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把从framebuffer抓出来的数据转换成jpg图像

2017-02-22 07:14 274 查看

把从framebuffer抓出来的数据转换成为jpg图象
2008-07-10 14:15

//gcc -o grab grab.c -ljpeg

//The source code of grab.c

//cat /dev/fb/0 >tmp

//./grab -i tmp -o grab.jpg

#include <setjmp.h>

#include <stdio.h>

#include <getopt.h>

#include <jpeglib.h>

#define W 800

#define H 480

/*The name of this program.*/

const char *program_name;

/*

   Prints usage information for this program to STREAM,and exit the program with EXIT_CODE.

*/

void print_usage(FILE* stream,int exit_code)

{

        fprintf(stream,"Usage: %s options [inputfile outputfile...]\n",program_name);

        fprintf(stream,

                        " -h --help Display this usage information\n"

                        " -i --input filename Read from file\n"

                        " -o --output filename Write output to file\n"

                   );

        exit(exit_code);

}

void convert_line( char *src, char *dst, int line,int weight,int height );

int main(int argc,char **argv)

{

        int next_option;

        unsigned int image_height = 0;

        unsigned int image_width = 0;

        const char* const short_opti;

        const struct option long_options[] = {

                {"help", 0, NULL, 'h'},

                {"input",1, NULL, 'i'},

                {"output",1, NULL, 'o'},

                {NULL, 0, NULL,0      }

        };

        const char *output_filename = NULL;

        char *input_filename = NULL;

        program_name = argv[0];

        do{

                next_option = getopt_long(argc,argv,short_options,long_options,NULL);

                switch(next_option)

                {

                        case 'h':

                                print_usage(stdout,0);

                        case 'o':

                                output_filename = optarg;

                                break;

                        case 'i':

                                input_filename = optarg;

                                break;

                        case '?':

                                print_usage(stdout,1);

                        case -1:

                                break;

                        default:

                                abort();

                }

        }

        while(next_option != -1);

        if(!output_filename){

                output_filename = "grab.jpg";

        }

        if(!input_filename)

        {

                input_filename = "tmp";

        }

        printf("outputfile = %s,inputfile = %s\n",output_filename,input_filename);

        struct jpeg_compress_struct cinfo;

        struct jpeg_error_mgr jerr;

        JSAMPLE *buffer;

        JSAMPLE *image_buffer;

        buffer = malloc(W*H*3);

        image_buffer = malloc(W*3);

        FILE *in;

        int ret = 0;

        in = fopen(input_filename,"r");

        if(!in){

                printf("please provide the rgb source\n");

                exit(0);

        }

        ret = fread(buffer, 1,W*H*2, in );

        if( ret == 0 ){

                printf("read image buffer error\n");

                exit(0);

        }

        int height = H;

        int width = W;

        FILE *outfile;

        JSAMPROW row_pointer[1];//points to JSAMPLE row[s]

        //setp 1:allocate and initialize JPEG compression object

        cinfo.err = jpeg_std_error(&jerr);

        jpeg_create_compress(&cinfo);

        //step 2:specify data destination

        //char *filename="grab1.jpg";

        if((outfile = fopen(output_filename,"wb")) == NULL){

                printf("cannot open file to write\n");

                exit(0);

        }

        jpeg_stdio_dest( &cinfo, outfile );

        //step 3:set parameters for compression

        cinfo.image_width = width;

        cinfo.image_height = height;

        cinfo.input_components = 3;

        cinfo.in_color_space = JCS_RGB;

        jpeg_set_defaults(&cinfo);

        jpeg_set_quality(&cinfo, 100, TRUE );

        //step 4:start compresor

        jpeg_start_compress(&cinfo, TRUE);

        //step 5:

        while(cinfo.next_scanline < cinfo.image_height ){

                convert_line( buffer,image_buffer,cinfo.next_scanline,height,width);

                //printf("%d======end",cinfo.next_scanline);

                row_pointer[0] = image_buffer;

                (void)jpeg_write_scanlines( &cinfo, row_pointer, 1);

        }

        jpeg_finish_compress(&cinfo);

        fclose( outfile );

        jpeg_destroy_compress(&cinfo);

        free(buffer);

        free(image_buffer);

}

void convert_line(char* src,char* dst,int line,int width,int height){

        int NUM1 = W*2;

        int NUM2 = W*3;

        char *p = src + line*NUM1;

        int i = 0;

        while( i < NUM2 ){

                dst[i] = (p[1]&0xf8 );

                dst[i+1] = ((p[1]&0x7)<<5) | ((p[0] & 0xe0)>>3);

                dst[i+2] = (p[0]&0x1f)<<3;

                i += 3;

                p += 2;

        }

}

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