AGG changes for MapScript maintainers

[Howard Butler]

Tamas,

Should we create our own buffer struct like the gdBuffer that is  
defined in mapscript.i, or should we add the necessary items to  
imageObj to support saving the unsigned char* data on that?  I see  
that imageObj.img currently has unsigned char *raw_byte (I think this  
is used for WCS) .  We would need to add a size_ptr to the img union  
(or use imageObj.size if that is appropriate) and an ownership flag  
to support MapScript.

imageObj already contains a outputFormatObj, so with the additions to  
the struct, our call could look like:

unsigned char* msSaveImageBuffer(imageObj *img);

We then let msFreeImage take care of clean up.

Look ok?

Howard


On Aug 12, 2007, at 4:13 PM, Tamas Szekeres wrote:

> Howard,
>
> I would prefer the policy to keep any of the AGG/GD specific switches
> inside the mapserver core if possible. In this regard we might want to
> establish the corresponding renderer neutral functions like:
>
> unsigned char *msSaveImageBuffer(imageObj *img, int *size_ptr,
> outputFormatObj *format);
>
> void imageFree(imageObj *img);
>
> The latter would wrap gdFree inside. As far as I can see currently
> gdFree is used by both of the renderers. However in the future we'll
> possibly have a renderer specific destroy function for the
> corresponding image that'll make the things more complicated.
>
> Best regards,
>
> Tamas
>
>
>
> 2007/8/12, Howard Butler <hobu.inc at gmail.com>:
>> Language-specific MapScript typemaps or specializations need to be
>> updated to not exclusively use MapServer GD functions.  Previously,
>> the default implementation of getBytes in image.i did:
>>
>> buffer.data = msSaveImageBufferGD(self->img.gd, &buffer.size, self-
>>> format);
>>
>> Additionally, there is now an if test to check for the presence of an
>> AGG driver and use the corresponding method to get the image buffer.
>> If your MapScript language just uses getBytes for all of its buffer/
>> image handling (other than the image.save() method which does not
>> require any swig interface changes), you should be ok.  If you
>> MapScript language has overrides or %extends of imageObj's methods,
>> they will need to be updated to do the following in the case of an
>> AGG format:
>>
>> buffer.data = msSaveImageBufferAGG(self->img.gd, &buffer.size, self-
>>> format);
>>
>> I have updated some of the Python extensions (I do not have its
>> image.write() done yet for AGG), and a quick browse showed at least
>> C# with some overrides that need to be updated.  Java and Ruby too?
>> Hopefully we can the necessary changes in before the next beta as
>> more folks start testing MapServer 5.0 to make pretty pictures :)
>>
>> Howard
>>