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144 lines
2.9 KiB
C
144 lines
2.9 KiB
C
/* scale.c - image scaling
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*
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* Raster graphics library
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*
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* Copyright (c) 1997 Alfredo K. Kojima
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free
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* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <config.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <X11/Xlib.h>
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#include <assert.h>
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#include "wraster.h"
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/*
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*----------------------------------------------------------------------
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* RScaleImage--
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* Creates a scaled copy of an image.
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*
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* Returns:
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* The new scaled image.
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*
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*----------------------------------------------------------------------
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*/
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RImage*
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RScaleImage(RImage *image, unsigned new_width, unsigned new_height)
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{
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int ox;
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int px, py;
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register int x, y, t;
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int dx, dy;
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unsigned char *sr, *sg, *sb, *sa;
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unsigned char *dr, *dg, *db, *da;
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RImage *img;
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assert(new_width >= 0 && new_height >= 0);
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if (new_width == image->width && new_height == image->height)
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return RCloneImage(image);
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img = RCreateImage(new_width, new_height, image->data[3]!=NULL);
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if (!img)
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return NULL;
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/* fixed point math idea taken from Imlib by
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* Carsten Haitzler (Rasterman) */
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dx = (image->width<<16)/new_width;
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dy = (image->height<<16)/new_height;
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py = 0;
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dr = img->data[0];
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dg = img->data[1];
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db = img->data[2];
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da = img->data[3];
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if (image->data[3]!=NULL) {
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int ot;
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ot = -1;
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for (y=0; y<new_height; y++) {
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t = image->width*(py>>16);
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sr = image->data[0]+t;
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sg = image->data[1]+t;
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sb = image->data[2]+t;
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sa = image->data[3]+t;
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ot = t;
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ox = 0;
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px = 0;
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for (x=0; x<new_width; x++) {
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px += dx;
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*(dr++) = *sr;
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*(dg++) = *sg;
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*(db++) = *sb;
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*(da++) = *sa;
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t = (px - ox)>>16;
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ox += t<<16;
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sr += t;
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sg += t;
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sb += t;
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sa += t;
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}
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py += dy;
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}
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} else {
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int ot;
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ot = -1;
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for (y=0; y<new_height; y++) {
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t = image->width*(py>>16);
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sr = image->data[0]+t;
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sg = image->data[1]+t;
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sb = image->data[2]+t;
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ot = t;
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ox = 0;
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px = 0;
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for (x=0; x<new_width; x++) {
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px += dx;
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*(dr++) = *sr;
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*(dg++) = *sg;
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*(db++) = *sb;
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t = (px-ox)>>16;
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ox += t<<16;
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sr += t;
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sg += t;
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sb += t;
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}
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py += dy;
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}
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}
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return img;
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}
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