From 77efa0c6319a87e2d6ec8af307917a9426f3164e Mon Sep 17 00:00:00 2001
From: Anna Schumaker <Anna@NoWheyCreamery.com>
Date: Thu, 19 Apr 2018 09:42:51 -0400
Subject: [PATCH] gui/model: Configure the gui model as a drag source

We'll need to do this to enable drag and drop to reorder playlists.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>
---
 gui/model.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
 gui/treeview.c      |  3 +++
 include/gui/model.h |  9 +++++++++
 3 files changed, 54 insertions(+)

diff --git a/gui/model.c b/gui/model.c
index 734c60eb..6966529d 100644
--- a/gui/model.c
+++ b/gui/model.c
@@ -28,6 +28,12 @@ static GType gui_model_columns[GUI_MODEL_N_COLUMNS] = {
 	[GUI_MODEL_FONT]      = G_TYPE_STRING,
 };
 
+const GtkTargetEntry gui_model_drag_targets[] = {
+	{ GUI_DRAG_DATA, GTK_TARGET_SAME_APP, 0 },
+};
+
+const unsigned int gui_model_n_targets = G_N_ELEMENTS(gui_model_drag_targets);
+
 static GtkTreeModelFlags __gui_model_get_flags(GtkTreeModel *model)
 {
 	return GTK_TREE_MODEL_LIST_ONLY;
@@ -169,6 +175,27 @@ static gboolean __gui_model_iter_parent(GtkTreeModel *model, GtkTreeIter *iter,
 	return FALSE;
 }
 
+static gboolean __gui_model_drag_data_get(GtkTreeDragSource *drag_source,
+					  GtkTreePath       *path,
+					  GtkSelectionData  *selection_data)
+{
+	struct gui_model_drag_data *data = g_malloc(sizeof(*data));
+
+	data->drag_row   = gtk_tree_path_get_indices(path)[0];
+	data->drag_track = gui_model_path_get_track(path);
+
+	gtk_selection_data_set(selection_data, gdk_atom_intern(GUI_DRAG_DATA, false),
+			       8 /* bytes */, (void *)data, sizeof(*data));
+	g_free(data);
+	return true;
+}
+
+static gboolean __gui_model_drag_data_delete(GtkTreeDragSource *drag_source,
+					     GtkTreePath *path)
+{
+	return true;
+}
+
 static void __gui_model_init(GuiModel *model)
 {
 	model->gm_stamp = g_random_int();
@@ -203,6 +230,12 @@ static void __gui_tree_model_init(GtkTreeModelIface *iface)
 	iface->iter_parent     = __gui_model_iter_parent;
 }
 
+static void __gui_drag_source_init(GtkTreeDragSourceIface *iface)
+{
+	iface->drag_data_get    = __gui_model_drag_data_get;
+	iface->drag_data_delete = __gui_model_drag_data_delete;
+}
+
 static const GTypeInfo gui_model_type_info = {
 	.class_size     = sizeof(GuiModelClass),
 	.base_init      = NULL,
@@ -221,6 +254,12 @@ static const GInterfaceInfo gui_tree_model = {
 	.interface_data     = NULL,
 };
 
+static const GInterfaceInfo gui_drag_source = {
+	.interface_init     = (GInterfaceInitFunc)__gui_drag_source_init,
+	.interface_finalize = NULL,
+	.interface_data     = NULL,
+};
+
 
 void gui_model_init(void)
 {
@@ -229,6 +268,9 @@ void gui_model_init(void)
 						(GTypeFlags)0);
 	g_type_add_interface_static(gui_model_type, GTK_TYPE_TREE_MODEL,
 				   &gui_tree_model);
+	g_type_add_interface_static(gui_model_type, GTK_TYPE_TREE_DRAG_SOURCE,
+				   &gui_drag_source);
+
 
 	gui_model = g_object_new(gui_model_type, NULL);
 	g_assert(gui_model != NULL);
diff --git a/gui/treeview.c b/gui/treeview.c
index f24a2852..d6ddd2da 100644
--- a/gui/treeview.c
+++ b/gui/treeview.c
@@ -167,6 +167,9 @@ void gui_treeview_init()
 
 	gtk_tree_view_set_model(gui_treeview(),
 				GTK_TREE_MODEL(gui_filter_get()));
+	gtk_tree_view_enable_model_drag_source(gui_treeview(), GDK_BUTTON1_MASK,
+				gui_model_drag_targets, gui_model_n_targets,
+				GDK_ACTION_MOVE);
 
 	for (i = 0; i < GUI_MODEL_N_COLUMNS; i++) {
 		col = gtk_tree_view_get_column(gui_treeview(), i);
diff --git a/include/gui/model.h b/include/gui/model.h
index 326ae8ac..f4d8543a 100644
--- a/include/gui/model.h
+++ b/include/gui/model.h
@@ -38,6 +38,15 @@ struct gui_model_class {
 };
 typedef struct gui_model_class GuiModelClass;
 
+struct gui_model_drag_data {
+	unsigned int  drag_row;
+	struct track *drag_track;
+};
+
+#define GUI_DRAG_DATA "GUI_DRAG_DATA"
+
+extern const GtkTargetEntry gui_model_drag_targets[];
+extern const unsigned int gui_model_n_targets;
 
 /* Called to initialize the GuiModel */
 void gui_model_init(void);