Re: about contibuting to octave

[Shai Ayal]

2009/3/4 xianghang liu <address@hidden>:
>
>
> On Wed, Mar 4, 2009 at 10:00 AM, Ben Abbott <address@hidden> wrote:
>>
>> On Mar 3, 2009, at 2:52 PM, Michael Goffioul wrote:
>>
>>> On Tue, Mar 3, 2009 at 6:51 PM, Shai Ayal <address@hidden> wrote:
>>>>
>>>> I think this is a good idea -- this will decouple the text object from
>>>> the backend.
>>>>
>>>> We will need to know what fonts gnuplot uses to get freetype to get us
>>>> gnuplot's font metrics?
>>>> I think we can get the standard postscript font metrics from similar
>>>> type1 fonts which freetype can use (I distributed a set of ps-similar
>>>> fonts with octplot)
>>>
>>> I guess gnuplot backend would use the back-up implementation.
>>> Or we could still use freetype, hoping that gnuplot will use the same
>>> metrics...
>>>
>>> Michael.
>>
>> Gnuplot uses the GD library.
>>
>>        http://en.wikipedia.org/wiki/GD_Graphics_Library
>>
>>        http://www.libgd.org/Main_Page
>>
>> After reading some hits via Google, it appears that this library can
>> calculate the bounding rectangle text without rendering it, and that gdlib
>> handles freetype, PS type 1 fonts, and truetype.
>>
>>        http://my.php.net/gd
>>
>>        imageftbbox — Give the bounding box of a text using fonts via
>> freetype2
>>
>>        imagepsbbox — Give the bounding box of a text rectangle using
>> PostScript Type1 fonts
>>
>>        imagettfbbox — Give the bounding box of a text using TrueType fonts
>>
>> Ben
>>
>>
> So there are already 3 methods to get the extent property without dependency
> on backends:

Well none of them are implemented in octave yet ...

> use GD library
> use freetype
> back-up method if these libraries is absent or the font is non-standard
>

Since it seems that GD uses freetype also, I would go for freetype +
very simple backup.

Shai