QmlDesigner: Fix crash with ColorEditorSingleton

Fix a crash that was caused by ColorPaletteSingleton being shared among
multiple QQnlEngines. Each engine requires a unique instance of
ColorEditorSingleton.

* Rewrite ColorEditorSingleton to not be a singleton anymore
* Rename ColorEditorSingleton to ColorEditorBackend
* Add meaningful warnings

Task-number: QDS-4728
Change-Id: I1ed3315add33754b41870ad6f43c1365a899102b
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

8 files changed, 72 insertions, 78 deletions

diff --git a/share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorEditor.qml b/share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorEditor.qml
index 2a292d4ab4..2ed45ea3e1 100644
--- a/share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorEditor.qml
+++ b/share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorEditor.qml
@@ -478,7 +478,7 @@ SecondColumnLayout {
                             icon: StudioTheme.Constants.eyeDropper
                             pixelSize: StudioTheme.Values.myIconFontSize * 1.4
                             tooltip: qsTr("Eye Dropper")
-                            onClicked: ColorPaletteSingleton.eyeDropper()
+                            onClicked: ColorPaletteBackend.eyeDropper()
                         }
 
                         IconIndicator {
@@ -700,7 +700,7 @@ SecondColumnLayout {
 
                             StudioControls.MenuItem {
                                 text: qsTr("Add to Favorites")
-                                onTriggered: ColorPaletteSingleton.addFavoriteColor(
+                                onTriggered: ColorPaletteBackend.addFavoriteColor(
                                                  contextMenuFavorite.currentColor)
                             }
                         }
diff --git a/share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorPalette.qml b/share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorPalette.qml
index 4ff74c7aa7..cc007f1463 100644
--- a/share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorPalette.qml
+++ b/share/qtcreator/qmldesigner/propertyEditorQmlSources/imports/HelperWidgets/ColorPalette.qml
@@ -41,12 +41,12 @@ Column {
     spacing: 10
 
     function addColorToPalette(colorStr) {
-        ColorPaletteSingleton.addRecentColor(colorStr)
+        ColorPaletteBackend.addRecentColor(colorStr)
     }
 
     function showColorDialog(color) {
         root.oldColor = color
-        ColorPaletteSingleton.showDialog(color)
+        ColorPaletteBackend.showDialog(color)
     }
 
     signal dialogColorChanged
@@ -92,14 +92,14 @@ Column {
                 StudioControls.MenuItem {
                     visible: colorMode.currentText === "Favorite"
                     text: qsTr("Remove from Favorites")
-                    onTriggered: ColorPaletteSingleton.removeFavoriteColor(index)
+                    onTriggered: ColorPaletteBackend.removeFavoriteColor(index)
                     height: visible ? implicitHeight : 0
                 }
 
                 StudioControls.MenuItem {
                     visible: colorMode.currentText !== "Favorite"
                     text: qsTr("Add to Favorites")
-                    onTriggered: ColorPaletteSingleton.addFavoriteColor(modelData)
+                    onTriggered: ColorPaletteBackend.addFavoriteColor(modelData)
                     height: visible ? implicitHeight : 0
                 }
             }
@@ -108,7 +108,7 @@ Column {
 
     Connections {
         id: singletonConnection
-        target: ColorPaletteSingleton
+        target: ColorPaletteBackend
 
         function onCurrentColorChanged(color) {
             root.selectedColor = color
@@ -132,18 +132,18 @@ Column {
                            + 4 * StudioTheme.Values.colorEditorPopupSpinBoxWidth
             width: implicitWidth
             actionIndicatorVisible: false
-            model: ColorPaletteSingleton.palettes
-            currentIndex: colorMode.find(ColorPaletteSingleton.currentPalette)
+            model: ColorPaletteBackend.palettes
+            currentIndex: colorMode.find(ColorPaletteBackend.currentPalette)
 
