[gnome-builder] project-tree: add DnD plumbing

[Christian Hergert <chergert src gnome org>]

commit 7bb23b356bfce550a3cdafb8477749317967a2ed
Author: Christian Hergert <chergert redhat com>
Date:   Tue Dec 5 04:42:45 2017 -0800

    project-tree: add DnD plumbing
    
    This doesn't yet use the DzlFileTransfer API to copy/move
    things, but it does land the plumbing we need to handle the
    node movements.
    
    The other annoying thing is that we are using single-click so
    that the treeview feels more like listbox. We need to do some
    special case handling so that we don't open the file while we
    are really trying to start a drag operation.

 src/plugins/project-tree/gb-project-tree-builder.c |  192 ++++++++++++++++++++
 src/plugins/project-tree/gb-project-tree.c         |   12 ++
 2 files changed, 204 insertions(+), 0 deletions(-)
---
diff --git a/src/plugins/project-tree/gb-project-tree-builder.c 
b/src/plugins/project-tree/gb-project-tree-builder.c
index 312ae3a..cf0a0a8 100644
--- a/src/plugins/project-tree/gb-project-tree-builder.c
+++ b/src/plugins/project-tree/gb-project-tree-builder.c
@@ -23,6 +23,8 @@
 #include "gb-project-tree.h"
 #include "gb-project-tree-builder.h"
 
+#define _ATOM gdk_atom_intern_static_string
+
 struct _GbProjectTreeBuilder
 {
   DzlTreeBuilder  parent_instance;
@@ -629,6 +631,190 @@ gb_project_tree_builder_node_collapsed (DzlTreeBuilder *builder,
   IDE_EXIT;
 }
 
+static gboolean
+gb_project_tree_builder_node_draggable (DzlTreeBuilder *builder,
+                                        DzlTreeNode    *node)
+{
+  GbProjectTreeBuilder *self = (GbProjectTreeBuilder *)builder;
+  GObject *item;
+
+  g_assert (GB_IS_PROJECT_TREE_BUILDER (self));
+  g_assert (DZL_IS_TREE_NODE (node));
+
+  item = dzl_tree_node_get_item (node);
+
+  return GB_IS_PROJECT_FILE (item);
+}
+
+static gboolean
+gb_project_tree_builder_node_droppable (DzlTreeBuilder   *builder,
+                                        DzlTreeNode      *node,
+                                        GtkSelectionData *data)
+{
+  GbProjectTreeBuilder *self = (GbProjectTreeBuilder *)builder;
+  GObject *item;
+
+  g_assert (GB_IS_PROJECT_TREE_BUILDER (self));
+  g_assert (DZL_IS_TREE_NODE (node));
+
+  item = dzl_tree_node_get_item (node);
+
+  return GB_IS_PROJECT_FILE (item);
+}
+
+static gboolean
+gb_project_tree_builder_drag_data_get (DzlTreeBuilder   *builder,
+                                       DzlTreeNode      *node,
+                                       GtkSelectionData *data)
+{
+  GbProjectTreeBuilder *self = (GbProjectTreeBuilder *)builder;
+  GObject *item;
+
+  g_assert (GB_IS_PROJECT_TREE_BUILDER (self));
+  g_assert (DZL_IS_TREE_NODE (node));
+
+  if (gtk_selection_data_get_target (data) != _ATOM ("text/uri-list"))
+    return FALSE;
+
+  item = dzl_tree_node_get_item (node);
+
+  if (GB_IS_PROJECT_FILE (item))
+    {
+      GFile *file = gb_project_file_get_file (GB_PROJECT_FILE (item));
+      g_autofree gchar *uri = g_file_get_uri (file);
+      gchar *uris[] = { uri, NULL };
+
+      return gtk_selection_data_set_uris (data, uris);
+    }
+
+  return FALSE;
+}
+
+static gboolean
+gb_project_tree_builder_drag_data_received (DzlTreeBuilder      *builder,
+                                            DzlTreeNode         *drop_node,
+                                            DzlTreeDropPosition  position,
+                                            GtkSelectionData    *data)
+{
+  GbProjectTreeBuilder *self = (GbProjectTreeBuilder *)builder;
+
+  g_assert (GB_IS_PROJECT_TREE_BUILDER (self));
+  g_assert (DZL_IS_TREE_NODE (drop_node));
+  g_assert (data != NULL);
+
+  /* We don't care about positioning before/after for the file tree.
+   * So if we get one of those, we will just ignore it and look at
+   * the parent instead.
+   */
+  if (position != DZL_TREE_DROP_INTO)
+    {
+      if (NULL == (drop_node = dzl_tree_node_get_parent (drop_node)) ||
+          dzl_tree_node_is_root (drop_node))
+        return FALSE;
+    }
+
+  /* For inter-process DnD, we only support dropping a URI list.
+   * We need to copy all those files into the directory represented
+   * by our drop node.
+   */
+  if (gtk_selection_data_get_target (data) == _ATOM ("text/uri-list"))
+    {
+      GObject *item = dzl_tree_node_get_item (drop_node);
+
+      if (GB_IS_PROJECT_FILE (item))
+        {
+          GFile *file = gb_project_file_get_file (GB_PROJECT_FILE (item));
+          g_auto(GStrv) uris = gtk_selection_data_get_uris (data);
+
+          if (uris != NULL && uris[0] != NULL)
+            {
+              g_autofree gchar *joined = g_strjoinv (" ", uris);
+              g_autofree gchar *dst_uri = g_file_get_uri (file);
+
+              g_debug ("Drop %s onto %s with position %d",
+                       joined, dst_uri, position);
+
+              return TRUE;
+            }
+        }
+    }
+
+  return FALSE;
+}
+
+static gboolean
+gb_project_tree_builder_drag_node_received (DzlTreeBuilder      *builder,
+                                            DzlTreeNode         *drag_node,
+                                            DzlTreeNode         *drop_node,
+                                            DzlTreeDropPosition  position,
+                                            GtkSelectionData    *data)
+{
+  GbProjectTreeBuilder *self = (GbProjectTreeBuilder *)builder;
+  GObject *drag_item;
+  GObject *drop_item;
+
+  g_assert (GB_IS_PROJECT_TREE_BUILDER (self));
+  g_assert (DZL_IS_TREE_NODE (drag_node));
+  g_assert (DZL_IS_TREE_NODE (drop_node));
+  g_assert (data != NULL);
+
+  /* We don't care about positioning before/after for the file tree.
+   * So if we get one of those, we will just ignore it and look at
+   * the parent instead.
+   */
+  if (position != DZL_TREE_DROP_INTO)
+    {
+      if (NULL == (drop_node = dzl_tree_node_get_parent (drop_node)) ||
+          dzl_tree_node_is_root (drop_node))
+        return FALSE;
+    }
+
+  /*
+   * Get our files and determine what we are copying to the new location.
+   * We always do a copy because the drag_delete signal will be used to
+   * remove the old files. Not exactly the most efficient, but it is fine
+   * for our purposes.
+   */
+  drag_item = dzl_tree_node_get_item (drag_node);
+  drop_item = dzl_tree_node_get_item (drop_node);
+
+  if (GB_IS_PROJECT_FILE (drag_item) && GB_IS_PROJECT_FILE (drop_item))
+    {
+      GFile *drag_file = gb_project_file_get_file (GB_PROJECT_FILE (drag_item));
+      GFile *drop_file = gb_project_file_get_file (GB_PROJECT_FILE (drop_item));
+
+      if (G_IS_FILE (drag_file) && G_IS_FILE (drop_file))
+        {
+          g_autofree gchar *src_uri = g_file_get_uri (drag_file);
+          g_autofree gchar *dst_uri = g_file_get_uri (drop_file);
+
+          g_debug ("Need to copy %s into %s", src_uri, dst_uri);
+
+          return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+
+static gboolean
+gb_project_tree_builder_drag_node_delete (DzlTreeBuilder *builder,
+                                          DzlTreeNode    *node)
+{
+  GbProjectTreeBuilder *self = (GbProjectTreeBuilder *)builder;
+
+  g_assert (GB_IS_PROJECT_TREE_BUILDER (self));
+  g_assert (DZL_IS_TREE_NODE (node));
+
+  /*
+   * We must have done a GTK_ACTION_MOVE, which means that we need to
+   * cleanup whatever it is that we moved. In our case, that means
+   * removing the files.
+   */
+
+  return FALSE;
+}
+
 static void
 gb_project_tree_builder_dispose (GObject *object)
 {
@@ -649,10 +835,16 @@ gb_project_tree_builder_class_init (GbProjectTreeBuilderClass *klass)
   object_class->dispose = gb_project_tree_builder_dispose;
 
