Changeset 187:b465e2c34f23 in glemon-0.x for graph_displayer_canvas-event.cc

Timestamp:

02/02/07 11:13:33 (17 years ago)

Author:

Hegyi Péter

Branch:

default

Phase:

public

Convert:

svn:c9d7d8f5-90d6-0310-b91f-818b3a526b0e/glemon/trunk@3150

Message:

Zoom is now available with mouse-wheel.

File:

• graph_displayer_canvas-event.cc (modified) (1 diff)

graph_displayer_canvas-event.cc

@@ -94 +94 @@
 {
   return actual_tool;
+}
+
+bool GraphDisplayerCanvas::scrollEventHandler(GdkEvent* e)
+{
+  bool handled=false;
+  if(e->type==GDK_SCROLL)
+    {
+
+      //pointer shows this win point before zoom
+      XY win_coord(((GdkEventScroll*)e)->x, ((GdkEventScroll*)e)->y);
+
+      //the original scroll settings
+      int scroll_offset_x, scroll_offset_y;
+      get_scroll_offsets(scroll_offset_x, scroll_offset_y);
+
+      //pointer shows this canvas point before zoom
+      XY canvas_coord;
+      window_to_world(win_coord.x, win_coord.y, canvas_coord.x, canvas_coord.y);
+
+      if(((GdkEventScroll*)e)->direction) //IN
+        {
+          zoomIn();
+        }
+      else
+        {
+          zoomOut();
+        }
+
+      //pointer shows this window point after zoom
+      XY post_win_coord;
+      world_to_window(canvas_coord.x, canvas_coord.y, post_win_coord.x, post_win_coord.y);
+
+      //we have to add the difference between new and old window point to original scroll offset
+      scroll_to(scroll_offset_x+(int)(post_win_coord.x-win_coord.x),scroll_offset_y+(int)(post_win_coord.y-win_coord.y));
+      
+      //no other eventhandler is needed
+      handled=true;
+    }
+  return handled;
 }