news

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

 * Three new functions were added to provide support for mixed cairo-
   and non-cairo drawing to the same surface:

	cairo_surface_mark_dirty
	cairo_surface_mark_dirty_rectangle
	cairo_surface_flush

 * The return type of the several "reference" functions was change,
   (API compatibly), from void to the same type as the argument. The
   affected functions are:

	cairo_font_face_reference
	cairo_scaled_font_reference
	cairo_pattern_reference
	cairo_surface_reference
	cairo_reference

   This allows a convenient way to assign and reference in a single
   statement.

Semantic changes
----------------
 * The behavior of cairo_set_source with a pattern with a non-identity
   matrix was previously not well-defined. The new behavior is as
   follows:

	The pattern's transformation matrix will be locked to the
	user space in effect at the time of cairo_set_source(). This means
	that further modifications of the CTM will not affect the source
	pattern.

cairo-win32
-----------
 * Some portability improvements, (eg. workaround for missing stdint.h).

cairo-ft
--------
 * Updated to allow compilation with older versions of freetype.

Bug fixes
---------
 * Fix the unbounded operators to actually produce a correct result,
   (previously the results were artificially restricted to the
   bounding box of whatever shape was being drawn rather than
   extending out infinitely). The fixed operators are:

	CAIRO_OPERATOR_CLEAR
	CAIRO_OPERATOR_SOURCE
	CAIRO_OPERATOR_OUT
	CAIRO_OPERATOR_IN
	CAIRO_OPERATOR_DEST_IN
	CAIRO_OPERATOR_DEST_ATOP

 * Fix cairo_mask and cairo_mask_surface to transform the mask by the
   current transformation matrix (CTM).

 * Fix cairo_set_source to lock the CTM used to transform the pattern.

 * Workaround for X server Render bug involving repeating patterns
   with a general transformation matrix.

 * cairo_get_font_face fixed to return a "nil" font face object rather
   than NULL on error.

 * cairo_set_font_face fixed to not crash if given a NULL font face,
   (which is the documented interface for restoring the default font
   face).

 * Fix xlib glyphset caching to not try to free a NULL glyph.

Snapshot 0.6.0 (2005-07-28 Carl Worth <[e-mail]>)
==========================================================
API changes
-----------
* The prototypes of the following functions have changed:

	cairo_xlib_surface_create_with_xrender_format
	cairo_xlib_surface_create_for_bitmap

  A Screen* parameter has been added to each. This allows the cairo
  xlib backend to work correctly with multi-head X servers.

* The following function has been modified:

	cairo_scaled_font_create

  to accept a cairo_font_options_t*. See below fore more details.

* All opaque, reference-counted cairo objects have now been moved to a
  standard error-handling scheme. The new objects to receive this
  treatment are cairo_font_face_t, cairo_scaled_font_t, and
  cairo_surface_t. (Previous snapshots already provided this scheme
  for cairo_t, cairo_path_t, and cairo_pattern_t.)

  This changes two functions to have a return type of void rather than
  cairo_status_t:

	cairo_scaled_font_extent
	cairo_surface_finish

  And significantly, none of the create functions for any of the
  objects listed above will return NULL. The pointer returned from any
  function will now always be a valid pointer and should always be
  passed to the corresponding destroy function when finished

  The simplest strategy for porting code is to switch from:

	object = cairo_<object>_create ();
	if (object == NULL)
	    goto BAILOUT;

	/* act on object */

	cairo_<object>_destroy (object);

  to:

	object = cairo_<object>_create ();
	if (cairo_<object>_status (object))
	    goto BAILOUT;

	/* act on object */

	cairo_<object>_destroy (object);

   But significantly, it is not required to check for an error status
   before the "act on object" portions of the code above. All
   operations on an object with an error status are, by definition,
   no-ops without side effect. So new code might be written in an
   easier-to-read style of:

	object = cairo_<object>_create ();

	/* act on object */

	cairo_<object>_destroy (object);

   with cairo_<object>_status checks placed only at strategic
   locations. For example, passing an error object to another object,
   (eg. cairo_set_source with an in-error pattern), will propagate the
   error to the subsequent object (eg. the cairo_t). This means that
   error checking can often be deferred even beyond the destruction of
   a temporary object.

API additions
-------------
* New functions for checking the status of objects that have been
  switched to the common error-handling scheme:

	cairo_font_face_status
	cairo_scaled_font_status
	cairo_surface_status

* The _cairo_error function which was added in 0.5.1 has now been made
  much more useful. In 0.5.1 only errors on cairo_t objects passed
  through _cairo_error. Now, an error on any object should pass
  through _cairo_error making it much more reliable as a debugging
  mechanism for finding when an error first occurs.

* Added new font options support with a myriad of functions:

	cairo_font_options_create
	cairo_font_options_copy
	cairo_font_options_destroy

	cairo_font_options_status

	cairo_font_options_merge
	cairo_font_options_equal
	cairo_font_options_hash

	cairo_font_options_set_antialias
	cairo_font_options_get_antialias
	cairo_font_options_set_subpixel_order
	cairo_font_options_get_subpixel_order
	cairo_font_options_set_hint_style
	cairo_font_options_get_hint_style
	cairo_font_options_set_hint_metrics
	cairo_font_options_get_hint_metrics

	cairo_surface_get_font_options

	cairo_ft_font_options_substitute

	cairo_set_font_options
	cairo_get_font_options

   This new font options support allows the application to have much
   more fine-grained control over how fonts are rendered.
   Significantly, it also allows surface backends to have some
   influence over the process. For example, the xlib backend now
   queries existing Xft properties to set font option defaults.

