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/*
* Copyright (C) 2007 Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; version 2.
*
* 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 General Public License for more details.
*
* You should have received a copy of the GNU 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.
*
* Author: Wolfgang Beck <bewo at users.berlios.de> 2007
*/
#include <stdlib.h>
#include <string.h>
#include "scale.h"
static void write_px_rgb(const pixel_t * const v, pixel_t * const p)
{
// memcpy(p, v, 3);
p[0] = v[2];
p[1] = v[1];
p[2] = v[0];
}
static void write_px_bgr(const pixel_t * const v, pixel_t * const p)
{
// memcpy(p, v, 3);
p[0] = v[0];
p[1] = v[1];
p[2] = v[2];
}
static inline void average(const pixel_t *x, const pixel_t *y, pixel_t *p)
{
p[0] = (x[0] + y[0]) / 2;
p[1] = (x[1] + y[1]) / 2;
p[2] = (x[2] + y[2]) / 2;
}
static void (*write_px)(const pixel_t * const v, pixel_t * const p)
= write_px_rgb;
void set_color_correction(int rgb)
{
if(rgb) {
write_px = write_px_bgr;
} else {
write_px = write_px_rgb;
}
}
/*
* Bresenham image scaling
* http://www.ddj.com/showArticle.jhtml?articleID=184405045
*/
void scale_line(
const pixel_t *src,
pixel_t *dst,
int src_w,
int dst_w
)
{
int num;
int ip;
int fp;
int e;
num = dst_w;
ip = src_w / dst_w;
fp = src_w % dst_w;
e = 0;
while(num > 0) {
write_px(src, dst);
dst += 3;
src += 3 * ip;
e += fp;
if(e >= dst_w) {
e -= dst_w;
src += 3;
}
--num;
}
}
void scale(
const pixel_t *src,
pixel_t *dst,
int src_w,
int src_h,
int dst_w,
int dst_h
)
{
int num;
int ip;
int fp;
int e;
const pixel_t *prev_src;
num = dst_h;
ip = (src_h / dst_h) * src_w;
fp = src_h % dst_h;
e = 0;
prev_src = NULL;
while(num > 0) {
if(prev_src == src) {
/*
* re-use last line
*/
memcpy(dst, dst - dst_w * 3, dst_w * 3);
} else {
scale_line(src, dst, src_w, dst_w);
prev_src = src;
}
dst += dst_w * 3;
src += ip * 3;
e += fp;
if(e >= dst_h) {
e -= dst_h;
src += src_w * 3;
}
--num;
}
}
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