[gtk/wip/otte/dnd: 118/126] colorswatch: Switch to dragged color during dnd

[Benjamin Otte <otte src gnome org>]

commit c3fb6ca747c4f49c3e5a21c287baf37f1ab4676d
Author: Benjamin Otte <otte redhat com>
Date:   Sun Mar 1 17:32:40 2020 +0100

    colorswatch: Switch to dragged color during dnd
    
    This is really simple to implement now, so do it.

 gtk/gtkcolorswatch.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)
---
diff --git a/gtk/gtkcolorswatch.c b/gtk/gtkcolorswatch.c
index ae424ad572..63dad35bd9 100644
--- a/gtk/gtkcolorswatch.c
+++ b/gtk/gtkcolorswatch.c
@@ -89,25 +89,35 @@ swatch_snapshot (GtkWidget   *widget,
   GtkColorSwatchPrivate *priv = gtk_color_swatch_get_instance_private (swatch);
   const int width = gtk_widget_get_width (widget);
   const int height = gtk_widget_get_height (widget);
+  const GdkRGBA *color;
+
+  color = &priv->color;
+  if (priv->dest)
+    {
+      const GValue *value = gtk_drop_target_get_value (priv->dest);
+
+      if (value)
+        color = g_value_get_boxed (value);
+    }
 
   if (priv->has_color)
     {
-      if (priv->use_alpha && !gdk_rgba_is_opaque (&priv->color))
+      if (priv->use_alpha && !gdk_rgba_is_opaque (color))
         {
           _gtk_color_chooser_snapshot_checkered_pattern (snapshot, width, height);
 
           gtk_snapshot_append_color (snapshot,
-                                     &priv->color,
+                                     color,
                                      &GRAPHENE_RECT_INIT (0, 0, width, height));
         }
       else
         {
-          GdkRGBA color = priv->color;
+          GdkRGBA opaque = *color;
 
-          color.alpha = 1.0;
+          opaque.alpha = 1.0;
 
           gtk_snapshot_append_color (snapshot,
-                                     &color,
+                                     &opaque,
                                      &GRAPHENE_RECT_INIT (0, 0, width, height));
         }
     }
@@ -654,7 +664,9 @@ gtk_color_swatch_set_can_drop (GtkColorSwatch *swatch,
   if (can_drop && !priv->dest)
     {
       priv->dest = gtk_drop_target_new (GDK_TYPE_RGBA, GDK_ACTION_COPY);
+      gtk_drop_target_set_preload (priv->dest, TRUE);
       g_signal_connect (priv->dest, "drop", G_CALLBACK (swatch_drag_drop), swatch);
+      g_signal_connect_swapped (priv->dest, "notify::value", G_CALLBACK (gtk_widget_queue_draw), swatch);
       gtk_widget_add_controller (GTK_WIDGET (swatch), GTK_EVENT_CONTROLLER (priv->dest));
     }
   if (!can_drop && priv->dest)