动手写 framebuffer 画点、划线程序 （七）

 本文的copyright归[e-mail] 所有，使用GPL发布，可以自由拷贝，转载。但转载请保持文档的完整性，注明原作者及原链接，严禁用于任何商业用途。
作者：[e-mail]
博客：yuweixian4230.blog.chinaunix.net 


  简单实现了 画点、划线、画矩形的程序编写，没有时间去编写其他的了，以后具体做到的这方面的事，在详细写吧。。
   
     没有写 颜色操作。

代码上传； framebuff-myself-press.rar  

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

typedef struct fbdev{
    int fdfd;     //open "dev/fb0"
    struct fb_var_screeninfo vinfo;
    struct fb_fix_screeninfo finfo;
    long int screensize;
    char *map_fb;

}FBDEV;

void init_dev(FBDEV *dev)
{
    FBDEV *fr_dev=dev;

    fr_dev->fdfd=open("/dev/fb0",O_RDWR);
    printf("the framebuffer device was opended successfully.\n");

    ioctl(fr_dev->fdfd,FBIOGET_FSCREENINFO,&(fr_dev->finfo)); //获取 固定参数

    ioctl(fr_dev->fdfd,FBIOGET_VSCREENINFO,&(fr_dev->vinfo)); //获取可变参数

    fr_dev->screensize=fr_dev->vinfo.xres*fr_dev->vinfo.yres*fr_dev->vinfo.bits_per_pixel/8;

    fr_dev->map_fb=(char *)mmap(NULL,fr_dev->screensize,PROT_READ|PROT_WRITE,MAP_SHARED,fr_dev->fdfd,0);

    printf("init_dev successfully.\n");
}

void draw_dot(FBDEV *dev,int x,int y)  //(x.y) 是坐标
{
    FBDEV *fr_dev=dev;
    int *xx=&x;
    int *yy=&y;

    long int location=0;
    location=location=(*xx+fr_dev->vinfo.xoffset)*(fr_dev->vinfo.bits_per_pixel/8)+
                 (*yy+fr_dev->vinfo.yoffset)*fr_dev->finfo.line_length;
    int b=10;
    int g=10;
    int r=10;
    unsigned short int t=r<<11|g<<5|b;
    *((unsigned short int *)(fr_dev->map_fb+location))=t;
}


void draw_line(FBDEV *dev,int x1,int y1,int x2,int y2)
{
    FBDEV *fr_dev=dev;
    int *xx1=&x1;
    int *yy1=&y1;
    int *xx2=&x2;
    int *yy2=&y2;

    int i=0;
    int j=0;
    int tekxx=*xx2-*xx1;
    int tekyy=*yy2-*yy1;

    //if((*xx2>=*xx1)&&(*yy2>=*yy1))
    if(*xx2>=*xx1)
    {
        for(i=*xx1;i<=*xx2;i++)
        {
            j=(i-*xx1)*tekyy/tekxx+*yy1;
            draw_dot(fr_dev,i,j);
        }
    }
    else
    {
        //if(*xx2<*xx1)
        for(i=*xx2;i<*xx1;i++)
        {
            j=(i-*xx2)*tekyy/tekxx+*yy2;
            draw_dot(fr_dev,i,j);
        }
    }


}

void draw_rect(FBDEV *dev,int x1,int y1,int x2,int y2)
{
    FBDEV *fr_dev=dev;
    int *xx1=&x1;
    int *yy1=&y1;
    int *xx2=&x2;
    int *yy2=&y2;
    int i=0,j=0;

    for(j=*yy1;j<*yy2;j++)               //注意 这里要 xx1 < xx2
        for(i=*xx1;i<*xx2;i++)
        {

            draw_dot(fr_dev,i,j);

        }

}
int main()
{
    FBDEV      fr_dev;
    fr_dev.fdfd=-1;
   
init_dev(&fr_dev);

    draw_line(&fr_dev,0,0,100,100);
    draw_line(&fr_dev,200,200,110,110);
   
draw_line(&fr_dev,10,200,150,100);
    draw_line(&fr_dev,300,10,160,90);
   
draw_rect(&fr_dev,300,200,320,240);

    printf("bye the framebuffer\n");
    munmap(fr_dev.map_fb,fr_dev.screensize);
    close(fr_dev.fdfd);

    return 0;
}

画了四条线，和一个矩形