[Qt] Invert parent/child notification mechanism in QQuickMapboxGLStyleProperty

Parent item (QQuickMapboxGL) should check for signals from its child
items e.g. QQuickMapboxGLStyleProperty, and not the opposite.

platform/qt/include/qquickmapboxgl.hpp

@@ -96,6 +96,10 @@ public:
 
     int swapSyncState();
 
+protected:
+    // QQuickItem implementation.
+    virtual void itemChange(QQuickItem::ItemChange change, const QQuickItem::ItemChangeData &value);
+
 signals:
     void minimumZoomLevelChanged();
     void maximumZoomLevelChanged();
@@ -116,6 +120,9 @@ signals:
 public slots:
     void setCenter(const QGeoCoordinate &center);
 
+private slots:
+    void onStylePropertyUpdated(const QVariantMap &params);
+
 private:
     qreal m_minimumZoomLevel = 0;
     qreal m_maximumZoomLevel = 20;

platform/qt/include/qquickmapboxglstyleproperty.hpp

@@ -12,10 +12,12 @@ class Q_DECL_EXPORT QQuickMapboxGLStyleProperty : public QQuickItem
     Q_PROPERTY(QVariant value READ value WRITE setValue NOTIFY valueChanged)
 
 public:
-    virtual ~QQuickMapboxGLStyleProperty() {}
+    enum Type {
+        LayoutType = 0,
+        PaintType,
+    };
 
-    // QQuickItem implementation
-    virtual void itemChange(QQuickItem::ItemChange, const QQuickItem::ItemChangeData &);
+    virtual ~QQuickMapboxGLStyleProperty() {}
 
     void setLayer(const QString &);
     QString layer() const;
@@ -30,10 +32,11 @@ signals:
     void layerChanged(const QString &);
     void propertyChanged(const QString &);
     void valueChanged(const QVariant &);
+    void updated(const QVariantMap& params);
 
 protected:
-    QQuickMapboxGLStyleProperty(QQuickItem *parent);
-    virtual void updateParent() = 0;
+    QQuickMapboxGLStyleProperty(QQuickItem *parent, Type);
+    void checkUpdated();
 
     QVariantMap m_map;
 };
@@ -43,9 +46,6 @@ class Q_DECL_EXPORT QQuickMapboxGLLayoutStyleProperty : public QQuickMapboxGLSty
 public:
     QQuickMapboxGLLayoutStyleProperty(QQuickItem *parent = 0);
     virtual ~QQuickMapboxGLLayoutStyleProperty() {}
-
-protected:
-    virtual void updateParent();
 };
 
 class Q_DECL_EXPORT QQuickMapboxGLPaintStyleProperty : public QQuickMapboxGLStyleProperty
@@ -62,9 +62,6 @@ public:
 
 signals:
     void classChanged(const QString &);
-
-protected:
-    virtual void updateParent();
 };
 
 #endif // QQUICKMAPBOXGLSTYLEPROPERTY_H

platform/qt/src/qquickmapboxgl.cpp

@@ -3,6 +3,7 @@
 #include <mbgl/util/constants.hpp>
 
 #include <QQuickMapboxGL>
+#include <QQuickMapboxGLStyleProperty>
 
 #include <QDebug>
 #include <QQuickItem>
@@ -257,3 +258,36 @@ int QQuickMapboxGL::swapSyncState()
 
     return oldState;
 }
+
+void QQuickMapboxGL::itemChange(QQuickItem::ItemChange change, const QQuickItem::ItemChangeData &value)
+{
+    QQuickFramebufferObject::itemChange(change, value);
+
+    switch (change) {
+    case QQuickItem::ItemChildAddedChange:
+        if (QQuickMapboxGLStyleProperty *property = qobject_cast<QQuickMapboxGLStyleProperty *>(value.item)) {
+            connect(property, SIGNAL(updated(QVariantMap)), this, SLOT(onStylePropertyUpdated(QVariantMap)));
+        }
+        break;
+    case QQuickItem::ItemChildRemovedChange:
+        if (QQuickMapboxGLStyleProperty *property = qobject_cast<QQuickMapboxGLStyleProperty *>(value.item)) {
+            disconnect(property, SIGNAL(updated(QVariantMap)), this, SLOT(onStylePropertyUpdated(QVariantMap)));
+        }
+    default:
+        break;
+    }
+}
+
+void QQuickMapboxGL::onStylePropertyUpdated(const QVariantMap &params)
+{
+    switch (params.value("type").toInt()) {
+    case QQuickMapboxGLStyleProperty::LayoutType:
+        m_layoutChanges << params;
+        break;
+    case QQuickMapboxGLStyleProperty::PaintType:
+        m_paintChanges << params;
+        break;
+    }
+
+    update();
+}

platform/qt/src/qquickmapboxglstyleproperty.cpp

@@ -1,55 +1,20 @@
 #include <QQuickMapboxGLStyleProperty>
-#include <QQuickMapboxGL>
 
