dia r4096 - in trunk: . app

[hans svn gnome org]

Author: hans
Date: Fri Jul 25 13:03:47 2008
New Revision: 4096
URL: http://svn.gnome.org/viewvc/dia?rev=4096&view=rev

Log:
2008-07-25  Hans Breuer  <hans breuer org>

	* app/display.c(ddisplay_zoom) : improved zoom behavior when using 
	ctrl+mouse wheel around the cursor position, based on code by 
	Ithai Levi, bug #540210 

	* app/mavigation.c : don't divide by zero when using the navigation
	window with an empty diagram


Modified:
   trunk/ChangeLog
   trunk/app/display.c
   trunk/app/navigation.c

Modified: trunk/app/display.c
==============================================================================
--- trunk/app/display.c	(original)
+++ trunk/app/display.c	Fri Jul 25 13:03:47 2008
@@ -759,11 +759,15 @@
 {
   Rectangle *visible;
   real width, height;
+  real rx, ry;
 
   visible = &ddisp->visible;
 
   width = (visible->right - visible->left)/magnify;
   height = (visible->bottom - visible->top)/magnify;
+  /* calculate cursor position ratios */
+  rx = (point->x - visible->left) / (visible->right - visible->left);
+  ry = (point->y - visible->top) / (visible->bottom - visible->top);
 
   if ((ddisp->zoom_factor <= DDISPLAY_MIN_ZOOM) && (magnify<=1.0))
     return;
@@ -772,7 +776,8 @@
 
   ddisp->zoom_factor *= magnify;
 
-  ddisplay_set_origo(ddisp, point->x - width/2.0, point->y - height/2.0);
+  /* set new origin based on the calculated ratios before zooming */
+  ddisplay_set_origo(ddisp, point->x-(width*rx),point->y-(height*ry));
   
   ddisplay_update_scrollbars(ddisp);
   ddisplay_add_update_all(ddisp);

Modified: trunk/app/navigation.c
==============================================================================
--- trunk/app/navigation.c	(original)
+++ trunk/app/navigation.c	Fri Jul 25 13:03:47 2008
@@ -177,6 +177,9 @@
     diagram_width  = (int) ddisplay_transform_length (nav->ddisp, (rect.right - rect.left));
     diagram_height = (int) ddisplay_transform_length (nav->ddisp, (rect.bottom - rect.top));
 
+    if (diagram_width * diagram_height == 0)
+      return; /* don't crash with no size, i.e. empty diagram */
+
     canvas_width   = nav->ddisp->canvas->allocation.width;
     canvas_height  = nav->ddisp->canvas->allocation.height;