/* pbmmask.c - create a mask bitmap from a portable bitmap
**
** Copyright (C) 1989, 1991 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation.  This software is provided "as is" without express or
** implied warranty.
*/

#include "pbm.h"
#include "mallocvar.h"

static bit ** bits;
static bit ** mask;
static bit backcolor;
static int rows, cols;



static short * fcols;
static short * frows;
static int fstacksize = 0;
static int fstackp = 0;



static void
addflood(int const col,
         int const row) {

    if ( bits[row][col] == backcolor && mask[row][col] == PBM_BLACK ) {
        if ( fstackp >= fstacksize ) {
            if ( fstacksize == 0 ) {
                fstacksize = 1000;
                MALLOCARRAY(fcols, fstacksize);
                MALLOCARRAY(frows, fstacksize);
                if ( fcols == NULL || frows == NULL )
                    pm_error( "out of memory" );
            } else {
                fstacksize *= 2;
                fcols = (short*) realloc(
                    (char*) fcols, fstacksize * sizeof(short) );
                frows = (short*) realloc(
                    (char*) frows, fstacksize * sizeof(short) );
                if ( fcols == (short*) 0 || frows == (short*) 0 )
                    pm_error( "out of memory" );
            }
        }
        fcols[fstackp] = col;
        frows[fstackp] = row;
        ++fstackp;
    }
}



static void
flood(void) {

    while ( fstackp > 0 ) {
        int col, row;
        --fstackp;
        col = fcols[fstackp];
        row = frows[fstackp];
        if ( bits[row][col] == backcolor && mask[row][col] == PBM_BLACK ) {
            int c;
            mask[row][col] = PBM_WHITE;
            if ( row - 1 >= 0 )
                addflood( col, row - 1 );
            if ( row + 1 < rows )
                addflood( col, row + 1 );
            for ( c = col + 1; c < cols; ++c ) {
                if ( bits[row][c] == backcolor && mask[row][c] == PBM_BLACK ) {
                    mask[row][c] = PBM_WHITE;
                    if ( row - 1 >= 0 && 
                         ( bits[row - 1][c - 1] != backcolor || 
                           mask[row - 1][c - 1] != PBM_BLACK ) )
                        addflood( c, row - 1 );
                    if ( row + 1 < rows && 
                         ( bits[row + 1][c - 1] != backcolor || 
                           mask[row + 1][c - 1] != PBM_BLACK ) )
                        addflood( c, row + 1 );
                }
                else
                    break;
            }
            for ( c = col - 1; c >= 0; --c ) {
                if ( bits[row][c] == backcolor && mask[row][c] == PBM_BLACK ) {
                    mask[row][c] = PBM_WHITE;
                    if ( row - 1 >= 0 && 
                         ( bits[row - 1][c + 1] != backcolor || 
                           mask[row - 1][c + 1] != PBM_BLACK ) )
                        addflood( c, row - 1 );
                    if ( row + 1 < rows && 
                         ( bits[row + 1][c + 1] != backcolor || 
                           mask[row + 1][c + 1] != PBM_BLACK ) )
                        addflood( c, row + 1 );
                } else
                    break;
            }
        }
    }
}



int
main(int argc, char * argv[]) {

    FILE* ifp;
    int argn, expand, wcount;
    register int row, col;
    const char* const usage = "[-expand] [pbmfile]";

    pbm_init( &argc, argv );

    argn = 1;
    expand = 0;

    if ( argn < argc && argv[argn][0] == '-' && argv[argn][1] != '\0' )
    {
        if ( pm_keymatch( argv[argn], "-expand", 2 ) )
            expand = 1;
        else if ( pm_keymatch( argv[argn], "-noexpand", 2 ) )
            expand = 0;
        else
            pm_usage( usage );
        ++argn;
    }

    if ( argn == argc )
        ifp = stdin;
    else
    {
        ifp = pm_openr( argv[argn] );
        ++argn;
    }

    if ( argn != argc )
        pm_usage( usage );

    bits = pbm_readpbm( ifp, &cols, &rows );
    pm_close( ifp );
    mask = pbm_allocarray( cols, rows );

    /* Clear out the mask. */
    for ( row = 0; row < rows; ++row )
        for ( col = 0; col < cols; ++col )
            mask[row][col] = PBM_BLACK;

    /* Figure out the background color, by counting along the edge. */
    wcount = 0;
    for ( row = 0; row < rows; ++row ) {
        if ( bits[row][0] == PBM_WHITE )
            ++wcount;
        if ( bits[row][cols - 1] == PBM_WHITE )
            ++wcount;
    }
    for ( col = 1; col < cols - 1; ++col ) {
        if ( bits[0][col] == PBM_WHITE )
            ++wcount;
        if ( bits[rows - 1][col] == PBM_WHITE )
            ++wcount;
    }
    if ( wcount >= rows + cols - 2 )
        backcolor = PBM_WHITE;
    else
        backcolor = PBM_BLACK;

    /* Flood the entire edge.  Probably the first call will be enough, but
       might as well be sure.
    */
    for ( col = cols - 3; col >= 2; col -= 2 ) {
        addflood( col, rows - 1 );
        addflood( col, 0 );
    }
    for ( row = rows - 1; row >= 0; row -= 2 ) {
        addflood( cols - 1, row );
        addflood( 0, row );
    }
    flood( );

    if ( ! expand )
        /* Done. */
        pbm_writepbm( stdout, mask, cols, rows, 0 );
    else {
        /* Expand by one pixel. */
        int srow, scol;
        unsigned int row;
        bit ** emask;

        emask = pbm_allocarray( cols, rows );

        for ( row = 0; row < rows; ++row ) {
            unsigned int col;
            for ( col = 0; col < cols; ++col )
                if ( mask[row][col] == PBM_BLACK )
                    emask[row][col] = PBM_BLACK;
                else {
                    emask[row][col] = PBM_WHITE;
                    for ( srow = row - 1; srow <= row + 1; ++srow )
                        for ( scol = col - 1; scol <= col + 1; ++scol )
                            if ( srow >= 0 && srow < rows &&
                                 scol >= 0 && scol < cols &&
                                 mask[srow][scol] == PBM_BLACK ) {

                                emask[row][col] = PBM_BLACK;
                                break;
                            }
                }
        }
        pbm_writepbm( stdout, emask, cols, rows, 0 );
    }

    pm_close( stdout );

    return 0;
}