[gimp/wip/animation: 331/373] plug-ins: add drag'n drop in storyboard.

[Jehan Pagès <jehanp src gnome org>]

commit e4748834d23f87fa0d831d6a26aa19bd0f96ce8c
Author: Jehan <jehan girinstud io>
Date:   Wed Jun 21 23:57:15 2017 +0200

    plug-ins: add drag'n drop in storyboard.
    
    Reorder panel by drag'n dropping them around. This also edits the order
    in the actual image. This first version reloads the storyboard, which is
    still kind of fast even with many dozens of layers.
    Yet we will want to have a proper reordering of the GUI without full
    reload at some point.

 plug-ins/animation-play/animation-utils.h          |    8 +
 .../animation-play/widgets/animation-storyboard.c  |  153 +++++++++++++++++++-
 2 files changed, 159 insertions(+), 2 deletions(-)
---
diff --git a/plug-ins/animation-play/animation-utils.h b/plug-ins/animation-play/animation-utils.h
index 79c598c..30d3bf2 100755
--- a/plug-ins/animation-play/animation-utils.h
+++ b/plug-ins/animation-play/animation-utils.h
@@ -30,6 +30,14 @@
 #define MAX_FRAMERATE      300.0
 #define DEFAULT_FRAMERATE  24.0
 
+typedef enum
+{
+  ANIMATION_DND_TYPE_NONE      = 0,
+  ANIMATION_DND_TYPE_PANEL     = 1,
+
+  GIMP_DND_TYPE_LAST         = ANIMATION_DND_TYPE_PANEL
+} AnimationDndType;
+
 void         total_alpha_preview (guchar            *drawing_data,
                                   guint              drawing_width,
                                   guint              drawing_height);
diff --git a/plug-ins/animation-play/widgets/animation-storyboard.c 
b/plug-ins/animation-play/widgets/animation-storyboard.c
index 3f2c11d..8e23376 100644
--- a/plug-ins/animation-play/widgets/animation-storyboard.c
+++ b/plug-ins/animation-play/widgets/animation-storyboard.c
@@ -51,6 +51,8 @@ struct _AnimationStoryboardPrivate
   GList              *panel_buttons;
   GList              *disposal_buttons;
   GList              *comments;
+
+  gint                dragged_panel;
 };
 
 /* GObject handlers */
@@ -89,9 +91,26 @@ static void animation_storyboard_disposal_toggled      (GtkToggleButton     *but
 static void animation_storyboard_button_clicked        (GtkWidget           *widget,
                                                         AnimationStoryboard *storyboard);
 
+/* Drag and drop */
+static void animation_storyboard_panel_drag_begin      (GtkWidget           *widget,
+                                                        GdkDragContext      *drag_context,
+                                                        AnimationStoryboard *storyboard);
+static void animation_storyboard_panel_drag_end        (GtkWidget           *widget,
+                                                        GdkDragContext      *drag_context,
+                                                        AnimationStoryboard *storyboard);
+static gboolean animation_storyboard_panel_drag_drop   (GtkWidget           *widget,
+                                                        GdkDragContext      *drag_context,
+                                                        gint                 x,
+                                                        gint                 y,
+                                                        guint                time,
+                                                        AnimationStoryboard *storyboard);
+
 /* Utils */
 static void animation_storyboard_jump                  (AnimationStoryboard *view,
                                                         gint                 panel);
+static void animation_storyboard_move                  (AnimationStoryboard *storyboard,
+                                                        gint                 from_panel,
+                                                        gint                 to_panel);
 
 G_DEFINE_TYPE (AnimationStoryboard, animation_storyboard, GTK_TYPE_SCROLLED_WINDOW)
 
@@ -128,6 +147,7 @@ animation_storyboard_init (AnimationStoryboard *view)
   view->priv = G_TYPE_INSTANCE_GET_PRIVATE (view,
                                             ANIMATION_TYPE_STORYBOARD,
                                             AnimationStoryboardPrivate);
+  view->priv->dragged_panel = -1;
 }
 
 /**** Public Functions ****/
@@ -243,6 +263,12 @@ animation_storyboard_finalize (GObject *object)
   G_OBJECT_CLASS (parent_class)->finalize (object);
 }
 
+static const GtkTargetEntry target_table[] = {
+      { "application/x-gimp-animation-panel",
+        GTK_TARGET_SAME_APP,
+        ANIMATION_DND_TYPE_PANEL }
+};
+
 /* animation_storyboard_load:
  * @view: the #AnimationStoryboard.
  *
@@ -255,13 +281,15 @@ animation_storyboard_load (Animation           *animation,
 {
   AnimationAnimatic *animatic = ANIMATION_ANIMATIC (animation);
   GtkWidget         *layout;
+  gint              *orig_layers;
   gint              *layers;
+  gint32             orig_image_id;
   gint32             image_id;
   gint               n_images;
   gint               i;
 
-  image_id = animation_get_image_id (animation);
-  image_id = gimp_image_duplicate (image_id);
+  orig_image_id = animation_get_image_id (animation);
+  image_id = gimp_image_duplicate (orig_image_id);
   gimp_image_undo_disable (image_id);
 
   /* The actual layout is the grand-child. */
@@ -289,6 +317,8 @@ animation_storyboard_load (Animation           *animation,
     }
 
   /* Setting new values. */
+  orig_layers = gimp_image_get_layers (orig_image_id,
+                                       &n_images);
   layers = gimp_image_get_layers (image_id,
                                   &n_images);
 
@@ -319,6 +349,8 @@ animation_storyboard_load (Animation           *animation,
                         GTK_EXPAND | GTK_FILL,
                         GTK_FILL,
                         1, 1);
+      g_object_set_data (G_OBJECT (panel_button), "layer-tattoo",
+                         GINT_TO_POINTER (gimp_item_get_tattoo (orig_layers[i])));
       g_object_set_data (G_OBJECT (panel_button), "panel-num",
                          GINT_TO_POINTER (panel_num));
       g_signal_connect (panel_button, "clicked",
@@ -333,8 +365,29 @@ animation_storyboard_load (Animation           *animation,
       thumbnail = gimp_drawable_get_thumbnail (layers[i], 250, 250,
                                                GIMP_PIXBUF_SMALL_CHECKS);
       image = gtk_image_new_from_pixbuf (thumbnail);
+
+      /* Make this button a drag source. */
+      gtk_drag_source_set (panel_button, GDK_BUTTON1_MASK,
+                           target_table, G_N_ELEMENTS (target_table),
+                           GDK_ACTION_MOVE);
+      gtk_drag_source_set_icon_pixbuf (panel_button, thumbnail);
+
       g_object_unref (thumbnail);
 
+      gtk_drag_dest_set (panel_button, GTK_DEST_DEFAULT_ALL,
+                         target_table, G_N_ELEMENTS (target_table),
+                         GDK_ACTION_MOVE);
+
+      g_signal_connect (panel_button, "drag-begin",
+                        G_CALLBACK (animation_storyboard_panel_drag_begin),
+                        view);
+      g_signal_connect (panel_button, "drag-end",
+                        G_CALLBACK (animation_storyboard_panel_drag_end),
+                        view);
+      g_signal_connect (panel_button, "drag-drop",
+                        G_CALLBACK (animation_storyboard_panel_drag_drop),
+                        view);
+
       /* Let's align top-right, in case the storyboard gets resized
        * and the image grows (the thumbnail right now stays as fixed size). */
       gtk_misc_set_alignment (GTK_MISC (image), 1.0, 0.0);
@@ -440,6 +493,7 @@ animation_storyboard_load (Animation           *animation,
                     (GCallback) animation_storyboard_stopped,
                     view);
   g_free (layers);
+  g_free (orig_layers);
   gimp_image_delete (image_id);
 }
 
@@ -577,6 +631,67 @@ animation_storyboard_button_clicked (GtkWidget           *widget,
   animation_playback_jump (storyboard->priv->playback, position);
 }
 
+/**** Drag and drop ****/
+
+static void
+animation_storyboard_panel_drag_begin (GtkWidget           *widget,
+                                       GdkDragContext      *drag_context,
+                                       AnimationStoryboard *storyboard)
+{
+  gpointer panel_num;
+
+  panel_num = g_object_get_data (G_OBJECT (widget), "panel-num");
+  storyboard->priv->dragged_panel = GPOINTER_TO_INT (panel_num);
+}
+
+static void
+animation_storyboard_panel_drag_end (GtkWidget           *widget,
+                                     GdkDragContext      *drag_context,
+                                     AnimationStoryboard *storyboard)
+{
+  storyboard->priv->dragged_panel = -1;
+}
+
+static gboolean
+animation_storyboard_panel_drag_drop (GtkWidget           *widget,
+                                      GdkDragContext      *context,
+                                      gint                 x,
+                                      gint                 y,
+                                      guint                time,
+                                      AnimationStoryboard *storyboard)
+{
+  gpointer       panel_num;
+  GtkAllocation  allocation;
+  gint           panel_dest;
+
+  g_return_val_if_fail (storyboard->priv->dragged_panel >= 0, FALSE);
+
+  panel_num = g_object_get_data (G_OBJECT (widget), "panel-num");
+  gtk_widget_get_allocation (widget, &allocation);
+  if (y > allocation.height / 2)
+    {
+      panel_dest = GPOINTER_TO_INT (panel_num) + 1;
+    }
+  else
+    {
+      panel_dest = GPOINTER_TO_INT (panel_num);
+    }
+  if (storyboard->priv->dragged_panel < panel_dest)
+    {
+      panel_dest--;
+    }
+  animation_storyboard_move (storyboard,
+                             storyboard->priv->dragged_panel,
+                             panel_dest);
+
+  gtk_drag_finish (context, TRUE,
+                   gdk_drag_context_get_selected_action (context) == GDK_ACTION_MOVE,
+                   time);
+  return TRUE;
+}
+
+/**** Utils ****/
+
 static void
 animation_storyboard_jump (AnimationStoryboard *view,
                            gint                 panel)
@@ -602,3 +717,37 @@ animation_storyboard_jump (AnimationStoryboard *view,
       show_scrolled_child (GTK_SCROLLED_WINDOW (view), button);
     }
 }
+
+static void
+animation_storyboard_move (AnimationStoryboard *storyboard,
+                           gint                 from_panel,
+                           gint                 to_panel)
+{
+  Animation *animation;
+  gint32     image_id;
+
+  animation = ANIMATION (storyboard->priv->animation);
+  image_id  = animation_get_image_id (animation);
+  if (from_panel != to_panel)
+    {
+      GtkWidget *button;
+      gpointer   tattoo;
+      gint32     layer;
+      gint       new_position;
+
+      button = g_list_nth_data (storyboard->priv->panel_buttons,
+                                from_panel);
+      tattoo = g_object_get_data (G_OBJECT (button), "layer-tattoo");
+      layer = gimp_image_get_layer_by_tattoo (image_id,
+                                              GPOINTER_TO_INT (tattoo));
+
+      /* Layers are ordered from top to bottom in GIMP. */
+      new_position = g_list_length (storyboard->priv->panel_buttons) - to_panel - 1;
+      gimp_image_reorder_item (image_id, layer, 0, new_position);
+
+      /* For now, do a full reload. Ugly but that's a first version.
+       * TODO: implement a saner, lighter reordering of the GUI.
+       */
+      animation_load (animation);
+    }
+}