Consider mouse wheel in composer map (ticket #1289)

git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@9297 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: mhugent

src/core/composer/qgscomposeritem.h

@@ -70,9 +70,17 @@ class CORE_EXPORT QgsComposerItem: public QGraphicsRectItem
     /**Moves item in canvas coordinates*/
     void move( double dx, double dy );
 
-    /**Move Content of item. Does nothing per default (but implemented in composer map)*/
+    /**Move Content of item. Does nothing per default (but implemented in composer map)
+       @param dx move in x-direction (canvas coordinates)
+       @param dy move in y-direction(canvas coordinates)*/
     virtual void moveContent( double dx, double dy ) {}
 
+    /**Zoom content of item. Does nothing per default (but implemented in composer map)
+     @param delta value from wheel event that describes magnitude and direction (positive /negative number)
+    @param x x-position of mouse cursor (in item coordinates)
+    @param y y-position of mouse cursor (in item coordinates)*/
+    virtual void zoomContent( int delta, double x, double y) {}
+
     /**Sets this items bound in scene coordinates such that 1 item size units
      corresponds to 1 scene size unit*/
     virtual void setSceneRect( const QRectF& rectangle );

src/core/composer/qgscomposermap.cpp

@@ -35,6 +35,7 @@
 #include <QGraphicsScene>
 #include <QGraphicsView>
 #include <QPainter>
+#include <QSettings>
 #include <iostream>
 #include <cmath>
 
@@ -278,6 +279,68 @@ void QgsComposerMap::moveContent( double dx, double dy )
   }
 }
 
+void QgsComposerMap::zoomContent( int delta, double x, double y)
+{
+  QSettings settings;
+  
+  //read zoom mode
+  //0: zoom, 1: zoom and recenter, 2: zoom to cursor, 3: nothing 
+  int zoomMode = settings.value("/qgis/wheel_action", 0 ).toInt();
+  if(zoomMode == 3) //do nothing
+    {
+      return;
+    }
+
+  double zoomFactor = settings.value("/qgis/zoom_factor", 2.0).toDouble();
+  
+  //find out new center point
+  double centerX = (mExtent.xMax() + mExtent.xMin()) / 2;
+  double centerY = (mExtent.yMax() + mExtent.yMin()) / 2;
+
+  if(zoomMode != 0)
+    {
+      //find out map coordinates of mouse position
+      double mapMouseX = mExtent.xMin() + (x / rect().width()) * (mExtent.xMax() - mExtent.xMin());
+      double mapMouseY = mExtent.yMin() + (1 - (y / rect().height())) * (mExtent.yMax() - mExtent.yMin());
+      if(zoomMode == 1) //zoom and recenter
+	{
+	  centerX = mapMouseX;
+	  centerY = mapMouseY;
+	}
+      else if(zoomMode == 2) //zoom to cursor
+	{
+	  centerX = mapMouseX + (centerX - mapMouseX) * (1.0 / zoomFactor);
+	  centerY = mapMouseY + (centerY - mapMouseY) * (1.0 / zoomFactor);
+	}
+    }
+
+  double newIntervalX, newIntervalY;
+
+  if(delta > 0)
+    {
+      newIntervalX = (mExtent.xMax() - mExtent.xMin()) / zoomFactor;
+      newIntervalY = (mExtent.yMax() - mExtent.yMin()) / zoomFactor;
+    }
+  else if(delta < 0)
+    {
+      newIntervalX = (mExtent.xMax() - mExtent.xMin()) * zoomFactor;
+      newIntervalY = (mExtent.yMax() - mExtent.yMin()) * zoomFactor;
+    }
+  else //no need to zoom
+    {
+      return;
+    }
+
+  mExtent.setXMaximum(centerX + newIntervalX / 2);
+  mExtent.setXMinimum(centerX - newIntervalX / 2);
+  mExtent.setYMaximum(centerY + newIntervalY / 2);
+  mExtent.setYMinimum(centerY - newIntervalY / 2);
+
+  emit extentChanged();
+  cache();
+  update();
+}
+
 void QgsComposerMap::setSceneRect( const QRectF& rectangle )
 {
   double w = rectangle.width();

src/core/composer/qgscomposermap.h

@@ -87,6 +87,12 @@ class CORE_EXPORT QgsComposerMap : /*public QWidget, private Ui::QgsComposerMapB
        @param dy move in y-direction (item and canvas coordinates)*/
     void moveContent( double dx, double dy );
 
+    /**Zoom content of map
+     @param delta value from wheel event that describes magnitude and direction (positive /negative number)
+    @param x x-coordinate of mouse position in item coordinates
+    @param y y-coordinate of mouse position in item coordinates*/
+    void zoomContent( int delta, double x, double y);
+
     /**Sets new scene rectangle bounds and recalculates hight and extent*/
     void setSceneRect( const QRectF& rectangle );
 

src/gui/qgscomposerview.cpp

@@ -336,6 +336,22 @@ void QgsComposerView::keyReleaseEvent( QKeyEvent * e )
   }
 }
 
+void QgsComposerView::wheelEvent( QWheelEvent* event)
+{
+  QPointF scenePoint = mapToScene( event->pos() );
+  
+  //select topmost item at position of event
+  QgsComposerItem* theItem = composition()->composerItemAt( scenePoint );
+  if (theItem)
+    {
+      if(theItem->isSelected())
+	{
+	  QPointF itemPoint = theItem->mapFromScene(scenePoint);
+	  theItem->zoomContent(event->delta(), itemPoint.x(), itemPoint.y());
+	}
+    }
+}
+
 void QgsComposerView::setComposition( QgsComposition* c )
 {
   setScene( c );

src/gui/qgscomposerview.h

@@ -79,6 +79,8 @@ class GUI_EXPORT QgsComposerView: public QGraphicsView
     void keyPressEvent( QKeyEvent * e );
     void keyReleaseEvent( QKeyEvent * e );
 
+    void wheelEvent( QWheelEvent* event);
+
   private:
     /**Status of shift key (used for multiple selection)*/
     bool mShiftKeyPressed;