QmlDesigner.PropertyEditor: Fix selection in gradient editing

Since property change signals can be emitted in any order we have to rely
on selection changed signals to guarantee a valid state.

I use the isInValidState which is only true after all properties have been
setup correctly after a selection change for this.

I added the signal selectionChanged for this.

Task-number: QTCREATORBUG-12642
Task-number: QTCREATORBUG-12506
Change-Id: Idf3bbe8236ece541ca267efb1bd68e0737c99716
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>

share/qtcreator/qmldesigner/propertyEditorQmlSources/HelperWidgets/ColorEditor.qml

@@ -62,6 +62,7 @@ Column {
         id: colorEditorTimer
         repeat: false
         interval: 100
+        running: false
         onTriggered: {
             if (backendendValue !== undefined)
                 backendendValue.value = colorEditor.color
@@ -69,21 +70,22 @@ Column {
     }
 
     onColorChanged: {
-        if (!gradientLine.isCompleted)
+        if (!gradientLine.isInValidState)
             return;
 
         if (supportGradient && gradientLine.hasGradient) {
-            gradientLine.currentColor = color
             textField.text = convertColorToString(color)
+            gradientLine.currentColor = color
         }
 
-        if (buttonRow.checkedIndex !== 1)
+        if (buttonRow.checkedIndex !== 1) {
             //Delay setting the color to keep ui responsive
             colorEditorTimer.restart()
+        }
     }
 
     GradientLine {
-        property bool isCompleted: false
+        property bool isInValidState: false
         visible: buttonRow.checkedIndex === 1
         id: gradientLine
 
@@ -108,20 +110,25 @@ Column {
             buttonRow.checkedIndex = buttonRow.initalChecked
         }
 
+        Connections {
+            target: modelNodeBackend
+            onSelectionToBeChanged: {
+                colorEditorTimer.stop()
+                gradientLine.isInValidState = false
+            }
+        }
+
         Connections {
             target: modelNodeBackend
             onSelectionChanged: {
                 if (supportGradient && gradientLine.hasGradient) {
                     colorEditor.color = gradientLine.currentColor
-                } else {
-                    colorEditor.color = colorEditor.value
+                    gradientLine.currentColor = color
                 }
+                gradientLine.isInValidState = true
             }
         }
 
-        Component.onCompleted: {
-            isCompleted= true
-        }
     }
 
     SectionLayout {

src/plugins/qmldesigner/components/propertyeditor/propertyeditorqmlbackend.cpp

@@ -443,6 +443,11 @@ void PropertyEditorQmlBackend::emitSelectionToBeChanged()
     m_backendModelNode.emitSelectionToBeChanged();
 }
 
+void PropertyEditorQmlBackend::emitSelectionChanged()
+{
+    m_backendModelNode.emitSelectionChanged();
+}
+
 QUrl PropertyEditorQmlBackend::getQmlUrlForModelNode(const ModelNode &modelNode, TypeName &className)
 {
     if (modelNode.isValid()) {

src/plugins/qmldesigner/components/propertyeditor/propertyeditorqmlbackend.h

@@ -75,6 +75,7 @@ public:
     static bool checkIfUrlExists(const QUrl &url);
 
     void emitSelectionToBeChanged();
+    void emitSelectionChanged();
 
 private:
     void createPropertyEditorValue(const QmlObjectNode &qmlObjectNode,

src/plugins/qmldesigner/components/propertyeditor/propertyeditorview.cpp

@@ -347,6 +347,9 @@ void PropertyEditorView::resetView()
 
     setupQmlBackend();
 
+    if (m_qmlBackEndForCurrentType)
+        m_qmlBackEndForCurrentType->emitSelectionChanged();
+
     m_locked = false;
 
     if (m_timerId)

src/plugins/qmldesigner/components/propertyeditor/qmlmodelnodeproxy.cpp

@@ -55,6 +55,11 @@ void QmlModelNodeProxy::emitSelectionToBeChanged()
     emit selectionToBeChanged();
 }
 
+void QmlModelNodeProxy::emitSelectionChanged()
+{
+    selectionChanged();
+}
+
 QmlItemNode QmlModelNodeProxy::qmlItemNode() const
 {
     return m_qmlItemNode;

src/plugins/qmldesigner/components/propertyeditor/qmlmodelnodeproxy.h

@@ -50,6 +50,7 @@ public:
     static void registerDeclarativeType();
 
     void emitSelectionToBeChanged();
+    void emitSelectionChanged();
 
     QmlItemNode qmlItemNode() const;
 
@@ -58,6 +59,7 @@ public:
 signals:
     void modelNodeChanged();
     void selectionToBeChanged();
+    void selectionChanged();
 
 public slots: