[postgis-devel] documentation images

[Kevin Neufeld]

Great.  Thanx Mark!  I'll make your changes so I can further improve the docs.  One thing I noticed already, is that 
ImageMagick seems to behave differently on the few different servers I've tried ... which really defeats the purpose of 
having repeatable generated results ... so I'll have to look into this further.

Thanx again,
Kevin

Mark Cave-Ayland wrote:
> Kevin Neufeld wrote:
> 
>> Hi all,
>>
>> I just committed some code that can generate most of the spatial 
>> images used in the documentation.
>>
>> Before, the image_src directory contained some svg files that were 
>> "supposed" to be the source of the png images used in the docs.  But I 
>> know of no way to import svg into PostGIS, I can't import them into 
>> JUMP to test or regenerate the svg ... they're pretty useless.
>>
>> So, I wrote a small program that will parse WKT files in the same 
>> directory using the liblwgeom module.  Then, using ImageMagick, 
>> automatically generate the png files of interest.  The advantage here, 
>> is that all the images have the same style (fill color, line 
>> thinkness, drop shadow, etc) and can be changed just by modifying a 
>> few variables.  Because the files are simple WKT, it's easy to modify 
>> the images or generate new ones.
>>
>> It's written in C, and my C skills are still on the upward learning 
>> curve :)  Can someone who is proficient at C review the work before I 
>> start removing images and from SVN and relying on the app for the 
>> generation of the documentation? Since the code is currently isolated, 
>> I thought it'd be OK to submit the stuff rather have a wack of .patch 
>> files for someone to review.
> 
> Hi Kevin,
> 
> This looks great. The commit seems reasonably well though out and has a 
> nice, easy to read style with good comments. Not bad for a first C 
> coding effort. Here are a few general things I noticed on review:
> 
> 
> - configure.ac doesn't check for ImageMagick's convert command
> 
> - comment in doc/html/image_src/Makefile.in still reads "Build the main 
> unit test executable"
> 
> 
> More specifically for generator.c:
> 
> I see this file appears to have some buffer overflow issues, for example:
> 
> Line 315: malloc() seems to be to small; you need to malloc the size of 
> the filename, plus 10 chars for the "../images/" prefix, plus 1 for the 
> trailing zero byte to indicate the length of the string. Don't worry 
> about the sizeof(char) multiplier - a char is always 1 byte.
> 
> It's generally considered good practice to always use the string "n" 
> functions such as snprintf()/strncat() rather than the plain versions 
> since if the end of the output buffer is reached the output will simply 
> be truncated rather than causing a segfault.
> 
> Finally, use of the "rm" command on line 262 is not great for 
> portability; check out remove() from the standard C libraries instead.
> 
> 
> HTH,
> 
> Mark.
>