Make the GUI work without crashing (avoid embedded event loop)

src/3d/qgscameracontroller.cpp

@@ -419,6 +419,9 @@ void QgsCameraController::setLookingAtPoint( const QgsVector3D &point, float dis
 
 void QgsCameraController::setCameraPose( const QgsCameraPose &camPose )
 {
+  if ( camPose == mCameraPose )
+    return;
+
   mCameraPose = camPose;
 
   if ( mCamera )

src/3d/qgslayoutitem3dmap.cpp

@@ -26,6 +26,7 @@
 QgsLayoutItem3DMap::QgsLayoutItem3DMap( QgsLayout *layout )
   : QgsLayoutItem( layout )
 {
+  connect( this, &QgsLayoutItem::sizePositionChanged, this, &QgsLayoutItem3DMap::onSizePositionChanged );
 }
 
 QgsLayoutItem3DMap::~QgsLayoutItem3DMap() = default;
@@ -43,30 +44,80 @@ int QgsLayoutItem3DMap::type() const
 
 void QgsLayoutItem3DMap::draw( QgsLayoutItemRenderContext &context )
 {
+  QgsRenderContext &ctx = context.renderContext();
+  QPainter *painter = ctx.painter();
+
+  int w = static_cast<int>( std::ceil( rect().width() * ctx.scaleFactor() ) );
+  int h = static_cast<int>( std::ceil( rect().height() * ctx.scaleFactor() ) );
+  QRect r( 0, 0, w, h );
+
+  painter->save();
+
   if ( !mSettings )
+  {
+    painter->drawText( r, Qt::AlignCenter, tr( "Scene not set" ) );
+    painter->restore();
+    return;
+  }
+
+  if ( !mCapturedImage.isNull() )
+  {
+    painter->drawImage( r, mCapturedImage );
+    painter->restore();
     return;
+  }
+
+  // we do not have a cached image of the rendered scene - let's request one from the engine
+
+  painter->drawText( r, Qt::AlignCenter, tr( "Loading" ) );
+  painter->restore();
 
-  QgsOffscreen3DEngine engine;
   QSizeF sizePixels = mLayout->renderContext().measurementConverter().convert( sizeWithUnits(), QgsUnitTypes::LayoutPixels ).toQSizeF();
-  engine.setSize( QSize( static_cast<int>( std::ceil( sizePixels.width() ) ),
-                         static_cast<int>( std::ceil( sizePixels.height() ) ) ) );
+  QSize sizePixelsInt = QSize( static_cast<int>( std::ceil( sizePixels.width() ) ),
+                               static_cast<int>( std::ceil( sizePixels.height() ) ) );
 
-  Qgs3DMapScene *scene = new Qgs3DMapScene( *mSettings, &engine );
-  engine.setRootEntity( scene );
+  if ( !mEngine )
+  {
+    mEngine.reset( new QgsOffscreen3DEngine );
+    connect( mEngine.get(), &QgsAbstract3DEngine::imageCaptured, this, &QgsLayoutItem3DMap::onImageCaptured );
 
-  scene->cameraController()->setCameraPose( mCameraPose );
+    mEngine->setSize( sizePixelsInt );
 
-  // XXX this should not be needed, but without it the scene often
-  // is not completely ready (e.g. a missing terrain tile).
-  // leaving it here until a more robust solution is found...
-  Qgs3DUtils::captureSceneImage( engine, scene );
+    mScene = new Qgs3DMapScene( *mSettings, mEngine.get() );
+    connect( mScene, &Qgs3DMapScene::sceneStateChanged, this, &QgsLayoutItem3DMap::onSceneStateChanged );
 
-  QImage img = Qgs3DUtils::captureSceneImage( engine, scene );
+    mEngine->setRootEntity( mScene );
+  }
 
-  QgsRenderContext &ctx = context.renderContext();
-  ctx.painter()->drawImage( 0, 0, img );
+  if ( mEngine->size() != sizePixelsInt )
+    mEngine->setSize( sizePixelsInt );
+
+  mScene->cameraController()->setCameraPose( mCameraPose );
+
+  onSceneStateChanged();
+}
+
+void QgsLayoutItem3DMap::onImageCaptured( const QImage &img )
+{
+  mCapturedImage = img;
+  update();
+}
+
+void QgsLayoutItem3DMap::onSceneStateChanged()
+{
+  if ( mCapturedImage.isNull() && mScene->sceneState() == Qgs3DMapScene::Ready )
+  {
+    mEngine->requestCaptureImage();
+  }
+}
+
+void QgsLayoutItem3DMap::onSizePositionChanged()
+{
+  mCapturedImage = QImage();
+  update();
 }
 
