转载时请注明出处和作者联系方式
文章出处：http://www.limodev.cn/blog
作者联系方式：李先静 <xianjimli@gmail.com>
微博:http://weibo.com/2352470455/profile
为了截几张图片给broncho的A1做宣传，昨天写了一个截图工具。这个工具与其它截图工具不同的是，它不基于任何具体的GUI，直接从framebuffer中截图，然后保存为jpeg图片，所以适用于任何嵌入式linux设备。
o 打开framebuffer
static int fb_open(struct FB *fb, const char* fbfilename){ fb->fd = open(fbfilename, O_RDWR); if (fb->fd < 0) { fprintf(stderr, "can't open %s\n", fbfilename); return -1; } if (ioctl(fb->fd, FBIOGET_FSCREENINFO, &fb->fi) < 0) goto fail; if (ioctl(fb->fd, FBIOGET_VSCREENINFO, &fb->vi) < 0) goto fail; fb->bits = mmap(0, fb_size(fb), PROT_READ | PROT_WRITE, MAP_SHARED, fb->fd, 0); if (fb->bits == MAP_FAILED) goto fail; return 0;fail: printf("%s is not a framebuffer.\n", fbfilename); close(fb->fd); return -1;}
o 读取数据并写入jpeg
static int snap(const char * filename, int quality, struct FB* fb){ int row_stride = 0; FILE * outfile = NULL; JSAMPROW row_pointer[1] = {0}; struct jpeg_error_mgr jerr = {0}; struct jpeg_compress_struct cinfo = {0}; cinfo.err = jpeg_std_error(&jerr); jpeg_create_compress(&cinfo); if ((outfile = fopen(filename, "wb+")) == NULL) { fprintf(stderr, "can't open %s\n", filename); return -1; } jpeg_stdio_dest(&cinfo, outfile); cinfo.image_width = fb_width(fb); cinfo.image_height = fb_height(fb); cinfo.input_components = 3; cinfo.in_color_space = JCS_RGB; jpeg_set_defaults(&cinfo); jpeg_set_quality(&cinfo, quality, TRUE); jpeg_start_compress(&cinfo, TRUE); row_stride = fb_width(fb) * 2; JSAMPLE* image_buffer = malloc(3 * fb_width(fb)); while (cinfo.next_scanline < cinfo.image_height) { int i = 0; unsigned short* line = fb->bits + cinfo.next_scanline * fb_width(fb); for(i = 0; i < fb_width(fb); i++) { int offset = i * 3; unsigned short color = line[i]; unsigned char r = ((color >> 11) & 0xff) << 3; unsigned char g = ((color >> 5) & 0xff) << 2; unsigned char b = (color & 0xff )<< 3; image_buffer[offset] = r; image_buffer[offset + 1] = g; image_buffer[offset + 2] = b; } row_pointer[0] = image_buffer; (void) jpeg_write_scanlines(&cinfo, row_pointer, 1); } jpeg_finish_compress(&cinfo); fclose(outfile); jpeg_destroy_compress(&cinfo); return 0;}
o 主函数
int main(int argc, char* argv[]){ struct FB fb = {0}; const char* filename = NULL; const char* fbfilename = NULL; if(argc != 3) { printf("\nusage: %s [jpeg] [framebuffer]\n", argv[0]); printf("-----------------------------------------\n"); printf("Powered by broncho(www.broncho.cn)\n"); return 0; } filename = argv[1]; fbfilename = argv[2]; if (fb_open(&fb, fbfilename) == 0) { snap(filename, 100, &fb); fb_close(&fb); } return 0;}
完整代码请到这里下载。
联系客服
