| From: | Oliver Roberts |
| Date: | 25 Apr 2001 at 20:56:35 |
| Subject: | Re: Datatypes |
Hi Joris,
On 25-Apr-01 13:09:09 BST, Joris Kempen wrote:
> Yes i was right, the descriptor and the datatype itself is fixed to each
> other.
> So when I install a new datatype I install the descriptor and the
> datatype that belong to each other...
Right.
>> You can keep as many different files in SYS:Classes/Datatypes as you
>> wish.
> What should you do that?
Well, I'm not saying you should - just that you can if you so desire :)
Say you want to install and try a new JPEG datatype... You could move
your old JPEG descriptor file out of DEVS:Datatypes to
SYS:Storage/Datatypes, before installing the new datatype. That way,
if you should want to switch between datatypes at all, until you're
happy you've chosen the best one, you can just move the descriptor files
about.
> But now I'm using the Picture.datatype from VGR that comes with CGFX4,
> this one doesn't handle all my JFIF pictures AFAIK, should i also install
Firstly, picture.datatype is the superclass for all datatypes that are
able to decode images - e.g. JFIF/JPEG, PNG, GIF, ILBM, etc (known as
subclasses). But, you're probably right that the jfif.datatype from the
CGFX PicDT V43 archive does not handle all your JPEG images, since it's
old and based on old codec.
> the akJFIF datatype, or will they override each other? What i hate about
Sure... you can use any modern JFIF/JPEG datatype (e.g. WarpJPEG, akJFIF,
Gunther Nikl's JFIFdt44) instead of the one supplied with the CGFX
picture.datatype, since they are compatible with the CGFX picture.datatype.
> some picture datatypes i used is that they open there own screen, i
> really hate this because i normally use Cyberwindow for viewing, and then
> it's not streamed to a window but to a screen. Is this because my JPG
> datatype isn't "good enough" for this file and akJFIF takes over or, is
> it that Cyberwindow internal decoding isn't "good enough" for this file
> and akJFIF takes over.
>
> I really prefer datatypes that don't open there own screen...
Datatypes themselves have no control over how images are displayed. All
they do is decode the image data and write it into a bitmap, passing
that bitmap back to the application so that it can display it, or do
whatever it wants with it. It will be the application software that
decides whether to display the image in a window or on a screen.
AFAIK, Cyberwindow /always/ displays images in a window - it has no
facility for displaying images on their own screen, unless you start it
with the PUBSCREEN option set. IIRC, the internal decoder does not
support progressive JPEGs, so it will use datatypes to decode those and
any other files it cannot handle. For the instances when you're images
getting displayed on their own screen, are you sure it is Cyberwindow
that is being used? (i.e if you're viewing images via DefIcons or DOpus
filetypes, for example).
>> Just install the ones that you think you'll need... Generally, the
>> newer the datatype is, the better it will be (i.e. a newer JPEG
>> datatype, is better than using some ancient old one form Aminet :)
> To be honest i only found quit old jpg datatypes. Only the akDatatypes
> are being updated AFAIK. Considering I have a 68k machine and not a PPC
> :(
There are 68k optimized versions of all my WarpDT (they're not just for
PPC :) My datatypes are still in development, and are updated as and
when there are enough changes to warrant doing so. As you say, the ak*
datatypes are still being updated too.
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