[gtk/widgetfactory-async-load] Add GtkLoader to gtk4-widget-factory

[Matthias Clasen <matthiasc src gnome org>]

commit 923c944abb6b5305c4f0adda3d20e9abb6381c8a
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Sep 21 23:04:33 2021 -0400

    Add GtkLoader to gtk4-widget-factory
    
    Add an async-loading paintable implementation
    to gtk4-widget-factory, and use it to load the
    jpegs in the background.

 demos/widget-factory/gtkloader.c        | 215 ++++++++++++++++++++++++++++++++
 demos/widget-factory/gtkloaderprivate.h |  35 ++++++
 demos/widget-factory/meson.build        |   2 +-
 demos/widget-factory/widget-factory.c   |   2 +
 demos/widget-factory/widget-factory.ui  |  18 ++-
 5 files changed, 268 insertions(+), 4 deletions(-)
---
diff --git a/demos/widget-factory/gtkloader.c b/demos/widget-factory/gtkloader.c
new file mode 100644
index 0000000000..be91fa1ef3
--- /dev/null
+++ b/demos/widget-factory/gtkloader.c
@@ -0,0 +1,215 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte gnome org>
+ */
+
+#include "gtkloaderprivate.h"
+#include <gtk/gtk.h>
+
+enum {
+  PROP_RESOURCE = 1,
+};
+
+struct _GtkLoader
+{
+  GObject parent_instance;
+
+  GdkTexture *texture;
+};
+
+struct _GtkLoaderClass
+{
+  GObjectClass parent_class;
+};
+
+static void
+gtk_loader_paintable_snapshot (GdkPaintable *paintable,
+                               GdkSnapshot  *snapshot,
+                               double        width,
+                               double        height)
+{
+  GtkLoader *self = GTK_LOADER (paintable);
+
+  if (self->texture)
+    gdk_paintable_snapshot (GDK_PAINTABLE (self->texture), snapshot, width, height);
+}
+
+static GdkPaintable *
+gtk_loader_paintable_get_current_image (GdkPaintable *paintable)
+{
+  GtkLoader *self = GTK_LOADER (paintable);
+
+  if (self->texture)
+    return gdk_paintable_get_current_image (GDK_PAINTABLE (self->texture));
+
+  // FIXME: return a loading image
+  return NULL;
+}
+
+static int
+gtk_loader_paintable_get_intrinsic_width (GdkPaintable *paintable)
+{
+  GtkLoader *self = GTK_LOADER (paintable);
+
+  if (self->texture)
+    return gdk_paintable_get_intrinsic_width (GDK_PAINTABLE (self->texture));
+
+  return 0;
+}
+
+static int
+gtk_loader_paintable_get_intrinsic_height (GdkPaintable *paintable)
+{
+  GtkLoader *self = GTK_LOADER (paintable);
+
+  if (self->texture)
+    return gdk_paintable_get_intrinsic_height (GDK_PAINTABLE (self->texture));
+
+  return 0;
+}
+
+static double
+gtk_loader_paintable_get_intrinsic_aspect_ratio (GdkPaintable *paintable)
+{
+  GtkLoader *self = GTK_LOADER (paintable);
+
+  if (self->texture)
+    return gdk_paintable_get_intrinsic_aspect_ratio (GDK_PAINTABLE (self->texture));
+
+  return 0;
+};
+
+static void
+gtk_loader_paintable_init (GdkPaintableInterface *iface)
+{
+  iface->snapshot = gtk_loader_paintable_snapshot;
+  iface->get_current_image = gtk_loader_paintable_get_current_image;
+  iface->get_intrinsic_width = gtk_loader_paintable_get_intrinsic_width;
+  iface->get_intrinsic_height = gtk_loader_paintable_get_intrinsic_height;
+  iface->get_intrinsic_aspect_ratio = gtk_loader_paintable_get_intrinsic_aspect_ratio;
+}
+
+G_DEFINE_TYPE_EXTENDED (GtkLoader, gtk_loader, G_TYPE_OBJECT, 0,
+                        G_IMPLEMENT_INTERFACE (GDK_TYPE_PAINTABLE,
+                                               gtk_loader_paintable_init))
+
+static void
+gtk_loader_dispose (GObject *object)
+{
+  GtkLoader *self = GTK_LOADER (object);
+
+  g_clear_object (&self->texture);
+
+  G_OBJECT_CLASS (gtk_loader_parent_class)->dispose (object);
+}
+
+static void gtk_loader_set_resource (GtkLoader *self, const char *resource);
+
+static void
+gtk_loader_set_property (GObject      *object,
+                         guint         prop_id,
+                         const GValue *value,
+                         GParamSpec   *pspec)
+{
+  GtkLoader *self = (GtkLoader *)object;
+
+  switch (prop_id)
+    {
+    case PROP_RESOURCE:
+      gtk_loader_set_resource (self, g_value_get_string (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_loader_class_init (GtkLoaderClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  gobject_class->dispose = gtk_loader_dispose;
+  gobject_class->set_property = gtk_loader_set_property;
+
+  g_object_class_install_property (gobject_class, PROP_RESOURCE,
+      g_param_spec_string ("resource", "", "",
+                           NULL,
+                           G_PARAM_WRITABLE|G_PARAM_CONSTRUCT_ONLY));
+}
+
+static void
+gtk_loader_init (GtkLoader *self)
+{
+}
+
+static void
+load_texture_in_thread (GTask        *task,
+                        gpointer      source_object,
+                        gpointer      task_data,
+                        GCancellable *cancellable)
+{
+  const char *resource = task_data;
+  GdkTexture *texture;
+  GError *error = NULL;
+
+  texture = gdk_texture_new_from_resource (resource);
+
+  if (texture)
+    g_task_return_pointer (task, texture, g_object_unref);
+  else
+    g_task_return_error (task, error);
+}
+
+static void
+texture_finished (GObject      *source,
+                  GAsyncResult *result,
+                  gpointer      data)
+{
+  GtkLoader *self = GTK_LOADER (source);
+  GdkTexture *texture;
+  GError *error = NULL;
+
+  texture = g_task_propagate_pointer (G_TASK (result), &error);
+
+  if (texture)
+    {
+      self->texture = g_object_ref (texture);
+
+      gdk_paintable_invalidate_size (GDK_PAINTABLE (self));
+      gdk_paintable_invalidate_contents (GDK_PAINTABLE (self));
+    }
+}
+
+static void
+gtk_loader_set_resource (GtkLoader  *self,
+                         const char *resource)
+{
+  GTask *task;
+
+  task = g_task_new (self, NULL, texture_finished, NULL);
+  g_task_set_task_data (task, g_strdup (resource), (GDestroyNotify)g_free);
+  g_task_run_in_thread (task, load_texture_in_thread);
+  g_object_unref (task);
+}
+
+GdkPaintable *
+gtk_loader_new (void)
+{
+  return g_object_new (GTK_TYPE_LOADER, NULL);
+}
diff --git a/demos/widget-factory/gtkloaderprivate.h b/demos/widget-factory/gtkloaderprivate.h
new file mode 100644
index 0000000000..c0b2072cd3
--- /dev/null
+++ b/demos/widget-factory/gtkloaderprivate.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright © 2021 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen <mclasen redhat com>
+ */
+
+#ifndef __GTK_LOADER_H__
+#define __GTK_LOADER_H__
+
+#include <gdk/gdk.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_LOADER (gtk_loader_get_type ())
+
+G_DECLARE_FINAL_TYPE (GtkLoader, gtk_loader, GTK, LOADER, GObject)
+
+GdkPaintable *  gtk_loader_new          (void);
+
+G_END_DECLS
+
+#endif /* __GTK_SCALER_H__ */
diff --git a/demos/widget-factory/meson.build b/demos/widget-factory/meson.build
index 1cebd4adc5..6b09db3e2b 100644
--- a/demos/widget-factory/meson.build
+++ b/demos/widget-factory/meson.build
@@ -6,7 +6,7 @@ widgetfactory_resources = gnome.compile_resources('widgetfactory_resources',
 )
 
