Add api to allow redrawing of previously collected results for a single

elevation profile source

And use this to just redraw the existing results whenever a setting
relating only to the appearance of the profile chart is changed,
instead of regenerating the whole chart

python/core/auto_generated/elevation/qgsabstractprofilegenerator.sip.in

@@ -140,6 +140,16 @@ Returns the range of the retrieved elevation values
     virtual QgsProfileSnapResult snapPoint( const QgsProfilePoint &point, const QgsProfileSnapContext &context );
 %Docstring
 Snaps a ``point`` to the generated elevation profile.
+%End
+
+    virtual void updateFromGenerator( const QgsAbstractProfileGenerator *generator );
+%Docstring
+Updates the results to match the properties from the specified ``generator``.
+
+For instance, this method can be used to replace any stored properties relating to rendering
+the gathered results to reflect the ``generator``'s current properties.
+
+The base class method does nothing.
 %End
 };
 

python/core/auto_generated/elevation/qgsprofilerenderer.sip.in

@@ -46,6 +46,11 @@ results.
 
     ~QgsProfilePlotRenderer();
 
+    QStringList sourceIds() const;
+%Docstring
+Returns the ordered list of source IDs for the sources used by the renderer.
+%End
+
     void startGeneration();
 %Docstring
 Start the generation job and immediately return.
@@ -73,6 +78,13 @@ Block until the current job has finished.
     bool isActive() const;
 %Docstring
 Returns ``True`` if the generation job is currently running in background.
+%End
+
+    void replaceSource( QgsAbstractProfileSource *source );
+%Docstring
+Replaces the existing source with matching ID.
+
+The matching stored source will be deleted and replaced with ``source``.
 %End
 
     bool invalidateResults( QgsAbstractProfileSource *source );
@@ -100,14 +112,18 @@ Does nothing if the generation is already in progress.
 Returns the limits of the retrieved elevation values.
 %End
 
-    QImage renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax );
+    QImage renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId = QString() );
 %Docstring
 Renders a portion of the profile to an image with the given ``width`` and ``height``.
+
+If ``sourceId`` is empty then all sources will be rendered, otherwise only the matching source will be rendered.
 %End
 
-    void render( QgsRenderContext &context, double width, double height, double distanceMin, double distanceMax, double zMin, double zMax );
+    void render( QgsRenderContext &context, double width, double height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId = QString() );
 %Docstring
 Renders a portion of the profile using the specified render ``context``.
+
+If ``sourceId`` is empty then all sources will be rendered, otherwise only the matching source will be rendered.
 %End
 
     QgsProfileSnapResult snapPoint( const QgsProfilePoint &point, const QgsProfileSnapContext &context );

src/core/elevation/qgsabstractprofilegenerator.cpp

@@ -63,3 +63,8 @@ QgsProfileSnapResult QgsAbstractProfileResults::snapPoint( const QgsProfilePoint
 {
   return QgsProfileSnapResult();
 }
+
+void QgsAbstractProfileResults::updateFromGenerator( const QgsAbstractProfileGenerator * )
+{
+
+}

src/core/elevation/qgsabstractprofilegenerator.h

@@ -116,6 +116,7 @@ class CORE_EXPORT QgsProfileRenderContext
 
 };
 
+class QgsAbstractProfileGenerator;
 
 /**
  * \brief Abstract base class for storage of elevation profiles.
@@ -164,6 +165,16 @@ class CORE_EXPORT QgsAbstractProfileResults
      * Snaps a \a point to the generated elevation profile.
      */
     virtual QgsProfileSnapResult snapPoint( const QgsProfilePoint &point, const QgsProfileSnapContext &context );
+
+    /**
+     * Updates the results to match the properties from the specified \a generator.
+     *
+     * For instance, this method can be used to replace any stored properties relating to rendering
+     * the gathered results to reflect the \a generator's current properties.
+     *
+     * The base class method does nothing.
+     */
+    virtual void updateFromGenerator( const QgsAbstractProfileGenerator *generator );
 };
 
 /**

src/core/elevation/qgsprofilerenderer.cpp

@@ -46,6 +46,17 @@ QgsProfilePlotRenderer::~QgsProfilePlotRenderer()
   }
 }
 
+QStringList QgsProfilePlotRenderer::sourceIds() const
+{
+  QStringList res;
+  res.reserve( mGenerators.size() );
+  for ( const auto &it : mGenerators )
+  {
+    res.append( it->sourceId() );
+  }
+  return res;
+}
+
 void QgsProfilePlotRenderer::startGeneration()
 {
   if ( isActive() )
@@ -125,7 +136,17 @@ bool QgsProfilePlotRenderer::isActive() const
   return mStatus != Idle;
 }
 