-            onActivated: ColorPaletteSingleton.currentPalette = colorMode.currentText
+            onActivated: ColorPaletteBackend.currentPalette = colorMode.currentText
 
-            Component.onCompleted: colorMode.currentIndex = colorMode.find(ColorPaletteSingleton.currentPalette)
+            Component.onCompleted: colorMode.currentIndex = colorMode.find(ColorPaletteBackend.currentPalette)
         }
     }
 
     GridView {
         id: colorPaletteView
-        model: ColorPaletteSingleton.currentPaletteColors
+        model: ColorPaletteBackend.currentPaletteColors
         delegate: colorItemDelegate
         cellWidth: StudioTheme.Values.colorEditorPopupSpinBoxWidth
                    + StudioTheme.Values.controlGap
diff --git a/src/plugins/qmldesigner/CMakeLists.txt b/src/plugins/qmldesigner/CMakeLists.txt
index 109368c0e5..e578445ac4 100644
--- a/src/plugins/qmldesigner/CMakeLists.txt
+++ b/src/plugins/qmldesigner/CMakeLists.txt
@@ -353,7 +353,7 @@ extend_qtc_plugin(QmlDesigner
   SOURCES_PREFIX components/propertyeditor
   SOURCES
     aligndistribute.cpp aligndistribute.h
-    colorpalettesingleton.cpp colorpalettesingleton.h
+    colorpalettebackend.cpp colorpalettebackend.h
     designerpropertymap.cpp designerpropertymap.h
     fileresourcesmodel.cpp fileresourcesmodel.h
     itemfiltermodel.cpp itemfiltermodel.h
diff --git a/src/plugins/qmldesigner/components/propertyeditor/colorpalettesingleton.cpp b/src/plugins/qmldesigner/components/propertyeditor/colorpalettebackend.cpp
index 65d78aa1d4..c848eed2db 100644
--- a/src/plugins/qmldesigner/components/propertyeditor/colorpalettesingleton.cpp
+++ b/src/plugins/qmldesigner/components/propertyeditor/colorpalettebackend.cpp
@@ -23,7 +23,7 @@
 **
 ****************************************************************************/
 
-#include "colorpalettesingleton.h"
+#include "colorpalettebackend.h"
 
 #include <QDebug>
 #include <QSettings>
@@ -36,9 +36,9 @@
 
 namespace QmlDesigner {
 
-QPointer<ColorPaletteSingleton> ColorPaletteSingleton::m_instance = nullptr;
+QPointer<ColorPaletteBackend> ColorPaletteBackend::m_instance = nullptr;
 
-ColorPaletteSingleton::ColorPaletteSingleton()
+ColorPaletteBackend::ColorPaletteBackend()
     : m_currentPalette()
     , m_data()
     , m_colorPickingEventFilter(nullptr)
@@ -58,24 +58,16 @@ ColorPaletteSingleton::ColorPaletteSingleton()
     dummyTransparentWindow.resize(1, 1);
     dummyTransparentWindow.setFlags(Qt::Tool | Qt::FramelessWindowHint);
     updateTimer = new QTimer(this);
-    connect(updateTimer, &QTimer::timeout, this, &ColorPaletteSingleton::updateEyeDropper);
+    connect(updateTimer, &QTimer::timeout, this, &ColorPaletteBackend::updateEyeDropper);
 #endif
 }
 
-ColorPaletteSingleton::~ColorPaletteSingleton()
+ColorPaletteBackend::~ColorPaletteBackend()
 {
     //writePalettes(); // TODO crash on QtDS close
 }
 
-ColorPaletteSingleton *ColorPaletteSingleton::instance()
-{
-    if (m_instance == nullptr)
-        m_instance = new ColorPaletteSingleton();
-
-    return m_instance;
-}
-
-void ColorPaletteSingleton::readPalettes()
+void ColorPaletteBackend::readPalettes()
 {
     QHash<QString, Palette>::iterator i = m_data.begin();
     while (i != m_data.end()) {
@@ -84,7 +76,7 @@ void ColorPaletteSingleton::readPalettes()
     }
 }
 
