Thread: Curious anomoly in allegro.

  1. #1
    Registered User ~Kyo~'s Avatar
    Join Date
    Jun 2004

    Question Curious anomoly in allegro.

    Ok so I decided to write some code to place a bunch of bitmap files into one FGD(fixed game data) file just for fire transfer's sake from a server to client update kinda deal I figured plain text would work great. This code though once we kick into the compression function decides to rename my filename variable say I pass in Slime.bmp I end up with S< at the end and a program crash. Anyone see something I am missing? Kinda late so maybe I am overlooking something simple...

    #include <iostream>
    #include <fstream>
    #include <string.h>
    #include <allegro.h>
    #include <winalleg.h>
    using namespace std;
    void compress(char *);
    ofstream FGD_FILE;
    int main(int argc, char *argv[])
        if(argc > 1)
            for(int comp = 1;comp < argc;comp++)
            cout<<"Files to compress are not specified."<<endl;
    	return 0;
    END_OF_MAIN();      //allegro specific to correct for winapi's main() function.
    void compress(char *filename)
        BITMAP *bmp;
        RGB *palette;
        char *isgoodfile = strstr(filename,".bmp");
        if(isgoodfile != NULL)//non null if it is a bitmap or has .bmp in it at least.
            bmp = load_bitmap(filename,palette);
            if (!bmp)
                cout<<"Problem loading bitmap: "<<filename<<endl
                    <<"Compression aborted check file extention is a .bmp file"<<endl;
                int color_locked = -1;      //technically valid for r=255 g=255 b=255 and a=255
                int looped = 1;
                FGD_FILE<<filename<<" "<<bmp->w<<" "<<bmp->h<<endl;
                for(int y = 0;y < bmp->h;y++)
                    for(int x = 0;x < bmp->w;x++)
                        if(color_locked != getpixel(bmp,x,y))
                            if(color_locked != -1)FGD_FILE<<looped<<" "<<color_locked<<" ";
                            color_locked = getpixel(bmp,x,y);
                            looped = 1;
                        }else looped++;
                FGD_FILE<<looped<<" "<<color_locked<<endl<<endl<<endl;
            cout<<"Compressed and added file: "<<filename<<endl;
        }else cout<<"Unable to verify file maybe it isn't a bitmap?"<<endl;

  2. #2
    Frequently Quite Prolix dwks's Avatar
    Join Date
    Apr 2005
    I've never used allegro, but notice that while the second parameter to load_bitmap() is actually an RGB*, the example in the docs actually uses a PALETTE. Allegro Manual: Loading image files

    Clicking on the links, a PALETTE is actually an array instead of just a pointer. What's probably happening is that since you pass in just an RGB* pointer, which could be pointing anywhere, you get memory corruption. Try using a PALETTE or, if you don't care about the palette at all, pass in a NULL pointer (according to the docs this is allowed).

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  3. #3
    Registered User ~Kyo~'s Avatar
    Join Date
    Jun 2004
    While this is true you can actually pass NULL to it and have it work fine... Yea ok so you were cut short on my e-mail note lol NULL works fine more often than not I don't remember what I did to fix it. but it is fixed moved onto other things sorry...

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