Wrap cairo_format_stride_for_width()

3 files changed, 34 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 52edb87..5e9c15c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2008-04-11  Jonathon Jongsma  <jjongsma@gnome.org>
+
+	* cairomm/surface.cc:
+	* cairomm/surface.h: wrap cairo_format_stride_for_width() as a static
+	function in Cairo::ImageSurface
+
 2008-04-11  Murray Cumming  <murrayc@murrayc.com>
 
 	* Add autoheader to autogen.sh, to create cairommconfig.h.in, to fix 
diff --git a/cairomm/surface.cc b/cairomm/surface.cc
index d3dece5..f7393ac 100644
--- a/cairomm/surface.cc
+++ b/cairomm/surface.cc
@@ -214,6 +214,11 @@ int ImageSurface::get_stride() const
   return cairo_image_surface_get_stride(m_cobject);
 }
 
+int ImageSurface::format_stride_for_width (Cairo::Format format, int width)
+{
+  return cairo_format_stride_for_width(static_cast<cairo_format_t>(format), width);
+}
+
 
 /*******************************************************************************
  * THE FOLLOWING SURFACE TYPES ARE EXPERIMENTAL AND NOT FULLY SUPPORTED
diff --git a/cairomm/surface.h b/cairomm/surface.h
index a6f3404..7043fc0 100644
--- a/cairomm/surface.h
+++ b/cairomm/surface.h
@@ -295,6 +295,29 @@ public:
    */
   int get_stride() const;
 
+  /**
+   * This function provides a stride value that will respect all
+   * alignment requirements of the accelerated image-rendering code
+   * within cairo. Typical usage will be of the form:
+   *
+   * @code
+   * int stride;
+   * unsigned char *data;
+   * Cairo::RefPtr<Cairo::ImageSurface> surface;
+   *
+   * stride = Cairo::ImageSurface::format_stride_for_width (format, width);
+   * data = malloc (stride * height);
+   * surface = Cairo::ImageSurface::create (data, format, width, height);
+   * @endcode
+   *
+   * @param format A Cairo::Format value
+   * @param width The desired width of an image surface to be created.
+   * @return the appropriate stride to use given the desired format and width, or
+   * -1 if either the format is invalid or the width too large.
+   *
+   * @since 1.6
+   **/
+  static int format_stride_for_width (Cairo::Format format, int width);
 
   /** Creates an image surface of the specified format and dimensions. The
    * initial contents of the surface is undefined; you must explicitely clear