+
 bool QgsLayoutItem3DMap::writePropertiesToElement( QDomElement &element, QDomDocument &document, const QgsReadWriteContext &context ) const
 {
   if ( mSettings )
@@ -83,6 +134,7 @@ bool QgsLayoutItem3DMap::writePropertiesToElement( QDomElement &element, QDomDoc
 
 bool QgsLayoutItem3DMap::readPropertiesFromElement( const QDomElement &element, const QDomDocument &document, const QgsReadWriteContext &context )
 {
+  Q_UNUSED( document );
   QDomElement elemSettings = element.firstChildElement( "qgis3d" );
   if ( !elemSettings.isNull() )
   {
@@ -102,4 +154,20 @@ bool QgsLayoutItem3DMap::readPropertiesFromElement( const QDomElement &element,
 void QgsLayoutItem3DMap::setMapSettings( Qgs3DMapSettings *settings )
 {
   mSettings.reset( settings );
+
+  mEngine.reset();
+  mScene = nullptr;
+
+  mCapturedImage = QImage();
+  update();
+}
+
+void QgsLayoutItem3DMap::setCameraPose( const QgsCameraPose &pose )
+{
+  if ( mCameraPose == pose )
+    return;
+
+  mCameraPose = pose;
+  mCapturedImage = QImage();
+  update();
 }

src/3d/qgslayoutitem3dmap.h

@@ -23,7 +23,9 @@
 #include "qgscamerapose.h"
 
 
+class Qgs3DMapScene;
 class Qgs3DMapSettings;
+class QgsOffscreen3DEngine;
 
 /**
  * \ingroup 3d
@@ -74,7 +76,7 @@ class _3D_EXPORT QgsLayoutItem3DMap : public QgsLayoutItem
     virtual int type() const override;
 
     //! Configures camera view
-    void setCameraPose( const QgsCameraPose &pose ) { mCameraPose = pose; }
+    void setCameraPose( const QgsCameraPose &pose );
     //! Returns camera view
     QgsCameraPose cameraPose() const { return mCameraPose; }
 
@@ -92,9 +94,18 @@ class _3D_EXPORT QgsLayoutItem3DMap : public QgsLayoutItem
     bool writePropertiesToElement( QDomElement &element, QDomDocument &document, const QgsReadWriteContext &context ) const override;
     bool readPropertiesFromElement( const QDomElement &element, const QDomDocument &document, const QgsReadWriteContext &context ) override;
 
+  private slots:
+    void onImageCaptured( const QImage &img );
+    void onSceneStateChanged();
+    void onSizePositionChanged();
+
   private:
     std::unique_ptr<Qgs3DMapSettings> mSettings;
+    std::unique_ptr<QgsOffscreen3DEngine> mEngine;
+    Qgs3DMapScene *mScene = nullptr;  //!< 3D scene (owned by the 3D engine)
+    QImage mCapturedImage;
     QgsCameraPose mCameraPose;
+    bool mDrawing = false;
 };
 
 #endif // QGSLAYOUTITEM3DMAP_H

src/app/layout/qgslayout3dmapwidget.cpp

@@ -27,6 +27,10 @@ QgsLayout3DMapWidget::QgsLayout3DMapWidget( QgsLayoutItem3DMap *map3D )
 {
   setupUi( this );
 
+  //add widget for general composer item properties
+  mItemPropertiesWidget = new QgsLayoutItemPropertiesWidget( this, map3D );
+  mainLayout->addWidget( mItemPropertiesWidget );
+
   mMenu3DCanvases = new QMenu( this );
   mCopySettingsButton->setMenu( mMenu3DCanvases );
   connect( mMenu3DCanvases, &QMenu::aboutToShow, this, [ = ]

src/app/layout/qgslayout3dmapwidget.h

@@ -34,6 +34,7 @@ class QgsLayout3DMapWidget : public QgsLayoutItemBaseWidget, private Ui::QgsLayo
 
   private:
     QPointer< QgsLayoutItem3DMap > mMap3D;
+    QgsLayoutItemPropertiesWidget *mItemPropertiesWidget = nullptr;
     QMenu *mMenu3DCanvases = nullptr;
 };
 

src/ui/layout/qgslayout3dmapwidgetbase.ui

@@ -54,12 +54,12 @@
       <property name="geometry">
        <rect>
         <x>0</x>
-        <y>-65</y>
+        <y>0</y>
         <width>510</width>
         <height>635</height>
        </rect>
       </property>
-      <layout class="QVBoxLayout" name="verticalLayout_6">
+      <layout class="QVBoxLayout" name="mainLayout">
        <item>
         <widget class="QGroupBox" name="groupBox_3">
          <property name="title">