[gegl-gtk] GeglGtkView: Add signals for drawing background and overlay

[Jon Nordby <jonnor src gnome org>]

commit 968ff0ff91073704c1fd3ac6a60fd6719a420a09
Author: Jon Nordby <jononor gmail com>
Date:   Mon Oct 10 01:36:38 2011 +0200

    GeglGtkView: Add signals for drawing background and overlay

 configure.ac                   |   18 +++++++++
 examples/c/gegl-gtk-paint.c    |   29 +++++++++++++++
 gegl-gtk/.gitignore            |    1 +
 gegl-gtk/Makefile.am           |   10 ++++-
 gegl-gtk/gegl-gtk-marshal.list |    1 +
 gegl-gtk/gegl-gtk-view.c       |   77 ++++++++++++++++++++++++++++++++++++----
 6 files changed, 127 insertions(+), 9 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index ab33828..4709ca8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -218,6 +218,23 @@ AM_CONDITIONAL(HAVE_GTK3, test "$have_gtk" = "3.0")
 AC_SUBST(GTK_CFLAGS)
 AC_SUBST(GTK_LIBS)
 
+##################
+# Cairo gobject
+###################
+AC_ARG_WITH(cairo-gobject, [  --without-cairo-gobject    build without Cairo GObject support])
+
+have_cairo_gobject="no"
+if test "x$with_cairo_gobject" != "xno"; then
+  PKG_CHECK_MODULES(CAIRO_GOBJECT, cairo-gobject,
+    [have_cairo_gobject="yes" AC_DEFINE(HAVE_CAIRO_GOBJECT, 1, [Define to 1 to compile for gtk2])],
+    have_cairo_gobject="no  (Cairo GObject not found)")
+fi
+
+AM_CONDITIONAL(HAVE_CAIRO_GOBJECT, test "$have_cairo_gobject" = "yes")
+
+AC_SUBST(CAIRO_GOBJECT_CFLAGS)
+AC_SUBST(CAIRO_GOBJECT_LIBS)
+
 ########################
 # Check GObject Introspection
 ########################
@@ -319,6 +336,7 @@ Building GEGL with prefix=$prefix
 
   GTK+ version:           $have_gtk
   Documentation:          $enable_gtk_doc
+  Cairo GObject: 	  $have_cairo_gobject
   GObject Introspection:  $enable_introspection
   Vala support:           $have_vala
 ]);
diff --git a/examples/c/gegl-gtk-paint.c b/examples/c/gegl-gtk-paint.c
index 9dcde2a..48a5545 100644
--- a/examples/c/gegl-gtk-paint.c
+++ b/examples/c/gegl-gtk-paint.c
@@ -152,6 +152,29 @@ static gboolean paint_release (GtkWidget      *widget,
   return FALSE;
 }
 
+static void
+draw_overlay (GeglGtkView *view, cairo_t *cr, GdkRectangle *rect)
+{
+    cairo_translate (cr, 200.0, 200.0);
+
+	cairo_set_source_rgba (cr, 0.0, 0.0, 0.0, 0.3);
+	cairo_rectangle (cr, 0.0, 0.0, 200.0, 50.0);
+	cairo_fill (cr);
+
+	cairo_set_source_rgba (cr, 0.0, 0.0, 0.0, 0.9);
+    cairo_translate (cr, 20.0, 20.0);
+	cairo_show_text (cr, "canvas overlay");
+	cairo_fill (cr);
+}
+
+static void
+draw_background (GeglGtkView *view, cairo_t *cr, GdkRectangle *rect)
+{
+	cairo_set_source_rgba (cr, 0.9, 0.9, 1.0, 1.0);
+	cairo_rectangle (cr, 0.0, 0.0, rect->width, rect->height);
+	cairo_fill (cr);
+}
+
 gint
 main (gint    argc,
       gchar **argv)
@@ -198,6 +221,12 @@ main (gint    argc,
     top  = loadbuf;
   }
 
