linux下的framebuffer（2）

目前根据自己对linux中framebuffer的了解写了如下的代码：

下面是用到的一些文件，在linux下编译通过，显示图形效果。

 效果：主要代码在fb.c中，在显卡x,y=(1100,100)出显示x0,y0=(130,150)大小的颜色，再在x0,y0的坐标基础上添加红色图像，如代码所所示。

main.c

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <time.h>
#include <sys/mman.h>
#include"fb.h"

 

int main()
{

  init_fb();//init framebuffer

 
 
 return 0;
}

 

fb.c

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <time.h>
#include <sys/mman.h>
#include"fb.h"

color_t color={0,0,150,100};   //the color of background
color_t color1={0,255,0,0};    //in window   red

int init_fb()
 {
  int fbfd = 0;
 struct fb_var_screeninfo vinfo;
 struct fb_fix_screeninfo finfo;
 long int screensize = 0;
 char *fbp = 0;
 int x = 0, y = 0;
 long int location = 0;
 long int location1 = 0;
 fbfd = open("/dev/fb0", O_RDWR); // Open the file for reading and writing
  if (!fbfd)
  {
  printf("Error: cannot open framebuffer device.\n");
  exit(0);
  }
  printf("The framebuffer device was opened successfully.\n");
  // Get fixed screen information
  if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo))
  {
  printf("Error reading fixed information.\n");
   exit(0);
  }
  // Get variable screen information
  if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo))
  {          
  printf("Error reading variable information.\n");
   exit(0);
  }
  printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel);
        // Figure out the size of the screen in bytes
  screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
  printf("screensize is %ldKB\n",screensize/1024);
        // Map the device to memory
  fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
  if((int)fbp == -1)
  {
  printf("Error: failed to map framebuffer device to memory.\n");
  exit(0);
  }
  printf("The framebuffer device was mapped to memory successfully.\n");

 for (x = 0; x < DISPLAY_WIDE; x++)
  for (y = 0; y < DISPLAY_HIGH; y++)
  {
  location = (x+1100+vinfo.xoffset) * (vinfo.bits_per_pixel/8) +(y+100+vinfo.yoffset) * finfo.line_length;
 //if (vinfo.bits_per_pixel == 32)
  
   *(fbp + location + 3) = color.t;// No transparency
   *(fbp + location + 2) = color.r;// A  red
   *(fbp + location + 1) = color.g;// A  green
   *(fbp + location) = color.b;    // Some blue 
     
  } 
  /*
    function:in window display red
    author  :sjmp
     time   :2012.06.02
  */
  for (x = 0; x < DISPLAY_WIDE-10; x++)
  for (y = 0; y < DISPLAY_HIGH-10; y++)
  {
  location1 = (x+5+(1100+vinfo.xoffset)) * (vinfo.bits_per_pixel/8) +(y+(5+100+vinfo.yoffset)) * finfo.line_length;
   *(fbp + location1 + 3) = color1.t;
   *(fbp + location1 + 2) = color1.r;
   *(fbp + location1 + 1) = color1.g;
   *(fbp + location1) = color1.b; 
   
   }
  munmap(fbp, screensize);
  return 0;
  close(fbfd);
 }

 

fb.h

#ifndef FBI_H_
#define FBI_H_

#define DISPLAY_WIDE  130      //display wide
#define DISPLAY_HIGH  150      //display high

typedef struct
 {
   int t;
   int r;
   int g;
   int b;
 } color_t;

int  init_fb();

#endif

 

Makefile

%.o : %.c        
 @gcc -Wall -c $< -o $@

OBJS= main.o fb.o                //only this need change

all: $(OBJS)
 @gcc $(OBJS) -o fb
 @strip fb                              //put 'fb ' in the first place
 
clean:
  @rm -f *.o
 @rm -f *.c~
  @rm -f fb