static acolorhist_vector pam_computeacolorhist(rgbaPixel **apixels, int cols, int rows, int maxacolors, int* acolorsP)
{
acolorhash_table acht;
acolorhist_vector achv;
acht = pam_computeacolorhash( apixels, cols, rows, maxacolors, acolorsP );
if ( acht == (acolorhash_table) 0 )
return (acolorhist_vector) 0;
achv = pam_acolorhashtoacolorhist( acht, maxacolors );
pam_freeacolorhash( acht );
return achv;
}
static acolorhash_table pam_computeacolorhash(rgbaPixel** apixels, int cols, int rows, int maxacolors, int* acolorsP)
{
acolorhash_table acht;
register rgbaPixel* pP;
acolorhist_list achl;
int col, row, hash;
acht = pam_allocacolorhash( );
*acolorsP = 0;
/* Go through the entire image, building a hash table of colors. */
for ( row = 0; row < rows; ++row )
for ( col = 0, pP = apixels[row]; col < cols; ++col, ++pP )
{
hash = pam_hashapixel( *pP );
for ( achl = acht[hash]; achl != (acolorhist_list) 0; achl = achl->next )
if ( PAM_EQUAL( achl->ch.acolor, *pP ) )
break;
if ( achl != (acolorhist_list) 0 )
++(achl->ch.value);
else
{
if ( ++(*acolorsP) > maxacolors )
{
pam_freeacolorhash( acht );
return (acolorhash_table) 0;
}
achl = (acolorhist_list) malloc( sizeof(struct acolorhist_list_item) );
if ( achl == 0 ) {
#ifdef _DEBUG_PNG8
printf( stderr, " out of memory computing hash table\n" );
#endif
exit(7);
}
achl->ch.acolor = *pP;
achl->ch.value = 1;
achl->next = acht[hash];
acht[hash] = achl;
}
}
return acht;
}
int msClassifyRasterBuffer(rasterBufferObj *rb, rasterBufferObj *qrb)
{
register int ind;
unsigned char *outrow,*pQ;
register rgbaPixel *pP;
acolorhash_table acht;
int usehash, row, col;
/*
** Step 4: map the colors in the image to their closest match in the
** new colormap, and write 'em out.
*/
acht = pam_allocacolorhash( );
usehash = 1;
for ( row = 0; row < qrb->height; ++row ) {
outrow = &(qrb->data.palette.pixels[row*qrb->width]);
col = 0;
pP = (rgbaPixel*)(&(rb->data.rgba.pixels[row * rb->data.rgba.row_step]));;
pQ = outrow;
do {
/* Check hash table to see if we have already matched this color. */
ind = pam_lookupacolor( acht, pP );
if ( ind == -1 ) {
/* No; search acolormap for closest match. */
register int i, r1, g1, b1, a1, r2, g2, b2, a2;
register long dist, newdist;
r1 = PAM_GETR( *pP );
g1 = PAM_GETG( *pP );
b1 = PAM_GETB( *pP );
a1 = PAM_GETA( *pP );
dist = 2000000000;
for ( i = 0; i < qrb->data.palette.num_entries; ++i ) {
r2 = PAM_GETR( qrb->data.palette.palette[i] );
g2 = PAM_GETG( qrb->data.palette.palette[i] );
b2 = PAM_GETB( qrb->data.palette.palette[i] );
a2 = PAM_GETA( qrb->data.palette.palette[i] );
/* GRR POSSIBLE BUG */
newdist = ( r1 - r2 ) * ( r1 - r2 ) + /* may overflow? */
( g1 - g2 ) * ( g1 - g2 ) +
( b1 - b2 ) * ( b1 - b2 ) +
( a1 - a2 ) * ( a1 - a2 );
if ( newdist < dist ) {
ind = i;
dist = newdist;
}
}
if ( usehash ) {
if ( pam_addtoacolorhash( acht, pP, ind ) < 0 ) {
usehash = 0;
}
}
}
/* *pP = acolormap[ind].acolor; */
*pQ = (unsigned char)ind;
++col;
++pP;
++pQ;
} while ( col != rb->width );
}
pam_freeacolorhash(acht);
return MS_SUCCESS;
}
