wip: Add async api to choose a color

This is an experiment to replace explicit use
of chooser dialogs with an async API.

2 files changed, 156 insertions, 0 deletions

diff --git a/gtk/gtkcolorchooser.h b/gtk/gtkcolorchooser.h
index 7a97865b8d..97cb0ed364 100644
--- a/gtk/gtkcolorchooser.h
+++ b/gtk/gtkcolorchooser.h
@@ -83,6 +83,32 @@ void     gtk_color_chooser_add_palette    (GtkColorChooser *chooser,
                                            int              n_colors,
                                            GdkRGBA         *colors);
 
+
+typedef void (*GtkColorChooserPrepareCallback) (GtkColorChooser *chooser,
+                                                gpointer         user_data);
+
+GDK_AVAILABLE_IN_ALL
+void     gtk_choose_color                 (GtkWindow                      *parent,
+                                           const char                     *title,
+                                           GCancellable                   *cancellable,
+                                           GAsyncReadyCallback             callback,
+                                           gpointer                        user_data);
+
+GDK_AVAILABLE_IN_ALL
+void     gtk_choose_color_full            (GtkWindow                      *parent,
+                                           const char                     *title,
+                                           GtkColorChooserPrepareCallback  prepare,
+                                           gpointer                        prepare_data,
+                                           GCancellable                   *cancellable,
+                                           GAsyncReadyCallback             callback,
+                                           gpointer                        user_data);
+
+GDK_AVAILABLE_IN_ALL
+gboolean gtk_choose_color_finish          (GtkColorChooser                *chooser,
+                                           GAsyncResult                   *result,
+                                           GdkRGBA                        *color,
+                                           GError                        **error);
+
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(GtkColorChooser, g_object_unref)
 
 G_END_DECLS
diff --git a/gtk/gtkcolorchooserdialog.c b/gtk/gtkcolorchooserdialog.c
index 81ac261880..3dc6a61c79 100644
--- a/gtk/gtkcolorchooserdialog.c
+++ b/gtk/gtkcolorchooserdialog.c
@@ -291,3 +291,133 @@ gtk_color_chooser_dialog_new (const char *title,
                        "transient-for", parent,
                        NULL);
 }
+
+static void
+cancelled_cb (GCancellable *cancellable,
+              GtkDialog    *dialog)
+{
+  gtk_dialog_response (dialog, GTK_RESPONSE_CANCEL);
+}
+
+static void
+response_cb (GtkDialog *dialog,
+             int        response,
+             GTask     *task)
+{
+  GCancellable *cancellable = g_task_get_cancellable (task);
+
+  if (cancellable)
+    g_signal_handlers_disconnect_by_func (cancellable, cancelled_cb, dialog);
+
+  if (response == GTK_RESPONSE_OK)
+    g_task_return_boolean (task, TRUE);
+  else
+    g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_CANCELLED, "Cancelled");
+
+  g_object_unref (task);
+  gtk_window_destroy (GTK_WINDOW (dialog));
+}
+
+/**
+ * gtk_choose_color:
+ * @parent: (nullable): parent window
+ * @title: title for the color chooser
+ * @cancellable: (nullable): a `GCancellable` to cancel the operation
+ * @callback: (scope async): callback to call when the action is complete
+ * @user_data: (closure callback): data to pass to @callback
+ *
+ * This function presents a color chooser to let the user
+ * pick a color.
+ *
+ * The @callback will be called when the dialog is closed.
+ * It should call [function@Gtk.choose_color_finish] to
+ * find out whether the operation was completed successfully,
+ * and to obtain the resulting color.
+ */
+void
+gtk_choose_color (GtkWindow           *parent,
+                  const char          *title,
+                  GCancellable        *cancellable,
+                  GAsyncReadyCallback  callback,
+                  gpointer             user_data)
+{
+  gtk_choose_color_full (parent, title, NULL, NULL, cancellable, callback, user_data);
+}
+
+/**
+ * gtk_choose_color_full:
+ * @parent: (nullable): parent window
+ * @title: title for the color chooser
+ * @prepare: (nullable) (scope call): callback to set up the color chooser
+ * @prepare_data: (closure prepare): data to pass to @prepare
+ * @cancellable: (nullable): a `GCancellable` to cancel the operation
+ * @callback: (scope async): callback to call when the action is complete
+ * @user_data: (closure callback): data to pass to @callback
+ *
+ * This function presents a color chooser to let the user
+ * pick a color.
+ *
+ * In addition to [function@Gtk.choose_color], this function takes
+ * a @prepare callback that lets you set up the color chooser according
+ * to your needs.
+ *
+ * The @callback will be called when the dialog is closed.
+ * It should call [function@Gtk.choose_color_finish] to
+ * find out whether the operation was completed successfully,
+ * and to obtain the resulting color.
+ */
+void
+gtk_choose_color_full (GtkWindow                      *parent,
+                       const char                     *title,
+                       GtkColorChooserPrepareCallback  prepare,
+                       gpointer                        prepare_data,
+                       GCancellable                   *cancellable,
+                       GAsyncReadyCallback             callback,
+                       gpointer                        user_data)
+{
+  GtkWidget *dialog;
+  GTask *task;
+
+  dialog = gtk_color_chooser_dialog_new (title, parent);
+  if (prepare)
+    prepare (GTK_COLOR_CHOOSER (dialog), prepare);
+
+  if (cancellable)
+    g_signal_connect (cancellable, "cancelled", G_CALLBACK (cancelled_cb), dialog);
+
+  task = g_task_new (dialog, cancellable, callback, user_data);
+  g_task_set_source_tag (task, gtk_choose_color_full);
+
+  g_signal_connect (dialog, "response", G_CALLBACK (response_cb), task);
+
+  gtk_window_present (GTK_WINDOW (dialog));
+}
+
+/**
+ * gtk_choose_color_finish:
+ * @chooser: the `GtkColorChooser`
+ * @result: `GAsyncResult` that was passed to @callback
+ * @color: return location for the color
+ * @error: return location for an error
+ *
+ * Finishes a gtk_choose_color() or gtk_choose_color_full() call
+ * and returns the results.
+ *
+ * If this function returns `TRUE`, @color contains
+ * the color that was chosen.
+ *
+ * Returns: `TRUE` if the operation was successful
+ */
+gboolean
+gtk_choose_color_finish (GtkColorChooser  *chooser,
+                         GAsyncResult     *result,
+                         GdkRGBA          *color,
+                         GError          **error)
+{
+  if (!g_task_propagate_boolean (G_TASK (result), error))
+    return FALSE;
+
+  gtk_color_chooser_get_rgba (chooser, color);
+
+  return TRUE;
+}