Allow to choose what axes to center on.

2008-07-13  Martin Nordholts  <martinn@svn.gnome.org>

	* app/display/gimpdisplayshell-scale.[ch]
	(gimp_display_shell_center_image): Allow to choose what axes to
	center on.

	(gimp_display_shell_scale_fill)
	(gimp_display_shell_scale_fit_in): Explicitly center on both axes.

	* app/display/gimpdisplayshell.c (gimp_display_shell_fill): Center
	the image in the filled display shell. Rather hackish, but seems
	to work fine.

svn path=/trunk/; revision=26185

ChangeLog

@@ -1,3 +1,16 @@
+2008-07-13  Martin Nordholts  <martinn@svn.gnome.org>
+
+	* app/display/gimpdisplayshell-scale.[ch]
+	(gimp_display_shell_center_image): Allow to choose what axes to
+	center on.
+
+	(gimp_display_shell_scale_fill)
+	(gimp_display_shell_scale_fit_in): Explicitly center on both axes.
+
+	* app/display/gimpdisplayshell.c (gimp_display_shell_fill): Center
+	the image in the filled display shell. Rather hackish, but seems
+	to work fine.
+
 2008-07-13  Sven Neumann  <sven@gimp.org>
 
 	* app/widgets/Makefile.am

app/display/gimpdisplayshell-scale.c

@@ -431,7 +431,7 @@ gimp_display_shell_scale_fit_in (GimpDisplayShell *shell)
                      (gdouble) shell->disp_height / (gdouble) image_height);
 
   gimp_display_shell_scale (shell, GIMP_ZOOM_TO, zoom_factor);
-  gimp_display_shell_center_image (shell);
+  gimp_display_shell_center_image (shell, TRUE, TRUE);
 }
 
 /**
@@ -470,18 +470,22 @@ gimp_display_shell_scale_fill (GimpDisplayShell *shell)
                      (gdouble) shell->disp_height / (gdouble) image_height);
 
   gimp_display_shell_scale (shell, GIMP_ZOOM_TO, zoom_factor);
-  gimp_display_shell_center_image (shell);
+  gimp_display_shell_center_image (shell, TRUE, TRUE);
 }
 
 /**
  * gimp_display_shell_center_image:
  * @shell:
+ * @horizontally:
+ * @vertically:
  *
- * Centers the image in the display shell.
+ * Centers the image in the display shell on the desired axes.
  *
  **/
 void
-gimp_display_shell_center_image (GimpDisplayShell *shell)
+gimp_display_shell_center_image (GimpDisplayShell *shell,
+                                 gboolean          horizontally,
+                                 gboolean          vertically)
 {
   gint sw, sh;
   gint target_offset_x, target_offset_y;
@@ -491,24 +495,33 @@ gimp_display_shell_center_image (GimpDisplayShell *shell)
   if (! shell->display)
     return;
 
+  target_offset_x = shell->offset_x;
+  target_offset_y = shell->offset_y;
+
   gimp_display_shell_get_scaled_image_size (shell, &sw, &sh);
 
-  if (sw < shell->disp_width)
+  if (horizontally)
     {
-      target_offset_x = -(shell->disp_width - sw) / 2;
+      if (sw < shell->disp_width)
-    }
+        {
-  else
+          target_offset_x = -(shell->disp_width - sw) / 2;
-    {
+        }
-      target_offset_x = (sw - shell->disp_width) / 2;
+      else
+        {
+          target_offset_x = (sw - shell->disp_width) / 2;
+        }
     }
 
-  if (sh < shell->disp_height)
+  if (vertically)
     {
-      target_offset_y = -(shell->disp_height - sh) / 2;
+      if (sh < shell->disp_height)
-    }
+        {
-  else
+          target_offset_y = -(shell->disp_height - sh) / 2;
-    {
+        }
-      target_offset_y = (sh - shell->disp_height) / 2;
+      else
+        {
+          target_offset_y = (sh - shell->disp_height) / 2;
+        }
     }
 
   /* Note that we can't use gimp_display_shell_scroll_private() here

app/display/gimpdisplayshell-scale.h

@@ -38,7 +38,9 @@ void   gimp_display_shell_scale_to              (GimpDisplayShell *shell,
                                                  gdouble           y);
 void   gimp_display_shell_scale_fit_in          (GimpDisplayShell *shell);
 void   gimp_display_shell_scale_fill            (GimpDisplayShell *shell);
-void   gimp_display_shell_center_image          (GimpDisplayShell *shell);
+void   gimp_display_shell_center_image          (GimpDisplayShell *shell,
+                                                 gboolean          horizontally,
+                                                 gboolean          vertically);
 void   gimp_display_shell_scale_by_values       (GimpDisplayShell *shell,
                                                  gdouble           scale,
                                                  gint              offset_x,

app/display/gimpdisplayshell.c

@@ -1316,6 +1316,35 @@ gimp_display_shell_empty (GimpDisplayShell *shell)
     gimp_ui_manager_update (shell->popup_manager, shell->display);
 }
 
+static void
+gimp_display_shell_center_image_callback (GimpDisplayShell *shell,
+                                          GtkAllocation    *allocation,
+                                          GtkWidget        *canvas)
+{
+  gint     sw, sh;
+  gboolean center_horizontally;
+  gboolean center_vertically;
+
+  gimp_display_shell_get_scaled_image_size (shell, &sw, &sh);
+
+  /* We only want to center on the axes on which the image is smaller
+   * than the display canvas. If it is larger, it will be centered on
+   * that axis later, and if we center on all axis unconditionally, we
+   * end up with the wrong centering if the image is larger than the
+   * display canvas.
+   */
+  center_horizontally = sw < shell->disp_width;
+  center_vertically   = sh < shell->disp_height;
+
+  gimp_display_shell_center_image (shell,
+                                   center_horizontally,
+                                   center_vertically);
+
+  g_signal_handlers_disconnect_by_func (canvas,
+                                        gimp_display_shell_center_image_callback,
+                                        shell);
+}
+
 static gboolean
 gimp_display_shell_fill_idle (GimpDisplayShell *shell)
 {
@@ -1351,6 +1380,15 @@ gimp_display_shell_fill (GimpDisplayShell *shell,
 
   gimp_help_set_help_data (shell->canvas, NULL, NULL);
 
+  /* Not pretty, but we need to center the image as soon as the canvas
+   * has got its new size allocated. The centering will be wrong if we
+   * do it too early, and if we do it too late flickering will occur
+   * due to the image being rendered twice.
+   */
+  g_signal_connect_swapped (shell->canvas, "size-allocate",
+                            G_CALLBACK (gimp_display_shell_center_image_callback),
+                            shell);
+
   shell->fill_idle_id = g_idle_add_full (G_PRIORITY_LOW,
                                          (GSourceFunc) gimp_display_shell_fill_idle,
                                          shell, NULL);