Merge pull request #5789 from nyalldawson/render_jobs

[Rendering] Only render in preview jobs layers that are fast enough

python/core/qgis.sip

@@ -241,6 +241,8 @@ const double DEFAULT_LINE_WIDTH;
 const double DEFAULT_SEGMENT_EPSILON;
 
 
+
+
 typedef unsigned long long qgssize;
 
 

python/core/qgsdataprovider.sip

@@ -380,6 +380,7 @@ Current time stamp of data source
 .. versionadded:: 3.0
 %End
 
+
   signals:
 
     void fullExtentCalculated();

python/core/qgsmaprendererjob.sip

@@ -137,10 +137,12 @@ List of errors that happened during the rendering job - available when the rende
 
     int renderingTime() const;
 %Docstring
-Find out how long it took to finish the job (in milliseconds)
+ Returns the total time it took to finish the job (in milliseconds).
+.. seealso:: perLayerRenderingTime()
  :rtype: int
 %End
 
+
     const QgsMapSettings &mapSettings() const;
 %Docstring
  Return map settings with which this job was started.
@@ -179,6 +181,7 @@ emitted when asynchronous rendering is finished (or canceled).
 
 
 
+
 };
 
 

src/core/qgis.h

@@ -440,6 +440,18 @@ const double DEFAULT_LINE_WIDTH = 0.26;
 //! Default snapping tolerance for segments
 const double DEFAULT_SEGMENT_EPSILON = 1e-8;
 
+///@cond PRIVATE
+#ifndef SIP_RUN
+
+//! Delay between the scheduling of 2 preview jobs
+const int PREVIEW_JOB_DELAY_MS = 250;
+
+//! Maximum rendering time for a layer of a preview job
+const int MAXIMUM_LAYER_PREVIEW_TIME_MS = 250;
+#endif
+
+///@endcond
+
 typedef QMap<QString, QString> QgsStringMap SIP_SKIP;
 
 /**

src/core/qgsdataprovider.cpp

@@ -42,3 +42,7 @@ void QgsDataProvider::setListening( bool isListening )
   Q_UNUSED( isListening );
 }
 
+bool QgsDataProvider::renderInPreview( const PreviewContext &context )
+{
+  return context.lastRenderingTimeMs <= context.maxRenderingTimeMs;
+}

src/core/qgsdataprovider.h

@@ -461,6 +461,37 @@ class CORE_EXPORT QgsDataProvider : public QObject
      */
     virtual void setListening( bool isListening );
 
+#ifndef SIP_RUN
+
+    /**
+     * Stores settings related to the context in which a preview job runs.
+     * \note Not available in Python bindings
+     * \since QGIS 3.0
+     */
+    struct PreviewContext
+    {
+      //! Previous rendering time for the layer, in ms
+      double lastRenderingTimeMs = -1;
+
+      //! Default maximum allowable render time, in ms
+      double maxRenderingTimeMs = MAXIMUM_LAYER_PREVIEW_TIME_MS;
+    };
+#endif
+
+    /**
+     * Returns whether the layer must be rendered in preview jobs.
+     *
+     * The \a context argument gives useful information which can be used
+     * to determine whether the layer should be rendered or not.
+     *
+     * The base implementation returns true if lastRenderingTimeMs <= maxRenderingTimeMs.
+     *
+     * \since QGIS 3.0
+     *
+     * \note not available in Python bindings
+     */
+    virtual bool renderInPreview( const QgsDataProvider::PreviewContext &context ); // SIP_SKIP
+
   signals:
 
     /**

src/core/qgsmaprendererjob.cpp

@@ -64,6 +64,17 @@ void QgsMapRendererJob::setCache( QgsMapRendererCache *cache )
   mCache = cache;
 }
 
+QHash<QgsMapLayer *, int> QgsMapRendererJob::perLayerRenderingTime() const
+{
+  QHash<QgsMapLayer *, int> result;
+  for ( auto it = mPerLayerRenderingTime.constBegin(); it != mPerLayerRenderingTime.constEnd(); ++it )
+  {
+    if ( it.key() )
+      result.insert( it.key(), it.value() );
+  }
+  return result;
+}
+
 const QgsMapSettings &QgsMapRendererJob::mapSettings() const
 {
   return mSettings;
@@ -412,8 +423,10 @@ void QgsMapRendererJob::cleanupJobs( LayerRenderJobs &jobs )
       delete job.renderer;
       job.renderer = nullptr;
     }
-  }
 
+    if ( job.layer )
+      mPerLayerRenderingTime.insert( job.layer, job.renderingTime );
+  }
 
   jobs.clear();
 }

src/core/qgsmaprendererjob.h

@@ -199,9 +199,19 @@ class CORE_EXPORT QgsMapRendererJob : public QObject
      */
     void setCache( QgsMapRendererCache *cache );
 
-    //! Find out how long it took to finish the job (in milliseconds)
+    /**
+     * Returns the total time it took to finish the job (in milliseconds).
+     * \see perLayerRenderingTime()
+     */
     int renderingTime() const { return mRenderingTime; }
 
+    /**
+     * Returns the render time (in ms) per layer.
+     * \note Not available in Python bindings.
+     * \since QGIS 3.0
+     */
+    QHash< QgsMapLayer *, int > perLayerRenderingTime() const SIP_SKIP;
+
     /**
      * Return map settings with which this job was started.
      * \returns A QgsMapSettings instance with render settings
@@ -239,6 +249,9 @@ class CORE_EXPORT QgsMapRendererJob : public QObject
 
     int mRenderingTime = 0;
 
