[gnome-control-center/wip/feborges/new-search-panel: 12/14] search: Make the list_box the DnD target

[Felipe Borges <felipeborges src gnome org>]

commit fd028ba6a024f948dfb42f93713d72b6a2c6fd1e
Author: Felipe Borges <felipeborges gnome org>
Date:   Thu Jun 29 13:02:16 2017 +0200

    search: Make the list_box the DnD target
    
    By making the list_box itself the Drag and Drop target, we are
    able to use CSS to create a gap between the rows while on hover.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=775958

 panels/search/cc-search-panel.c |  213 +++++++++++++++++++++++++++++++++++++--
 1 files changed, 204 insertions(+), 9 deletions(-)
---
diff --git a/panels/search/cc-search-panel.c b/panels/search/cc-search-panel.c
index 9dae72a..b67c67a 100644
--- a/panels/search/cc-search-panel.c
+++ b/panels/search/cc-search-panel.c
@@ -334,6 +334,9 @@ drag_begin (GtkWidget      *widget,
 
   cairo_destroy (cr);
   cairo_surface_destroy (surface);
+
+  g_object_set_data (G_OBJECT (gtk_widget_get_parent (row)), "drag-row", row);
+  gtk_style_context_add_class (gtk_widget_get_style_context (row), "draw-row");
 }
 
 static void
@@ -341,6 +344,13 @@ drag_end (GtkWidget      *widget,
           GdkDragContext *context,
           CcSearchPanel  *self)
 {
+  GtkWidget *row;
+
+  row = gtk_widget_get_ancestor (widget, GTK_TYPE_LIST_BOX_ROW);
+  g_object_set_data (G_OBJECT (gtk_widget_get_parent (row)), "drag-row", NULL);
+  gtk_style_context_remove_class (gtk_widget_get_style_context (row), "drag-row");
+  gtk_style_context_remove_class (gtk_widget_get_style_context (row), "drag-hover");
+
   /* Lets undo the things done in drag_begin. */
   gtk_list_box_set_sort_func (GTK_LIST_BOX (self->priv->list_box),
                               (GtkListBoxSortFunc)list_sort_func, self, NULL);
@@ -361,6 +371,32 @@ drag_data_get (GtkWidget        *widget,
                           sizeof (gpointer));
 }
 
+static GtkListBoxRow *
+get_last_row (CcSearchPanel *self)
+{
+  guint pos = g_hash_table_size (self->priv->sort_order) - 1;
+
+  return gtk_list_box_get_row_at_index (GTK_LIST_BOX (self->priv->list_box), pos);
+}
+
+static GtkListBoxRow *
+get_row_before (GtkListBox *list,
+                GtkListBoxRow *row)
+{
+  int pos = gtk_list_box_row_get_index (row);
+
+  return gtk_list_box_get_row_at_index (list, pos - 1);
+}
+
+static GtkListBoxRow *
+get_row_after (GtkListBox *list,
+               GtkListBoxRow *row)
+{
+  int pos = gtk_list_box_row_get_index (row);
+
+  return gtk_list_box_get_row_at_index (list, pos + 1);
+}
+
 static void
 drag_data_received (GtkWidget        *widget,
                     GdkDragContext   *context,
@@ -372,19 +408,28 @@ drag_data_received (GtkWidget        *widget,
                     gpointer          data)
 {
   CcSearchPanel *self = CC_SEARCH_PANEL (data);
-  GtkWidget *target;
+  GtkWidget *row_before;
+  GtkWidget *row_after;
   GtkWidget *row;
   GtkWidget *source;
   gboolean success = TRUE;
-  int idx;
+  int pos;
+
+  row_before = GTK_WIDGET (g_object_get_data (G_OBJECT (widget), "row-before"));
+  row_after = GTK_WIDGET (g_object_get_data (G_OBJECT (widget), "row-after"));
+
+  g_object_set_data (G_OBJECT (widget), "row-before", NULL);
+  g_object_set_data (G_OBJECT (widget), "row-after", NULL);
 
-  target = widget;
+  if (row_before)
+    gtk_style_context_remove_class (gtk_widget_get_style_context (row_before), "drag-hover-bottom");
+  if (row_after)
+    gtk_style_context_remove_class (gtk_widget_get_style_context (row_after), "drag-hover-top");
 
   row = (gpointer)* (gpointer*)gtk_selection_data_get_data (selection_data);
   source = gtk_widget_get_ancestor (row, GTK_TYPE_LIST_BOX_ROW);
-  idx = gtk_list_box_row_get_index (GTK_LIST_BOX_ROW (target));
 