+void QgsProfilePlotRenderer::replaceSource( QgsAbstractProfileSource *source )
+{
+  replaceSourceInternal( source, false );
+}
+
 bool QgsProfilePlotRenderer::invalidateResults( QgsAbstractProfileSource *source )
+{
+  return replaceSourceInternal( source, true );
+}
+
+bool QgsProfilePlotRenderer::replaceSourceInternal( QgsAbstractProfileSource *source, bool clearPreviousResults )
 {
   if ( !source )
     return false;
@@ -141,9 +162,16 @@ bool QgsProfilePlotRenderer::invalidateResults( QgsAbstractProfileSource *source
     if ( job.generator && job.generator->sourceId() == sourceId )
     {
       res = true;
-      job.results.reset();
+      if ( clearPreviousResults )
+      {
+        job.results.reset();
+        job.complete = false;
+      }
+      else if ( job.results )
+      {
+        job.results->updateFromGenerator( generator.get() );
+      }
       job.generator = generator.get();
-      job.complete = false;
       for ( auto it = mGenerators.begin(); it != mGenerators.end(); )
       {
         if ( ( *it )->sourceId() == sourceId )
@@ -186,7 +214,7 @@ QgsDoubleRange QgsProfilePlotRenderer::zRange() const
   return QgsDoubleRange( min, max );
 }
 
-QImage QgsProfilePlotRenderer::renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax )
+QImage QgsProfilePlotRenderer::renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId )
 {
   QImage res( width, height, QImage::Format_ARGB32_Premultiplied );
   res.fill( Qt::transparent );
@@ -196,13 +224,13 @@ QImage QgsProfilePlotRenderer::renderToImage( int width, int height, double dist
   QgsRenderContext context = QgsRenderContext::fromQPainter( &p );
   context.setFlag( Qgis::RenderContextFlag::Antialiasing, true );
   context.setPainterFlagsUsingContext( &p );
-  render( context, width, height, distanceMin, distanceMax, zMin, zMax );
+  render( context, width, height, distanceMin, distanceMax, zMin, zMax, sourceId );
   p.end();
 
   return res;
 }
 
-void QgsProfilePlotRenderer::render( QgsRenderContext &context, double width, double height, double distanceMin, double distanceMax, double zMin, double zMax )
+void QgsProfilePlotRenderer::render( QgsRenderContext &context, double width, double height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId )
 {
   QPainter *painter = context.painter();
   if ( !painter )
@@ -221,7 +249,7 @@ void QgsProfilePlotRenderer::render( QgsRenderContext &context, double width, do
 
   for ( const ProfileJob &job : mJobs )
   {
-    if ( job.complete && job.results )
+    if ( job.complete && job.results && ( sourceId.isEmpty() || job.generator->sourceId() == sourceId ) )
       job.results->renderResults( profileRenderContext );
   }
 }
@@ -272,3 +300,4 @@ void QgsProfilePlotRenderer::generateProfileStatic( ProfileJob &job )
   job.results.reset( job.generator->takeResults() );
   job.complete = true;
 }
+

src/core/elevation/qgsprofilerenderer.h

@@ -70,6 +70,11 @@ class CORE_EXPORT QgsProfilePlotRenderer : public QObject
 
     ~QgsProfilePlotRenderer() override;
 
+    /**
+     * Returns the ordered list of source IDs for the sources used by the renderer.
+     */
+    QStringList sourceIds() const;
+
     /**
      * Start the generation job and immediately return.
      * Does nothing if the generation is already in progress.
@@ -95,6 +100,13 @@ class CORE_EXPORT QgsProfilePlotRenderer : public QObject
     //! Returns TRUE if the generation job is currently running in background.
     bool isActive() const;
 
+    /**
+     * Replaces the existing source with matching ID.
+     *
+     * The matching stored source will be deleted and replaced with \a source.
+     */
+    void replaceSource( QgsAbstractProfileSource *source );
+
     /**
      * Invalidates the profile results from the source with matching ID.
      *
@@ -122,13 +134,17 @@ class CORE_EXPORT QgsProfilePlotRenderer : public QObject
 
     /**
      * Renders a portion of the profile to an image with the given \a width and \a height.
+     *
+     * If \a sourceId is empty then all sources will be rendered, otherwise only the matching source will be rendered.
      */
-    QImage renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax );
+    QImage renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId = QString() );
 