-void ColorPaletteSingleton::writePalettes()
+void ColorPaletteBackend::writePalettes()
 {
     QHash<QString, Palette>::iterator i = m_data.begin();
     while (i != m_data.end()) {
@@ -93,10 +85,10 @@ void ColorPaletteSingleton::writePalettes()
     }
 }
 
-void ColorPaletteSingleton::addColor(const QString &color, const QString &palette)
+void ColorPaletteBackend::addColor(const QString &color, const QString &palette)
 {
     if (!m_data.contains(palette)) {
-        qWarning() << "TODO";
+        qWarning() << Q_FUNC_INFO << "Unknown palette: " << palette;
         return;
     }
 
@@ -116,15 +108,15 @@ void ColorPaletteSingleton::addColor(const QString &color, const QString &palett
     m_data[palette].write();
 }
 
-void ColorPaletteSingleton::removeColor(int id, const QString &palette)
+void ColorPaletteBackend::removeColor(int id, const QString &palette)
 {
     if (!m_data.contains(palette)) {
-        qWarning() << "TODO";
+        qWarning() << Q_FUNC_INFO << "Unknown palette: " << palette;
         return;
     }
 
     if (id >= m_data[palette].m_colors.size()) {
-        qWarning() << "TODO";
+        qWarning() << Q_FUNC_INFO << "Id(" << id << ") is out of bounds for palette " << palette;
         return;
     }
 
@@ -143,7 +135,7 @@ void ColorPaletteSingleton::removeColor(int id, const QString &palette)
     m_data[palette].write();
 }
 
-void ColorPaletteSingleton::addRecentColor(const QString &item)
+void ColorPaletteBackend::addRecentColor(const QString &item)
 {
     if (m_data[g_recent].m_colors.isEmpty()) {
         addColor(item, g_recent);
@@ -155,30 +147,30 @@ void ColorPaletteSingleton::addRecentColor(const QString &item)
         addColor(item, g_recent);
 }
 
-void ColorPaletteSingleton::addFavoriteColor(const QString &item)
+void ColorPaletteBackend::addFavoriteColor(const QString &item)
 {
     addColor(item, g_favorite);
 }
 
-void ColorPaletteSingleton::removeFavoriteColor(int id)
+void ColorPaletteBackend::removeFavoriteColor(int id)
 {
     removeColor(id, g_favorite);
 }
 
-QStringList ColorPaletteSingleton::palettes() const
+QStringList ColorPaletteBackend::palettes() const
 {
     return m_data.keys();
 }
 
-const QString &ColorPaletteSingleton::currentPalette() const
+const QString &ColorPaletteBackend::currentPalette() const
 {
     return m_currentPalette;
 }
 
-void ColorPaletteSingleton::setCurrentPalette(const QString &palette)
+void ColorPaletteBackend::setCurrentPalette(const QString &palette)
 {
     if (!m_data.contains(palette)) {
-        qWarning() << "TODO";
+        qWarning() << Q_FUNC_INFO << "Unknown palette: " << palette;
         return;
     }
 
@@ -207,35 +199,35 @@ void ColorPaletteSingleton::setCurrentPalette(const QString &palette)
     emit currentPaletteColorsChanged();
 }
 
-const QStringList &ColorPaletteSingleton::currentPaletteColors() const
+const QStringList &ColorPaletteBackend::currentPaletteColors() const
 {
     return m_currentPaletteColors;
 }
 
-void ColorPaletteSingleton::registerDeclarativeType()
+void ColorPaletteBackend::registerDeclarativeType()
 {
-    static const int typeIndex = qmlRegisterSingletonType<ColorPaletteSingleton>(
-        "QtQuickDesignerColorPalette", 1, 0, "ColorPaletteSingleton", [](QQmlEngine *, QJSEngine *) {
-            return ColorPaletteSingleton::instance();
+    static const int typeIndex = qmlRegisterSingletonType<ColorPaletteBackend>(
+        "QtQuickDesignerColorPalette", 1, 0, "ColorPaletteBackend", [](QQmlEngine *, QJSEngine *) {
+            return new ColorPaletteBackend();
     });
     Q_UNUSED(typeIndex)
 }
 
