Background: allow to load wallpaper from GSettings

To test:

    gsettings set org.gnome.desktop.background picture-uri file:///path/to/img

This currently displays the image without distortion. Other scaling
modes can be added later.

src/background.c

@@ -5,14 +5,23 @@
  * Author: Guido Günther <agx@sigxcpu.org>
  */
 
-#include "phosh.h"
 #include "background.h"
+#include "phosh.h"
+#include "panel.h"
 
 #include <math.h>
+#include <string.h>
+
+enum {
+  BACKGROUND_LOADED,
+  N_SIGNALS
+};
+static guint signals[N_SIGNALS];
 
 typedef struct
 {
   GdkPixbuf *pixbuf;
+  GSettings *settings;
 } PhoshBackgroundPrivate;
 
 
@@ -26,33 +35,90 @@ G_DEFINE_TYPE_WITH_PRIVATE (PhoshBackground, phosh_background, GTK_TYPE_WINDOW)
 
 
 static GdkPixbuf *
-scale_background (GdkPixbuf *original_pixbuf)
+image_background (GdkPixbuf *image)
 {
-  GdkDisplay *display = gdk_display_get_default ();
-  /* There's no primary monitor on nested wayland so just use the
-     first one for now */
-  GdkMonitor *monitor = gdk_display_get_monitor (display, 0);
-  GdkRectangle geom;
-  gint original_width, original_height;
+  gint orig_width, orig_height, width, height;
   gint final_width, final_height;
-  gdouble ratio_horizontal, ratio_vertical;
-
-  /* FIXME: handle org.gnome.desktop.background gsettings */
-  g_return_val_if_fail(monitor, NULL);
-
-  gdk_monitor_get_geometry (monitor, &geom);
-
-  original_width = gdk_pixbuf_get_width (original_pixbuf);
-  original_height = gdk_pixbuf_get_height (original_pixbuf);
+  gint x, y, off_x, off_y;
+  gdouble ratio_horiz, ratio_vert, ratio;
+  GdkPixbuf *bg, *scaled_bg;
+  const gchar *xpm_data[] = {"1 1 1 1", "_ c WebGrey", "_"};
 
-  ratio_horizontal = (double) geom.width / original_width;
-  ratio_vertical = (double) geom.height / original_height;
+  phosh_shell_get_usable_area (phosh(), &x, &y, &width, &height);
+  bg = gdk_pixbuf_new_from_xpm_data (xpm_data);
+  scaled_bg = gdk_pixbuf_scale_simple (bg,
+                                       width,
+                                       /* since we can't offset the pixmap */
+                                       height + y,
+                                       GDK_INTERP_BILINEAR);
+  g_object_unref (bg);
+
+  /* FIXME: we should allow more modes
+     none, wallpaper, centered, scaled, stretched, zoom
+     I think GNOME calls this zoom:
+  */
+  orig_width = gdk_pixbuf_get_width (image);
+  orig_height = gdk_pixbuf_get_height (image);
+  ratio_horiz = (double) width / orig_width;
+  ratio_vert = (double) height / orig_height;
+  ratio = ratio_horiz > ratio_vert ? ratio_vert : ratio_horiz;
+  final_width = ceil (ratio * orig_width);
+  final_height = ceil (ratio * orig_height);
+
+  off_x = (width - final_width) / 2;
+  off_y = (height - final_height) / 2;
+
+  gdk_pixbuf_composite (image,
+                        scaled_bg,
+                        off_x, off_y, /* dest x,y */
+                        final_width,
+                        final_height,
+                        off_x, off_y, /* offset x, y */
+                        ratio,
+                        ratio,
+                        GDK_INTERP_BILINEAR,
+                        255);
+  return scaled_bg;
+}
 
-  final_width = ceil (ratio_horizontal * original_width);
-  final_height = ceil (ratio_vertical * original_height);
 
-  return gdk_pixbuf_scale_simple (original_pixbuf,
-      final_width, final_height, GDK_INTERP_BILINEAR);
+static void
+load_background (PhoshBackground *self,
+                 const char* uri)
+{
+  PhoshBackgroundPrivate *priv = phosh_background_get_instance_private (self);
+  GdkPixbuf *image = NULL;
+  const gchar *xpm_data[] = {"1 1 1 1", "_ c WebGrey", "_"};
+  GError *err = NULL;
+
+  if (priv->pixbuf) {
+    g_object_unref (priv->pixbuf);
+    priv->pixbuf = NULL;
+  }
+
+  /* FIXME: support GnomeDesktop.BGSlideShow as well */
+  if (!g_str_has_prefix(uri, "file:///")) {
+    g_warning ("Only file URIs supported for backgrounds not %s", uri);
+  } else {
+    image = gdk_pixbuf_new_from_file (&uri[strlen("file://")], &err);
+    if (!image) {
+      const char *reason = err ? err->message : "unknown error";
+      g_warning ("Failed to load background: %s", reason);
+      if (err)
+        g_clear_error (&err);
+    }
+  }
+
+  /* Fallback if image can't be loaded */
+  if (!image)
+    image = gdk_pixbuf_new_from_xpm_data (xpm_data);
+
+  priv->pixbuf = image_background (image);
+  g_object_unref (image);
+
+  /* force background redraw */
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+  g_signal_emit(self, signals[BACKGROUND_LOADED], 0);
 }
 