     /**
      * Renders a portion of the profile using the specified render \a context.
+     *
+     * If \a sourceId is empty then all sources will be rendered, otherwise only the matching source will be rendered.
      */
-    void render( QgsRenderContext &context, double width, double height, double distanceMin, double distanceMax, double zMin, double zMax );
+    void render( QgsRenderContext &context, double width, double height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId = QString() );
 
     /**
      * Snap a \a point to the results.
@@ -154,6 +170,7 @@ class CORE_EXPORT QgsProfilePlotRenderer : public QObject
     };
 
     static void generateProfileStatic( ProfileJob &job );
+    bool replaceSourceInternal( QgsAbstractProfileSource *source, bool clearPreviousResults );
 
     std::vector< std::unique_ptr< QgsAbstractProfileGenerator > > mGenerators;
     QgsProfileRequest mRequest;

src/core/mesh/qgsmeshlayerprofilegenerator.cpp

@@ -135,6 +135,13 @@ QgsProfileSnapResult QgsMeshLayerProfileResults::snapPoint( const QgsProfilePoin
   return result;
 }
 
+void QgsMeshLayerProfileResults::updateFromGenerator( const QgsAbstractProfileGenerator *generator )
+{
+  const QgsMeshLayerProfileGenerator *mlGenerator = qgis::down_cast<  const QgsMeshLayerProfileGenerator * >( generator );
+
+  lineSymbol.reset( mlGenerator->mLineSymbol->clone() );
+}
+
 //
 // QgsMeshLayerProfileGenerator
 //

src/core/mesh/qgsmeshlayerprofilegenerator.h

@@ -63,6 +63,7 @@ class CORE_EXPORT QgsMeshLayerProfileResults : public QgsAbstractProfileResults
     QVector< QgsGeometry > asGeometries() const override;
     void renderResults( QgsProfileRenderContext &context ) override;
     QgsProfileSnapResult snapPoint( const QgsProfilePoint &point, const QgsProfileSnapContext &context ) override;
+    void updateFromGenerator( const QgsAbstractProfileGenerator *generator ) override;
 };
 
 
@@ -116,6 +117,8 @@ class CORE_EXPORT QgsMeshLayerProfileGenerator : public QgsAbstractProfileGenera
 
     std::unique_ptr< QgsMeshLayerProfileResults > mResults;
 
+    friend class QgsMeshLayerProfileResults;
+
 
 };
 

src/core/raster/qgsrasterlayerprofilegenerator.cpp

@@ -138,6 +138,13 @@ void QgsRasterLayerProfileResults::renderResults( QgsProfileRenderContext &conte
   lineSymbol->stopRender( context.renderContext() );
 }
 
+void QgsRasterLayerProfileResults::updateFromGenerator( const QgsAbstractProfileGenerator *generator )
+{
+  const QgsRasterLayerProfileGenerator *rlGenerator = qgis::down_cast<  const QgsRasterLayerProfileGenerator * >( generator );
+
+  lineSymbol.reset( rlGenerator->mLineSymbol->clone() );
+}
+
 
 //
 // QgsRasterLayerProfileGenerator

src/core/raster/qgsrasterlayerprofilegenerator.h

@@ -62,6 +62,7 @@ class CORE_EXPORT QgsRasterLayerProfileResults : public QgsAbstractProfileResult
     QVector< QgsGeometry > asGeometries() const override;
     QgsProfileSnapResult snapPoint( const QgsProfilePoint &point, const QgsProfileSnapContext &context ) override;
     void renderResults( QgsProfileRenderContext &context ) override;
+    void updateFromGenerator( const QgsAbstractProfileGenerator *generator ) override;
 };
 
 /**
@@ -113,6 +114,8 @@ class CORE_EXPORT QgsRasterLayerProfileGenerator : public QgsAbstractProfileGene
 
     double mStepDistance = std::numeric_limits<double>::quiet_NaN();
 
+    friend class QgsRasterLayerProfileResults;
+
 };
 
 #endif // QGSRASTERLAYERPROFILEGENERATOR_H

src/core/vector/qgsvectorlayerprofilegenerator.cpp

@@ -398,6 +398,16 @@ void QgsVectorLayerProfileResults::renderResults( QgsProfileRenderContext &conte
   }
 }
 