+    //! Render time (in ms) per layer, by layer ID
+    QHash< QgsWeakMapLayerPointer, int > mPerLayerRenderingTime;
+
     /**
      * Prepares the cache for storing the result of labeling. Returns false if
      * the render cannot use cached labels and should not cache the result.

src/gui/qgsmapcanvas.cpp

@@ -66,7 +66,6 @@ email                : sherman at mrcc.com
 #include "qgsmapthemecollection.h"
 #include <cmath>
 
-
 /**
  * \ingroup gui
  * Deprecated to be deleted, stuff from here should be moved elsewhere.
@@ -612,6 +611,13 @@ void QgsMapCanvas::rendererJobFinished()
     p.end();
 
     mMap->setContent( img, imageRect( img, mSettings ) );
+
+    mLastLayerRenderTime.clear();
+    const auto times = mJob->perLayerRenderingTime();
+    for ( auto it = times.constBegin(); it != times.constEnd(); ++it )
+    {
+      mLastLayerRenderTime.insert( it.key()->id(), it.value() );
+    }
     if ( mUsePreviewJobs )
       startPreviewJobs();
   }
@@ -633,6 +639,13 @@ void QgsMapCanvas::previewJobFinished()
   {
     mMap->addPreviewImage( job->renderedImage(), job->mapSettings().extent() );
     mPreviewJobs.removeAll( job );
+
+    int number = job->property( "number" ).toInt();
+    if ( number < 8 )
+    {
+      startPreviewJob( number + 1 );
+    }
+
     delete job;
   }
 }
@@ -2269,15 +2282,29 @@ void QgsMapCanvas::startPreviewJob( int number )
   jobSettings.setFlag( QgsMapSettings::DrawLabeling, false );
   jobSettings.setFlag( QgsMapSettings::RenderPreviewJob, true );
 
+  // truncate preview layers to fast layers
+  const QList<QgsMapLayer *> layers = jobSettings.layers();
+  QList< QgsMapLayer * > previewLayers;
+  QgsDataProvider::PreviewContext context;
+  context.maxRenderingTimeMs = MAXIMUM_LAYER_PREVIEW_TIME_MS;
+  for ( QgsMapLayer *layer : layers )
+  {
+    context.lastRenderingTimeMs = mLastLayerRenderTime.value( layer->id(), 0 );
+    if ( !layer->dataProvider()->renderInPreview( context ) )
+    {
+      QgsDebugMsgLevel( QString( "Layer %1 not rendered because it does not match the renderInPreview criterion %2" ).arg( layer->id() ).arg( mLastLayerRenderTime.value( layer->id() ) ), 3 );
+      continue;
+    }
+
+    previewLayers << layer;
+  }
+  jobSettings.setLayers( previewLayers );
+
   QgsMapRendererQImageJob *job = new QgsMapRendererSequentialJob( jobSettings );
+  job->setProperty( "number", number );
   mPreviewJobs.append( job );
   connect( job, &QgsMapRendererJob::finished, this, &QgsMapCanvas::previewJobFinished );
   job->start();
-
-  if ( number < 8 )
-  {
-    schedulePreviewJob( number + 1 );
-  }
 }
 
 void QgsMapCanvas::stopPreviewJobs()
@@ -2299,7 +2326,7 @@ void QgsMapCanvas::stopPreviewJobs()
 void QgsMapCanvas::schedulePreviewJob( int number )
 {
   mPreviewTimer.setSingleShot( true );
-  mPreviewTimer.setInterval( 250 );
+  mPreviewTimer.setInterval( PREVIEW_JOB_DELAY_MS );
   disconnect( mPreviewTimerConnection );
   mPreviewTimerConnection = connect( &mPreviewTimer, &QTimer::timeout, this, [ = ]()
   {

src/gui/qgsmapcanvas.h

@@ -1000,6 +1000,8 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
 
     bool mUsePreviewJobs = false;
 
+    QHash< QString, int > mLastLayerRenderTime;
+
     /**
      * Force a resize of the map canvas item
      * \since QGIS 2.16

src/providers/wms/qgswmsprovider.cpp

@@ -3199,18 +3199,25 @@ QString QgsWmsProvider::lastErrorFormat()
 QString  QgsWmsProvider::name() const
 {
   return WMS_KEY;
-} //  QgsWmsProvider::name()
+}
 
 
 QString  QgsWmsProvider::description() const
 {
   return WMS_DESCRIPTION;
-} //  QgsWmsProvider::description()
+}
 
 void QgsWmsProvider::reloadData()
 {
 }
 
+bool QgsWmsProvider::renderInPreview( const QgsDataProvider::PreviewContext &context )
+{
+  if ( mSettings.mTiled || mSettings.mXyz )
+    return true;
+
+  return QgsRasterDataProvider::renderInPreview( context );
+}
 
 QVector<QgsWmsSupportedFormat> QgsWmsProvider::supportedFormats()
 {

src/providers/wms/qgswmsprovider.h

@@ -208,6 +208,7 @@ class QgsWmsProvider : public QgsRasterDataProvider
     QString name() const override;
     QString description() const override;
     virtual void reloadData() override;
+    bool renderInPreview( const QgsDataProvider::PreviewContext &context ) override;
 
     static QVector<QgsWmsSupportedFormat> supportedFormats();