *>lookupNodeByClassName(Qt3DCore::QNode *root, const QString &className)
+{
+    auto children = root->childNodes();
+    QVector<Qt3DCore::QNode *> childrenList;
+    for (auto i : children) {
+        if (i->metaObject()->className() == className)
+            childrenList << i;
+        else
+            childrenList << lookupNodeByClassName(i, className);
+    }
+    return childrenList;
+}
+
+class tst_qtext2dentity : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void checkChangeArbiter();
+};
+
+void tst_qtext2dentity::checkChangeArbiter()
+{
+#if !defined(QT_OPENGL_ES_2_ANGLE)
+    // GIVEN
+    Qt3DExtras::Quick::Qt3DQuickWindow view;
+    view.setSource(QUrl("qrc:/qtext2dentity.qml"));
+    view.show();
+    QCoreApplication::processEvents();
+
+    // THEN
+    auto rootEntity = view.engine()->aspectEngine()->rootEntity();
+    QVERIFY(rootEntity != nullptr);
+    auto atlases = lookupNodeByClassName(rootEntity.data(), "Qt3DExtras::QTextureAtlas");
+    QVERIFY(atlases.length() == 1);
+    auto atlas = atlases[0];
+    QTRY_VERIFY(Qt3DCore::QNodePrivate::get(atlas)->m_changeArbiter);
+#endif
+}
+
+QTEST_MAIN(tst_qtext2dentity)
+#include "tst_qtext2dentity.moc"