-void ColorPaletteSingleton::showDialog(QColor color)
+void ColorPaletteBackend::showDialog(QColor color)
 {
     auto colorDialog = new QColorDialog(Core::ICore::dialogParent());
     colorDialog->setCurrentColor(color);
     colorDialog->setAttribute(Qt::WA_DeleteOnClose);
 
     connect(colorDialog, &QDialog::rejected,
-            this, &ColorPaletteSingleton::colorDialogRejected);
+            this, &ColorPaletteBackend::colorDialogRejected);
     connect(colorDialog, &QColorDialog::currentColorChanged,
-            this, &ColorPaletteSingleton::currentColorChanged);
+            this, &ColorPaletteBackend::currentColorChanged);
 
     QTimer::singleShot(0, [colorDialog](){ colorDialog->exec(); });
 }
 
-void ColorPaletteSingleton::eyeDropper()
+void ColorPaletteBackend::eyeDropper()
 {
     QWidget *widget = QApplication::activeWindow();
     if (!widget)
@@ -274,12 +266,12 @@ const int g_screenGrabHeight = 7;
 const int g_pixelX = 3;
 const int g_pixelY = 3;
 
-QColor ColorPaletteSingleton::grabScreenColor(const QPoint &p)
+QColor ColorPaletteBackend::grabScreenColor(const QPoint &p)
 {
     return grabScreenRect(p).pixel(g_pixelX, g_pixelY);
 }
 
-QImage ColorPaletteSingleton::grabScreenRect(const QPoint &p)
+QImage ColorPaletteBackend::grabScreenRect(const QPoint &p)
 {
     QScreen *screen = QGuiApplication::screenAt(p);
     if (!screen)
@@ -289,7 +281,7 @@ QImage ColorPaletteSingleton::grabScreenRect(const QPoint &p)
     return pixmap.toImage();
 }
 
-void ColorPaletteSingleton::updateEyeDropper()
+void ColorPaletteBackend::updateEyeDropper()
 {
 #ifndef QT_NO_CURSOR
     static QPoint lastGlobalPos;
@@ -306,12 +298,12 @@ void ColorPaletteSingleton::updateEyeDropper()
 #endif // ! QT_NO_CURSOR
 }
 
-void ColorPaletteSingleton::updateEyeDropperPosition(const QPoint &globalPos)
+void ColorPaletteBackend::updateEyeDropperPosition(const QPoint &globalPos)
 {
     updateCursor(grabScreenRect(globalPos));
 }
 
-void ColorPaletteSingleton::updateCursor(const QImage &image)
+void ColorPaletteBackend::updateCursor(const QImage &image)
 {
     QWidget *widget = QApplication::activeWindow();
     if (!widget)
@@ -351,7 +343,7 @@ void ColorPaletteSingleton::updateCursor(const QImage &image)
     widget->setCursor(cursor);
 }
 
-void ColorPaletteSingleton::releaseEyeDropper()
+void ColorPaletteBackend::releaseEyeDropper()
 {
     QWidget *widget = QApplication::activeWindow();
     if (!widget)
@@ -369,13 +361,13 @@ void ColorPaletteSingleton::releaseEyeDropper()
     widget->unsetCursor();
 }
 
-bool ColorPaletteSingleton::handleEyeDropperMouseMove(QMouseEvent *e)
+bool ColorPaletteBackend::handleEyeDropperMouseMove(QMouseEvent *e)
 {
     updateEyeDropperPosition(e->globalPos());
     return true;
 }
 
