Framebuffer 画点，画线，画多边形，画圆

转自 http://blog.chinaunix.net/uid-22666248-id-283558.html

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <asm/page.h>
#include <linux/fb.h>
#define TRUE 1
#define FALSE 0
#define MIN(x,y) ((x)>(y)?(y):(x))
#define MAX(x,y) ((x)>(y)?(x):(y))
typedef struct fbdev{
int fb;
unsigned long fb_mem_offset;
unsigned long fb_mem;
struct fb_fix_screeninfo fb_fix;
struct fb_var_screeninfo fb_var;
char dev[20];
} FBDEV, *PFBDEV;
typedef struct point{
int x;
int y;
int z;
} POINT, *PPOINT;
void draw_dot (PFBDEV pFbdev, POINT p, uint8_t r, uint8_t g, uint8_t b);
void draw_line(PFBDEV pFbdev, POINT p1, POINT p2, uint8_t r, uint8_t g, uint8_t b);
void draw_polygon(PFBDEV pFbdev, uint32_t num, PPOINT array, uint8_t r, uint8_t g, uint8_t b);
void draw_triangle(PFBDEV pFbdev, POINT p1, POINT p2, POINT p3, uint8_t r, uint8_t g, uint8_t b);
void draw_circle(PFBDEV pFbdev, POINT center, uint32_t radius, uint8_t r, uint8_t g, uint8_t b);
void draw_parabola_x(PFBDEV pFbdev, POINT center, int a, uint8_t r, uint8_t g, uint8_t b);
void draw_parabola_y(PFBDEV pFbdev, POINT center, int a, uint8_t r, uint8_t g, uint8_t b);
int fb_open(PFBDEV pFbdev)
{
pFbdev->fb = open(pFbdev->dev, O_RDWR);
if(pFbdev->fb < 0)
{
printf("Error opening %s: %m. Check kernel config\n", pFbdev->dev);
return FALSE;
}
if (-1 == ioctl(pFbdev->fb,FBIOGET_VSCREENINFO,&(pFbdev->fb_var)))
{
printf("ioctl FBIOGET_VSCREENINFO\n");
return FALSE;
}
if (-1 == ioctl(pFbdev->fb,FBIOGET_FSCREENINFO,&(pFbdev->fb_fix)))
{
printf("ioctl FBIOGET_FSCREENINFO\n");
return FALSE;
}
pFbdev->fb_mem_offset = (unsigned long)(pFbdev->fb_fix.smem_start) & (~PAGE_MASK);
pFbdev->fb_mem = (unsigned long int)mmap(NULL, pFbdev->fb_fix.smem_len +
pFbdev->fb_mem_offset,
PROT_READ | PROT_WRITE, MAP_SHARED, pFbdev->fb, 0);
if (-1L == (long) pFbdev->fb_mem)
{
printf("mmap error! mem:%ld offset:%ld\n", pFbdev->fb_mem,
pFbdev->fb_mem_offset);
return FALSE;
}
return TRUE;
}
void fb_close(PFBDEV pFbdev)
{
close(pFbdev->fb);
pFbdev->fb=-1;
}
void fb_memcpy(void *addr, void *color, size_t len)
{
memcpy(addr, color, len);
}
void draw_dot (PFBDEV pFbdev, POINT p, uint8_t r, uint8_t g, uint8_t b)
{
uint32_t offset;
uint8_t color[4];
color[0] = b;
color[1] = g;
color[2] = r;
color[3] = 0x0;
offset = p.y*pFbdev->fb_fix.line_length+4*p.x;
fb_memcpy((void*)(pFbdev->fb_mem + pFbdev->fb_mem_offset + offset), color, 4);
}
void draw_line(PFBDEV pFbdev, POINT p1, POINT p2, uint8_t r, uint8_t g, uint8_t b)
{
POINT p;
int x,y;
for( x=MIN(p1.x,p2.x); x<=MAX(p1.x,p2.x); x++ )
{
y = (p2.y-p1.y)*(x-p1.x)/(p2.x-p1.x) + p1.y;
p.x = x;
p.y = y;
draw_dot(pFbdev, p, r, g, b);
}
}
void draw_triangle(PFBDEV pFbdev, POINT p1, POINT p2, POINT p3, uint8_t r, uint8_t g, uint8_t b)
{
POINT p[3];
p[0] = p1;
p[1] = p2;
p[2] = p3;
draw_polygon(pFbdev, 3, p, r, g, b);
}
void draw_polygon(PFBDEV pFbdev, uint32_t num, PPOINT array, uint8_t r, uint8_t g, uint8_t b)
{
int i;
for(i=0; i<num; i++)
{
draw_line(pFbdev, array[i], array[(i+1)%num], r, g, b);
}
}
void draw_circle(PFBDEV pFbdev, POINT center, uint32_t radius, uint8_t r, uint8_t g, uint8_t b)
{
POINT p;
int x,y,tmp;
for(x=center.x-radius; x<=center.x+radius; x++)
{
p.x = x;
tmp = sqrt(radius*radius -(x-center.x)*(x-center.x));
p.y = center.y + tmp;
draw_dot(pFbdev, p, r, g, b);
p.y = center.y - tmp;
draw_dot(pFbdev, p, r, g, b);
}
for(y=center.y-radius; y<=center.y+radius; y++)
{
p.y = y;
tmp = sqrt(radius*radius - (y-center.y)*(y-center.y));
p.x = center.x + tmp;
draw_dot(pFbdev, p, r, g, b);
p.x = center.x - tmp;
draw_dot(pFbdev, p, r, g, b);
}
}
void draw_parabola_x(PFBDEV pFbdev, POINT center, int a, uint8_t r, uint8_t g, uint8_t b)
{
int x;
POINT p;
for(x=center.x-100; x<center.x+100; x++)
{
p.x = x;
p.y = (x-center.x)*(x-center.x)/a + center.y;
draw_dot(pFbdev, p, r, g, b);
}
}
void draw_parabola_y(PFBDEV pFbdev, POINT center, int a, uint8_t r, uint8_t g, uint8_t b)
{
int y;
POINT p;
for(y=center.y-100; y<center.y+100; y++)
{
p.y = y;
p.x = (y-center.y)*(y-center.y)/a + center.x;
draw_dot(pFbdev, p, r, g, b);
}
}
int main(void)
{
FBDEV fb;
memset(&fb, 0, sizeof(FBDEV));
strcpy(fb.dev, "/dev/fb0");
if(fb_open(&fb)==FALSE)
{
printf("open frame buffer error\n");
return 0;
}
POINT p1, p2, p3;
p1.x = 300;
p1.y = 450;
p2.x = 500;
p2.y = 300;
draw_line( &fb, p1, p2, 0x0, 0xff, 0x0 );
p1.x = 200;
p1.y = 200;
p2.x = 300;
p2.y = 400;
p3.x = 500;
p3.y = 250;
draw_triangle(&fb, p1, p2, p3, 0x0, 0xff, 0x0);
POINT center = { 600, 500, 0 };
int radius = 100;
draw_circle(&fb, center, radius, 0x0, 0xff, 0x0);
center.x = 700;
center.y = 250;
int a = -100;
draw_parabola_x(&fb, center, a, 0x0, 0xff, 0x0);
draw_parabola_x(&fb, center, -a, 0x0, 0xff, 0x0);
draw_parabola_y(&fb, center, a, 0x0, 0xff, 0x0);
draw_parabola_y(&fb, center, -a, 0x0, 0xff, 0x0);
fb_close(&fb);
return 0;
}

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