Drawing maps (.blp images) ?

[eLaps]

Hi,
I'm want to draw map files (with blp files found in MPQs) in a out-of-process gui and I know some of you already did it, so asking you may save me a lot of time.
I would want to know if you just made it from scratch or if there is a trick to avoid all the boring (and hard if DXT encoding) work, maybe an external lib?

[namreeb]

Should be pretty straight forward.

BLP format: BLP - WoW.Dev Wiki

DXT (de)compression lib: libsquish - Project Hosting on Google Code

It may be easier to convert them to a standard format using something like this:

http://www.mmowned.com/forums/simple...converter.html

[eLaps]

Thanks.
I was trying to avoid any pre-conversion (making the conversion at execution in the RAM) but surprisingly I didn't find any RGBA8888 to PNG conversion lightweight library (ImageMagick does that but is over-complicated).
But whatever, making preconverted copies is ok.

edit:
Finally, with Magick++:

#include <stdint.h>
#include <fstream>
#include <iostream>

#include <Magick++.h>
#include "squish.h"

bool BLP2_Convert(const std::string& _blpfile, const std::string& _extension) {

    struct {
        char        BLP2[4];
        uint32_t    version;
        uint8_t        compression;
        uint8_t        alpha_depth;
        uint8_t        alpha_encoding;
        uint8_t        mipmaps;
        uint32_t    width;
        uint32_t    height;
        uint32_t     mipmaps_offsets[16];
        uint32_t     mipmaps_sizes[16];
    } blpheader;

    std::ifstream ifs(_blpfile.c_str(), std::ifstream::in|std::ifstream::binary);

        //Get header informations
    ifs.read((char*)&blpheader, 0x94);
    if (*(uint32_t*)&blpheader.BLP2[0] != 844123202) {
        std::cout << "Not BLP2\n";
        return false;
    }

        //Copy first mipmap
    squish::u8* blpimage = new squish::u8[blpheader.mipmaps_sizes[0]];
    ifs.seekg(blpheader.mipmaps_offsets[0], std::ios::beg);
    ifs.read((char*)blpimage, blpheader.mipmaps_sizes[0]);
    ifs.close();

        //Decompress it
    squish::u8* uncompressed;
    if (blpheader.compression == 2) {
        int dxtver;
        switch (blpheader.alpha_encoding) {
            case 0: dxtver = squish::kDxt1; break;
            case 1: dxtver = squish::kDxt3; break;
            case 7: dxtver = squish::kDxt5; break;
            default: std::cout << "DXT version not recognized.\n"; return false; break;
        }
        uncompressed = new squish::u8[blpheader.width * blpheader.height * 4];
        squish::DecompressImage(uncompressed, blpheader.width, blpheader.height, blpimage, dxtver);
    } else
        uncompressed = blpimage;

        //Convert and save it
    Magick::Blob blob(uncompressed, blpheader.width * blpheader.height * 4);
    Magick::Image converted;
    converted.size("256x256");
    converted.magick("RGBA");
    converted.depth(8);
    converted.read(blob);
    converted.write(_blpfile.substr(0, _blpfile.find_last_of('.')+1)+_extension);

    delete[] blpimage;
    if (blpheader.compression == 2)
        delete[] uncompressed;
}

int main() {
    BLP2_Convert("AzjolNerub3_2.blp", "jpg");
    BLP2_Convert("AzjolNerub3_2.blp", "png");
    return 0;
}