Patch for correct mapping of page.

[Serg Sh <merblud mail ru>]

I apologise, has not found on a site where to dispatch patches. Therefore I write to the mailing list. I hope 
that my patch will be useful.

The patch realises calculation quantity of pixels on centimetre for the current screen. As a result of 
boundary of page and the diagramme sizes are displayed more precisely in relation to real at 100 % scale.


diff -urNp dia-0.97/app/display.c dia-0.97/app/display.c
--- dia-0.97/app/display.c      2009-04-17 12:25:23 +0400
+++ dia-0.97/app/display.c      2010-06-29 21:01:24 +0400
@@ -71,11 +71,10 @@ static void
 update_zoom_status(DDisplay *ddisp)
 {
   gchar* zoom_text;
-
   if (is_integrated_ui ())
   {
     zoom_text = g_strdup_printf("%.0f%%",
-          ddisp->zoom_factor * 100.0 / DDISPLAY_NORMAL_ZOOM);
+           ddisp->zoom_factor * 100.0 / ddisp->ppcm);
 
     integrated_ui_toolbar_set_zoom_text (ddisp->common_toolbar, zoom_text);  
   }
@@ -83,7 +82,7 @@ update_zoom_status(DDisplay *ddisp)
   {
     GtkWidget *zoomcombo;
     zoom_text = g_strdup_printf("%.1f%%",
-            ddisp->zoom_factor * 100.0 / DDISPLAY_NORMAL_ZOOM);
+            ddisp->zoom_factor * 100.0 / ddisp->ppcm);
     zoomcombo = ddisp->zoom_status;
     gtk_entry_set_text(GTK_ENTRY (g_object_get_data (G_OBJECT(zoomcombo), "user_data")),
                       zoom_text);
@@ -266,6 +265,8 @@ copy_display(DDisplay *orig_ddisp)
   ddisp->zoom_factor = orig_ddisp->zoom_factor;
   ddisp->visible = orig_ddisp->visible;
 
+  ddisp->ppcm = orig_ddisp->ppcm;
+
   initialize_display_widgets(ddisp);
   return ddisp;  /*  set the user data  */
 }
@@ -280,6 +281,9 @@ new_display(Diagram *dia)
 {
   DDisplay *ddisp;
   Rectangle visible;
+  GdkScreen *dscreen;
+  gint wsc, hsc;
+  gint wscmm, hscmm;
   
   ddisp = g_new0(DDisplay,1);
 
@@ -305,7 +309,16 @@ new_display(Diagram *dia)
   g_signal_connect (dia, "selection_changed", G_CALLBACK(selection_changed), ddisp);
   ddisp->origo.x = 0.0;
   ddisp->origo.y = 0.0;
-  ddisp->zoom_factor = prefs.new_view.zoom/100.0*DDISPLAY_NORMAL_ZOOM;
+
+  dscreen = gdk_screen_get_default();
+  wsc = gdk_screen_get_width(dscreen);
+  hsc = gdk_screen_get_height(dscreen);
+  wscmm = gdk_screen_get_width_mm(dscreen);
+  hscmm = gdk_screen_get_height_mm(dscreen);
+  ddisp->ppcm = hsc/(hscmm/10);
+  if (ddisp->ppcm < wsc/(wscmm/10)) ddisp->ppcm = wsc/(wscmm/10);
+
+  ddisp->zoom_factor = prefs.new_view.zoom/100.0*ddisp->ppcm;
   if ((ddisp->diagram) && (ddisp->diagram->data)) {
     Rectangle *extents = &ddisp->diagram->data->extents;
 
@@ -319,6 +332,7 @@ new_display(Diagram *dia)
   visible.bottom = visible.top + prefs.new_view.height/ddisp->zoom_factor;
 
   ddisp->visible = visible;
+  
 
   initialize_display_widgets(ddisp);
   return ddisp;  /*  set the user data  */
diff -urNp dia-0.97/app/display.h dia-0.97/app/display.h
--- dia-0.97/app/display.h      2009-04-17 12:25:23 +0400
+++ dia-0.97/app/display.h      2010-06-29 20:52:21 +0400
@@ -20,6 +20,7 @@
 
 #include <gtk/gtk.h>
 #include <gtk/gtkimcontext.h>
+#include <gdk/gdk.h>
 
 typedef struct _DDisplay DDisplay;
 
@@ -107,6 +108,9 @@ struct _DDisplay {
 
   /* Private field, indicates which text, if any, is being edited */
   Focus *active_focus;
+
+  /* Defines the pixels per cm for current screen  */
+  gint ppcm;
 };
 
 extern GdkCursor *default_cursor;
diff -urNp dia-0.97/app/interface.c dia-0.97/app/interface.c
--- dia-0.97/app/interface.c    2009-04-17 12:25:23 +0400
+++ dia-0.97/app/interface.c    2010-06-28 22:16:13 +0400
@@ -331,7 +331,7 @@ view_zoom_set (float factor)
   middle.x = visible->left*0.5 + visible->right*0.5;
   middle.y = visible->top*0.5 + visible->bottom*0.5;
 
-  scale = ((real) factor)/1000.0 * DDISPLAY_NORMAL_ZOOM;
+  scale = ((real) factor)/1000.0 * ddisp->ppcm;
 
   ddisplay_zoom(ddisp, &middle, scale / ddisp->zoom_factor);  
 }
@@ -360,7 +360,7 @@ zoom_activate_callback(GtkWidget *item, 
     zoomamount = g_strdup_printf("%f%%\n", zoom_amount);
     gtk_entry_set_text(GTK_ENTRY(gtk_object_get_user_data(GTK_OBJECT(ddisp->zoom_status))), zoomamount);
     g_free(zoomamount);
-    magnify = (zoom_amount*DDISPLAY_NORMAL_ZOOM/100.0)/ddisp->zoom_factor;
+    magnify = (zoom_amount*ddisp->ppcm/100.0)/ddisp->zoom_factor;
     if (fabs(magnify - 1.0) > 0.000001) {
       visible = &ddisp->visible;
       middle.x = visible->left*0.5 + visible->right*0.5;