colored.c Example C Language Program

/*Example colored.c

Edit the colormap and display the results in the graphics window.

This program works on any 3d adapter.
*/

#include <gl/gl.h>
#include <gl/device.h>

#define START 64
#define CURRENTCOLOR 63
#define BARWIDTH 67
#define REDBAR   934
#define GREENBAR 800
#define BLUEBAR  666
#define STARTBAR 250
#define ENDBAR   1082
#define indextovalue(index) (4*index + 3)

short redindex = 0, greenindex = 0, blueindex = 0;
short whichbar();
long xorg,yorg,xsize,ysize;
long redbar,greenbar,bluebar;
long startbar,endbar;

main()
{
  short index, val;
  Device xpos, ypos;
  initialize();
  while (TRUE) {
    switch (qread(&val)) {
    case ESCKEY:
      greset();
      gexit();
      exit(0);
    case REDRAW:
      reshapeviewport();
      getwindowsize();
      buildmap();
      displaymap();
      break;
    case LEFTMOUSE:
      if (val){
        qread(&xpos);
        qread(&ypos);
        qread(&val);
        qread(&val);
        qread(&val);
        if (insideport(xpos,ypos)) {
          index = -1;
          switch (whichbar(xpos,ypos,&index)) {
          case 0:
            redindex = index;
            break;
          case 1:
            greenindex = index;
            break;
          case 2:
            blueindex = index;
            break;
          default:
            break;
          }

          if (index != -1) {
            buildmap();
            displaymap();
          }
        }
      }
      break;
    }
  }

}

initialize()
{
  int gid;

  prefposition(10, XMAXSCREEN-10, 10, YMAXSCREEN-20);
  keepaspect(5,4);
  gid = winopen("colored");
  ortho2(-0.5, (float)XMAXSCREEN-0.5, -0.5, (float)YMAXSCREEN-0.5);
  color(0);
  clear();
  mapcolor(CURRENTCOLOR, 0, 0, 0);
  qdevice(LEFTMOUSE);
  tie(LEFTMOUSE, MOUSEX, MOUSEY);
  qdevice(ESCKEY);
  qdevice(REDRAW);
  qenter(REDRAW,gid);
}

getwindowsize()
{
  getorigin(&xorg,&yorg);
  getsize(&xsize,&ysize);
  redbar = ((REDBAR * ysize) / YMAXSCREEN) + yorg;
  greenbar = ((GREENBAR * ysize) / YMAXSCREEN) + yorg;
  bluebar = ((BLUEBAR * ysize) / YMAXSCREEN) + yorg;
  startbar = ((STARTBAR * xsize) / XMAXSCREEN) + xorg;
  endbar = ((ENDBAR * xsize) / XMAXSCREEN) + xorg;
}

buildmap()
{
  register i, j;
  for (i = 0; i < 3; i++) {
    for (j = 0; j < 64; j++) {
      switch (i) {
      case 0:                /* red */
        mapcolor(START+i*64+j, indextovalue(j),
            indextovalue(greenindex),
            indextovalue(blueindex));
        break;
      case 1:                /* green */
        mapcolor(START+i*64+j, indextovalue(redindex),
            indextovalue(j),
            indextovalue(blueindex));
        break;
      case 2:                /* blue */
        mapcolor(START+i*64+j, indextovalue(redindex),
            indextovalue(greenindex),
            indextovalue(j));
        break;
      }

    }

  }

  mapcolor(CURRENTCOLOR, indextovalue(redindex),
      indextovalue(greenindex),
      indextovalue(blueindex));
}

displaymap()
{
  register i, j;
  char redstr[10], greenstr[10], bluestr[10];
  color(BLACK);
  clear();
  for (i = 0; i < 3; i++)
    for (j = 0; j < 64; j++) {
      color(START+i*64 + j);
      rectfi(250 + 13*j, 934 - i*133, 263 + 13*j, 
          867 - i*133);
      color(WHITE);
      recti(250 + 13*j, 934 - i*133, 263 + 13*j, 
          867 - i*133);
    }

  color(CURRENTCOLOR);
  rectfi(500, 267, 750, 400);
  color(WHITE);
  recti(500, 267, 750, 400);
  cmov2i(186, 894);
  charstr("RED");
  cmov2i(186, 760);
  charstr("GREEN");
  cmov2i(186, 627);
  charstr("BLUE");
  cmov2i(343, 327);
  charstr("CURRENT COLOR");
  cmov2i(475, 133);
  charstr("Left mouse button: choose a color");
  cmov2i(475, 112);
  charstr("Escape key : exit");
  move2i(startbar + 13*redindex, 934);
  draw2i(startbar + 13*redindex, 960);
  cmov2i(startbar + 6 + 13*redindex, 940);
  sprintf(redstr, "%d", indextovalue(redindex));
  charstr(redstr);
  move2i(startbar + 13*greenindex, 800);
  draw2i(startbar + 13*greenindex, 827);
  cmov2i(startbar + 6 + 13*greenindex, 806);
  sprintf(greenstr, "%d", indextovalue(greenindex));
  charstr(greenstr);
  move2i(startbar + 13*blueindex, 666);
  draw2i(startbar + 13*blueindex, 694);
  cmov2i(startbar + 6 + 13*blueindex, 674);
  sprintf(bluestr, "%d", indextovalue(blueindex));
  charstr(bluestr);
  cmov2i(563, 414);
  charstr("(");
  charstr(redstr);
  charstr(", ");
  charstr(greenstr);
  charstr(", ");
  charstr(bluestr);
  charstr(")");
}

/* return 1 if the position of the cursor is within the window */
insideport(x,y)
int x, y;
{
  if(x<xorg)
    return 0;
  if(x>(xorg+xsize))
    return 0;
  if(y<yorg)
    return 0;
  if(y>(yorg+ysize))
    return 0;
  return 1;
}
/*
returns 0 if in the redbar, 1 if in the greenbar and 2 if in the 
blue bar
*/
short whichbar(xpos,ypos,index)
long xpos,ypos;
short *index;
{
  short i;
  i = -1;
  if (redbar - BARWIDTH <= ypos && ypos <= redbar)  /* red color bar */
    i = 0;
  else if (greenbar-BARWIDTH <= ypos && 
      ypos <= greenbar)                   /* green color bar */
    i = 1;
  else if (bluebar - BARWIDTH <= ypos && 
      ypos <= bluebar) /* blue color bar */
    i = 2;
  if (i != -1) {
    if (startbar <= xpos && xpos < endbar) {
      *index = (xpos - startbar)/13;
      return(i);
    }

  }
  return(-1);

}
/*
Changes:
  - Added the define of start.  Before this addition this program
    did not work on a gl adapter with an 8-bit color table
    #define START 512
    change to:
    #define START 64
  - Changed the CURRENTCOLOR to 63
    Keep in mind that this program will alter the colormap and it
    does not put it back the way it was before
  - The comments at the beginning of the documentation are incorrect.
    The way that the program was before this program only worked on a
    machine with at least a 10-bit color look up table.
*/

Related Information

The keepaspect subroutine, mapcolor subroutine, prefposition subroutine, setlinestyle subroutine, wincontraints subroutine, winopen subroutine.