1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
/*
* Copyright (c) 2017, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* ----------------------------------------------------------------------------
*
* This file implements the LOLWUT command. The command should do something
* fun and interesting, and should be replaced by a new implementation at
* each new version of Redis.
*/
#include "server.h"
/* This function represents our canvas. Drawing functions will take a pointer
* to a canvas to write to it. Later the canvas can be rendered to a string
* suitable to be printed on the screen, using unicode Braille characters. */
typedef struct lwCanvas {
int width;
int height;
char *pixels;
} lwCanvas;
/* Translate a group of 8 pixels (2x4 vertical rectangle) to the corresponding
* braille character. The byte should correspond to the pixels arranged as
* follows, where 0 is the least significant bit, and 7 the most significant
* bit:
*
* 0 3
* 1 4
* 2 5
* 6 7
*
* The corresponding utf8 encoded character is set into the three bytes
* pointed by 'output'.
*/
#include <stdio.h>
void lwTranslatePixelsGroup(int byte, char *output) {
int code = 0x2800 + byte;
/* Convert to unicode. This is in the U0800-UFFFF range, so we need to
* emit it like this in three bytes:
* 1110xxxx 10xxxxxx 10xxxxxx. */
output[0] = 0xE0 | (code >> 12); /* 1110-xxxx */
output[1] = 0x80 | ((code >> 6) & 0x3F); /* 10-xxxxxx */
output[2] = 0x80 | (code & 0x3F); /* 10-xxxxxx */
}
/* Allocate and return a new canvas of the specified size. */
lwCanvas *lwCreateCanvas(int width, int height) {
lwCanvas *canvas = zmalloc(sizeof(*canvas));
canvas->width = width;
canvas->height = height;
canvas->pixels = zmalloc(width*height);
memset(canvas->pixels,0,width*height);
return canvas;
}
/* Free the canvas created by lwCreateCanvas(). */
void lwFreeCanvas(lwCanvas *canvas) {
zfree(canvas->pixels);
zfree(canvas);
}
/* Set a pixel to the specified color. Color is 0 or 1, where zero means no
* dot will be displyed, and 1 means dot will be displayed.
* Coordinates are arranged so that left-top corner is 0,0. You can write
* out of the size of the canvas without issues. */
void lwPutPixel(lwCanvas *canvas, int x, int y, int color) {
if (x < 0 || x >= canvas->width ||
y < 0 || y >= canvas->height) return;
canvas->pixels[x+y*canvas->width] = color;
}
/* Return the value of the specified pixel on the canvas. */
int lwGetPixel(lwCanvas *canvas, int x, int y) {
if (x < 0 || x >= canvas->width ||
y < 0 || y >= canvas->height) return 0;
return canvas->pixels[x+y*canvas->width];
}
/* Converts the canvas to an SDS string representing the UTF8 characters to
* print to the terminal in order to obtain a graphical representaiton of the
* logical canvas. The actual returned string will require a terminal that is
* width/2 large and height/4 tall in order to hold the whole image without
* overflowing or scrolling, since each Barille character is 2x4. */
sds lwRenderCanvas(lwCanvas *canvas) {
sds text = sdsempty();
for (int y = 0; y < canvas->height; y += 4) {
for (int x = 0; x < canvas->width; x += 2) {
/* We need to emit groups of 8 bits according to a specific
* arrangement. See lwTranslatePixelsGroup() for more info. */
int byte = 0;
if (lwGetPixel(canvas,x,y)) byte |= (1<<0);
if (lwGetPixel(canvas,x,y+1)) byte |= (1<<1);
if (lwGetPixel(canvas,x,y+2)) byte |= (1<<2);
if (lwGetPixel(canvas,x+1,y)) byte |= (1<<3);
if (lwGetPixel(canvas,x+1,y+1)) byte |= (1<<4);
if (lwGetPixel(canvas,x+1,y+2)) byte |= (1<<5);
if (lwGetPixel(canvas,x,y+3)) byte |= (1<<6);
if (lwGetPixel(canvas,x+1,y+3)) byte |= (1<<7);
char unicode[3];
lwTranslatePixelsGroup(byte,unicode);
text = sdscatlen(text,unicode,3);
}
if (y != canvas->height-1) text = sdscatlen(text,"\n",1);
}
return text;
}
int main(void) {
lwCanvas *c = lwCreateCanvas(80,80);
for (int i = 0; i < 40; i++) {
lwPutPixel(c,i,i,1);
}
sds rendered = lwRenderCanvas(c);
printf("%s\n", rendered);
}
|
