Add cairo_device_t

The device is a generic method for accessing the underlying interface
with the native graphics subsystem, typically the X connection or
perhaps the GL context. By exposing a cairo_device_t on a surface and
its various methods we enable finer control over interoperability with
external interactions of the device by applications. The use case in
mind is, for example, a multi-threaded gstreamer which needs to serialise
its own direct access to the device along with Cairo's across many
threads.

Secondly, the cairo_device_t is a unifying API for the mismash of
backend specific methods for controlling creation of surfaces with
explicit devices and a convenient hook for debugging and introspection.

The principal components of the API are the memory management of:

  cairo_device_reference(),
  cairo_device_finish() and
  cairo_device_destroy();

along with a pair of routines for serialising interaction:

  cairo_device_acquire() and
  cairo_device_release()

and a method to flush any outstanding accesses:

  cairo_device_flush().

The device for a particular surface may be retrieved using:

  cairo_surface_get_device().

The device returned is owned by the surface.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/cairo-misc.c b/src/cairo-misc.c
index c0a792ebc..5f9cba5f1 100644
--- a/src/cairo-misc.c
+++ b/src/cairo-misc.c
@@ -126,6 +126,10 @@ cairo_status_to_string (cairo_status_t status)
 	return "invalid value (typically too big) for the size of the input (surface, pattern, etc.)";
     case CAIRO_STATUS_USER_FONT_NOT_IMPLEMENTED:
 	return "user-font method not implemented";
+    case CAIRO_STATUS_DEVICE_TYPE_MISMATCH:
+	return "the device type is not appropriate for the operation";
+    case CAIRO_STATUS_DEVICE_ERROR:
+	return "an operation to the device caused an unspecified error";
     default:
     case CAIRO_STATUS_LAST_STATUS:
 	return "<unknown error status>";