Using the picture.datatype

[Karlos]

Hi all,

Whilst the tumbleweed blows through my other query, I have another one :-)

Can anybody point me in the direction of any example/tutorial C sources for using the datatypes.library?

In particular, I'm interested in using the v43+ picture datatype to decode an image format into a 24-bit RGB (or 32-bit ARGB where applicable) buffer in memory. I'm not concerned in rendering the datatype to a window or anything, I just want to get the pixel data itself.

I found a small program on aminet that converts images to .ppm format via datatypes so I assume this kind of thing is relatively straightforward (at least I hope it is)...

Cheers,

K

[Karlos]

I only have the 3.5 NDK...

Is it possible to get that file anywhere else?

-edit-

Assuming its not illegal to do so, that is :-)

[Karlos]

Bloody hell.

I must be blind as a bat - I have it on the 3.5 version :lol:

Ignore me!

-edit-

Thanks anyway matey :-)

[Karlos]

Hmm, this still doesnt quite look like what I need - this is reading a datatype object from a raw memory source.

What I need is to take the decoded image data from a datatype and use it for my own ends,,,

Is there a DoMethod() method for reading the decoded RGB pixels in the image?

[Karlos]

Well I procured a copy just now anyway :-)

I'm still unclear how to go about pinching those pixels ;-)

[Karlos]

Me neither, hence my problem :-)

As I said, I'm not interested in actually rendering the datatype (which is what they seem to be aimed at), just using it as a nice codec...

Still, thanks anyway ;-)

[Karlos]

Thanks Thomas, that looks a bit more like what I need :-)

[Karlos]

Hi again...

Well at the risk of sounding like a newbie...

I see the v43 extensions support exactly what I need - that is it supports PDTM_WRITEPIXELARRAY ans PDTM_READPIXELARRAY.

The latter would seem to be the method I need. The pictureclass.h header doesn't really go into much depth. There is a pdtBlitPixelArray struct defined also, containing width, height, modulus and buffer address, so I assume its the argument for the above methods.

I'm just a bit nonplussed that it also contains a ULONG MethodID field The header contains no hint as to what this is for. Is this just a copy of PDTM_READ/WRITEPIXELARRAY? Seems odd that it would be needed :-?

Can anybody confirm the usage of these methods for me?

So far I'm guessing its...

void* buffer;
....
struct Object* picObject;
...
struct pdtBlitPixelArray myPixelArray;

myPixelArray.MethoodID = PDTM_READPIXELARRAY;
myPixelArray.pbpa_PixelData = buffer;
...
DoMethod(picObject, PDTM_READPIXELARRAY, &myPixelArray);

Is this correct?

[Karlos]

You should read the autodocs.

Well that's the most polite RTFM I've seen :-D

Anyway, I have been - I'm just not fully up to speed with the BOOPSI mechanisms for method/attribute handling - I come from a pure C++ background and find all this GetAttrs / DoMethod stuff a bit arcane...

So MethodID is not a copy of PDTM_READPIXELARRAY, it is the place where PDTM_READPIXELARRAY belongs to.

Ah, I get it :-) I was filling in the structure when it's really the job of the varargs DoMethod() to do so from the arguments I pass...

Silly me :oops: :lol:

Well, thanks a lot, that's cleared that one up nicely :-)

In line with the sig, oldDog->teach(new Trick)