ShaderEffect: Allow use of shaders without QML engine

Change-Id: I43a18b94be6d17f6cca745a23bb006515c567de3
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

2 files changed, 28 insertions, 5 deletions

diff --git a/src/quick/items/qquickopenglshadereffect.cpp b/src/quick/items/qquickopenglshadereffect.cpp
index cad598d2c0..3aa00340b2 100644
--- a/src/quick/items/qquickopenglshadereffect.cpp
+++ b/src/quick/items/qquickopenglshadereffect.cpp
@@ -245,7 +245,11 @@ void QQuickOpenGLShaderEffectCommon::connectPropertySignals(QQuickItem *item,
                                                             const QMetaObject *itemMetaObject,
                                                             Key::ShaderType shaderType)
 {
-    QQmlPropertyCache *propCache = QQmlData::ensurePropertyCache(qmlEngine(item), item);
+    auto engine = qmlEngine(item);
+    if (!engine)
+        return;
+
+    QQmlPropertyCache *propCache = QQmlData::ensurePropertyCache(engine, item);
     for (int i = 0; i < uniformData[shaderType].size(); ++i) {
         if (signalMappers[shaderType].at(i) == 0)
             continue;
@@ -317,7 +321,8 @@ void QQuickOpenGLShaderEffectCommon::lookThroughShaderCode(QQuickItem *item,
                                                            Key::ShaderType shaderType,
                                                            const QByteArray &code)
 {
-    QQmlPropertyCache *propCache = QQmlData::ensurePropertyCache(qmlEngine(item), item);
+    auto engine = qmlEngine(item);
+    QQmlPropertyCache *propCache = (engine) ? QQmlData::ensurePropertyCache(engine, item) : nullptr;
     int index = 0;
     int typeIndex = -1;
     int typeLength = 0;
@@ -350,9 +355,11 @@ void QQuickOpenGLShaderEffectCommon::lookThroughShaderCode(QQuickItem *item,
             } else if (nameLength > srLen && qstrncmp("qt_SubRect_", s + nameIndex, srLen) == 0) {
                 d.specialType = UniformData::SubRect;
             } else {
-                if (QQmlPropertyData *pd = propCache->property(QString::fromUtf8(d.name), nullptr, nullptr)) {
-                    if (!pd->isFunction())
-                        d.propertyIndex = pd->coreIndex();
+                if (propCache) {
+                    if (QQmlPropertyData *pd = propCache->property(QString::fromUtf8(d.name), nullptr, nullptr)) {
+                        if (!pd->isFunction())
+                            d.propertyIndex = pd->coreIndex();
+                    }
                 }
                 const int mappedId = uniformData[shaderType].size() | (shaderType << 16);
                 mapper = new QtPrivate::MappedSlotObject([this, mappedId](){
diff --git a/tests/auto/quick/qquickshadereffect/tst_qquickshadereffect.cpp b/tests/auto/quick/qquickshadereffect/tst_qquickshadereffect.cpp
index f601f520bb..a57b7d4c1f 100644
--- a/tests/auto/quick/qquickshadereffect/tst_qquickshadereffect.cpp
+++ b/tests/auto/quick/qquickshadereffect/tst_qquickshadereffect.cpp
@@ -46,6 +46,10 @@ class TestShaderEffect : public QQuickShaderEffect
     Q_PROPERTY(QMatrix4x4 mat4x4 READ mat4x4Read NOTIFY dummyChanged)
 
 public:
+    TestShaderEffect(QQuickItem* parent = nullptr) : QQuickShaderEffect(parent)
+    {
+    }
+
     QMatrix4x4 mat4x4Read() const { return QMatrix4x4(1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1); }
     QVariant dummyRead() const { return QVariant(); }
 
@@ -79,6 +83,8 @@ private slots:
     void deleteShaderEffectSource();
     void twoImagesOneShaderEffect();
 
+    void withoutQmlEngine();
+
 private:
     enum PresenceFlags {
         VertexPresent = 0x01,
@@ -320,6 +326,16 @@ void tst_qquickshadereffect::twoImagesOneShaderEffect()
     delete view;
 }
 
+void tst_qquickshadereffect::withoutQmlEngine()
+{
+    // using a shader without QML engine used to crash
+    auto window = new QQuickWindow;
+    auto shaderEffect = new TestShaderEffect(window->contentItem());
+    shaderEffect->setVertexShader("");
+    QVERIFY(shaderEffect->isComponentComplete());
+    delete window;
+}
+
 QTEST_MAIN(tst_qquickshadereffect)
 
 #include "tst_qquickshadereffect.moc"