libvips/libsrc/inplace/im_circle.c

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2007-08-29 18:23:50 +02:00
/* @(#) writes a circle in a vasari file
* @(#) The circle is centred in the middle of the file (xsize/2, ysize/2)
* @(#) im must be a valid image
* @(#) int im_circle(pim, cx, cy, radius, intensity)
* @(#) IMAGE *pim;
* @(#) int cx, cy, radius, intensity;
* @(#)
* @(#) Return -1 on error 0 on sucess.
*
* Copyright 1990, N. Dessipris.
*
* Author N. Dessipris
* Written on 30/05/1990
* Updated on:
* 22/7/93 JC
* - im_incheck() call added
* 16/8/94 JC
* - im_incheck() changed to im_makerw()
* 5/12/06
* - im_invalidate() after paint
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <vips/vips.h>
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
int
im_circle( IMAGE *im, int cx, int cy, int radius, int intensity)
{
PEL *start;
int size = 0;
int x, y, d, offset;
if( im_rwcheck( im ) )
return( -1 );
/* Check args */
if ( (im->data == NULL)||(im->BandFmt != IM_BANDFMT_UCHAR)||(im->Bands != 1)
||(im->Bbits != IM_BBITS_BYTE) )
{
im_errormsg("im_circle: unable to write input image");
return(-1);
}
if ((intensity > 255)||(intensity <= 0))
{
im_errormsg("im_circle: intensity between 0 and 255");
return(-1);
}
/* Check if circle fits into image */
if ( ((radius+cy)> im->Ysize - 1) || ((cy-radius)< 0 ) ||
((radius+cx)> im->Xsize - 1) || ((cx-radius) < 0 ) )
{
im_errormsg("im_circle: The circle doesnot fit in image");
return(-1);
}
/* Draw the circle */
size = im->Xsize;
start = (PEL*)im->data;
offset = cy * im->Xsize + cx; /* point at the center of the circle */
x = 0;
y = radius;
d = 3 - 2 * radius;
while ( x < y )
{
*(start + offset + size * y + x) = (PEL)intensity;
*(start + offset + size * x + y) = (PEL)intensity;
*(start + offset + size * y - x) = (PEL)intensity;
*(start + offset + size * x - y) = (PEL)intensity;
*(start + offset - size * y - x) = (PEL)intensity;
*(start + offset - size * x - y) = (PEL)intensity;
*(start + offset - size * y + x) = (PEL)intensity;
*(start + offset - size * x + y) = (PEL)intensity;
if (d < 0 )
d += ( 4 * x + 6 );
else
{
d += ( 4 * ( x - y ) + 10 );
y--;
}
x++;
}
if ( x== y )
{
*(start + offset + size * y + x) = (PEL)intensity;
*(start + offset + size * x + y) = (PEL)intensity;
*(start + offset + size * y - x) = (PEL)intensity;
*(start + offset + size * x - y) = (PEL)intensity;
*(start + offset - size * y - x) = (PEL)intensity;
*(start + offset - size * x - y) = (PEL)intensity;
*(start + offset - size * y + x) = (PEL)intensity;
*(start + offset - size * x + y) = (PEL)intensity;
}
im_invalidate( im );
return(0);
}