[dia] Introduce ddisplay_zoom_middle() to reduce code duplication

[Hans Breuer <hans src gnome org>]

commit efde1a7bc403407673f50025ed5c7b791c0580e8
Author: Hans Breuer <hans breuer org>
Date:   Fri Jul 27 22:27:26 2012 +0200

    Introduce ddisplay_zoom_middle() to reduce code duplication

 app/commands.c       |   14 ++------------
 app/disp_callbacks.c |   12 ++----------
 app/display.c        |   15 ++++++++++++++-
 app/display.h        |    2 ++
 app/interface.c      |   16 ++--------------
 5 files changed, 22 insertions(+), 37 deletions(-)
---
diff --git a/app/commands.c b/app/commands.c
index 542af9f..0bdb7aa 100644
--- a/app/commands.c
+++ b/app/commands.c
@@ -979,32 +979,22 @@ void
 view_zoom_in_callback (GtkAction *action)
 {
   DDisplay *ddisp;
-  Point middle;
-  Rectangle *visible;
 
   ddisp = ddisplay_active();
   if (!ddisp) return;
-  visible = &ddisp->visible;
-  middle.x = visible->left*0.5 + visible->right*0.5;
-  middle.y = visible->top*0.5 + visible->bottom*0.5;
   
-  ddisplay_zoom(ddisp, &middle, M_SQRT2);
+  ddisplay_zoom_middle(ddisp, M_SQRT2);
 }
 
 void
 view_zoom_out_callback (GtkAction *action)
 {
   DDisplay *ddisp;
-  Point middle;
-  Rectangle *visible;
   
   ddisp = ddisplay_active();
   if (!ddisp) return;
-  visible = &ddisp->visible;
-  middle.x = visible->left*0.5 + visible->right*0.5;
-  middle.y = visible->top*0.5 + visible->bottom*0.5;
   
-  ddisplay_zoom(ddisp, &middle, M_SQRT1_2);
+  ddisplay_zoom_middle(ddisp, M_SQRT1_2);
 }
 
 void 
diff --git a/app/disp_callbacks.c b/app/disp_callbacks.c
index e83b26d..c17299f 100644
--- a/app/disp_callbacks.c
+++ b/app/disp_callbacks.c
@@ -906,19 +906,11 @@ ddisplay_canvas_events (GtkWidget *canvas,
 		break;
               case GDK_KP_Add:
               case GDK_plus:
-                visible = &ddisp->visible;
-                middle.x = visible->left*0.5 + visible->right*0.5;
-                middle.y = visible->top*0.5 + visible->bottom*0.5;
-	  
-                ddisplay_zoom(ddisp, &middle, M_SQRT2);
+                ddisplay_zoom_middle(ddisp, M_SQRT2);
                 break;
               case GDK_KP_Subtract:
               case GDK_minus:
-                visible = &ddisp->visible;
-                middle.x = visible->left*0.5 + visible->right*0.5;
-                middle.y = visible->top*0.5 + visible->bottom*0.5;
-	  
-                ddisplay_zoom(ddisp, &middle, M_SQRT1_2);
+                ddisplay_zoom_middle(ddisp, M_SQRT1_2);
                 break;
               case GDK_Shift_L:
               case GDK_Shift_R:
diff --git a/app/display.c b/app/display.c
index 3c1d8fc..ce929a6 100644
--- a/app/display.c
+++ b/app/display.c
@@ -807,6 +807,19 @@ ddisplay_zoom(DDisplay *ddisp, Point *point, real magnify)
   update_zoom_status (ddisp);
 }
 
+/* Zoom around the middle point of the visible area
+ */
+void
+ddisplay_zoom_middle(DDisplay *ddisp, real magnify)
+{
+  Point middle;
+  Rectangle *visible;
+
+  visible = &ddisp->visible;
+  middle.x = visible->left*0.5 + visible->right*0.5;
+  middle.y = visible->top*0.5 + visible->bottom*0.5;
+}
+
 /*
    When using the mouse wheel button to zoom in and out, it is more 
    intuitive to maintain the drawing zoom center-point based on the 
@@ -819,7 +832,7 @@ ddisplay_zoom_centered(DDisplay *ddisp, Point *point, real magnify)
   Rectangle *visible;
   real width, height;
   /* cursor position ratios */
-  real rx,ry; 
+  real rx,ry;
 
   if ((ddisp->zoom_factor <= DDISPLAY_MIN_ZOOM) && (magnify<=1.0))
     return;
diff --git a/app/display.h b/app/display.h
index 4bf9541..cdc8e4e 100644
--- a/app/display.h
+++ b/app/display.h
@@ -145,6 +145,8 @@ void ddisplay_set_origo(DDisplay *ddisp,
 			coord x, coord y);
 void ddisplay_zoom(DDisplay *ddisp, Point *point,
 		   real zoom_factor);
+void ddisplay_zoom_middle(DDisplay *ddisp, real magnify);
+
 void ddisplay_zoom_centered(DDisplay *ddisp, Point *point, real magnify);
 void ddisplay_set_snap_to_grid(DDisplay *ddisp, gboolean snap);
 void ddisplay_set_snap_to_objects(DDisplay *ddisp, gboolean magnetic);
diff --git a/app/interface.c b/app/interface.c
index d09a42a..6cd9a75 100644
--- a/app/interface.c
+++ b/app/interface.c
@@ -179,19 +179,13 @@ view_zoom_set (float factor)
 {
   DDisplay *ddisp;
   real scale;
-  Point middle;
-  Rectangle *visible;
 
   ddisp = ddisplay_active();
   if (!ddisp) return;
 
-  visible = &ddisp->visible;
-  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;
 
-  ddisplay_zoom(ddisp, &middle, scale / ddisp->zoom_factor);  
+  ddisplay_zoom_middle(ddisp, scale / ddisp->zoom_factor);
 }
 
 static void
@@ -207,9 +201,6 @@ zoom_activate_callback(GtkWidget *item, gpointer user_data)
   }
 
   if (sscanf(zoom_text, "%f", &zoom_amount) == 1) {
-    Point middle;
-    Rectangle *visible;
-
     /* Set limits to avoid crashes, see bug #483384 */
     if (zoom_amount < .1) {
       zoom_amount = .1;
@@ -221,10 +212,7 @@ zoom_activate_callback(GtkWidget *item, gpointer user_data)
     g_free(zoomamount);
     magnify = (zoom_amount*DDISPLAY_NORMAL_ZOOM/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;
-      middle.y = visible->top*0.5 + visible->bottom*0.5;
-      ddisplay_zoom(ddisp, &middle, magnify);
+      ddisplay_zoom_middle(ddisp, magnify);
     }
   }
 }