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

    its text support. Every glyph is represented by a filled path in
    the PDF file. The causes file sizes to be much larger and
    rendering to be much slower than desired.

It is anticipated that both of these shortcomings will see some
improvements before the final 1.2 release.

In spite of those shortcomings, we hope that the PS and PDF backends
will yield faithful results for pretty much any cairo operations you
can throw at them. Please let us know if you are getting obviously
"different" results from the PS/PDF backends than from the image or
xlib backends.

Other new experimental backends
-------------------------------
This snapshot includes three new backends that did not exist in the
1.0 series:

	* beos backend

	* directfb backend

	* svg backend

These are all currently marked "experimental" and are disabled by
default. But the SVG backend in particular has seen a lot of recent
development and is very close to passing the entire cairo test
suite. It is possible that this backend will become a fully supported
backend by the time of the cairo 1.2 release.

Public API additions
--------------------
There have been a few new API functions added to cairo, including:

New get_type functions for querying sub-types of object:

	cairo_surface_get_type
	cairo_pattern_get_type
	cairo_font_face_get_type
	cairo_scaled_font_get_type

More convenience in working with cairo_scaled_font_t with new getter
functions:

	cairo_scaled_font_get_font_face
	cairo_scaled_font_get_font_matrix
	cairo_scaled_font_get_ctm
	cairo_scaled_font_get_font_options

As well as a convenience function for setting a scaled font into a
cairo context:

	cairo_set_scaled_font

and a function to allow text extents to be queried directly from a
scaled font, (without requiring a cairo_surface_t or a cairo_t):

	cairo_scaled_font_text_extents

These new scaled font functions were motivated by the needs of the
pango library.

Finally, a new path-construction function was added which clears the
current point in preparation for a new sub path. This makes cairo_arc
easier to use in some situations:

	cairo_new_sub_path

Before the 1.2 release is final we do still plan a few more API
additions specifically motivated by the needs of Mozilla/Firefox.

Optimizations and bug fixes
---------------------------
Shortly after the 1.0 maintenance series branched off the mainline
there was a major rework of the cairo font internals. This should
provide some good performance benefits, but it's also another area
people should look at closely for potential regressions.

There has not yet been any widespread, systematic optimization of
cairo, but various performance improvements have been made, (and some
of them are fairly significant). So if some things seem faster than
1.0 then things are good. If there are any performance regressions
compared to 1.0 then there is a real problem and we would like to hear
about that.

There has been a huge number of bug fixes---too many to mention in
detail. Again, things should be better, and never worse compared to
1.0. Please let us know if your testing shows otherwise.

Release 1.0.2 (2005-10-03 Carl Worth <[e-mail]>)
=========================================================
For each bug number XXXX below, see:

	https://bugs.freedesktop.org/show_bug.cgi?id=XXXX

for more details.

General bug fixes
-----------------
 * 4408 - Add support for dashing of stroked curves
	  (Carl Worth)

 * 4409 - Fix dashing so that each dash is capped on both ends
	  (Carl Worth)

 * 4414 - Prevent SIGILL failures (proper use of -mmmx and -msse flags)
	  (Sebastien Bacher, Billy Biggs)

 * 4299 - Fix crashes with text display in multi-threaded program
	  (Alexey Shabalin, Carl Worth)

 * 4401 - Do not use sincos function since it is buggy on some platforms)
	  (Tim Mooney, Carl Worth)

 * 4245 - Fix several bugs in the test suite exposed by amd64 systems
	  (Seemant Kulleen, Carl Worth)

 * 4321 - Add missing byteswapping on GetImage/PutImage
	  (Sjoerd Simons, Owen Taylor)

 * 4220 - Make the check for rectangular trapezoids simpler and more accurate
	  (Richard Stellingwerff, Owen Taylor)

 * 4260 - Add missing channel-order swapping for antialised fonts
	  (Barbie LeVile, Owen Taylor)

 * 4283 - Fix compilation failure with aggressive inlining (gcc -O3)
	  (Marco Manfredini, Owen Taylor)

 * 4208 - Fix some warnings from sparse
	  (Kjartan Maraas, Billy Biggs)

 * 4269 - Fix to not crash when compiled with -fomit-frame-pointer
	  (Ronald Wahl, Owen Taylor)