-QQuickMapboxGLStyleProperty::QQuickMapboxGLStyleProperty(QQuickItem *parent_)
+// QQuickMapboxGLStyleProperty
+
+QQuickMapboxGLStyleProperty::QQuickMapboxGLStyleProperty(QQuickItem *parent_, Type type)
     : QQuickItem(parent_)
 {
+    m_map["type"] = type;
 }
 
-QQuickMapboxGLLayoutStyleProperty::QQuickMapboxGLLayoutStyleProperty(QQuickItem *parent_)
-    : QQuickMapboxGLStyleProperty(parent_)
+void QQuickMapboxGLStyleProperty::checkUpdated()
 {
-}
-
-QQuickMapboxGLPaintStyleProperty::QQuickMapboxGLPaintStyleProperty(QQuickItem *parent_)
-    : QQuickMapboxGLStyleProperty(parent_)
-{
-}
-
-void QQuickMapboxGLLayoutStyleProperty::updateParent()
-{
-    if (m_map.value("layer").isNull() || m_map.value("property").isNull() || m_map.value("value").isNull()) {
-        return;
-    }
-
-    QQuickMapboxGL *map = qobject_cast<QQuickMapboxGL *>(parentItem());
-    if (map) {
-        map->setLayoutProperty(layer(), property(), value());
-    } else {
-        qWarning() << "Style property requires QQuickMapboxGL as parent item.";
-    }
-}
-
-void QQuickMapboxGLPaintStyleProperty::updateParent()
-{
-    if (m_map.value("layer").isNull() || m_map.value("property").isNull() || m_map.value("value").isNull()) {
-        return;
-    }
-
-    QQuickMapboxGL *map = qobject_cast<QQuickMapboxGL *>(parentItem());
-    if (map) {
-        map->setPaintProperty(layer(), property(), value(), styleClass());
-    } else {
-        qWarning() << "Style property requires QQuickMapboxGL as parent item.";
-    }
-}
-
-void QQuickMapboxGLStyleProperty::itemChange(QQuickItem::ItemChange change, const QQuickItem::ItemChangeData &data)
-{
-    QQuickItem::itemChange(change, data);
-
-    if (change == QQuickItem::ItemParentHasChanged) {
-        updateParent();
+    if (m_map.value("type").isValid()
+            && m_map.value("layer").isValid()
+            && m_map.value("property").isValid()
+            && m_map.value("value").isValid()) {
+        emit updated(m_map);
     }
 }
 
@@ -61,7 +26,7 @@ void QQuickMapboxGLStyleProperty::setLayer(const QString &layer)
 
     m_map["layer"] = layer;
     emit layerChanged(layer);
-    updateParent();
+    checkUpdated();
 }
 
 QString QQuickMapboxGLStyleProperty::layer() const
@@ -77,7 +42,7 @@ void QQuickMapboxGLStyleProperty::setProperty(const QString &property)
 
     m_map["property"] = property;
     emit propertyChanged(property);
-    updateParent();
+    checkUpdated();
 }
 
 QString QQuickMapboxGLStyleProperty::property() const
@@ -93,7 +58,7 @@ void QQuickMapboxGLStyleProperty::setValue(const QVariant &value)
 
     m_map["value"] = value;
     emit valueChanged(value);
-    updateParent();
+    checkUpdated();
 }
 
 QVariant QQuickMapboxGLStyleProperty::value() const
@@ -109,10 +74,24 @@ void QQuickMapboxGLPaintStyleProperty::setStyleClass(const QString &styleClass)
 
     m_map["class"] = styleClass;
     emit classChanged(styleClass);
-    updateParent();
+    checkUpdated();
 }
 
 QString QQuickMapboxGLPaintStyleProperty::styleClass() const
 {
     return m_map.value("class").toString();
 }
+
+// QQuickMapboxGLLayoutStyleProperty
+
+QQuickMapboxGLLayoutStyleProperty::QQuickMapboxGLLayoutStyleProperty(QQuickItem *parent_)
+    : QQuickMapboxGLStyleProperty(parent_, LayoutType)
+{
+}
+
+// QQuickMapboxGLPaintStyleProperty
+
+QQuickMapboxGLPaintStyleProperty::QQuickMapboxGLPaintStyleProperty(QQuickItem *parent_)
+    : QQuickMapboxGLStyleProperty(parent_, PaintType)
+{
+}