[cairo] cair Is there anyone who interested in OpenGLES backend of CAIRO?

Yogesh Gole yogeshgole27 at gmail.com
Tue Apr 6 08:02:29 PDT 2010


Hi Joshua,

I don't know whether it will work or not but, If there is OpenGL backend to
cairo, then you just need to replace all OpenGL drawing with OpenGLES
drawing and need to add native surface creation and EGL context creation
logic.

Regards,
Yogesh,


 Hello.
> This is Joshua.
>
> What I  want to know is, is there any plan to build OpenGLES backend of
> Cairo?
> Or, is there anyone who interested in it?
>
>
> I know OpenVG backend is supported now(1.9.4 & 1.9.6) for GPU acceleration
> on the embedded environment.
> And as I know, the concept of OpenVG is similar with Cairo as a vector
> graphics, more that OpenGL/GLES.
>
> But I'm still interested about OpenGLES backend, and the the performance
> versus OpenVG backend.
> Could OpenVG backend show better performance than OpenGLES backend in all
> of
> the cases?
>
> And, I'm curious about why only OpenGL & OpenVG backend are supported
> officially, except OpenGLES.
>
>
> Could you give me any comments about those?
>
> Thanks.
>
> Best Regards,
> Joshua.
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> Message: 2
> Date: Mon, 05 Apr 2010 11:17:24 GMT
> From: "Tim Teulings" <rael at edge.ping.de>
> Subject: [cairo] How do I...?
> To: cairo at cairographics.org
> Message-ID: <20100405111724.3853.qmail at lilly.ping.de>
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>
> Hallo!
>
> I use cairo as part of my libosmsocut project (http://libosmscout.sf.net)
> to
> draw maps based on OpenStreetMap data (after using it as possibly backend
> for drawing widgets as part of libIllumination).
>
> Cairo is very useful for this on over all I'm very happy (thanks for that
> great work!)!
>
> I'm now starting to implement more sophisticated draw features and have
> some
> questions how to realize this using cairo and how much I can handle using
> cairo features itself and how much of this I have to do in my code (by
> doing
> some preprocessing for example). I'm searching for solutions that are
> optimized for visual quality but even more for drawing speed (especially on
> slow devices).
>
> Currently ways are drawn by just stroking paths using move_to and line_to
> and setting color, pen thickness as appropiate. Coordinates are a result of
> the (mercator) transformed coordinates I get from OSM nodes (as part of a
> way).
>
> This should be OK, I assume ;-)?
>
> For outlines I simply draw a line twice with different line thickness.
> Should be still OK, but is there possibly a faster/simpler solution (=>
> path
> outline?)?
>
> Now I want to further decorate the drawn way.
>
> * First I want to have periodical markers on the way like for example
> arrows
> that show the driving direction (oneway) or images that signal bumpers. The
> markers should be centered on the line. How do I do this?
>
> * Now, in the case that a way has multiple lanes (motorway for example), I
> also want to draw lane seperation markers (at least on higher zoom level
> :-)). For the case that the the way exists of two lanes this is simple
> because I just can draw another line with different color and width over
> the
> existing path. But what do I do in case where a motorway has three lanes?
> If
> I still just draw another line over the existing way I now have to
> calculate
> new polygon point coordinates that do the necessary "away from line center"
> transformation or is there a way where cairo can do this for me, too?
>
> --
> Gru?...
>      Tim.
>
>
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