 * 4263 - Improve performance for vertical gradients
	  (Richard Stellingwerff, Owen Taylor)

 * 4231
 * 4298 - Accomodate gentoo and Mandriva versions in X server vendor string check
	  (Billy Biggs, Frederic Crozat, Owen Taylor)

win32-specific fixes
--------------------
 * 4599 - Fix "missing wedges" on some stroked paths (win32)
	  (Tim Rowley, Jonathan Watt, Bertram Felgenhauer, Carl Worth, Keith Packard)

 * 4612 - Fix disappearing text if first character out of surface (win32)
	  (Tim Rowley)

 * 4602 - Fix shutdown of cairo from failing intermediate, size-0 bitmaps (win32)
	  Aka. the "white rectangles" bug from mozilla-svg testing
	  (Tim Rowley)

 * Various portability improvements for win32
	  (Hans Breuer, Owen Taylor, Carl Worth)

 * 4593 - Fix font sizes to match user expectations (win32)
	  (Tor Lillqvist, Owen Taylor)

 * 3927 - Fix to report metrics of size 0 for glyph-not-available (win32)
	  (Hans Breuer, Owen Taylor, Tor Lillqvist)

 * Add locking primitives for win32
	  (Hans Breuer)

xlib-specific fixes
-------------------
 * Fix crash from size-0 pixmap due to empty clip region (xlib)
	  (Radek Doulík, Carl Worth)

Release 1.0.0 (2005-08-24 Carl Worth <[e-mail]>)
=========================================================
Experimental backends
---------------------
 * The Glitz, PS, PDF, Quartz, and XCB backends have been declared
   experimental, and are not part of the API guarantees that accompany
   this release. They are not built by default, even when the required
   libraries are available, and must be enabled explicitly with
   --enable-ps, --enable-pdf, --enable-quartz or --enable-xcb.

   It is very painful for us to be pushing out a major release without
   these backends enabled. There has been a tremendous amount of work
   put into each one and all are quite functional to some
   extent. However, each also has some limitations. And none of these
   backends have been tested to the level of completeness and
   correctness that we expect from cairo backends.

   We do encourage people to experiment with these backends and report
   success, failure, or means of improving them.

Operator behavior
-----------------
 * Prior to 0.9.0 the SOURCE, CLEAR and a number of other operators
   behaved in an inconsistent and buggy fashion and could affect areas
   outside the clip mask. In 0.9.0, these six "unbounded" operators
   were fixed to consistently clear areas outside the shape but within
   the clip mask.  This is useful behavior for an operator such as IN,
   but not what was expected for SOURCE and CLEAR. So, in this release
   the behavior of SOURCE and CLEAR has been changed again. They now
   affect areas only within both the source and shape. We can write
   the new operators as:

     SOURCE: dest' = (mask IN clip) ? source : dest
     CLEAR:  dest' = (mask IN clip) ? 0 : dest

Behavior and API changes
------------------------
 * Setting the filter on a gradient pattern would change the
   interpolation between color stops away from the normal linear
   interpolation. This dubious behavior has been removed.

 * The CAIRO_CONTENT_VALID() and CAIRO_FORMAT_VALID() macros --
   implementation details that leaked into cairo.h -- have been moved
   into an internal header.

 * The cairo_show_text function now advances the current point
   according to the total advance values of the string.

API additions
-------------
 * cairo_set_dash can now detect error and can set
   CAIRO_STATUS_INVALID_DASH.

Features
--------
 * When compiled against recent versions of fontconfig and FreeType,
   artificial bold fonts can now be turned on from fonts.conf using
   the FC_EMBOLDEN fontconfig key.

Optimization
------------
 * The compositing code from the 'xserver' code tree has now been
   completely merged into libpixman. This includes MMX optimization of
   common operations.

 * The image transformation code in libpixman has been improved and
   now performs significantly faster.

Bug fixes
---------
 * Several crashes related to corruption in the font caches have been
   fixed.

 * All test cases now match pixel-for-pixel on x86 and PPC; this
   required fixing bugs in the compositing, stroking, and pattern
   rendering code.

 * Negative dash offsets have been fixed to work correctly.

 * The stroking of paths with mutiple subpaths has now been fixed to
   apply caps to all subpaths rather than just the last one.

