Re: XPM support for NSImage

[Richard Frith-Macdonald]

On 8 Nov 2006, at 07:31, Hubert Chan wrote:

> On Wed, 8 Nov 2006 06:30:11 +0000, Richard Frith-Macdonald  
> <address@hidden> said:
>
> [...]
>
> > I think what Fred probably intended was to have a lot of filter
> > services available for different image file formats.  Then in the gui
> > library have an NSImageRep subclass which would use any filter  
> > service
> > as required.  That way, the only extra code in the gui library (and
> > hence linked in to apps) would be the little bit letting the
> > NSImageRep use filter services.  The gui package could install a set
> > of image filters, but other packages/applications would also be able
> > to supply more or better filters.  When the gui needs to convert from
> > format A to B it would just ask the NSImageRep to do it, and that
> > would automatically pick one of the available filters to perform the
> > actual conversion.
>
> Ah, OK.  So the idea is to use the service to, say, convert an XPM  
> to a
> PPM, and use the PNM loading code that is already in gui.

Yes ... or PNG or TIFF etc.

> Sounds a bit
> inefficient, but I guess it would allow us to reuse a lot of code from
> netpbm (or maybe even just create a wrapper around the netpbm  
> programs).

Yes.

> This would probably work for a simple bitmap format such as XPM,  
> but it
> probably wouldn't work so well for, say, SVG, where we would want to
> keep all that vector goodness, or for PDF, where the Apple API  
> includes
> extra methods like -setCurrentPage:.
>
> But if we could take advantage of netpbm (and ImageMagick), we would
> have free support for an insane number of file formats.
>
> Another thing is, does this also allow for writing files?

Not directly ... but it would be easy to take data in one image  
format, filter it to produce data in another format, then write the  
resulting data to file.