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pablo.caviglia
PostPosted: Wed May 16, 2012 2:12 pm 
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Joined: Mon Apr 09, 2012 5:11 pm
Posts: 8
Hi all!

I am implementing an application for android using Slick-AE.
The application must use JPEG images, but this platform only support PNG files through the PNGDecoder class.

I have modified the Slick-AE code to support JPEGDecoder by using the pure-Java Matthias' decoder implementation.
After a lot of work i did work this, but the decoder is not coloring the image correctly... something is bad in there, but i dont know what, and it looks pretty complex to start debugging the JPEGDecoder.

Attachment:
File comment: Bad decoded JPEG image
bad_colors.jpg
bad_colors.jpg [ 82.39 KiB | Viewed 694 times ]


I have also implemented a 'LoadableImageData' class called JPEGImageData that configures the decoder to start working.

There are a lot of things already done, but they dont work. Maybe someone already had this issue and can help me.

Maybe another JPEGDecoder implemenetation :S

Regards,

Pablo
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davedes
PostPosted: Wed May 16, 2012 3:03 pm 
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Joined: Sat Jan 27, 2007 7:10 pm
Posts: 1469
Matthias' pure-java decoders should work great. In fact, if I ever get a chance, I'd love to overhaul Slick2D's texture loaders to use all of Matthias' decoders (instead of just PNG).

I'm guessing GL_UNPACK_ALIGNMENT is causing your problem. Try this before glTexImage2D:
Code:
        GL11.glPixelStorei(GL11.GL_UNPACK_ROW_LENGTH, 0);
        GL11.glPixelStorei(GL11.GL_UNPACK_ALIGNMENT, 1); // <-- by default this is 4


Also make sure you're setting the right decode formats for JPGDecoder. When you call decodeRGB, the stride is based on how many components your decode format has:
Code:
public class ImageDecoderJPEG extends ImageDecoder {
   
    private JPEGDecoder decoder;

    public ImageDecoderJPEG(URL url) {
        super(url);
    }

    @Override
    public boolean open() throws IOException {
        inputStream = url.openStream();
        decoder = new JPEGDecoder(inputStream);
        decoder.decodeHeader();
        width = decoder.getImageWidth();
        height = decoder.getImageHeight();
        format = Texture.Format.RGBA;
        return decoder.startDecode();
    }

    @Override
    public void decode(ByteBuffer bb) throws IOException {
        decoder.decodeRGB(bb, width*format.getBytesPerPixel(), decoder.getNumMCURows());
    }
}
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pablo.caviglia
PostPosted: Wed May 16, 2012 3:31 pm 
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Joined: Mon Apr 09, 2012 5:11 pm
Posts: 8
Hi davedes, thank you very much for the fast reply.

I tried to do the GL11 thing, but it does not work... it is still being viewed corrupt.

I am not sure if i will continue try doing this. I dont really understand too much about libgdx and its OpenGL calls, so i am too blind while doing this, and i am just changing code that i am not sure for what it is.

I'll be glad if some day you make it work and you share it with us.

Thx a lot!

Pablo
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pablo.caviglia
PostPosted: Wed May 16, 2012 3:52 pm 
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Joined: Mon Apr 09, 2012 5:11 pm
Posts: 8
I found another implementation of the decoder:

http://webuser.fh-furtwangen.de/~dersch ... ecoder.zip

I will be working on it, maybe i can make it work!
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pablo.caviglia
PostPosted: Wed May 16, 2012 4:29 pm 
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Joined: Mon Apr 09, 2012 5:11 pm
Posts: 8
Finally! IT WORKED! :D

I used the decoder i have found on the following link:

http://webuser.fh-furtwangen.de/~dersch ... ecoder.zip

And then using a Slick ImageBuffer i created the image successfully.

The only issue is that it takes a couple of seconds to decode an image of 700x1024...
If someone founds a better decoder, it would be great!

Regards, and if someone needs the code, please let me know!

PAblo
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MatthiasM
PostPosted: Wed May 16, 2012 6:56 pm 
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Joined: Fri Jan 29, 2010 7:02 pm
Posts: 1172
No idea what you are doing - but my decoder is working 100%

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pablo.caviglia
PostPosted: Wed May 16, 2012 7:02 pm 
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Joined: Mon Apr 09, 2012 5:11 pm
Posts: 8
I am not saying your decoder does not work, probably i dont really know how to use it.
Dont worry, i guess it should work very well. :)

You said something about RGB and RGBA. What is the output of you decoder? RGB?
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MatthiasM
PostPosted: Wed May 16, 2012 9:25 pm 
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Joined: Fri Jan 29, 2010 7:02 pm
Posts: 1172
It outputs RGBA (as written in the javadoc). Take a look at my texture loading library

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