 executable('gtk4-widget-factory',
-  sources: ['widget-factory.c', widgetfactory_resources],
+  sources: ['widget-factory.c', 'gtkloader.c', widgetfactory_resources],
   c_args: common_cflags,
   dependencies: [ libgtk_dep, demo_conf_h ],
   include_directories: confinc,
diff --git a/demos/widget-factory/widget-factory.c b/demos/widget-factory/widget-factory.c
index 0c4b21c81c..c18b502bcf 100644
--- a/demos/widget-factory/widget-factory.c
+++ b/demos/widget-factory/widget-factory.c
@@ -26,6 +26,7 @@
 #include <gtk/gtk.h>
 
 #include "demo_conf.h"
+#include "gtkloaderprivate.h"
 
 static void
 change_dark_state (GSimpleAction *action,
@@ -2054,6 +2055,7 @@ activate (GApplication *app)
   GtkEventController *controller;
 
   g_type_ensure (my_text_view_get_type ());
+  g_type_ensure (gtk_loader_get_type ());
 
   provider = gtk_css_provider_new ();
   gtk_css_provider_load_from_resource (provider, "/org/gtk/WidgetFactory4/widget-factory.css");
diff --git a/demos/widget-factory/widget-factory.ui b/demos/widget-factory/widget-factory.ui
index 1f2258d06d..b7a6ee442f 100644
--- a/demos/widget-factory/widget-factory.ui
+++ b/demos/widget-factory/widget-factory.ui
@@ -1251,7 +1251,11 @@ Suspendisse feugiat quam quis dolor accumsan cursus.</property>
                               <object class="GtkNotebookPage">
                                 <property name="child">
                                   <object class="GtkPicture">
-                                    <property 
name="file">resource:///org/gtk/WidgetFactory4/sunset.jpg</property>
+                                    <property name="paintable">
+                                      <object class="GtkLoader">
+                                        <property 
name="resource">/org/gtk/WidgetFactory4/sunset.jpg</property>
+                                      </object>
+                                    </property> 
                                     <child>
                                       <object class="GtkDragSource">
                                         <property name="actions">copy</property>
@@ -1278,7 +1282,11 @@ Suspendisse feugiat quam quis dolor accumsan cursus.</property>
                               <object class="GtkNotebookPage">
                                 <property name="child">
                                   <object class="GtkPicture">
-                                    <property 
name="file">resource:///org/gtk/WidgetFactory4/nyc.jpg</property>
+                                    <property name="paintable">
+                                      <object class="GtkLoader">
+                                        <property name="resource">/org/gtk/WidgetFactory4/nyc.jpg</property>
+                                      </object>
+                                    </property>
                                     <child>
                                       <object class="GtkDragSource">
                                         <property name="actions">copy</property>
@@ -1305,7 +1313,11 @@ Suspendisse feugiat quam quis dolor accumsan cursus.</property>
                               <object class="GtkNotebookPage">
                                 <property name="child">
                                   <object class="GtkPicture">
-                                    <property 
name="file">resource:///org/gtk/WidgetFactory4/beach.jpg</property>
+                                    <property name="paintable">
+                                      <object class="GtkLoader">
+                                        <property 
name="resource">/org/gtk/WidgetFactory4/beach.jpg</property>
+                                      </object>
+                                    </property>
                                     <child>
                                       <object class="GtkDragSource">
                                         <property name="actions">copy</property>