If the first layers loaded into a project is non-valid (e.g. qlrs

nyalldawson · nyalldawson · commit 0224b8e4ffb1 · 2019-06-12T18:25:57.000+10:00
pointing to a broken path), then defer the default zoom to the layer's extent
until AFTER the layer path is fixed

Avoids the situation where a user:
- loads a broken qlr
- canvas goes to a invalid extent, since the first loaded layer has an invalid extent
- user fixes the layer path, but there's no visible changes -- because the canvas
is pointing to some random location
diff --git a/src/gui/layertree/qgslayertreemapcanvasbridge.cpp b/src/gui/layertree/qgslayertreemapcanvasbridge.cpp
@@ -37,6 +37,8 @@ QgsLayerTreeMapCanvasBridge::QgsLayerTreeMapCanvasBridge( QgsLayerTree *root, Qg
   connect( root, &QgsLayerTreeNode::visibilityChanged, this, &QgsLayerTreeMapCanvasBridge::nodeVisibilityChanged );
   connect( root, &QgsLayerTree::layerOrderChanged, this, &QgsLayerTreeMapCanvasBridge::deferredSetCanvasLayers );
 
+  connect( QgsProject::instance(), &QgsProject::layersAdded, this, &QgsLayerTreeMapCanvasBridge::layersAdded );
+
   setCanvasLayers();
 }
 
@@ -70,21 +72,27 @@ void QgsLayerTreeMapCanvasBridge::setCanvasLayers()
 
   const QList<QgsLayerTreeLayer *> layerNodes = mRoot->findLayers();
   int currentSpatialLayerCount = 0;
+  int currentValidSpatialLayerCount = 0;
   for ( QgsLayerTreeLayer *layerNode : layerNodes )
   {
     if ( layerNode->layer() && layerNode->layer()->isSpatial() )
+    {
       currentSpatialLayerCount++;
+      if ( layerNode->layer()->isValid() )
+        currentValidSpatialLayerCount++;
+    }
   }
 
   bool firstLayers = mAutoSetupOnFirstLayer && !mHasLayersLoaded && currentSpatialLayerCount != 0;
+  bool firstValidLayers = mAutoSetupOnFirstLayer && !mHasValidLayersLoaded && currentValidSpatialLayerCount != 0;
 
   mCanvas->setLayers( canvasLayers );
   if ( mOverviewCanvas )
     mOverviewCanvas->setLayers( overviewLayers );
 
-  if ( firstLayers )
+  if ( firstValidLayers )
   {
-    // if we are moving from zero to non-zero layers, let's zoom to those data
+    // if we are moving from zero to non-zero layers, let's zoom to those data (only consider valid layers here!)
     mCanvas->zoomToFullExtent();
   }
 
@@ -116,6 +124,7 @@ void QgsLayerTreeMapCanvasBridge::setCanvasLayers()
   }
 
   mHasLayersLoaded = currentSpatialLayerCount;
+  mHasValidLayersLoaded = currentValidSpatialLayerCount;
   if ( currentSpatialLayerCount == 0 )
     mFirstCRS = QgsCoordinateReferenceSystem();
 
@@ -164,3 +173,22 @@ void QgsLayerTreeMapCanvasBridge::nodeCustomPropertyChanged( QgsLayerTreeNode *n
   if ( key == QLatin1String( "overview" ) )
     deferredSetCanvasLayers();
 }
+
+void QgsLayerTreeMapCanvasBridge::layersAdded( const QList<QgsMapLayer *> &layers )
+{
+  for ( QgsMapLayer *l : layers )
+  {
+    if ( l )
+    {
+      connect( l, &QgsMapLayer::dataSourceChanged, this, [ this, l ]
+      {
+        if ( l->isValid() && l->isSpatial() && mAutoSetupOnFirstLayer && !mHasValidLayersLoaded )
+        {
+          mHasValidLayersLoaded = true;
+          // if we are moving from zero valid layers to non-zero VALID layers, let's zoom to those data
+          mCanvas->zoomToFullExtent();
+        }
+      } );
+    }
+  }
+}
diff --git a/src/gui/layertree/qgslayertreemapcanvasbridge.h b/src/gui/layertree/qgslayertreemapcanvasbridge.h
@@ -102,6 +102,7 @@ class GUI_EXPORT QgsLayerTreeMapCanvasBridge : public QObject
   private slots:
     void nodeVisibilityChanged();
     void nodeCustomPropertyChanged( QgsLayerTreeNode *node, const QString &key );
+    void layersAdded( const QList<QgsMapLayer *> &layers );
 
   private:
     //! Fill canvasLayers and overviewLayers lists from node and its descendants
@@ -120,6 +121,7 @@ class GUI_EXPORT QgsLayerTreeMapCanvasBridge : public QObject
 
     bool mHasFirstLayer;
     bool mHasLayersLoaded;
+    bool mHasValidLayersLoaded = false;
     bool mUpdatingProjectLayerOrder = false;
 
     QgsCoordinateReferenceSystem mFirstCRS;