-bool ColorPaletteSingleton::handleEyeDropperMouseButtonRelease(QMouseEvent *e)
+bool ColorPaletteBackend::handleEyeDropperMouseButtonRelease(QMouseEvent *e)
 {
     if (e->button() == Qt::LeftButton)
         emit currentColorChanged(grabScreenColor(e->globalPos()));
@@ -386,7 +378,7 @@ bool ColorPaletteSingleton::handleEyeDropperMouseButtonRelease(QMouseEvent *e)
     return true;
 }
 
-bool ColorPaletteSingleton::handleEyeDropperKeyPress(QKeyEvent *e)
+bool ColorPaletteBackend::handleEyeDropperKeyPress(QKeyEvent *e)
 {
 #if QT_CONFIG(shortcut)
     if (e->matches(QKeySequence::Cancel)) {
diff --git a/src/plugins/qmldesigner/components/propertyeditor/colorpalettesingleton.h b/src/plugins/qmldesigner/components/propertyeditor/colorpalettebackend.h
index 153cc52f9e..2042b30802 100644
--- a/src/plugins/qmldesigner/components/propertyeditor/colorpalettesingleton.h
+++ b/src/plugins/qmldesigner/components/propertyeditor/colorpalettebackend.h
@@ -78,7 +78,7 @@ struct Palette
     QStringList m_colors;
 };
 
-class ColorPaletteSingleton : public QObject
+class ColorPaletteBackend : public QObject
 {
     Q_OBJECT
 
@@ -94,9 +94,7 @@ class ColorPaletteSingleton : public QObject
                NOTIFY palettesChanged)
 
 public:
-    static ColorPaletteSingleton *instance();
-
-    ~ColorPaletteSingleton();
+    ~ColorPaletteBackend();
 
     void readPalettes();
     void writePalettes();
@@ -140,8 +138,8 @@ public:
     bool handleEyeDropperKeyPress(QKeyEvent *e);
 
 
-    ColorPaletteSingleton(const ColorPaletteSingleton &) = delete;
-    void operator=(const ColorPaletteSingleton &) = delete;
+    ColorPaletteBackend(const ColorPaletteBackend &) = delete;
+    void operator=(const ColorPaletteBackend &) = delete;
 
 signals:
     void currentPaletteChanged(const QString &palette);
@@ -154,10 +152,10 @@ signals:
     void eyeDropperRejected();
 
 private:
-    ColorPaletteSingleton();
+    ColorPaletteBackend();
 
 private:
-    static QPointer<ColorPaletteSingleton> m_instance;
+    static QPointer<ColorPaletteBackend> m_instance;
     QString m_currentPalette;
     QStringList m_currentPaletteColors;
     QHash<QString, Palette> m_data;
@@ -171,29 +169,33 @@ private:
 
 class QColorPickingEventFilter : public QObject {
 public:
-    explicit QColorPickingEventFilter(QObject *parent = 0)
-        : QObject(parent)
+    explicit QColorPickingEventFilter(ColorPaletteBackend *colorPalette)
+        : QObject(colorPalette)
+        , m_colorPalette(colorPalette)
     {}
 
     bool eventFilter(QObject *, QEvent *event) override
     {
         switch (event->type()) {
         case QEvent::MouseMove:
-            return ColorPaletteSingleton::instance()->handleEyeDropperMouseMove(
+            return m_colorPalette->handleEyeDropperMouseMove(
                         static_cast<QMouseEvent *>(event));
         case QEvent::MouseButtonRelease:
-            return ColorPaletteSingleton::instance()->handleEyeDropperMouseButtonRelease(
+            return m_colorPalette->handleEyeDropperMouseButtonRelease(
                         static_cast<QMouseEvent *>(event));
         case QEvent::KeyPress:
-            return ColorPaletteSingleton::instance()->handleEyeDropperKeyPress(
+            return m_colorPalette->handleEyeDropperKeyPress(
                         static_cast<QKeyEvent *>(event));
         default:
             break;
         }
         return false;
     }
+
+private:
+    ColorPaletteBackend *m_colorPalette;
 };
 
