[cairo] question on cairo, opengl and x-window

Guo Tang guo.tang at sonoartis.com
Fri May 11 13:27:53 PDT 2012

Hi, Henry,

Could you elaborate what is a  "cairo gl surface that binds to a X window"?
 Where can I find example of it?


On Fri, May 11, 2012 at 12:28 PM, Henry (Yu) Song - SISA <
hsong at sisa.samsung.com> wrote:

> Hi, Guo
> Cairo has GL backend.  However, current cairo gl backend in cairo snapshot
> is not as good as expected.  We have created a new MSAA-enabled gl
> compositor.  It can be downloaded from
> http://code.google.com/p/cairogles/source/checkout,  checkout the code,
> and switch to "release" branch.  It supports MSAA for both glx and egl. We
> are still actively fixing bugs and optimization.  Please let us know if you
> encounter any problem.  The "release" branch is fully synced with cairo
> 1.12.2, and in the coming months, we hope we can upstream our code to cairo
> mainline.  It also supports using a non-texture surface as source/mask.  I
> will add a new API that fast-path of supporting non-texture surface as
> source/mask shortly.
> Cairo GL supports both non-texture surface (e.g., x window, pixmap,
> pbuffer) as well as texture surface.  I don't see in your new logic why
> create cairo surface without window, you can create a cairo gl surface that
> binds to a X window., then you can draw into the surface and swap buffer
> directly on the window.
> Henry
> ________________________________________
> From: cairo-bounces+henry.song=samsung.com at cairographics.org[cairo-bounces+henry.song=
> samsung.com at cairographics.org] on behalf of Guo Tang [
> guo.tang at sonoartis.com]
> Sent: Friday, May 11, 2012 12:04 PM
> To: cairo at cairographics.org
> Subject: [cairo] question on cairo, opengl and x-window
> Hi,
> We have a software that uses cairo and X window system. The old design is
> using several X windows, several of them are transparent. We use Cairo to
> draw
> image, curves and text annotation.
> The design with several X windows causes us some problems when we move to
> a newer version of Linux. It also has lots of trouble with Xming X window
> manager.
> We are thinking about a new design with just one X window. The image
> display part is already moved to OpenGL (for better performance reason). I
> am thinking about
> still keep our old cairo codes for text annotation, but avoiding a
> separate X window.
> The old logic:
> from X window, create_cairo_context.
> from a transparent png file, create a surface.
> set the surface to cairo context
> then draw things on cairo context
> If I want to just use one X window (this window already has OpenGL context
> in it). Is the solution this way?
> new logic:
> create a cairo context without any X window (?).
> png file to surface.
> set the surface to cairo context
> then draw things on cairo context
> get the drawing result back to memory.
> then use OpenGL to render it to hardware.
> I am wondering whether new logic is possible? Will all the cairo rendering
> all done in software without hardware acceleration, versus old logic has?
> If without HW acceleration, I will only
> be able to keep cairo for non real time drawing.
> Any better way to link OpenGL and cairo together? Like user still uses
> cairo API to draw, but it is actually drawing using hardware (openGL), in a
> specify depth, and
> with the opacity setting that I can control?
> Your advise is appreciated.
> Thanks,
> Guo
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