linux frame buffer grab

linux的驱动就是个字符设备，可以用read write ioctl mmap操作，通过/dev/fbx可以像文件一样直接读写
截屏dd if=/dev/fb0 of=snapshot
恢复cat snapshot > /dev/fb0
开源的有fbgrab工具，不过是生成png文件，我自己写了一个生成bmp文件的工具叫fbcap，录制成avi格式，通过socket或serial把设备的操作发送到host上：）。
保存bmp文件代码：
 int savebmp(char* filename, int size, int bmWidth, int bmHeight, int bmBitsPixel, unsigned char* buffer)
{
FILE *fp = NULL;
int j = bmHeight;
int nColors = 0;
int nPeletteLen = 0;
RGBQUAD *rgbquad = NULL;
fp = fopen(filename, "w+");
if(fp == NULL)
{
printf("open file :%s fail\n", filename);
return -1;
}
printf("size=%d, width=%d, height=%d, bitsPixel=%d\n", size, bmWidth, bmHeight, bmBitsPixel);
if (bmBitsPixel <= 8)
{
nColors = bmBitsPixel << 1;
nPeletteLen = nColors * sizeof(RGBQUAD);
rgbquad= malloc(sizeof(RGBQUAD)*nColors);
if (rgbquad == NULL)
{
fclose(fp);
return -1;
}
memset(rgbquad, 0, nColors * sizeof(RGBQUAD));
int index = 0;
for(index = 0; index < nColors; index++)
{
rgbquad[index].rgbBlue = index;
rgbquad[index].rgbGreen = index;
rgbquad[index].rgbRed = index;
}
#if 1
if (bmBitsPixel == 1)//blue word,white backgroud
{
rgbquad[nColors -2].rgbBlue = 255;
rgbquad[nColors -2].rgbGreen = 255;
rgbquad[nColors -2].rgbRed = 255;
rgbquad[nColors -1].rgbBlue = 0xff;
rgbquad[nColors -1].rgbGreen = 0;
rgbquad[nColors -1].rgbRed = 0;
}
#else
if (bmBitsPixel == 1)//white word,black backgroud
{
rgbquad[nColors -2].rgbBlue = 0 ;
rgbquad[nColors -2].rgbGreen = 0;
rgbquad[nColors -2].rgbRed = 0;
rgbquad[nColors -1].rgbBlue =0xFF;
rgbquad[nColors -1].rgbGreen = 0xff;
rgbquad[nColors -1].rgbRed = 0xFF;
}
#endif
}
printf("nColors=%d,pelettelen=%d\n",nColors, nPeletteLen);
//
BITMAPFILEHEADER bfh;
bfh.bfType = ((unsigned short)('M'<< 8)|'B');
bfh.bfRe