嵌入式linux通用截图工具

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文章出处：http://www.limodev.cn/blog
作者联系方式：李先静
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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。