/* rotate.c - code modified from pnmrotate.c which included the following
copyright notice
*/
/* pnmrotate.c - read a portable anymap and rotate it by some angle
**
** 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 <stdlib.h>
#include <math.h>
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif /*M_PI*/
#define SCALE 4096
#define HALFSCALE 2048
typedef unsigned char imT; /* image type */
static imT* my_allocarray(int cols, int rows)
{
imT *arr = NULL;
if ((arr = malloc(sizeof(imT)*cols*rows)) == NULL)
croak("error getting memory for temporary array");
return arr;
}
int getnewsize(int cols, int rows, float fangle, int *newcols, int *newrows)
{
float xshearfac, yshearfac, new0;
int tempcols, yshearjunk, x2shearjunk;
if ( fangle < -90.0 || fangle > 90.0 )
/* error( "angle must be between -90 and 90 degrees" ); */
return -1;
fangle = fangle * M_PI / 180.0; /* convert to radians */
xshearfac = tan( fangle / 2.0 );
if ( xshearfac < 0.0 )
xshearfac = -xshearfac;
yshearfac = sin( fangle );
if ( yshearfac < 0.0 )
yshearfac = -yshearfac;
tempcols = rows * xshearfac + cols + 0.999999;
yshearjunk = ( tempcols - cols ) * yshearfac;
*newrows = tempcols * yshearfac + rows + 0.999999;
x2shearjunk = ( *newrows - rows - yshearjunk ) * xshearfac;
*newrows -= 2 * yshearjunk;
*newcols = *newrows * xshearfac + tempcols + 0.999999 - 2 * x2shearjunk;
/* printf("oldrows: %d, oldcols: %d\n",rows,cols);
printf("newrows: %d, newcols: %d\n",*newrows,*newcols);
*/
return 0; /* OK */
}
int rotate(imT *im, imT *out, int cols, int rows, int nc, int nr,
float fangle, imT bgval, int antialias)
{
float xshearfac, yshearfac, new0;
int intnew0;
imT *xelrow, *newxelrow, *temp1xels, *temp2xels, *nxP, *xP, prevxel, x;
int tempcols, newcols, yshearjunk, x2shearjunk, row, col, new, newrows;
register long fracnew0, omfracnew0;
/* other angles should do a simple multiple of 90 degrees rotate before
calling this one */
if ( fangle < -90.0 || fangle > 90.0 )
/* error( "angle must be between -90 and 90 degrees" ); */
return -1;
fangle = fangle * M_PI / 180.0; /* convert to radians */
xshearfac = tan( fangle / 2.0 );
if ( xshearfac < 0.0 )
xshearfac = -xshearfac;
yshearfac = sin( fangle );
if ( yshearfac < 0.0 )
yshearfac = -yshearfac;
tempcols = rows * xshearfac + cols + 0.999999;
yshearjunk = ( tempcols - cols ) * yshearfac;
newrows = tempcols * yshearfac + rows + 0.999999;
x2shearjunk = ( newrows - rows - yshearjunk ) * xshearfac;
newrows -= 2 * yshearjunk;
newcols = newrows * xshearfac + tempcols + 0.999999 - 2 * x2shearjunk;
/* check that the output has the right size */
if (nc != newcols || nr != newrows)
return -2;
/* First shear X into temp1xels. */
temp1xels = my_allocarray( tempcols, rows );
for ( row = 0; row < rows; ++row )
{
xelrow = im + row * cols; /* current row to process */
if ( fangle > 0 )
new0 = row * xshearfac;
else
