Fix constant CPU load when project contains qml files

Checking whether a file is a behavior or qml stream is expensive, and
it was getting done continuously for some reason. Now we cache
the result of the first check for each file.

Task-number: QT3DS-2404
Change-Id: Iaf7fab48559790c6561ecf6b00d60febd68e6a08
Reviewed-by: Kimmo Leppälä <kimmo.leppala@qt.io>
Reviewed-by: Antti Määttä <antti.maatta@qt.io>
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

4 files changed, 29 insertions, 24 deletions

diff --git a/src/Authoring/Studio/Application/StudioApp.cpp b/src/Authoring/Studio/Application/StudioApp.cpp
index a5328c13..8a684b01 100644
--- a/src/Authoring/Studio/Application/StudioApp.cpp
+++ b/src/Authoring/Studio/Application/StudioApp.cpp
@@ -1754,7 +1754,27 @@ QString CStudioApp::getMostRecentProjectParentDir() const
     return parentDirectory;
 }
 
-//=============================================================================
+bool CStudioApp::isQmlStream(const QString &fileName)
+{
+    bool retval = false;
+    if (m_qmlStreamMap.contains(fileName)) {
+        retval = m_qmlStreamMap[fileName];
+    } else {
+        if (!fileName.endsWith(QLatin1String(".qml"))) {
+            retval = false;
+        } else {
+            QQmlApplicationEngine qmlEngine(fileName);
+            if (qmlEngine.rootObjects().size() > 0) {
+                const char *rootClassName = qmlEngine.rootObjects().at(0)
+                                            ->metaObject()->superClass()->className();
+                retval = strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0;
+            }
+        }
+        m_qmlStreamMap.insert(fileName, retval);
+    }
+    return retval;
+}
+
 /**
  * Called by OnLoadDocument, to allow the error reporting to be inserted.
  * Because of the nature of the error reporting, OnLoadDocument has to have
diff --git a/src/Authoring/Studio/Application/StudioApp.h b/src/Authoring/Studio/Application/StudioApp.h
index e91be9e8..0332618a 100644
--- a/src/Authoring/Studio/Application/StudioApp.h
+++ b/src/Authoring/Studio/Application/StudioApp.h
@@ -147,6 +147,7 @@ private:
 public:
     CMainFrame* m_pMainWnd;
     QWidget *m_lastActiveView = nullptr;
+    QHash<QString, bool> m_qmlStreamMap;
 
     CCore *GetCore();
     CViews *GetViews();
@@ -264,6 +265,8 @@ public:
 
     void setLastActiveView(QWidget *widget) { m_lastActiveView = widget; }
     QWidget *lastActiveView() const { return m_lastActiveView; }
+
+    bool isQmlStream(const QString &fileName);
 };
 
 extern CStudioApp g_StudioApp;
diff --git a/src/Authoring/Studio/Palettes/Project/ProjectView.cpp b/src/Authoring/Studio/Palettes/Project/ProjectView.cpp
index 6b7a5a49..fcfa8c2b 100644
--- a/src/Authoring/Studio/Palettes/Project/ProjectView.cpp
+++ b/src/Authoring/Studio/Palettes/Project/ProjectView.cpp
@@ -50,7 +50,6 @@
 #include <QtQml/qqmlengine.h>
 #include <QtQml/qqmlfile.h>
 #include <QtQuick/qquickitem.h>
-#include <QtQml/qqmlapplicationengine.h>
 
 ProjectView::ProjectView(const QSize &preferredSize, QWidget *parent) : QQuickWidget(parent)
   , m_ProjectModel(new ProjectFileSystemModel(this))
@@ -369,19 +368,7 @@ bool ProjectView::isPresentation(int row) const
 
 bool ProjectView::isQmlStream(int row) const
 {
-    const QString filePath = m_ProjectModel->filePath(row);
-
-    if (!filePath.endsWith(QLatin1String(".qml")))
-        return false;
-
-    QQmlApplicationEngine qmlEngine(filePath);
-    if (qmlEngine.rootObjects().size() > 0) {
-        const char *rootClassName = qmlEngine.rootObjects().at(0)
-                                    ->metaObject()->superClass()->className();
-        return strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0;
-    } else {
-        return false;
-    }
+    return g_StudioApp.isQmlStream(m_ProjectModel->filePath(row));
 }
 
 bool ProjectView::isRefreshable(int row) const
diff --git a/src/Authoring/Studio/Utils/ImportUtils.cpp b/src/Authoring/Studio/Utils/ImportUtils.cpp
index 2bb4807c..933afe97 100644
--- a/src/Authoring/Studio/Utils/ImportUtils.cpp
+++ b/src/Authoring/Studio/Utils/ImportUtils.cpp
@@ -31,7 +31,7 @@
 #include "ImportUtils.h"
 #include "Dialogs.h"
 #include "Qt3DSFileTools.h"
-#include <QtQml/qqmlapplicationengine.h>
+#include "StudioApp.h"
 
 namespace Q3DStudio {
 
@@ -56,14 +56,9 @@ SObjectFileType ImportUtils::GetObjectFileTypeForFile(const CFilePath &inFile,
             DocumentEditorFileType::Image); // Drag-drop image to scene will auto-map to Rectangle.
     } else if (theExtension.Compare(CDialogs::GetQmlFileExtension(),
                                     Q3DStudio::CString::ENDOFSTRING, false)) {
-        QQmlApplicationEngine qmlEngine(inFile.absoluteFilePath());
-        if (qmlEngine.rootObjects().size() > 0) {
-            const char *rootClassName = qmlEngine.rootObjects().at(0)
-                                        ->metaObject()->superClass()->className();
-            bool isQmlStream =  strcmp(rootClassName, "Q3DStudio::Q3DSQmlBehavior") != 0;
-            return isQmlStream ? SObjectFileType(OBJTYPE_QML_STREAM, DocumentEditorFileType::QmlStream)
-                               : SObjectFileType(OBJTYPE_BEHAVIOR, DocumentEditorFileType::Behavior);
-        } // If qml file is invalid, it will be of unknown type
+        return g_StudioApp.isQmlStream(inFile.absoluteFilePath())
+                ? SObjectFileType(OBJTYPE_QML_STREAM, DocumentEditorFileType::QmlStream)
+                : SObjectFileType(OBJTYPE_BEHAVIOR, DocumentEditorFileType::Behavior);
     } else if (CDialogs::IsFontFileExtension(theExtension)) {
         return SObjectFileType(OBJTYPE_TEXT, DocumentEditorFileType::Font);
     } else if (CDialogs::IsEffectFileExtension(theExtension)) {