GRASS GIS 8 Programmer's Manual 8.3.2(2024)-exported
Loading...
Searching...
No Matches
pngdriver/draw_bitmap.c
Go to the documentation of this file.
1/*!
2 \file lib/pngdriver/draw_bitmap.c
3
4 \brief GRASS png display driver - draw bitmap
5
6 (C) 2003-2014 by Per Henrik Johansen and the GRASS Development Team
7
8 This program is free software under the GNU General Public License
9 (>=v2). Read the file COPYING that comes with GRASS for details.
10
11 \author Per Henrik Johansen (original contributor)
12 \author Glynn Clements
13 */
14
15#include <math.h>
16#include "pngdriver.h"
17
18#ifndef min
19#define min(a, b) ((a) < (b) ? (a) : (b))
20#endif
21#ifndef max
22#define max(a, b) ((a) > (b) ? (a) : (b))
23#endif
24
25/*!
26 \brief Draw bitmap
27
28 \param ncols,nrows number of columns and rows
29 \param threshold threshold value
30 \param buf data buffer
31 */
32
33void PNG_draw_bitmap(int ncols, int nrows, int threshold,
34 const unsigned char *buf)
35{
36 int i0 = max(png.clip_left - cur_x, 0);
37 int i1 = min(png.clip_rite - cur_x, ncols);
38 int j0 = max(png.clip_top - cur_y, 0);
39 int j1 = min(png.clip_bot - cur_y, nrows);
40
41 if (!png.true_color) {
42 int i, j;
43
44 for (j = j0; j < j1; j++) {
45 int y = cur_y + j;
46
47 for (i = i0; i < i1; i++) {
48 int x = cur_x + i;
49 unsigned int k = buf[j * ncols + i];
50 unsigned int *p = &png.grid[y * png.width + x];
51
52 if (k > (unsigned int)threshold)
53 *p = png.current_color;
54 }
55 }
56 }
57 else {
58 int r1, g1, b1, a1;
59 int i, j;
60
61 png_get_pixel(png.current_color, &r1, &g1, &b1, &a1);
62
63 for (j = j0; j < j1; j++) {
64 int y = cur_y + j;
65
66 for (i = i0; i < i1; i++) {
67 int x = cur_x + i;
68 unsigned int k = buf[j * ncols + i];
69 unsigned int *p = &png.grid[y * png.width + x];
70 int a0, r0, g0, b0;
71 unsigned int a, r, g, b;
72
73 png_get_pixel(*p, &r0, &g0, &b0, &a0);
74
75 a = (a0 * (255 - k) + a1 * k) / 255;
76 r = (r0 * (255 - k) + r1 * k) / 255;
77 g = (g0 * (255 - k) + g1 * k) / 255;
78 b = (b0 * (255 - k) + b1 * k) / 255;
79
80 *p = png_get_color(r, g, b, a);
81 }
82 }
83 }
84
85 png.modified = 1;
86}
unsigned int png_get_color(int r, int g, int b, int a)
void png_get_pixel(unsigned int pixel, int *r, int *g, int *b, int *a)
double b
double r
double cur_x
Definition driver/init.c:32
double cur_y
Definition driver/init.c:33
float g
Definition named_colr.c:7
void PNG_draw_bitmap(int ncols, int nrows, int threshold, const unsigned char *buf)
Draw bitmap.
#define min(a, b)
#define max(a, b)
struct png_state png
GRASS png display driver - header file.
double clip_left
Definition pngdriver.h:41
double clip_bot
Definition pngdriver.h:41
double clip_top
Definition pngdriver.h:41
int current_color
Definition pngdriver.h:33
int true_color
Definition pngdriver.h:34
unsigned int * grid
Definition pngdriver.h:43
int width
Definition pngdriver.h:42
double clip_rite
Definition pngdriver.h:41
int modified
Definition pngdriver.h:46
#define x