Linux下framebuffer操作方法

帧缓冲区接口编程

最新推荐文章于 2024-08-06 21:28:16 发布

原创最新推荐文章于 2024-08-06 21:28:16 发布 · 1.3k 阅读

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#linux #buffer #null

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本文介绍了一种使用帧缓冲区接口进行编程的方法。通过打开设备文件/dev/fb0并使用ioctl进行配置，获取了固定屏幕信息及可变屏幕信息。此外，还检查了视觉模式是否为真彩色或直接色彩，并将帧缓冲区映射到内存。

unsigned char *fmem;

int FrameBufferFD;

FrameBufferFD = open("/dev/fb0", O_RDWR);

if (FrameBufferFD < 0)

     {
           fprintf(stderr, "Error opening /dev/fb0/n");
           return (-1);
      }

     /* Get the fixed screen info */
     if (ioctl(*FrameBufferFD, FBIOGET_FSCREENINFO, &FixedInfo))

    {
           fprintf(stderr, "error: ioctl(FBIOGET_FSCREENINFO) failed/n");
           return (-1);
    }

/* get the variable screen info */
if (ioctl(*FrameBufferFD, FBIOGET_VSCREENINFO, &OrigVarInfo))

    {
          fprintf(stderr, "error: ioctl(FBIOGET_VSCREENINFO) failed/n");
          return (-1);
    }

     if (FixedInfo.visual != FB_VISUAL_TRUECOLOR && FixedInfo.visual != FB_VISUAL_DIRECTCOLOR)

    {
         fprintf(stderr, "non-TRUE/DIRECT-COLOR visuals (0x%x) not supported by this demo./n", FixedInfo.visual);
        return (-1);
    }

     /*
      * fbdev says the frame buffer is at offset zero, and the mmio region
      * is immediately after.
      */
     /* mmap the framebuffer into our address space */
      fmem = mmap(0, /* start */
        FixedInfo.smem_len, /* bytes */
        PROT_READ | PROT_WRITE, /* prot */
        MAP_SHARED, /* flags */
        FrameBufferFD, /* fd */
        0 /* offset */);
     if (fmem == NULL)

    {
         fprintf(stderr, "error: unable to mmap framebuffer/n");
         return(-1);
    }
   printf("fmem in %x/n",fmem);
    return fmem;