-  if (source == target)
+  if (source == row_after)
     {
       success = FALSE;
       goto out;
@@ -392,7 +437,14 @@ drag_data_received (GtkWidget        *widget,
 
   g_object_ref (source);
   gtk_container_remove (GTK_CONTAINER (gtk_widget_get_parent (source)), source);
-  gtk_list_box_insert (GTK_LIST_BOX (gtk_widget_get_parent (target)), source, idx);
+
+  if (row_after)
+    pos = gtk_list_box_row_get_index (GTK_LIST_BOX_ROW (row_after));
+  else
+    pos = gtk_list_box_row_get_index (GTK_LIST_BOX_ROW (row_before)) + 1;
+
+
+  gtk_list_box_insert (GTK_LIST_BOX (widget), source, pos);
   g_object_unref (source);
 
   gtk_container_foreach (GTK_CONTAINER (self->priv->list_box), update_row_position, self);
@@ -403,6 +455,95 @@ out:
   gtk_drag_finish (context, success, TRUE, time);
 }
 
+static gboolean
+drag_motion (GtkWidget *widget,
+             GdkDragContext *context,
+             int x,
+             int y,
+             guint time,
+             gpointer data)
+{
+  CcSearchPanel *self = CC_SEARCH_PANEL (data);
+  GtkAllocation alloc;
+  GtkWidget *row;
+  int hover_row_y;
+  int hover_row_height;
+  GtkWidget *drag_row;
+  GtkWidget *row_before;
+  GtkWidget *row_after;
+
+  row = GTK_WIDGET (gtk_list_box_get_row_at_y (GTK_LIST_BOX (widget), y));
+
+  drag_row = GTK_WIDGET (g_object_get_data (G_OBJECT (widget), "drag-row"));
+  row_before = GTK_WIDGET (g_object_get_data (G_OBJECT (widget), "row-before"));
+  row_after = GTK_WIDGET (g_object_get_data (G_OBJECT (widget), "row-after"));
+
+  gtk_style_context_remove_class (gtk_widget_get_style_context (drag_row), "drag-hover");
+  if (row_before)
+    gtk_style_context_remove_class (gtk_widget_get_style_context (row_before), "drag-hover-bottom");
+  if (row_after)
+    gtk_style_context_remove_class (gtk_widget_get_style_context (row_after), "drag-hover-top");
+
+  if (row)
+    {
+      gtk_widget_get_allocation (row, &alloc);
+      hover_row_y = alloc.y;
+      hover_row_height = alloc.height;
+
+      if (y < hover_row_y + hover_row_height/2)
+        {
+          row_after = row;
+          row_before = GTK_WIDGET (get_row_before (GTK_LIST_BOX (widget), GTK_LIST_BOX_ROW (row)));
+        }
+      else
+        {
+          row_before = row;
+          row_after = GTK_WIDGET (get_row_after (GTK_LIST_BOX (widget), GTK_LIST_BOX_ROW (row)));
+        }
+    }
+  else
+    {
+      row_before = GTK_WIDGET (get_last_row (self));
+      row_after = NULL;
+    }
+
+  g_object_set_data (G_OBJECT (widget), "row-before", row_before);
+  g_object_set_data (G_OBJECT (widget), "row-after", row_after);
+
+  if (drag_row == row_before || drag_row == row_after)
+    {
+      gtk_style_context_add_class (gtk_widget_get_style_context (drag_row), "drag-hover");
+      return FALSE;
+    }
+
+  if (row_before)
+    gtk_style_context_add_class (gtk_widget_get_style_context (row_before), "drag-hover-bottom");
+  if (row_after)
+    gtk_style_context_add_class (gtk_widget_get_style_context (row_after), "drag-hover-top");
+
+  return TRUE;
+}
+
+static void
+drag_leave (GtkWidget *widget,
+            GdkDragContext *context,
+            guint time)
+{
+  GtkWidget *drag_row;
+  GtkWidget *row_before;
+  GtkWidget *row_after;
+
+  drag_row = GTK_WIDGET (g_object_get_data (G_OBJECT (widget), "drag-row"));
+  row_before = GTK_WIDGET (g_object_get_data (G_OBJECT (widget), "row-before"));
+  row_after = GTK_WIDGET (g_object_get_data (G_OBJECT (widget), "row-after"));
+
+  gtk_style_context_remove_class (gtk_widget_get_style_context (drag_row), "drag-hover");
+  if (row_before)
+    gtk_style_context_remove_class (gtk_widget_get_style_context (row_before), "drag-hover-bottom");
+  if (row_after)
+    gtk_style_context_remove_class (gtk_widget_get_style_context (row_after), "drag-hover-top");
+}
+
 static void
 search_panel_add_one_app_info (CcSearchPanel *self,
                                GAppInfo *app_info,
@@ -437,14 +578,12 @@ search_panel_add_one_app_info (CcSearchPanel *self,
                      gtk_image_new_from_icon_name ("open-menu-symbolic", GTK_ICON_SIZE_MENU));
   gtk_container_add (GTK_CONTAINER (box), handle);
 