+void QgsVectorLayerProfileResults::updateFromGenerator( const QgsAbstractProfileGenerator *generator )
+{
+  const QgsVectorLayerProfileGenerator *vlGenerator = qgis::down_cast<  const QgsVectorLayerProfileGenerator * >( generator );
+
+  respectLayerSymbology = vlGenerator->mRespectLayerSymbology;
+  profileLineSymbol.reset( vlGenerator->mProfileLineSymbol->clone() );
+  profileFillSymbol.reset( vlGenerator->mProfileFillSymbol->clone() );
+  profileMarkerSymbol.reset( vlGenerator->mProfileMarkerSymbol->clone() );
+}
+
 //
 // QgsVectorLayerProfileGenerator
 //

src/core/vector/qgsvectorlayerprofilegenerator.h

@@ -85,6 +85,7 @@ class CORE_EXPORT QgsVectorLayerProfileResults : public QgsAbstractProfileResult
     QVector< QgsGeometry > asGeometries() const override;
     QgsProfileSnapResult snapPoint( const QgsProfilePoint &point, const QgsProfileSnapContext &context ) override;
     void renderResults( QgsProfileRenderContext &context ) override;
+    void updateFromGenerator( const QgsAbstractProfileGenerator *generator ) override;
 };
 
 
@@ -168,6 +169,8 @@ class CORE_EXPORT QgsVectorLayerProfileGenerator : public QgsAbstractProfileGene
     // NOT for use in the background thread!
     QPointer< QgsVectorLayer > mLayer;
 
+    friend class QgsVectorLayerProfileResults;
+
 };
 
 #endif // QGSVECTORLAYERPROFILEGENERATOR_H

src/gui/elevation/qgselevationprofilecanvas.cpp

@@ -64,6 +64,7 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
       setPos( mRect.topLeft() );
 
       mImage = QImage();
+      mCachedImages.clear();
       mPlotArea = QRectF();
       update();
     }
@@ -71,10 +72,22 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
     void updatePlot()
     {
       mImage = QImage();
+      mCachedImages.clear();
       mPlotArea = QRectF();
       update();
     }
 
+    bool redrawResults( const QString &sourceId )
+    {
+      auto it = mCachedImages.find( sourceId );
+      if ( it == mCachedImages.end() )
+        return false;
+
+      mCachedImages.erase( it );
+      mImage = QImage();
+      return true;
+    }
+
     QRectF boundingRect() const override
     {
       return mRect;
@@ -92,7 +105,7 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
       return mPlotArea;
     }
 
-    QgsProfilePoint canvasPointToPlotPoint( const QPointF &point )
+    QgsProfilePoint canvasPointToPlotPoint( QPointF point )
     {
       if ( !mPlotArea.contains( point.x(), point.y() ) )
         return QgsProfilePoint();
@@ -119,8 +132,22 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
       if ( !mRenderer )
         return;
 
-      const QImage plot = mRenderer->renderToImage( plotArea.width(), plotArea.height(), xMinimum(), xMaximum(), yMinimum(), yMaximum() );
-      rc.painter()->drawImage( plotArea.left(), plotArea.top(), plot );
+      const QStringList sourceIds = mRenderer->sourceIds();
+      for ( const QString &source : sourceIds )
+      {
+        QImage plot;
+        auto it = mCachedImages.constFind( source );
+        if ( it != mCachedImages.constEnd() )
+        {
+          plot = it.value();
+        }
+        else
+        {
+          plot = mRenderer->renderToImage( plotArea.width(), plotArea.height(), xMinimum(), xMaximum(), yMinimum(), yMaximum(), source );
+          mCachedImages.insert( source, plot );
+        }
+        rc.painter()->drawImage( plotArea.left(), plotArea.top(), plot );
+      }
     }
 
     void paint( QPainter *painter ) override
@@ -149,6 +176,9 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
   private:
 
     QImage mImage;
+
+    QMap< QString, QImage > mCachedImages;
+
     QRectF mRect;
     QRectF mPlotArea;
     QgsProfilePlotRenderer *mRenderer = nullptr;
@@ -290,6 +320,11 @@ QgsElevationProfileCanvas::QgsElevationProfileCanvas( QWidget *parent )
   mDeferredUpdateTimer->stop();
   connect( mDeferredUpdateTimer, &QTimer::timeout, this, &QgsElevationProfileCanvas::startDeferredUpdate );
 
+  mDeferredRedrawTimer = new QTimer( this );
+  mDeferredRedrawTimer->setSingleShot( true );
+  mDeferredRedrawTimer->stop();
+  connect( mDeferredRedrawTimer, &QTimer::timeout, this, &QgsElevationProfileCanvas::startDeferredRedraw );
+
 }
 
