about contibuting to octave

[xianghang liu]

On Tue, Mar 3, 2009 at 2:13 PM, Ben Abbott <bpabbott at mac.com> wrote:

> - Show quoted text -
>
> On Mar 3, 2009, at 12:44 AM, Shai Ayal wrote:
>
>  On Tue, Mar 3, 2009 at 7:17 AM, xianghang liu <xianghangliu at gmail.com>
>> wrote:
>>
>>> Yes, I think I am interested in this. Would you please tell me how to
>>> start
>>> and give me more details about this?
>>> Thanks.
>>>
>>> Xianghang
>>> On Tue, Mar 3, 2009 at 12:33 PM, Shai Ayal <shaiay at gmail.com> wrote:
>>>
>>>>
>>>> On Tue, Mar 3, 2009 at 4:36 AM, xianghang liu <xianghangliu at gmail.com>
>>>> wrote:
>>>>
>>>>> Hi,
>>>>> I am a C++ developer very interested in Octave and would like to
>>>>> contribute.
>>>>> I have had a look at projects listed at
>>>>> http://www.gnu.org/software/octave/projects.html. I would like to
>>>>> contribute
>>>>> numerical  and IO related projects in the list. Would you please show
>>>>> me
>>>>> a
>>>>> more current copy of this?
>>>>>
>>>> Hi,
>>>>
>>>> I'm not sure it's what you meant by IO related, but the graphics
>>>> system is really in need of a c++ developer. We need someone to
>>>> implement text objects.
>>>> If this interests you, I'm sure Michael and I could help you start out
>>>>
>>>> Shai
>>>>
>>>
>>>
>> Great!
>> I'll give you a very brief overview with which you can start, and just
>> ask question as you go. It's also better if you ask on the maintainers
>> list (or at least cc the list) instead of me directly for 3 reasons:
>> 1. someone else might be able to answer better/before me
>> 2. someone else will be able to correct me!
>> 3. we will have a record of the discussion and changes that everyone can
>> see.
>>
>> Also, please use bottom posting as it is much easier to read later
>>
>> The graphics system in octave is made of two parts -
>> 1. core graphics, which includes all the parts that are independent of
>> the actual graphics implementation and underlaying OS (i.e. the object
>> hierarchy,  setting/getting properties and more). Core graphics is
>> implemented in the (very large) files:
>> graphics.h.in, graphics.cc. graphics.h.in is converted to graphics.h
>> by the script genprops.awk. all of these files are in the src
>> directory
>> 2. backends - these are in charge of the actual rendering and deal
>> with the underlaying graphics system. Currently we have 2 backends,
>> the gnuplot backend and the fltk backend which uses the
>> opengl-renderer.
>>
>> The text object is very complex (probably why it is left undone) in
>> that it is a core graphics object, but also has dependencies on the
>> backend: As Ben noted, the text object has an "extent" property which
>> should hold the text bounding box. This is dependent on the text and
>> font properties. Only the backend knows the font properties, so this
>> has to communicated from the backend to the core-graphics system. We
>> need to decide how to do this and implement.
>> Also there is the whole issue of simple TeX rendering for text.
>>
>> Shai
>>
>
> Shai,
>
> Regarding the comment "Only the backend knows the font properties", are
> font properties independent of the backend?
>
> Ben
>
>
>
> Thanks for your descriptions. I have get some rough understanding about
what we want to do.
As far as I know, there is a properity called 'Extent' in Matlab text
object, which is the range of the text objects and is read-only. I think we
would like to implement something similar. To do this we need to add a
read-only property 'extent' to class text definded in graphics.h. But this
property is only known to backends so we need to communication from the
backends to the frontend. Any mistakes?
And would please tell me in which files backend of the graphics system
implemented?

Thanks.
Xianghang
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