+
+  g_signal_connect (G_OBJECT (view), "draw-overlay",
+                    (GCallback) draw_overlay, NULL); 
+  g_signal_connect (G_OBJECT (view), "draw-background",
+                    (GCallback) draw_background, NULL); 
+
   eventbox = gtk_event_box_new ();
 
   g_signal_connect (G_OBJECT (eventbox), "motion-notify-event",
diff --git a/gegl-gtk/.gitignore b/gegl-gtk/.gitignore
index ce962ec..95b99f3 100644
--- a/gegl-gtk/.gitignore
+++ b/gegl-gtk/.gitignore
@@ -2,3 +2,4 @@
 *.typelib
 *.vapi
 gegl-gtk-enums.c
+gegl-gtk-marshal.*
diff --git a/gegl-gtk/Makefile.am b/gegl-gtk/Makefile.am
index c5feda7..82f2800 100644
--- a/gegl-gtk/Makefile.am
+++ b/gegl-gtk/Makefile.am
@@ -1,6 +1,6 @@
 CLEANFILES = 
 
-gen_sources = gegl-gtk-enums.c
+gen_sources = gegl-gtk-enums.c gegl-gtk-marshal.c gegl-gtk-marshal.h
 CLEANFILES += $(gen_sources)
 
 headers = gegl-gtk.h gegl-gtk-view.h gegl-gtk-enums.h
@@ -19,12 +19,18 @@ gegl-gtk-enums.c: $(srcdir)/gegl-gtk-enums.h
 			   --vtail "	  { 0, NULL, NULL }\n	};\n	etype = g_ type@_register_static (\"@EnumName \", values);\n  }\n  return etype;\n}\n\n" \
 			   $(srcdir)/gegl-gtk-enums.h > gegl-gtk-enums.c
 
+gegl-gtk-marshal.h: $(srcdir)/gegl-gtk-marshal.list
+	glib-genmarshal --prefix=gegl_gtk_marshal $(srcdir)/gegl-gtk-marshal.list --header >> gegl-gtk-marshal.h
+
+gegl-gtk-marshal.c: gegl-gtk-marshal.h
+	echo "#include \"gegl-gtk-marshal.h\"" >> gegl-gtk-marshal.c \
+	&& glib-genmarshal --prefix=gegl_gtk_marshal $(srcdir)/gegl-gtk-marshal.list --body >> gegl-gtk-marshal.c
 
 gegl_gtk_includedir=$(includedir)/gegl-gtk$(GEGL_GTK_GTK_VERSION)-$(GEGL_GTK_API_VERSION)
 gegl_gtk_include_HEADERS = $(headers)
 
 gegl_gtk_SOURCES = $(headers) $(sources) $(internal_headers) $(internal_sources)
-gegl_gtk_LIBADD  = $(GTK_LIBS) $(GEGL_LIBS)
+gegl_gtk_LIBADD  = $(GTK_LIBS) $(GEGL_LIBS) $(CAIRO_GOBJECT_LIBS)
 gegl_gtk_CFLAGS  = $(INCLUDES) $(CFLAGS)
 
 if HAVE_GTK2
diff --git a/gegl-gtk/gegl-gtk-marshal.list b/gegl-gtk/gegl-gtk-marshal.list
new file mode 100644
index 0000000..73ccad0
--- /dev/null
+++ b/gegl-gtk/gegl-gtk-marshal.list
@@ -0,0 +1 @@
+VOID:BOXED,BOXED
diff --git a/gegl-gtk/gegl-gtk-view.c b/gegl-gtk/gegl-gtk-view.c
index cda52de..f0c3790 100644
--- a/gegl-gtk/gegl-gtk-view.c
+++ b/gegl-gtk/gegl-gtk-view.c
@@ -22,9 +22,13 @@
 #include <gtk/gtk.h>
 #include <gegl.h>
 
+#ifdef HAVE_CAIRO_GOBJECT
+#include <cairo-gobject.h>
+#endif
+
 #include "gegl-gtk-view.h"
 #include "internal/view-helper.h"
-
+#include "gegl-gtk-marshal.h"
 
 /**
  * This class is responsible for providing the public interface
@@ -50,6 +54,16 @@ enum
   PROP_AUTOSCALE_POLICY
 };
 