* New function:

	cairo_xlib_surface_set_drawable

  which allows the target drawable for an xlib cairo_surface_t to be
  changed to another with the same format, screen, and display. This
  is necessary in certain double-buffering techniques.

New features
------------
* Sub-pixel text antialiasing is now supported.

Bug fixes
---------
* Fixed assertion failure in cairo_surface_create_similar when
  application commits an error by passing a cairo_format_t rather than
  a cairo_content_t.

* Avoid division by zero in various places (cairo-ft).

* Fix infinite loop when using non-default visuals (cairo-xlib).

* Eliminate segfault in cairo_image_surface_create_from_png_stream.

* Prevent errant sign-extension of masks on 64-bit architectures
  (cairo-xlib and cairo-xcb).

* Other miscellaneous fixes.

Snapshot 0.5.2 (2005-07-18 Carl Worth <[e-mail]>)
==========================================================
API changes
-----------
* New functions for creating patterns of a single color:

	cairo_pattern_create_rgb
	cairo_pattern_create_rgba

* Change cairo_surface_create_similar to accept a new type of
  cairo_content_t rather than cairo_format_t:

	typedef enum _cairo_content {
	    CAIRO_CONTENT_COLOR		= 0x1000,
	    CAIRO_CONTENT_ALPHA		= 0x2000,
	    CAIRO_CONTENT_COLOR_ALPHA	= 0x3000
	} cairo_content_t;

* Add new CAIRO_FORMAT_VALID and CAIRO_CONTENT_VALID macros.

* Remove unused status value:

	CAIRO_STATUS_NO_TARGET_SURFACE

* Add new status values:

	CAIRO_STATUS_INVALID_STATUS

* Require libpixman >= 0.1.5 (for necessary bug fixes)

Bug fixes
---------
* Fix cairo_surface_write_to_png for RGB24 images.

* Fix broken metrics and rendering for bitmap fonts. Add mostly
  useless bitmap glyph transformation.

* Fix glyph caches to not eject entries that might be immediately
  needed, (fixing intermittent crashes when rendering text).

* Fix all memory leaks found by running "make check-valgrind".

ATSUI backend changes
---------------------
* Allow building against < 10.3 SDK.

* Prevent crash on empty strings.

Glitz backend changes
---------------------
* Require glitz >= 0.4.4.

* Use frame buffer objects instead of pbuffers for accelerated
  offscreen drawing.

* Minor improvement to gradient pattern creation.

PostScript backend fixes
------------------------
* Rewrite of the PS backend to generate more interesting output that
  the old big-image implementation.

Win32 backend fixes
-------------------
* Implement glyph path support.

* Fix swap of blue and green values in the fill_rectangles path.

Xlib backend fixes
------------------
* Add optimization to use XCopyArea rather than XRenderComposite when
  transforming only with an integer translation, and using SOURCE
  operator or OVER with a source pattern without alpha.

Snapshot 0.5.1 (2005-06-20 Carl Worth <[e-mail]>)
==========================================================
API changes
-----------
* Removed cairo_status_string(cairo_t*) and add
  cairo_status_to_string(cairo_status_t) in its place. Code using
  cairo_status_string can be ported forward as follows:

	cairo_status (cr);
	->
	cairo_status_to_string (cairo_status (cr));

* Removed the BAD_NESTING restriction which means that two different
  cairo_t objects can now interleave drawing to the same
  cairo_surface_t without causing an error.

* The following functions which previously had a return type of
  cairo_status_t now have a return type of void:

	cairo_pattern_add_color_stop_rgba
	cairo_pattern_set_matrix
	cairo_pattern_get_matrix
	cairo_pattern_set_extend
	cairo_pattern_set_filter

  See discussion of cairo_pattern_status below for more details.

API additions
-------------
* Improved error handling:

	cairo_status_t
	cairo_pattern_status (cairo_pattern_t *pattern);

  This snapshot expands the status-based error handling scheme from
  cairo_t to cairo_path_t and cairo_pattern_t. It also expands the
  scheme so that object-creating functions, (cairo_create,
  cairo_pattern_create_*, cairo_copy_path_*), are now guaranteed to
  not return NULL. Instead, in the case of out-of-memory these
  functions will return a static object with
  status==CAIRO_STATUS_NO_MEMORY. The status can be checked with the
  functions cairo_status and cairo_pattern_status, or by direct
  inspection of the new status field in cairo_path_t.

  Please note that some objects, including cairo_surface_t and all of
  the font-related objects have not been converted to this
  error-handling scheme.

* In addition to the above changes, a new private function has been added:

	_cairo_error

  This function can be used to set a breakpoint in a debugger to make
  it easier to find programming error in cairo-using code. (Currently,
  _cairo_error is called when any error is detected within a cairo_t
  context, but is not called for non-cairo_t errors such as for
  cairo_path_t and cairo_pattern_t).

* Fixed cairo_path_data_t so that its enum is visible to C++ code, (as
  cairo_path_data_type_t).

Performance improvements
------------------------
* Made a minor performance improvement for clipping, (restrict clip
  surface to the new intersected bounds).

* Optimize rendering of a solid source pattern with a pixel-aligned
  rectangular path to use backend clipping rather than rasterization
  and backend compositing.

* Optimize cairo_paint_with_alpha to defer to cairo_paint when alpha
  is 1.0.

Bug fixes
---------
* Fixed memory leak in cairo_copy_path.