Applied patch 1004 that adds zoom to direction of mouse cursor

mhugent · mhugent · commit 698d69346b75 · 2008-03-25T15:36:49.000Z
git-svn-id: http://svn.osgeo.org/qgis/trunk@8265 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/gui/qgsmapcanvas.cpp b/src/gui/qgsmapcanvas.cpp
@@ -819,12 +819,30 @@ void QgsMapCanvas::wheelEvent(QWheelEvent *e)
       // zoom without changing extent
       zoom(e->delta() > 0);
       break;
-      
+
     case WheelZoomAndRecenter:
       // zoom and don't change extent
       zoomWithCenter(e->x(), e->y(), e->delta() > 0);
       break;
-      
+
+    case WheelZoomToMouseCursor:
+    {
+      // zoom map to mouse cursor
+      double scaleFactor = e->delta() > 0 ? 1 / mWheelZoomFactor : mWheelZoomFactor;
+
+      QgsPoint oldCenter(mMapRender->extent().center());
+      QgsPoint mousePos(getCoordinateTransform()->toMapPoint(e->x(), e->y()));
+      QgsPoint newCenter(mousePos.x() + ((oldCenter.x() - mousePos.x()) * scaleFactor), 
+        mousePos.y() + ((oldCenter.y() - mousePos.y()) * scaleFactor));
+
+      // same as zoomWithCenter (no coordinate transformations are needed)
+      QgsRect extent = mMapRender->extent();
+      extent.scale(scaleFactor, &newCenter);
+      setExtent(extent);
+      refresh();
+      break;
+    }
+
     case WheelNothing:
       // well, nothing!
       break;
diff --git a/src/gui/qgsmapcanvas.h b/src/gui/qgsmapcanvas.h
@@ -95,7 +95,7 @@ class GUI_EXPORT QgsMapCanvas : public QGraphicsView
 
   public:
     
-    enum WheelAction { WheelZoom, WheelZoomAndRecenter, WheelNothing };
+    enum WheelAction { WheelZoom, WheelZoomAndRecenter, WheelZoomToMouseCursor, WheelNothing };
         
     //! Constructor
     QgsMapCanvas(QWidget * parent = 0, const char *name = 0);
diff --git a/src/ui/qgsoptionsbase.ui b/src/ui/qgsoptionsbase.ui
@@ -487,6 +487,11 @@
               <string>Zoom and recenter</string>
              </property>
             </item>
+            <item>
+             <property name="text" >
+              <string>Zoom to mouse cursor</string>
+             </property>
+            </item>
             <item>
              <property name="text" >
               <string>Nothing</string>
