keep extent of overview set to union of extents of layer in overview;…

… dont shrink on resize; fixes #1788

python/gui/qgsmapoverviewcanvas.sip

@@ -26,7 +26,7 @@ class QgsMapOverviewCanvas : QWidget
 
     void enableAntiAliasing( bool flag );
 
-    void updateFullExtent( const QgsRectangle& rect );
+    void updateFullExtent();
 
   public slots:
 

src/gui/qgsmapcanvas.cpp

@@ -265,45 +265,48 @@ void QgsMapCanvas::setLayerSet( QList<QgsMapCanvasLayer> &layers )
   bool layerSetChanged = layerSetOld != layerSet;
 
   // update only if needed
-  if ( !layerSetChanged )
-    return;
-
-  QgsDebugMsg( "Layer changed to: " + layerSet.join( ", " ) );
-
-  for ( i = 0; i < layerCount(); i++ )
+  if ( layerSetChanged )
   {
-    // Add check if vector layer when disconnecting from selectionChanged slot
-    // Ticket #811 - racicot
-    QgsMapLayer *currentLayer = layer( i );
-    disconnect( currentLayer, SIGNAL( repaintRequested() ), this, SLOT( refresh() ) );
-    disconnect( currentLayer, SIGNAL( screenUpdateRequested() ), this, SLOT( updateMap() ) );
-    QgsVectorLayer *isVectLyr = qobject_cast<QgsVectorLayer *>( currentLayer );
-    if ( isVectLyr )
+    QgsDebugMsg( "Layers changed to: " + layerSet.join( ", " ) );
+
+    for ( i = 0; i < layerCount(); i++ )
     {
-      disconnect( currentLayer, SIGNAL( selectionChanged() ), this, SLOT( selectionChangedSlot() ) );
+      // Add check if vector layer when disconnecting from selectionChanged slot
+      // Ticket #811 - racicot
+      QgsMapLayer *currentLayer = layer( i );
+      disconnect( currentLayer, SIGNAL( repaintRequested() ), this, SLOT( refresh() ) );
+      disconnect( currentLayer, SIGNAL( screenUpdateRequested() ), this, SLOT( updateMap() ) );
+      QgsVectorLayer *isVectLyr = qobject_cast<QgsVectorLayer *>( currentLayer );
+      if ( isVectLyr )
+      {
+        disconnect( currentLayer, SIGNAL( selectionChanged() ), this, SLOT( selectionChangedSlot() ) );
+      }
     }
-  }
 
-  mMapRenderer->setLayerSet( layerSet );
+    mMapRenderer->setLayerSet( layerSet );
 
-  for ( i = 0; i < layerCount(); i++ )
-  {
-    // Add check if vector layer when connecting to selectionChanged slot
-    // Ticket #811 - racicot
-    QgsMapLayer *currentLayer = layer( i );
-    connect( currentLayer, SIGNAL( repaintRequested() ), this, SLOT( refresh() ) );
-    connect( currentLayer, SIGNAL( screenUpdateRequested() ), this, SLOT( updateMap() ) );
-    QgsVectorLayer *isVectLyr = qobject_cast<QgsVectorLayer *>( currentLayer );
-    if ( isVectLyr )
+    for ( i = 0; i < layerCount(); i++ )
     {
-      connect( currentLayer, SIGNAL( selectionChanged() ), this, SLOT( selectionChangedSlot() ) );
+      // Add check if vector layer when connecting to selectionChanged slot
+      // Ticket #811 - racicot
+      QgsMapLayer *currentLayer = layer( i );
+      connect( currentLayer, SIGNAL( repaintRequested() ), this, SLOT( refresh() ) );
+      connect( currentLayer, SIGNAL( screenUpdateRequested() ), this, SLOT( updateMap() ) );
+      QgsVectorLayer *isVectLyr = qobject_cast<QgsVectorLayer *>( currentLayer );
+      if ( isVectLyr )
+      {
+        connect( currentLayer, SIGNAL( selectionChanged() ), this, SLOT( selectionChangedSlot() ) );
+      }
     }
+
+    QgsDebugMsg( "Layers have changed, refreshing" );
+    emit layersChanged();
+
+    refresh();
   }
 
   if ( mMapOverview )
   {
-    mMapOverview->updateFullExtent( fullExtent() );
-
     QStringList& layerSetOvOld = mMapOverview->layerSet();
     if ( layerSetOvOld != layerSetOverview )
     {
@@ -314,12 +317,6 @@ void QgsMapCanvas::setLayerSet( QList<QgsMapCanvasLayer> &layers )
     // because full extent might have changed
     updateOverview();
   }
-
-  QgsDebugMsg( "Layers have changed, refreshing" );
-  emit layersChanged();
-
-  refresh();
-
 } // setLayerSet
 
 void QgsMapCanvas::enableOverviewMode( QgsMapOverviewCanvas* overview )
@@ -514,11 +511,6 @@ void QgsMapCanvas::updateFullExtent()
   QgsDebugMsg( "updating full extent" );
 
   mMapRenderer->updateFullExtent();
-  if ( mMapOverview )
-  {
-    mMapOverview->updateFullExtent( fullExtent() );
-    updateOverview();
-  }
   refresh();
 }
 

src/gui/qgsmapoverviewcanvas.cpp

@@ -95,6 +95,7 @@ void QgsMapOverviewCanvas::paintEvent( QPaintEvent* pe )
   {
     mPixmap = QPixmap( mNewSize );
     mMapRenderer->setOutputSize( mNewSize, mPixmap.logicalDpiX() );
+    updateFullExtent();
     mNewSize = QSize();
     refresh();
   }
@@ -106,10 +107,12 @@ void QgsMapOverviewCanvas::paintEvent( QPaintEvent* pe )
 
 void QgsMapOverviewCanvas::drawExtentRect()
 {
+  if ( !mMapCanvas || !mMapRenderer ) return;
+
   const QgsRectangle& extent = mMapCanvas->extent();
 
   // show only when valid extent is set
-  if ( extent.isEmpty() )
+  if ( extent.isEmpty() || mMapRenderer->extent().isEmpty() )
   {
     mPanningWidget->hide();
     return;
@@ -290,11 +293,23 @@ void QgsMapOverviewCanvas::setBackgroundColor( const QColor& color )
 
 void QgsMapOverviewCanvas::setLayerSet( const QStringList& layerSet )
 {
+  QgsDebugMsg( "layerSet: " + layerSet.join( ", " ) );
+  if ( !mMapRenderer ) return;
   mMapRenderer->setLayerSet( layerSet );
+  mMapRenderer->updateFullExtent();
+  updateFullExtent();
 }
 
-void QgsMapOverviewCanvas::updateFullExtent( const QgsRectangle& rect )
+void QgsMapOverviewCanvas::updateFullExtent()
 {
+  if ( !mMapRenderer ) return;
+  QgsRectangle rect;
+  if ( !mMapRenderer->layerSet().isEmpty() )
+  {
+    rect = mMapRenderer->fullExtent();
+    // expand a bit to keep features on margin
+    rect.scale( 1.1 );
+  }
   mMapRenderer->setExtent( rect );
   drawExtentRect();
 }

src/gui/qgsmapoverviewcanvas.h

@@ -59,7 +59,7 @@ class GUI_EXPORT QgsMapOverviewCanvas : public QWidget
 
     void enableAntiAliasing( bool flag ) { mAntiAliasing = flag; }
 
-    void updateFullExtent( const QgsRectangle& rect );
+    void updateFullExtent();
 
   public slots: