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Initial revision
This commit is contained in:
scottc
535
wrlib/draw.c
Normal file
535
wrlib/draw.c
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@@ -0,0 +1,535 @@
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/* draw.c - pixel plotting, line drawing
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*
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* Raster graphics library
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*
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* Copyright (c) 1998 Dan Pascu
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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 <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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#include "wraster.h"
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#define MIN(a,b) ((a) < (b) ? (a) : (b))
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#define MAX(a,b) ((a) > (b) ? (a) : (b))
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/*
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* Returns the color of the pixel at coordinates (x, y) in "color".
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*/
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Bool
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RGetPixel(RImage *image, int x, int y, RColor *color)
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{
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int ofs;
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assert(image!=NULL);
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if (x < 0 || x >= image->width
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|| y < 0 || y >= image->height)
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return False;
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ofs = y*image->width + x;
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color->red = image->data[0][ofs];
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color->green = image->data[1][ofs];
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color->blue = image->data[2][ofs];
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/* If the image does not have alpha channel, we consider alpha 255 */
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if (image->data[3])
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color->alpha = image->data[3][ofs];
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else
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color->alpha = 255;
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return True;
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}
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void
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RPutPixel(RImage *image, int x, int y, RColor *color)
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{
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int ofs;
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unsigned char *sr, *sg, *sb, *sa;
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assert(image!=NULL);
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assert(color!=NULL);
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assert(x >= 0 && x < image->width);
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assert(y >= 0 && y < image->height);
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ofs = y*image->width + x;
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sr = image->data[0] + ofs;
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sg = image->data[1] + ofs;
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sb = image->data[2] + ofs;
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sa = image->data[3] + ofs;
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if (color->alpha==255) {
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*sr = color->red;
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*sg = color->green;
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*sb = color->blue;
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if (image->data[3])
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*sa = 255;
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} else {
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register int alpha, nalpha, r, g, b;
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r = color->red;
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g = color->green;
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b = color->blue;
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alpha = color->alpha;
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nalpha = 255 - alpha;
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*sr = (((int)*sr * nalpha) + (r * alpha))/256;
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*sg = (((int)*sg * nalpha) + (g * alpha))/256;
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*sb = (((int)*sb * nalpha) + (b * alpha))/256;
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if (image->data[3])
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*sa = alpha + ((int)*sa * nalpha)/256;
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}
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}
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static void
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operatePixel(RImage *image, int ofs, int operation, RColor *color)
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{
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unsigned char *sr, *sg, *sb, *sa;
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register int alpha, nalpha, tmp;
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int hasAlpha = image->data[3]!=NULL;
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alpha = color->alpha;
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nalpha = 255 - alpha;
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sr = image->data[0] + ofs;
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sg = image->data[1] + ofs;
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sb = image->data[2] + ofs;
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sa = image->data[3] + ofs;
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switch (operation) {
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case RClearOperation:
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*sr = 0;
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*sg = 0;
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*sb = 0;
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if (hasAlpha)
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*sa = 0;
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break;
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case RCopyOperation:
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*sr = color->red;
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*sg = color->green;
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*sb = color->blue;
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if (hasAlpha)
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*sa = color->alpha;
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break;
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case RNormalOperation:
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if (color->alpha==255) {
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*sr = color->red;
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*sg = color->green;
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*sb = color->blue;
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if (hasAlpha)
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*sa = 255;
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} else {
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*sr = (((int)*sr * nalpha) + ((int)color->red * alpha))/256;
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*sg = (((int)*sg * nalpha) + ((int)color->green * alpha))/256;
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*sb = (((int)*sb * nalpha) + ((int)color->blue * alpha))/256;
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}
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break;
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case RAddOperation:
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tmp = color->red + *sr;
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*sr = MIN(255, tmp);
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tmp = color->green + *sg;
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*sg = MIN(255, tmp);
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tmp = color->blue + *sb;
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*sb = MIN(255, tmp);
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if (hasAlpha)
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*sa = MIN(*sa, color->alpha);
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break;
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case RSubtractOperation:
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tmp = *sr - color->red;
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*sr = MAX(0, tmp);
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tmp = *sg - color->green;
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*sg = MAX(0, tmp);
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tmp = *sb - color->blue;
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*sb = MAX(0, tmp);
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if (hasAlpha)
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*sa = MIN(*sa, color->alpha);
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break;
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}
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}
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void
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ROperatePixel(RImage *image, int operation, int x, int y, RColor *color)
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{
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int ofs;
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assert(image!=NULL);
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assert(color!=NULL);
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assert(x >= 0 && x < image->width);
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assert(y >= 0 && y < image->height);
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ofs = y*image->width + x;
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operatePixel(image, ofs, operation, color);
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}
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void
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RPutPixels(RImage *image, RPoint *points, int npoints, int mode, RColor *color)
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{
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register int x, y, i;
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assert(image!=NULL);
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assert(points!=NULL);
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x = y = 0;
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for (i=0; i<npoints; i++) {
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if (mode == RAbsoluteCoordinates) {
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x = points[i].x;
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y = points[i].y;
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} else {
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x += points[i].x;
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y += points[i].y;
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}
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RPutPixel(image, x, y, color);
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}
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}
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void
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ROperatePixels(RImage *image, int operation, RPoint *points, int npoints,
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int mode, RColor *color)
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{
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register int x, y, i;
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assert(image!=NULL);
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assert(points!=NULL);
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x = y = 0;
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for (i=0; i<npoints; i++) {
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if (mode == RAbsoluteCoordinates) {
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x = points[i].x;
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y = points[i].y;
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} else {
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x += points[i].x;
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y += points[i].y;
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}
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ROperatePixel(image, operation, x, y, color);
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}
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}
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/*
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* This routine is a generic drawing routine, based on Bresenham's line
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* drawing algorithm.
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*/
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static int
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genericLine(RImage *image, int x0, int y0, int x1, int y1, RColor *color,
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int operation, int polyline)
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{
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int i, err, du, dv, du2, dv2, uofs, vofs, last;
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assert(image!=NULL);
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assert(x0 >= 0 && x0 <= image->width);
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assert(x1 >= 0 && x1 <= image->width);
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assert(y0 >= 0 && y0 <= image->height);
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assert(y1 >= 0 && y1 <= image->height);
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if (x0 < x1) {
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du = x1 - x0;
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uofs = 1;
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} else {
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du = x0 - x1;
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uofs = -1;
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}
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if (y0 < y1) {
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dv = y1 -y0;
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vofs = image->width;
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} else {
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dv = y0 - y1;
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vofs = -image->width;
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}
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if (du < dv) {
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/* Swap coordinates between them, so that always du>dv */
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i = du; du = dv; dv = i;
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i = uofs; uofs = vofs; vofs = i;
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}
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err = 0;
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du2 = du<<1;
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dv2 = dv<<1;
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last = (polyline) ? du-1 : du;
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if (color->alpha==255 || operation==RCopyOperation) {
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unsigned char *sr, *sg, *sb, *sa;
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i = y0*image->width + x0;
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sr = image->data[0] + i;
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sg = image->data[1] + i;
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sb = image->data[2] + i;
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sa = image->data[3] + i;
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for (i=0; i<=last; i++) {
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/* Draw the pixel */
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*sr = color->red;
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*sg = color->green;
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*sb = color->blue;
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if (image->data[3])
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*sa = 255;
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/* Compute error for NeXT Step */
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err += dv2;
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if (err >= du) {
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sr += vofs; sg += vofs;
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sb += vofs; sa += vofs;
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err -= du2;
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}
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sr += uofs; sg += uofs;
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sb += uofs; sa += uofs;
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}
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} else {
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register int ofs = y0*image->width + x0;
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for (i=0; i<=last; i++) {
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/* Draw the pixel */
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operatePixel(image, ofs, operation, color);
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/* Compute error for NeXT Step */
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err += dv2;
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if (err >= du) {
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ofs += vofs;
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err -= du2;
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}
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ofs += uofs;
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}
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}
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#if 0
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if (mode == RALTER_PIXELS) {
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RColorOffset *cdelta = (RColorOffset*)cdata;
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register short r, g, b, a;
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for (i=0; i<=last; i++) {
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/* Change the pixel with offset */
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r = (short)*sr + cdelta->red;
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g = (short)*sg + cdelta->green;
|
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b = (short)*sb + cdelta->blue;
|
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if (r>255) r = 255; else if (r<0) r = 0;
|
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if (g>255) g = 255; else if (g<0) g = 0;
|
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if (b>255) b = 255; else if (b<0) b = 0;
|
||||
*sr = (unsigned char) r;
|
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*sg = (unsigned char) g;
|
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*sb = (unsigned char) b;
|
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if (image->data[3]) {
|
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a = (short)*sa + cdelta->alpha;
|
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if (a>255) a = 255; else if (a<0) a = 0;
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*sa = (unsigned char) a;
|
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}
|
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|
||||
/* Compute error for NeXT Step */
|
||||
err += dv2;
|
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if (err >= du) {
|
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sr += vofs; sg += vofs;
|
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sb += vofs; sa += vofs;
|
||||
err -= du2;
|
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}
|
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sr += uofs; sg += uofs;
|
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sb += uofs; sa += uofs;
|
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}
|
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} else {
|
||||
RColor *color = (RColor*)cdata;
|
||||
|
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if (color->alpha==255) {
|
||||
for (i=0; i<=last; i++) {
|
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/* Draw the pixel */
|
||||
*sr = color->red;
|
||||
*sg = color->green;
|
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*sb = color->blue;
|
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if (image->data[3])
|
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*sa = 255;
|
||||
|
||||
/* Compute error for NeXT Step */
|
||||
err += dv2;
|
||||
if (err >= du) {
|
||||
sr += vofs; sg += vofs;
|
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sb += vofs; sa += vofs;
|
||||
err -= du2;
|
||||
}
|
||||
sr += uofs; sg += uofs;
|
||||
sb += uofs; sa += uofs;
|
||||
}
|
||||
} else {
|
||||
register short alpha, nalpha, r, g ,b;
|
||||
|
||||
alpha = color->alpha;
|
||||
nalpha = 255 - alpha;
|
||||
r = color->red;
|
||||
g = color->green;
|
||||
b = color->blue;
|
||||
|
||||
for (i=0; i<=last; i++) {
|
||||
/* Draw the pixel */
|
||||
*sr = (((int)*sr * nalpha) + (r * alpha))/256;
|
||||
*sg = (((int)*sg * nalpha) + (g * alpha))/256;
|
||||
*sb = (((int)*sb * nalpha) + (b * alpha))/256;
|
||||
if (image->data[3])
|
||||
*sa = alpha + ((int)*sa * nalpha)/256;
|
||||
|
||||
/* Compute error for NeXT Step */
|
||||
err += dv2;
|
||||
if (err >= du) {
|
||||
sr += vofs; sg += vofs;
|
||||
sb += vofs; sa += vofs;
|
||||
err -= du2;
|
||||
}
|
||||
sr += uofs; sg += uofs;
|
||||
sb += uofs; sa += uofs;
|
||||
}
|
||||
}
|
||||
}
|
||||
#endif
|
||||
return True;
|
||||
}
|
||||
|
||||
|
||||
int
|
||||
RDrawLine(RImage *image, int x0, int y0, int x1, int y1, RColor *color)
|
||||
{
|
||||
return genericLine(image, x0, y0, x1, y1, color, RNormalOperation, False);
|
||||
}
|
||||
|
||||
|
||||
int
|
||||
ROperateLine(RImage *image, int operation, int x0, int y0, int x1,
|
||||
int y1, RColor *color)
|
||||
{
|
||||
return genericLine(image, x0, y0, x1, y1, color, operation, False);
|
||||
}
|
||||
|
||||
|
||||
void
|
||||
RDrawLines(RImage *image, RPoint *points, int npoints, int mode, RColor *color)
|
||||
{
|
||||
register int x1, y1, x2, y2, i;
|
||||
|
||||
assert(points!=NULL);
|
||||
|
||||
if (npoints==0)
|
||||
return;
|
||||
|
||||
x1 = points[0].x;
|
||||
y1 = points[0].y;
|
||||
x2 = y2 = 0;
|
||||
|
||||
for (i=1; i<npoints-1; i++) {
|
||||
if (mode == RAbsoluteCoordinates) {
|
||||
x2 = points[i].x;
|
||||
y2 = points[i].y;
|
||||
} else {
|
||||
x2 += points[i-1].x;
|
||||
y2 += points[i-1].y;
|
||||
}
|
||||
/* Don't draw pixels at junction points twice */
|
||||
genericLine(image, x1, y1, x2, y2, color, RNormalOperation, True);
|
||||
x1 = x2;
|
||||
y1 = y2;
|
||||
}
|
||||
i = npoints-1; /* last point */
|
||||
if (mode == RAbsoluteCoordinates) {
|
||||
x2 = points[i].x;
|
||||
y2 = points[i].y;
|
||||
} else {
|
||||
x2 += points[i-1].x;
|
||||
y2 += points[i-1].y;
|
||||
}
|
||||
i = (points[0].x==x2 && points[0].y==y2 && npoints>1);
|
||||
genericLine(image, x1, y1, x2, y2, color, RNormalOperation, i);
|
||||
}
|
||||
|
||||
|
||||
void
|
||||
ROperateLines(RImage *image, int operation, RPoint *points,
|
||||
int npoints, int mode, RColor *color)
|
||||
{
|
||||
register int x1, y1, x2, y2, i;
|
||||
|
||||
assert(points!=NULL);
|
||||
|
||||
if (npoints==0)
|
||||
return;
|
||||
|
||||
x1 = points[0].x;
|
||||
y1 = points[0].y;
|
||||
x2 = y2 = 0;
|
||||
|
||||
for (i=1; i<npoints-1; i++) {
|
||||
if (mode == RAbsoluteCoordinates) {
|
||||
x2 = points[i].x;
|
||||
y2 = points[i].y;
|
||||
} else {
|
||||
x2 += points[i-1].x;
|
||||
y2 += points[i-1].y;
|
||||
}
|
||||
/* Don't draw pixels at junction points twice */
|
||||
genericLine(image, x1, y1, x2, y2, color, operation, True);
|
||||
x1 = x2;
|
||||
y1 = y2;
|
||||
}
|
||||
i = npoints-1; /* last point */
|
||||
if (mode == RAbsoluteCoordinates) {
|
||||
x2 = points[i].x;
|
||||
y2 = points[i].y;
|
||||
} else {
|
||||
x2 += points[i-1].x;
|
||||
y2 += points[i-1].y;
|
||||
}
|
||||
i = (points[0].x==x2 && points[0].y==y2 && npoints>1);
|
||||
genericLine(image, x1, y1, x2, y2, color, operation, i);
|
||||
}
|
||||
|
||||
|
||||
void
|
||||
RDrawSegments(RImage *image, RSegment *segs, int nsegs, RColor *color)
|
||||
{
|
||||
register int i;
|
||||
|
||||
assert(segs!=NULL);
|
||||
|
||||
for (i=0; i<nsegs; i++) {
|
||||
genericLine(image, segs->x1, segs->y1, segs->x2, segs->y2, color,
|
||||
RNormalOperation, False);
|
||||
segs++;
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
void
|
||||
ROperateSegments(RImage *image, int operation, RSegment *segs,
|
||||
int nsegs, RColor *color)
|
||||
{
|
||||
register int i;
|
||||
|
||||
assert(segs!=NULL);
|
||||
|
||||
for (i=0; i<nsegs; i++) {
|
||||
genericLine(image, segs->x1, segs->y1, segs->x2, segs->y2, color,
|
||||
operation, False);
|
||||
segs++;
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
Reference in New Issue
Block a user