Linux Framebuffer编程简介

时间:2014-04-28 06:03:48   收藏:0   阅读:843

linux下,framebuffer设备文件名通常是/

dev/fb0,1,2等。
控制framebuffer设备的一般步骤如下:
1) 打开设备,映射framebuffer
2)依照硬件要求,准备好数据
3)把数据复制到framebuffer

例子程序如下:

1)打开设备,映射framebuffer
static void *fbbuf;
int openfb(char *devname)
{
    int fd;
    fd = open(devname, O_RDWR);
    if (ioctl(fd, FBIOGET_VSCREENINFO, &fbvar) < 0)
        return -1;
    bpp = fbvar.bits_per_pixel;
    screen_size = fbvar.xres * fbvar.yres * bpp / 8;
    fbbuf = mmap(0, screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    return fd;
}

2)数据准备,假设lcd控制器被初始化为565,16bit格式的
static inline int  make_pixel(unsigned int a, unsigned int r, unsigned int g, unsigned int b)
{
    return (unsigned int)(((r>>3)<<11)|((g>>2)<<5|(b>>3)));
}

3) 把想要显示的数据复制到framebuffer,假设把framebuffer填充成一种颜色
static void fill_pixel(unsigned int pixel, int x0, int y0, int w, int h)
{
    int i, j;
    unsigned short *pbuf = (unsigned short *)fbbuf;
    for (i = y0; i < h; i ++) {
        for (j = x0; j < w; j ++) {
            pbuf[i * screen_width + j] = pixel;
        }
    }
}

下面程序把lcd屏幕填充成蓝色
fill_pixel(make_pixel(0, 0, 0,0xff), 0, 0, screen_width, screen_height);
 
 

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