[gtk/treeview-sort-arrows] treeviewcolumn: Redo sort arrows

[Matthias Clasen <matthiasc src gnome org>]

commit e3abd624c2515aeac4efffaaf09b8192fe636738
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jan 18 16:11:57 2021 -0500

    treeviewcolumn: Redo sort arrows
    
    Instead of hardcoding icon names in the widget,
    use arrow:ascending and arrow:descending styles
    and set the icon to use with -gtk-icon-source.
    This lets themes change the icon thats used
    here, without forcing all uses of pan-up/down-symbolic
    to be treated the same.
    
    Fixes: #3577

 gtk/gtktreeviewcolumn.c        | 43 +++++++++++++++++++-----------------------
 gtk/theme/Adwaita/_common.scss | 11 +++++++++++
 2 files changed, 30 insertions(+), 24 deletions(-)
---
diff --git a/gtk/gtktreeviewcolumn.c b/gtk/gtktreeviewcolumn.c
index e321bed4b6..b18ea4bb07 100644
--- a/gtk/gtktreeviewcolumn.c
+++ b/gtk/gtktreeviewcolumn.c
@@ -38,6 +38,7 @@
 #include "gtkgesturedrag.h"
 #include "gtkeventcontrollerfocus.h"
 #include "gtkeventcontrollerkey.h"
+#include "gtkbuiltiniconprivate.h"
 
 #include <string.h>
 
@@ -879,7 +880,7 @@ gtk_tree_view_column_create_button (GtkTreeViewColumn *tree_column)
   gtk_widget_set_halign (priv->frame, GTK_ALIGN_START);
 
   hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
-  priv->arrow = gtk_image_new_from_icon_name ("pan-down-symbolic");
+  priv->arrow = gtk_builtin_icon_new ("arrow");
 
   if (priv->child)
     child = priv->child;
@@ -905,7 +906,7 @@ gtk_tree_view_column_create_button (GtkTreeViewColumn *tree_column)
   gtk_button_set_child (GTK_BUTTON (priv->button), hbox);
 }
 
-static void 
+static void
 gtk_tree_view_column_update_button (GtkTreeViewColumn *tree_column)
 {
   GtkTreeViewColumnPrivate *priv = tree_column->priv;
@@ -914,7 +915,6 @@ gtk_tree_view_column_update_button (GtkTreeViewColumn *tree_column)
   GtkWidget *frame;
   GtkWidget *arrow;
   GtkWidget *current_child;
-  const char *icon_name = "missing-image";
   GtkTreeModel *model;
 
   if (priv->tree_view)
@@ -948,17 +948,17 @@ gtk_tree_view_column_update_button (GtkTreeViewColumn *tree_column)
       g_return_if_fail (GTK_IS_LABEL (current_child));
 
       if (priv->title)
-       gtk_label_set_text_with_mnemonic (GTK_LABEL (current_child),
-                                         priv->title);
+        gtk_label_set_text_with_mnemonic (GTK_LABEL (current_child),
+                                          priv->title);
       else
-       gtk_label_set_text_with_mnemonic (GTK_LABEL (current_child),
-                                         "");
+        gtk_label_set_text_with_mnemonic (GTK_LABEL (current_child),
+                                          "");
     }
 
   if (GTK_IS_TREE_SORTABLE (model))
     gtk_tree_sortable_get_sort_column_id (GTK_TREE_SORTABLE (model),
-                                         &sort_column_id,
-                                         NULL);
+                                          &sort_column_id,
+                                          NULL);
 
   if (priv->show_sort_indicator)
     {
@@ -971,24 +971,19 @@ gtk_tree_view_column_update_button (GtkTreeViewColumn *tree_column)
       else
         alternative = FALSE;
 
-      switch (priv->sort_order)
+      if ((!alternative && priv->sort_order == GTK_SORT_ASCENDING) ||
+          (alternative && priv->sort_order == GTK_SORT_DESCENDING))
         {
-         case GTK_SORT_ASCENDING:
-            icon_name = alternative ? "pan-up-symbolic" : "pan-down-symbolic";
-           break;
-
-         case GTK_SORT_DESCENDING:
-            icon_name = alternative ? "pan-down-symbolic" : "pan-up-symbolic";
-           break;
-
-         default:
-           g_warning (G_STRLOC": bad sort order");
-           break;
-       }
+          gtk_widget_remove_css_class (arrow, "descending");
+          gtk_widget_add_css_class (arrow, "ascending");
+        }
+      else
+        {
+          gtk_widget_remove_css_class (arrow, "ascending");
+          gtk_widget_add_css_class (arrow, "descending");
+        }
     }
 
-  gtk_image_set_from_icon_name (GTK_IMAGE (arrow), icon_name);
-
   /* Put arrow on the right if the text is left-or-center justified, and on the
    * left otherwise; do this by packing boxes, so flipping text direction will
    * reverse things
diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index b5094c68e6..3e02c97b63 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -1766,6 +1766,17 @@ treeview.view {
         color: $fg_color;
         transition: none; //I shouldn't need this
       }
+      arrow {
+        &.ascending {
+          -gtk-icon-source: -gtk-icontheme('pan-up-symbolic');
+        }
+        &.descending {
+          -gtk-icon-source: -gtk-icontheme('pan-down-symbolic');
+        }
+
+        min-height: 16px;
+        min-width: 16px;
+      }
     }
   }