+  gtk_style_context_add_class (gtk_widget_get_style_context (row), "row");
   gtk_drag_source_set (handle, GDK_BUTTON1_MASK, drag_target_entries, 1, GDK_ACTION_MOVE);
   g_signal_connect (handle, "drag-begin", G_CALLBACK (drag_begin), self->priv->list_box);
   g_signal_connect (handle, "drag-end", G_CALLBACK (drag_end), self);
   g_signal_connect (handle, "drag-data-get", G_CALLBACK (drag_data_get), NULL);
 
-  gtk_drag_dest_set (row, GTK_DEST_DEFAULT_ALL, drag_target_entries, 1, GDK_ACTION_MOVE);
-  g_signal_connect (row, "drag-data-received", G_CALLBACK (drag_data_received), self);
-
   icon = g_app_info_get_icon (app_info);
   if (icon == NULL)
     icon = g_themed_icon_new ("application-x-executable");
@@ -733,9 +872,43 @@ cc_search_panel_constructed (GObject *object)
   cc_shell_embed_widget_in_header (cc_panel_get_shell (CC_PANEL (self)), box);
 }
 
+static const char *css =
+  ".row:not(:first-child) { "
+  "  border-top: 1px solid alpha(gray,0.5); "
+  "  border-bottom: 1px solid transparent; "
+  "}"
+  ".row:first-child { "
+  "  border-top: 1px solid transparent; "
+  "  border-bottom: 1px solid transparent; "
+  "}"
+  ".row:last-child { "
+  "  border-top: 1px solid alpha(gray,0.5); "
+  "  border-bottom: 1px solid alpha(gray,0.5); "
+  "}"
+  ".row.drag-icon { "
+  "  background: @theme_base_color; "
+  "  border: 1px solid @borders; "
+  "}"
+  ".row.drag-row { "
+  "  color: gray; "
+  "  background: alpha(gray,0.2); "
+  "}"
+  ".row.drag-hover image, "
+  ".row.drag-hover label { "
+  "  color: @theme_text_color; "
+  "}"
+  ".row.drag-hover-top {"
+  "  border-top: 48px solid @theme_bg_color; "
+  "}"
+  ".row.drag-hover-bottom {"
+  "  border-bottom: 1px solid @theme_bg_color; "
+  "}"
+;
+
 static void
 cc_search_panel_init (CcSearchPanel *self)
 {
+  GtkCssProvider *provider;
   GError    *error;
   GtkWidget *widget;
   GtkWidget *frame;
@@ -768,6 +941,28 @@ cc_search_panel_init (CcSearchPanel *self)
   self->priv->list_box = widget;
   gtk_widget_show (widget);
 
+  /* Drag and Drop */
+  gtk_drag_dest_set (self->priv->list_box,
+                     GTK_DEST_DEFAULT_MOTION | GTK_DEST_DEFAULT_DROP,
+                     drag_target_entries, 1,
+                     GDK_ACTION_MOVE);
+  g_signal_connect (self->priv->list_box,
+                    "drag-data-received",
+                    G_CALLBACK (drag_data_received), self);
+  g_signal_connect (self->priv->list_box,
+                    "drag-motion",
+                    G_CALLBACK (drag_motion), self);
+  g_signal_connect (self->priv->list_box,
+                    "drag-leave",
+                    G_CALLBACK (drag_leave), NULL);
+
+  provider = gtk_css_provider_new ();
+  gtk_css_provider_load_from_data (provider, css, -1, NULL);
+  gtk_style_context_add_provider_for_screen (gdk_screen_get_default (),
+                                             GTK_STYLE_PROVIDER (provider),
+                                             GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+  g_object_unref (provider);
+
   widget = WID ("settings_button");
   g_signal_connect (widget, "clicked",
                     G_CALLBACK (settings_button_clicked), self);