+#ifdef HAVE_CAIRO_GOBJECT
+enum
+{
+  SIGNAL_DRAW_BACKGROUND,
+  SIGNAL_DRAW_OVERLAY,
+  N_SIGNALS
+};
+
+static guint gegl_view_signals[N_SIGNALS];
+#endif
 
 static ViewHelper *
 get_private(GeglGtkView *self)
@@ -149,6 +163,28 @@ gegl_gtk_view_class_init (GeglGtkViewClass * klass)
                                                       G_PARAM_READWRITE |
                                                       G_PARAM_CONSTRUCT));
 
+#ifdef HAVE_CAIRO_GOBJECT
+  gegl_view_signals[SIGNAL_DRAW_BACKGROUND] =
+      g_signal_new ("draw-background",
+      G_TYPE_FROM_CLASS (klass),
+      0,
+      0,
+      NULL,
+      NULL,
+      gegl_gtk_marshal_VOID__BOXED_BOXED,
+      G_TYPE_NONE, 2, CAIRO_GOBJECT_TYPE_CONTEXT, GDK_TYPE_RECTANGLE);
+
+  gegl_view_signals[SIGNAL_DRAW_OVERLAY] =
+      g_signal_new ("draw-overlay",
+      G_TYPE_FROM_CLASS (klass),
+      0,
+      0,
+      NULL,
+      NULL,
+      gegl_gtk_marshal_VOID__BOXED_BOXED,
+      G_TYPE_NONE, 2, CAIRO_GOBJECT_TYPE_CONTEXT, GDK_TYPE_RECTANGLE);
+#endif
+
 }
 
 static void
@@ -274,11 +310,38 @@ size_allocate(GtkWidget *widget, GdkRectangle *allocation, gpointer user_data)
     view_helper_set_allocation(GET_PRIVATE(self), allocation);
 }
 
+static void
+draw_implementation(GeglGtkView *self, cairo_t *cr, GdkRectangle *rect)
+{
+  ViewHelper *priv = GET_PRIVATE (self);
+
+#ifdef HAVE_CAIRO_GOBJECT
+  /* Draw background */
+  cairo_save(cr);
+  g_signal_emit(G_OBJECT(self), gegl_view_signals[SIGNAL_DRAW_BACKGROUND], 
+                0, cr, rect, NULL);
+  cairo_restore(cr);
+#endif
+
+  /* Draw the gegl node */
+  cairo_save(cr);
+  view_helper_draw(priv, cr, rect);
+  cairo_restore(cr);
+
+#ifdef HAVE_CAIRO_GOBJECT
+  /* Draw overlay */
+  cairo_save(cr);
+  g_signal_emit(G_OBJECT(self), gegl_view_signals[SIGNAL_DRAW_OVERLAY],
+                0, cr, rect, NULL);
+  cairo_restore(cr);
+#endif
+}
+
 #ifdef HAVE_GTK3
 static gboolean
 draw (GtkWidget * widget, cairo_t *cr)
 {
-  GeglGtkView      *view = GEGL_GTK_VIEW (widget);
+  GeglGtkView *self = GEGL_GTK_VIEW (widget);
   ViewHelper *priv = GET_PRIVATE (view);
   GdkRectangle rect;
 
@@ -286,8 +349,8 @@ draw (GtkWidget * widget, cairo_t *cr)
     return FALSE;
 
   gdk_cairo_get_clip_rectangle (cr, &rect);
-
-  view_helper_draw (priv, cr, &rect);
+  
+  draw_implementation(self, cr, &rect);
 
   return FALSE;
 }
@@ -298,8 +361,8 @@ static gboolean
 expose_event (GtkWidget      *widget,
               GdkEventExpose *event)
 {
-  GeglGtkView      *view = GEGL_GTK_VIEW (widget);
-  ViewHelper *priv = GET_PRIVATE (view);
+  GeglGtkView *self = GEGL_GTK_VIEW (widget);
+  ViewHelper *priv = GET_PRIVATE (self);
   cairo_t      *cr;
   GdkRectangle rect;
 
@@ -311,7 +374,7 @@ expose_event (GtkWidget      *widget,
   cairo_clip (cr);
   gdk_region_get_clipbox (event->region, &rect);
 
-  view_helper_draw (priv, cr, &rect);
+  draw_implementation(self, cr, &rect);
 
   cairo_destroy (cr);