   tree_builder_class->build_node = gb_project_tree_builder_build_node;
+  tree_builder_class->drag_data_get = gb_project_tree_builder_drag_data_get;
+  tree_builder_class->drag_data_received = gb_project_tree_builder_drag_data_received;
+  tree_builder_class->drag_node_received = gb_project_tree_builder_drag_node_received;
+  tree_builder_class->drag_node_delete = gb_project_tree_builder_drag_node_delete;
   tree_builder_class->node_activated = gb_project_tree_builder_node_activated;
   tree_builder_class->node_collapsed = gb_project_tree_builder_node_collapsed;
   tree_builder_class->node_expanded = gb_project_tree_builder_node_expanded;
   tree_builder_class->node_popup = gb_project_tree_builder_node_popup;
+  tree_builder_class->node_draggable = gb_project_tree_builder_node_draggable;
+  tree_builder_class->node_droppable = gb_project_tree_builder_node_droppable;
 }
 
 static void
diff --git a/src/plugins/project-tree/gb-project-tree.c b/src/plugins/project-tree/gb-project-tree.c
index 056c8ad..2775391 100644
--- a/src/plugins/project-tree/gb-project-tree.c
+++ b/src/plugins/project-tree/gb-project-tree.c
@@ -314,6 +314,10 @@ gb_project_tree_class_init (GbProjectTreeClass *klass)
 static void
 gb_project_tree_init (GbProjectTree *self)
 {
+  static const GtkTargetEntry drag_targets[] = {
+    { "GTK_TREE_MODEL_ROW", GTK_TARGET_SAME_WIDGET, 0 },
+    { "text/uri-list", 0, 0 },
+  };
   DzlTreeBuilder *builder;
   GMenu *menu;
 
@@ -341,6 +345,14 @@ gb_project_tree_init (GbProjectTree *self)
   menu = dzl_application_get_menu_by_id (DZL_APPLICATION_DEFAULT,
                                          "gb-project-tree-popup-menu");
   dzl_tree_set_context_menu (DZL_TREE (self), G_MENU_MODEL (menu));
+
+  gtk_tree_view_enable_model_drag_source (GTK_TREE_VIEW (self),
+                                          GDK_BUTTON1_MASK,
+                                          drag_targets, G_N_ELEMENTS (drag_targets),
+                                          GDK_ACTION_COPY | GDK_ACTION_MOVE);
+  gtk_tree_view_enable_model_drag_dest (GTK_TREE_VIEW (self),
+                                        drag_targets, G_N_ELEMENTS (drag_targets),
+                                        GDK_ACTION_COPY | GDK_ACTION_MOVE);
 }
 
 gboolean