/**
 ** buildaux.c ---- generate and store a rotated character for a font
 **
 ** Copyright (c) 1995 Csaba Biegl, 820 Stirrup Dr, Nashville, TN 37221
 ** [e-mail: csaba@vuse.vanderbilt.edu]
 **
 ** This file is part of the GRX graphics library.
 **
 ** The GRX graphics library is free software; you can redistribute it
 ** and/or modify it under some conditions; see the "copying.grx" file
 ** for details.
 **
 ** This library is distributed in the hope that it will be useful,
 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 **
 **/

#include "libgrx.h"
#include "arith.h"

char *GrBuildAuxiliaryBitmap(GrFont *f,unsigned int chr,int dir,int ul)
{
    unsigned int idx = (unsigned int)chr - f->h.minchar;
    unsigned int bpos,rbpos,size,rsize,w,h;
    int  boff,rboff,rbinc;
    char *stdmap,*cvtmap;
    if(idx >= f->h.numchars) return(NULL);
    stdmap = &f->bitmap[f->chrinfo[idx].offset];
    dir = (dir & 3) + ((ul && (f->h.ulheight > 0)) ? 4 : 0);
    if(dir == GR_TEXT_RIGHT) return(stdmap);
    if(f->auxoffs[--dir] != NULL) {
        unsigned int offs = f->auxoffs[dir][idx];
        if(offs > 0) return(&f->auxmap[offs - 1]);
    }
    else {
        size = sizeof(f->auxoffs[0][0]) * f->h.numchars;
        f->auxoffs[dir] = malloc(size);
        if(f->auxoffs[dir] == NULL) return(NULL);
        memset(f->auxoffs[dir],0,size);
    }
    h     = f->h.height;
    w     = f->chrinfo[idx].width;
    size  = h * (boff  = (w + 7) & ~7);
    rsize = w * (rboff = (h + 7) & ~7);
    switch(dir) {
      case (GR_TEXT_RIGHT - 1 + 4):
        rboff = boff;
        rsize = size;
        rbpos = 0;
        rbinc = 1;
        break;
      case (GR_TEXT_DOWN - 1):              /* downward */
      case (GR_TEXT_DOWN - 1 + 4):
        rbpos = h - 1;
        rbinc = rboff;
        rboff = -1;
        break;
      case (GR_TEXT_LEFT - 1):              /* upside down, right to left */
      case (GR_TEXT_LEFT - 1 + 4):
        rboff = boff;
        rsize = size;
        rbpos = rsize - rboff + w - 1;
        rbinc = -1;
        rboff = -rboff;
        break;
      case (GR_TEXT_UP - 1):                /* upward */
      case (GR_TEXT_UP - 1 + 4):
        rbpos = rsize - rboff;
        rbinc = -rboff;
        rboff = 1;
        break;
      default:
        return(NULL);
    }
    if((rsize >>= 3) == 0) return(NULL);
    if(rsize > (f->auxsize - f->auxnext)) {
        /* add space for 32 (average) characters */
        unsigned int newsize = (((f->h.width + 7) >> 3) * f->h.height) << 6;
        newsize = umax(newsize,(rsize << 2));
        newsize = umin(newsize,((unsigned int)(-4) - f->auxsize));
        newsize += f->auxsize;
        if(rsize > (newsize - f->auxnext)) return(NULL);
        cvtmap = malloc(newsize);
        if(cvtmap == NULL) return(NULL);
        if(f->auxsize > 0) {
            memcpy(cvtmap,f->auxmap,f->auxsize);
            free(f->auxmap);
        }
        f->auxmap  = cvtmap;
        f->auxsize = newsize;
    }
    cvtmap = &f->auxmap[f->auxnext];
    f->auxoffs[dir][idx] = f->auxnext + 1;
    f->auxnext += rsize;
    memset(cvtmap,0,rsize);
    for(h = bpos = 0; bpos < size; bpos += boff,rbpos += rboff,h++) {
        unsigned int bp    = bpos;
        unsigned int bptop = bpos + w;
        unsigned int rbp   = rbpos;
        unsigned int ulrow = ul && ((h - f->h.ulpos) < f->h.ulheight);
        for( ; bp < bptop; bp++,rbp += rbinc) {
            if(stdmap[bp >> 3] & (0x80 >> (bp & 7)) || ulrow) {
                cvtmap[rbp >> 3] |= (0x80 >> (rbp & 7));
            }
        }
    }
    return(cvtmap);
}