/*  getwinlut.c -- Reads the hardware gamma ramps (look-up tables) on MS Windows systems, and saves
 *                 them to OUTPUTFILE. It then reads new gamma ramps from INPUTFILE and writes them
 *                 to the hardware (i.e. the video card).
 *
 *  Only works on MS Windows systems with a video card capable of writable gamma tables (most are).
 *
 *  Compiled with MinGW (www.mingw.org) on Win98SE/XP using:  
 *
 *     windres -i getwinlut.rc -ogetwinrc.o
 *     gcc -mwindows getwinlut.c -o getwinlut.exe getwinrc.o
 *
 *  Not tested with other compilers or on other systems.
 *
 *  Dirk Beer (rdbeer@ucsd.edu)  1 November 2002
 *
 */
#include <windows.h>
#include <wingdi.h>
#include <stdio.h>

#define INPUTFILE  "inputluttable.txt"
#define OUTPUTFILE "oldluttable.txt"
#define RED     0
#define GREEN   1
#define BLUE    2

// function to make an error message and exit
void error(char *messagestr)
{
    char str[256];
    strcpy(str, messagestr);
    MessageBox(NULL, strcat(str, " Exiting ..."), "Error", MB_OK);
    exit(EXIT_FAILURE);
}

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
HDC hDC;
HANDLE hStdout;
FILE * outfp, * infp;
char str[256];
WORD oldgam[3][256], newgam[3][256];
int i, good;

// create a hardware device context for the default display
hDC = CreateDC("DISPLAY", NULL, NULL, NULL);

// get the gamma ramps
if(!GetDeviceGammaRamp(hDC, oldgam))
   error("GetDeviceGammaRamp failed.");

// write the current gamma ramps to the output file
if((outfp = fopen(OUTPUTFILE, "w")) == NULL)
        error("Could not open output file");
for(i=0; i<256; i++)
{
   sprintf(str, "%d\t%d\t%d\n", oldgam[RED][i], oldgam[GREEN][i], oldgam[BLUE][i]);
   fprintf(outfp, str);
}
fclose(outfp);
MessageBox(NULL, "Current gamma ramps written to output file." , "", MB_OK);

// get the new gamma ramps from the input file
if((infp = fopen(INPUTFILE, "r")) == NULL)
    error("Could not open input file.");
for(i=0; i<256; i++)
{
   fscanf(infp, "%d\t%d\t%d\n", &newgam[RED][i], &newgam[GREEN][i], &newgam[BLUE][i]);
}
fclose(infp);
MessageBox(NULL, "New gamma ramps read from input file." , "", MB_OK);

// set the hardware to the new gamma ramps
if(!SetDeviceGammaRamp(hDC, newgam))
   error("SetDeviceGammaRamp failed.");
MessageBox(NULL, "New gamma ramps written to hardware." , "", MB_OK);

return (EXIT_SUCCESS);
}