[gimp] app: add (disabled) support for rendering the image at high resolution

[Michael Natterer <mitch src gnome org>]

commit 2491a3a088b263bf62834c5f3d6912c853bcc9d0
Author: Michael Natterer <mitch gimp org>
Date:   Fri Jan 18 16:36:22 2013 +0100

    app: add (disabled) support for rendering the image at high resolution
    
    for what Apple calls "Retina". Disabled because the GDK API to figure
    the scale factor doesn't exist yet.

 app/display/gimpdisplayshell-render.c |   32 +++++++++++++++++++++++++-------
 app/display/gimpdisplayshell-render.h |    8 ++++++++
 app/display/gimpdisplayshell.c        |    6 ++++--
 3 files changed, 37 insertions(+), 9 deletions(-)
---
diff --git a/app/display/gimpdisplayshell-render.c b/app/display/gimpdisplayshell-render.c
index 252e4d4..67d1c50 100644
--- a/app/display/gimpdisplayshell-render.c
+++ b/app/display/gimpdisplayshell-render.c
@@ -54,6 +54,7 @@ gimp_display_shell_render (GimpDisplayShell *shell,
   GimpImage      *image;
   GimpProjection *projection;
   GeglBuffer     *buffer;
+  gdouble         window_scale = 1.0;
   gint            viewport_offset_x;
   gint            viewport_offset_y;
   gint            viewport_width;
@@ -67,6 +68,13 @@ gimp_display_shell_render (GimpDisplayShell *shell,
   projection = gimp_image_get_projection (image);
   buffer     = gimp_pickable_get_buffer (GIMP_PICKABLE (projection));
 
+#ifdef GIMP_DISPLAY_RENDER_ENABLE_SCALING
+  /* if we had this future API, things would look pretty on hires (retina) */
+  window_scale = gdk_window_get_scale_factor (gtk_widget_get_window (gtk_widget_get_toplevel (GTK_WIDGET (shell))));
+#endif
+
+  window_scale = MIN (window_scale, GIMP_DISPLAY_RENDER_MAX_SCALE);
+
   gimp_display_shell_scroll_get_scaled_viewport (shell,
                                                  &viewport_offset_x,
                                                  &viewport_offset_y,
@@ -74,10 +82,11 @@ gimp_display_shell_render (GimpDisplayShell *shell,
                                                  &viewport_height);
 
   gegl_buffer_get (buffer,
-                   GEGL_RECTANGLE (x + viewport_offset_x,
-                                   y + viewport_offset_y,
-                                   w, h),
-                   shell->scale_x,
+                   GEGL_RECTANGLE ((x + viewport_offset_x) * window_scale,
+                                   (y + viewport_offset_y) * window_scale,
+                                   w * window_scale,
+                                   h * window_scale),
+                   shell->scale_x * window_scale,
                    babl_format ("cairo-ARGB32"),
                    cairo_image_surface_get_data (shell->render_surface),
                    cairo_image_surface_get_stride (shell->render_surface),
@@ -91,7 +100,9 @@ gimp_display_shell_render (GimpDisplayShell *shell,
       if (w != GIMP_DISPLAY_RENDER_BUF_WIDTH ||
           h != GIMP_DISPLAY_RENDER_BUF_HEIGHT)
         sub = cairo_image_surface_create_for_data (cairo_image_surface_get_data (sub),
-                                                   CAIRO_FORMAT_ARGB32, w, h,
+                                                   CAIRO_FORMAT_ARGB32,
+                                                   w * window_scale,
+                                                   h * window_scale,
                                                    GIMP_DISPLAY_RENDER_BUF_WIDTH * 4);
 
       gimp_color_display_stack_convert_surface (shell->filter_stack, sub);
@@ -100,7 +111,9 @@ gimp_display_shell_render (GimpDisplayShell *shell,
         cairo_surface_destroy (sub);
     }
 
-  cairo_surface_mark_dirty_rectangle (shell->render_surface, 0, 0, w, h);
+  cairo_surface_mark_dirty_rectangle (shell->render_surface,
+                                      0, 0,
+                                      w * window_scale, h * window_scale);
 
 #if 0
   if (shell->mask)
@@ -136,7 +149,12 @@ gimp_display_shell_render (GimpDisplayShell *shell,
   cairo_rectangle (cr, x, y, w, h);
   cairo_clip (cr);
 
-  cairo_set_source_surface (cr, shell->render_surface, x, y);
+  cairo_scale (cr, 1.0 / window_scale, 1.0 / window_scale);
+
+  cairo_set_source_surface (cr, shell->render_surface,
+                            x * window_scale,
+                            y * window_scale);
+
   cairo_paint (cr);
 
 #if 0
diff --git a/app/display/gimpdisplayshell-render.h b/app/display/gimpdisplayshell-render.h
index 01cac48..652cddd 100644
--- a/app/display/gimpdisplayshell-render.h
+++ b/app/display/gimpdisplayshell-render.h
@@ -19,9 +19,17 @@
 #define __GIMP_DISPLAY_SHELL_RENDER_H__
 
 
+/* #define GIMP_DISPLAY_RENDER_ENABLE_SCALING 1 */
+
 #define GIMP_DISPLAY_RENDER_BUF_WIDTH  256
 #define GIMP_DISPLAY_RENDER_BUF_HEIGHT 256
 
+#ifdef GIMP_DISPLAY_RENDER_ENABLE_SCALING
+#define GIMP_DISPLAY_RENDER_MAX_SCALE 2.0
+#else
+#define GIMP_DISPLAY_RENDER_MAX_SCALE 1.0
+#endif
+
 
 void  gimp_display_shell_render (GimpDisplayShell *shell,
                                  cairo_t          *cr,
diff --git a/app/display/gimpdisplayshell.c b/app/display/gimpdisplayshell.c
index 6410d48..3e99799 100644
--- a/app/display/gimpdisplayshell.c
+++ b/app/display/gimpdisplayshell.c
@@ -300,8 +300,10 @@ gimp_display_shell_init (GimpDisplayShell *shell)
   shell->y_src_dec   = 1;
 
   shell->render_surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
-                                                      GIMP_DISPLAY_RENDER_BUF_WIDTH,
-                                                      GIMP_DISPLAY_RENDER_BUF_HEIGHT);
+                                                      GIMP_DISPLAY_RENDER_BUF_WIDTH *
+                                                      GIMP_DISPLAY_RENDER_MAX_SCALE,
+                                                      GIMP_DISPLAY_RENDER_BUF_HEIGHT *
+                                                      GIMP_DISPLAY_RENDER_MAX_SCALE);
 
   gimp_display_shell_items_init (shell);