[gimp] libgimpwidgets: making GimpCellRenderer symbolic and DPI aware.

[Jehan <jehanp src gnome org>]

commit f3347d6961f412df311581ff35f0ef82de989300
Author: Jehan <jehan girinstud io>
Date:   Wed May 30 16:12:57 2018 +0200

    libgimpwidgets: making GimpCellRenderer symbolic and DPI aware.
    
    This commit makes 2 improvements to this renderer. First it will allow
    it to find symbolic variants of icons. Second it properly renders icons
    when the display is scaled, by producing pixbuf size double to logical
    drawing size and making cairo rendering it at the expected logical size.

 libgimpwidgets/gimpcellrenderertoggle.c | 50 ++++++++++++++++++++++++++-------
 1 file changed, 40 insertions(+), 10 deletions(-)
---
diff --git a/libgimpwidgets/gimpcellrenderertoggle.c b/libgimpwidgets/gimpcellrenderertoggle.c
index 854e6dbd5d..cdf148b722 100644
--- a/libgimpwidgets/gimpcellrenderertoggle.c
+++ b/libgimpwidgets/gimpcellrenderertoggle.c
@@ -255,6 +255,7 @@ gimp_cell_renderer_toggle_get_size (GtkCellRenderer    *cell,
   GimpCellRendererTogglePrivate *priv    = GET_PRIVATE (cell);
   GtkStyleContext               *context = gtk_widget_get_style_context (widget);
   GtkBorder                      border;
+  gint                           scale_factor;
   gint                           calc_width;
   gint                           calc_height;
   gint                           pixbuf_width;
@@ -264,6 +265,8 @@ gimp_cell_renderer_toggle_get_size (GtkCellRenderer    *cell,
   gint                           xpad;
   gint                           ypad;
 
+  scale_factor = gtk_widget_get_scale_factor (widget);
+
   if (! priv->icon_name)
     {
       GTK_CELL_RENDERER_CLASS (parent_class)->get_size (cell,
@@ -285,8 +288,9 @@ gimp_cell_renderer_toggle_get_size (GtkCellRenderer    *cell,
   pixbuf_width  = gdk_pixbuf_get_width  (priv->pixbuf);
   pixbuf_height = gdk_pixbuf_get_height (priv->pixbuf);
 
-  calc_width  = pixbuf_width  + (gint) xpad * 2;
-  calc_height = pixbuf_height + (gint) ypad * 2;
+  /* The pixbuf size may be bigger than the logical size. */
+  calc_width  = pixbuf_width / scale_factor + (gint) xpad * 2;
+  calc_height = pixbuf_height / scale_factor + (gint) ypad * 2;
 
   gtk_style_context_add_class (context, GTK_STYLE_CLASS_BUTTON);
 
@@ -333,9 +337,12 @@ gimp_cell_renderer_toggle_render (GtkCellRenderer      *cell,
   GdkRectangle                   toggle_rect;
   GtkStateFlags                  state;
   gboolean                       active;
+  gint                           scale_factor;
   gint                           xpad;
   gint                           ypad;
 
+  scale_factor = gtk_widget_get_scale_factor (widget);
+
   if (! priv->icon_name)
     {
       GTK_CELL_RENDERER_CLASS (parent_class)->render (cell, cr, widget,
@@ -375,7 +382,6 @@ gimp_cell_renderer_toggle_render (GtkCellRenderer      *cell,
                                       &toggle_rect.y,
                                       &toggle_rect.width,
                                       &toggle_rect.height);
-
   gtk_style_context_save (context);
 
   gtk_style_context_add_class (context, GTK_STYLE_CLASS_BUTTON);
@@ -415,10 +421,14 @@ gimp_cell_renderer_toggle_render (GtkCellRenderer      *cell,
 
       gtk_style_context_get_border (context, 0, &border);
       toggle_rect.x      += border.left;
+      toggle_rect.x      *= scale_factor;
       toggle_rect.y      += border.top;
+      toggle_rect.y      *= scale_factor;
       toggle_rect.width  -= border.left + border.right;
       toggle_rect.height -= border.top + border.bottom;
 
+      /* For high DPI displays, pixbuf size is bigger than logical size. */
+      cairo_scale (cr, (gdouble) 1.0 / scale_factor, (gdouble) 1.0 / scale_factor);
       gdk_cairo_set_source_pixbuf (cr, priv->pixbuf,
                                    toggle_rect.x, toggle_rect.y);
       cairo_paint (cr);
@@ -484,17 +494,37 @@ gimp_cell_renderer_toggle_create_pixbuf (GimpCellRendererToggle *toggle,
 
   if (priv->icon_name)
     {
-      gint width, height;
+      GdkScreen    *screen;
+      GtkIconTheme *icon_theme;
+      GtkIconInfo  *icon_info;
+      gchar        *icon_name;
+      gint          scale_factor;
+      gint          width, height;
 
       if (! gtk_icon_size_lookup (priv->stock_size, &width, &height))
+        gtk_icon_size_lookup (DEFAULT_ICON_SIZE, &width, &height);
+
+      scale_factor = gtk_widget_get_scale_factor (widget);
+      screen       = gtk_widget_get_screen (widget);
+      icon_theme   = gtk_icon_theme_get_for_screen (screen);
+
+      /* Look for symbolic and fallback to color icon. */
+      icon_name = g_strdup_printf ("%s-symbolic", priv->icon_name);
+      icon_info = gtk_icon_theme_lookup_icon_for_scale (icon_theme, icon_name,
+                                                        MIN (width, height), scale_factor,
+                                                        GTK_ICON_LOOKUP_GENERIC_FALLBACK);
+
+      g_free (icon_name);
+      if (icon_info)
         {
-          width  = 20;
-          height = 20;
-        }
+          GdkPixbuf *pixbuf;
 
-      priv->pixbuf = gtk_icon_theme_load_icon (gtk_icon_theme_get_default (),
-                                               priv->icon_name,
-                                               MIN (width, height), 0, NULL);
+          pixbuf = gtk_icon_info_load_symbolic_for_context (icon_info,
+                                                            gtk_widget_get_style_context (widget),
+                                                            NULL, NULL);
+          priv->pixbuf = pixbuf;
+          g_object_unref (icon_info);
+        }
     }
 }