 } // namespace QmlDesigner
 
-QML_DECLARE_TYPE(QmlDesigner::ColorPaletteSingleton)
+QML_DECLARE_TYPE(QmlDesigner::ColorPaletteBackend)
diff --git a/src/plugins/qmldesigner/components/propertyeditor/propertyeditor.pri b/src/plugins/qmldesigner/components/propertyeditor/propertyeditor.pri
index 0360652fbf..dc8407e66b 100644
--- a/src/plugins/qmldesigner/components/propertyeditor/propertyeditor.pri
+++ b/src/plugins/qmldesigner/components/propertyeditor/propertyeditor.pri
@@ -16,7 +16,7 @@ SOURCES += propertyeditorview.cpp \
     gradientpresetlistmodel.cpp \
     gradientpresetdefaultlistmodel.cpp \
     gradientpresetcustomlistmodel.cpp \
-    colorpalettesingleton.cpp \
+    colorpalettebackend.cpp \
     itemfiltermodel.cpp \
     aligndistribute.cpp \
     tooltip.cpp
@@ -37,7 +37,7 @@ HEADERS += propertyeditorview.h \
     gradientpresetlistmodel.h \
     gradientpresetdefaultlistmodel.h \
     gradientpresetcustomlistmodel.h \
-    colorpalettesingleton.h \
+    colorpalettebackend.h \
     itemfiltermodel.h \
     aligndistribute.h \
     tooltip.h
diff --git a/src/plugins/qmldesigner/components/propertyeditor/quick2propertyeditorview.cpp b/src/plugins/qmldesigner/components/propertyeditor/quick2propertyeditorview.cpp
index 6298448bbc..09450cdb7c 100644
--- a/src/plugins/qmldesigner/components/propertyeditor/quick2propertyeditorview.cpp
+++ b/src/plugins/qmldesigner/components/propertyeditor/quick2propertyeditorview.cpp
@@ -29,7 +29,7 @@
 #include "annotationeditor/annotationeditor.h"
 #include "bindingeditor/actioneditor.h"
 #include "bindingeditor/bindingeditor.h"
-#include "colorpalettesingleton.h"
+#include "colorpalettebackend.h"
 #include "fileresourcesmodel.h"
 #include "gradientmodel.h"
 #include "gradientpresetcustomlistmodel.h"
@@ -63,7 +63,7 @@ void Quick2PropertyEditorView::registerQmlTypes()
         GradientPresetDefaultListModel::registerDeclarativeType();
         GradientPresetCustomListModel::registerDeclarativeType();
         ItemFilterModel::registerDeclarativeType();
-        ColorPaletteSingleton::registerDeclarativeType();
+        ColorPaletteBackend::registerDeclarativeType();
         Internal::QmlAnchorBindingProxy::registerDeclarativeType();
         BindingEditor::registerDeclarativeType();
         ActionEditor::registerDeclarativeType();
diff --git a/src/plugins/qmldesigner/qmldesignerplugin.qbs b/src/plugins/qmldesigner/qmldesignerplugin.qbs
index 37d8bf84be..8b95987a7b 100644
--- a/src/plugins/qmldesigner/qmldesignerplugin.qbs
+++ b/src/plugins/qmldesigner/qmldesignerplugin.qbs
@@ -677,8 +677,8 @@ Project {
                 "navigator/previewtooltip.ui",
                 "propertyeditor/aligndistribute.cpp",
                 "propertyeditor/aligndistribute.h",
-                "propertyeditor/colorpalettesingleton.cpp",
-                "propertyeditor/colorpalettesingleton.h",
+                "propertyeditor/colorpalettebackend.cpp",
+                "propertyeditor/colorpalettebackend.h",
                 "propertyeditor/designerpropertymap.cpp",
                 "propertyeditor/designerpropertymap.h",
                 "propertyeditor/fileresourcesmodel.cpp",