 
@@ -62,8 +128,10 @@ background_draw_cb (PhoshBackground *self,
                     gpointer         data)
 {
   PhoshBackgroundPrivate *priv = phosh_background_get_instance_private (self);
+  gint x, y, width, height;
 
-  gdk_cairo_set_source_pixbuf (cr, priv->pixbuf, 0, 0);
+  phosh_shell_get_usable_area (phosh(), &x, &y, &width, &height);
+  gdk_cairo_set_source_pixbuf (cr, priv->pixbuf, x, y);
   cairo_paint (cr);
   return TRUE;
 }
@@ -73,32 +141,60 @@ static void
 background_destroy_cb (GObject *object,
                        gpointer data)
 {
+  /* FIXME: does this make any sense ? */
   gtk_main_quit ();
 }
 
 
+static void
+background_setting_changed_cb (GSettings       *settings,
+                               const gchar     *key,
+                               PhoshBackground *self)
+{
+  g_autofree gchar *uri = g_settings_get_string (settings, key);
+
+  if (!uri)
+    return;
+
+  load_background (self, uri);
+}
+
+
+static void
+rotation_notify_cb (PhoshBackground *self,
+                    PhoshShell *shell)
+{
+  PhoshBackgroundPrivate *priv = phosh_background_get_instance_private (self);
+  background_setting_changed_cb (priv->settings, "picture-uri", self);
+}
+
+
 static void
 phosh_background_constructed (GObject *object)
 {
   PhoshBackground *self = PHOSH_BACKGROUND (object);
   PhoshBackgroundPrivate *priv = phosh_background_get_instance_private (self);
 
-  GdkPixbuf *unscaled_background;
-  const gchar *xpm_data[] = {"1 1 1 1", "_ c WebGrey", "_"};
-
-  unscaled_background = gdk_pixbuf_new_from_xpm_data (xpm_data);
-  priv->pixbuf = scale_background (unscaled_background);
-  g_object_unref (unscaled_background);
+  G_OBJECT_CLASS (phosh_background_parent_class)->constructed (object);
 
   g_signal_connect (self, "destroy", G_CALLBACK (background_destroy_cb), NULL);
   g_signal_connect (self, "draw", G_CALLBACK (background_draw_cb), NULL);
 
+  priv->settings = g_settings_new ("org.gnome.desktop.background");
+  g_signal_connect (priv->settings, "changed::picture-uri",
+                    G_CALLBACK (background_setting_changed_cb), self);
+  /* Load background initially */
+  background_setting_changed_cb (priv->settings, "picture-uri", self);
+
   /* Window properties */
   gtk_window_set_title (GTK_WINDOW (self), "phosh background");
   gtk_window_set_decorated (GTK_WINDOW (self), FALSE);
   gtk_widget_realize (GTK_WIDGET (self));
 
-  G_OBJECT_CLASS (phosh_background_parent_class)->constructed (object);
+  g_signal_connect_swapped (phosh(),
+                            "notify::rotation",
+                            G_CALLBACK (rotation_notify_cb),
+                            self);
 }
 
 
@@ -120,6 +216,10 @@ phosh_background_class_init (PhoshBackgroundClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
+  signals[BACKGROUND_LOADED] = g_signal_new ("background-loaded",
+      G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST, 0, NULL, NULL,
+      NULL, G_TYPE_NONE, 0);
+
   object_class->constructed = phosh_background_constructed;
   object_class->finalize = phosh_background_finalize;
 }
@@ -128,6 +228,10 @@ phosh_background_class_init (PhoshBackgroundClass *klass)
 static void
 phosh_background_init (PhoshBackground *self)
 {
+  PhoshBackgroundPrivate *priv = phosh_background_get_instance_private (PHOSH_BACKGROUND(self));
+
+  priv->pixbuf = NULL;
+  priv->settings = NULL;
 }
 
 

src/phosh.c

@@ -47,6 +47,7 @@ typedef struct
   struct wl_pointer *pointer;
 
   GdkDisplay *gdk_display;
+  gint rotation;
 
   /* Top panel */
   struct elem *panel;