 QgsElevationProfileCanvas::~QgsElevationProfileCanvas()
@@ -375,11 +410,13 @@ void QgsElevationProfileCanvas::setupLayerConnections( QgsMapLayer *layer, bool
   if ( isDisconnect )
   {
     disconnect( layer->elevationProperties(), &QgsMapLayerElevationProperties::profileGenerationPropertyChanged, this, &QgsElevationProfileCanvas::onLayerProfileGenerationPropertyChanged );
+    disconnect( layer->elevationProperties(), &QgsMapLayerElevationProperties::renderingPropertyChanged, this, &QgsElevationProfileCanvas::onLayerProfileRendererPropertyChanged );
     disconnect( layer, &QgsMapLayer::dataChanged, this, &QgsElevationProfileCanvas::updateResultsForLayer );
   }
   else
   {
     connect( layer->elevationProperties(), &QgsMapLayerElevationProperties::profileGenerationPropertyChanged, this, &QgsElevationProfileCanvas::onLayerProfileGenerationPropertyChanged );
+    connect( layer->elevationProperties(), &QgsMapLayerElevationProperties::renderingPropertyChanged, this, &QgsElevationProfileCanvas::onLayerProfileRendererPropertyChanged );
     connect( layer, &QgsMapLayer::dataChanged, this, &QgsElevationProfileCanvas::updateResultsForLayer );
   }
 
@@ -412,7 +449,6 @@ void QgsElevationProfileCanvas::setupLayerConnections( QgsMapLayer *layer, bool
     case QgsMapLayerType::PointCloudLayer:
     case QgsMapLayerType::GroupLayer:
       break;
-
   }
 }
 
@@ -622,6 +658,27 @@ void QgsElevationProfileCanvas::onLayerProfileGenerationPropertyChanged()
   }
 }
 
+void QgsElevationProfileCanvas::onLayerProfileRendererPropertyChanged()
+{
+  // TODO -- handle nicely when existing job is in progress
+  if ( !mCurrentJob || mCurrentJob->isActive() )
+    return;
+
+  QgsMapLayerElevationProperties *properties = qobject_cast< QgsMapLayerElevationProperties * >( sender() );
+  if ( !properties )
+    return;
+
+  if ( QgsMapLayer *layer = qobject_cast< QgsMapLayer * >( properties->parent() ) )
+  {
+    if ( QgsAbstractProfileSource *source = dynamic_cast< QgsAbstractProfileSource * >( layer ) )
+    {
+      mCurrentJob->replaceSource( source );
+    }
+    if ( mPlotItem->redrawResults( layer->id() ) )
+      scheduleDeferredRedraw();
+  }
+}
+
 void QgsElevationProfileCanvas::updateResultsForLayer()
 {
   if ( QgsMapLayer *layer = qobject_cast< QgsMapLayer * >( sender() ) )
@@ -643,6 +700,15 @@ void QgsElevationProfileCanvas::scheduleDeferredUpdate()
   }
 }
 
+void QgsElevationProfileCanvas::scheduleDeferredRedraw()
+{
+  if ( !mDeferredRedrawScheduled )
+  {
+    mDeferredRedrawTimer->start( 1 );
+    mDeferredRedrawScheduled = true;
+  }
+}
+
 void QgsElevationProfileCanvas::startDeferredUpdate()
 {
   if ( mCurrentJob && !mCurrentJob->isActive() )
@@ -653,6 +719,12 @@ void QgsElevationProfileCanvas::startDeferredUpdate()
   mDeferredUpdateScheduled = false;
 }
 
+void QgsElevationProfileCanvas::startDeferredRedraw()
+{
+  mPlotItem->update();
+  mDeferredRedrawScheduled = false;
+}
+
 QgsProfilePoint QgsElevationProfileCanvas::canvasPointToPlotPoint( QPointF point ) const
 {
   if ( !mPlotItem->plotArea().contains( point.x(), point.y() ) )

src/gui/elevation/qgselevationprofilecanvas.h

@@ -205,9 +205,12 @@ class GUI_EXPORT QgsElevationProfileCanvas : public QgsPlotCanvas
 
     void generationFinished();
     void onLayerProfileGenerationPropertyChanged();
+    void onLayerProfileRendererPropertyChanged();
     void updateResultsForLayer();
     void scheduleDeferredUpdate();
+    void scheduleDeferredRedraw();
     void startDeferredUpdate();
+    void startDeferredRedraw();
 
   private:
 
@@ -236,6 +239,8 @@ class GUI_EXPORT QgsElevationProfileCanvas : public QgsPlotCanvas
     QgsProfilePlotRenderer *mCurrentJob = nullptr;
     QTimer *mDeferredUpdateTimer = nullptr;
     bool mDeferredUpdateScheduled = false;
+    QTimer *mDeferredRedrawTimer = nullptr;
+    bool mDeferredRedrawScheduled = false;
 
     std::unique_ptr< QgsCurve > mProfileCurve;
     double mTolerance = 0;