new0 = ( rows - row ) * xshearfac;
intnew0 = (int) new0;
if ( antialias )
{
fracnew0 = ( new0 - intnew0 ) * SCALE;
omfracnew0 = SCALE - fracnew0;
for ( col = 0, nxP = temp1xels+row*tempcols;
col < tempcols; ++col, ++nxP )
*nxP = bgval;
prevxel = bgval;
for ( col = 0, nxP = temp1xels+row*tempcols+intnew0, xP = xelrow;
col < cols; ++col, ++nxP, ++xP )
{
*nxP = (fracnew0 * prevxel + omfracnew0 * *xP + HALFSCALE )
/ SCALE;
prevxel = *xP;
}
if ( fracnew0 > 0 && intnew0 + cols < tempcols )
{
*nxP =
( fracnew0 * prevxel + omfracnew0 * bgval + HALFSCALE )
/ SCALE;
}
}
else
{
for ( col = 0, nxP = temp1xels+row*tempcols;
col < intnew0; ++col, ++nxP )
*nxP = bgval;
for ( col = 0, xP = xelrow; col < cols; ++col, ++nxP, ++xP )
*nxP = *xP;
for ( col = intnew0 + cols; col < tempcols; ++col, ++nxP )
*nxP = bgval;
}
}
/* Now inverse shear Y from temp1 into temp2. */
temp2xels = my_allocarray( tempcols, newrows );
for ( col = 0; col < tempcols; ++col )
{
if ( fangle > 0 )
new0 = ( tempcols - col ) * yshearfac;
else
new0 = col * yshearfac;
intnew0 = (int) new0;
fracnew0 = ( new0 - intnew0 ) * SCALE;
omfracnew0 = SCALE - fracnew0;
intnew0 -= yshearjunk;
for ( row = 0; row < newrows; ++row )
temp2xels[row*tempcols+col] = bgval;
if ( antialias )
{
prevxel = bgval;
for ( row = 0; row < rows; ++row )
{
new = row + intnew0;
if ( new >= 0 && new < newrows )
{
nxP = temp2xels+new*tempcols+col;
x = temp1xels[row*tempcols+col];
*nxP =
( fracnew0 * prevxel + omfracnew0 * x + HALFSCALE )
/ SCALE;
prevxel = x;
}
}
if ( fracnew0 > 0 && intnew0 + rows < newrows )
{
nxP = temp2xels+(intnew0 + rows)*tempcols+col;
*nxP = ( fracnew0 * prevxel + omfracnew0 * bgval + HALFSCALE )
/ SCALE ;
}
}
else
{
for ( row = 0; row < rows; ++row )
{
new = row + intnew0;
if ( new >= 0 && new < newrows )
temp2xels[new*tempcols+col] = temp1xels[row*tempcols+col];
}
}
}
free(temp1xels);
for ( row = 0; row < newrows; ++row )
{
newxelrow = out + row*newcols;;
if ( fangle > 0 )
new0 = row * xshearfac;
else
new0 = ( newrows - row ) * xshearfac;
intnew0 = (int) new0;
fracnew0 = ( new0 - intnew0 ) * SCALE;
omfracnew0 = SCALE - fracnew0;
intnew0 -= x2shearjunk;
for ( col = 0, nxP = newxelrow; col < newcols; ++col, ++nxP )
*nxP = bgval;
if ( antialias )
{
prevxel = bgval;
for ( col = 0, xP = temp2xels+row*tempcols;
col < tempcols; ++col, ++xP )
{
new = intnew0 + col;
if ( new >= 0 && new < newcols )
{
nxP = &(newxelrow[new]);
*nxP =
( fracnew0 * prevxel + omfracnew0 * *xP + HALFSCALE )
/ SCALE;
prevxel = *xP;
}
}
if ( fracnew0 > 0 && intnew0 + tempcols < newcols )
{
nxP = &(newxelrow[intnew0 + tempcols]);
*nxP =
( fracnew0 * prevxel + omfracnew0 * bgval + HALFSCALE )
/ SCALE;
}
}
else
{
for ( col = 0, xP = temp2xels+row*tempcols;
col < tempcols; ++col, ++xP )
{
new = intnew0 + col;
if ( new >= 0 && new < newcols )
newxelrow[new] = *xP;
}
}
}
free(temp2xels);
return 0; /* OK */
}