 * Many build fixes for better portability on various systems.

 * Lots of other bug fixes, but we're too tired to describe them in
   more detail here.

Release 0.9.2 (2005-08-13 Carl Worth <[e-mail]>)
=========================================================
Release numbering
-----------------
 * You will notice that this release jumped from 0.9.0 to 0.9.2. We've
   decided to use an odd micro version number (eg. 0.9.1) to indicate
   in-progress development between releases. As soon as 0.9.2 is
   tagged, the version will be incremented in CVS to 0.9.3 where it
   will stay until just before 0.9.4 is built, uploaded, and tagged.

   So, even-micro == a released version, odd-micro == something in-between.

Libpixman dependency dropped
----------------------------
 * As of this release, the dependency on an external libpixman has
   been dropped. Instead, the code from libpixman needed for cairo has
   been incorporated into the cairo source tree. The motivation for
   this change is that while cairo's API is stable and ready to be
   maintained after the 1.0 release, libpixman's API is not, so we do
   not want to expose it at this time.

   Also, the incorporation of libpixman into cairo also renames all
   previously-public libpixman symbols in order to avoid any conflict
   with a future release of libpixman

API additions
-------------
 * Macros and functions have been added so that the version of cairo
   can be queried at either compile-time or at run-time. The version
   is made available as both a human-readable string and as a single
   integer:

	CAIRO_VERSION_STRING		   eg. "0.9.2"
	CAIRO_VERSION			   eg. 000902

	const char*
	cairo_version_string (void);	/* eg. "0.9.2" */

	int
	cairo_version (void);		/* eg. 000902 */

   A macro is provided to convert a three-part component version into
   the encoded single-integer form:

	CAIRO_VERSION_ENCODE(X,Y,Z)

   For example, the CAIRO_VERSION value of 000902 is obtained as
   CAIRO_VERSION_ENCODE(0,9,2). The intent is to make version
   comparisons easy, either at compile-time:

	#if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(0,9,2)
	...
	#endif

   Or at run-time:

	if (cairo_version() >= CAIRO_VERSION_ENCODE(0,9,2)) { /* ... */ }

Thread safety
-------------
 * This release adds pthread-based locking (when available) to make
   the caches used by cairo safe for threaded programs. Some may
   remember a failed experiment with this locking between the 0.5.1
   and 0.5.2 snapshots, (where even single-threaded programs that
   linked with -lpthread would deadlock). We believe that that problem
   has been fixed, so we are looking forward to testing and reports
   from users with threaded applications.

Bug fixes
---------
 * The XCB and Quartz backends failed to compiled in the 0.9.0 release
   due to minor syntax errors. These have now been fixed.

 * Various crashes in glitz and pixman due to size 0 glyphs have been
   fixed.

Release 0.9.0 (2005-08-08 Carl Worth <[e-mail]>)
=========================================================
Soname change
-------------
 * In all prior snapshots, the libtool library versioning was set to
   1:0:0. As this release is intended to mark the beginning of
   backwards-compatible releases, the versioning has been incremented
   to 2:0:0. You will notice that the numeric extension on the
   installed library filename will change similarly.

   This change will also require all cairo-using applications to be
   recompiled. We recognize that this may cause some frustration since
   this release is backwards-compatible with 0.6.0 and in that sense
   "shouldn't" require re-compilation. However, since all historical
   snapshots have used the same 1:0:0 version in spite of incompatible
   API changes between them, it was essential that the upcoming 1.0
   release series have distinct library versioning.

   All future releases will use the library versioning to properly
   indicate compatibility between releases. So, any application
   re-compiled now to work with the 0.9.0 will not need to be
   recompiled when a compatible 1.0 release of cairo is made in the
   future.

API additions
-------------
 * Add new function calls to set/get the current antialiasing mode in
   the graphics state:

	cairo_set_antialias
	cairo_get_antialias

   This call accepts the same modes recently added for font options
   (NONE or GRAY) but affects the rendering of geometry other than
   text. The intent of this call is to enable more precise control of
   which pixels are affected by each operation, for example to allow
   for full-scene antialiasing for seam-free rendering. It is not
   expected that non-antialiased rendering will perform better than
   anti-aliased rendering.