九乡新闻网衡阳金色家族酒店桑拿:【2011.03.21】jpeg图片的显示
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include #include #include #include #include #include #include #include #include #include #define FB_DEV "/dev/fb0"/***************** function declaration ******************/void usage(char *msg);unsigned short RGB888toRGB565(unsigned char red, unsigned char green, unsigned char blue);int fb_open(char *fb_device);int fb_close(int fd);int fb_stat(int fd, int *width, int *height, int *depth);void *fb_mmap(int fd, unsigned int screensize);int fb_munmap(void *start, size_t length);int fb_pixel(void *fbmem, int width, int height, int x, int y, unsigned short color);/************ function implementation ********************/int main(int argc, char *argv[]){ /* * declaration for jpeg decompression */ //分配并初始化一个JPEG解压对象
struct jpeg_decompress_struct cinfo; struct jpeg_error_mgr jerr; //指定要解压缩的图像文件
FILE *infile; unsigned char *buffer; /* * declaration for framebuffer device */ int fbdev; char *fb_device; unsigned char *fbmem; unsigned int screensize; unsigned int fb_width; unsigned int fb_height; unsigned int fb_depth; unsigned int x; unsigned int y; /* * check auguments */ if (argc != 2) { usage("insuffient auguments"); exit(-1); } /* * open framebuffer device */ if ((fb_device = getenv("FRAMEBUFFER")) == NULL) fb_device = FB_DEV; fbdev = fb_open(fb_device); /* * get status of framebuffer device */ fb_stat(fbdev, &fb_width, &fb_height, &fb_depth); /* * map framebuffer device to shared memory */ screensize = fb_width * fb_height * fb_depth / 8; fbmem = fb_mmap(fbdev, screensize); /* * open input jpeg file */ if ((infile = fopen(argv[1], "rb")) == NULL) { fprintf(stderr, "open %s failed\n", argv[1]); exit(-1); } /* * init jpeg decompress object error handler */ cinfo.err = jpeg_std_error(&jerr); jpeg_create_decompress(&cinfo); /* * bind jpeg decompress object to infile */ jpeg_stdio_src(&cinfo, infile); /* * read jpeg header */ jpeg_read_header(&cinfo, TRUE); /* * decompress process. * note: after jpeg_start_decompress() is called * the dimension infomation will be known, * so allocate memory buffer for scanline immediately */ jpeg_start_decompress(&cinfo); if ((cinfo.output_width > fb_width) || (cinfo.output_height > fb_height)) { printf("too large JPEG file,cannot display\n"); return (-1); } buffer = (unsigned char *) malloc(cinfo.output_width * cinfo.output_components); y = 0; while (cinfo.output_scanline < cinfo.output_height) { jpeg_read_scanlines(&cinfo, &buffer, 1); if (fb_depth == 16) { unsigned short color; for (x = 0; x < cinfo.output_width; x++) { color = RGB888toRGB565(buffer[x * 3], buffer[x * 3 + 1], buffer[x * 3 + 2]); fb_pixel(fbmem, fb_width, fb_height, x, y, color); } } else if (fb_depth == 24) { memcpy((unsigned char *) fbmem + y * fb_width * 3, buffer, cinfo.output_width * cinfo.output_components); } y++; // next scanline } /* * finish decompress, destroy decompress object */ jpeg_finish_decompress(&cinfo); jpeg_destroy_decompress(&cinfo); /* * release memory buffer */ free(buffer); /* * close jpeg inputing file */ fclose(infile); /* * unmap framebuffer's shared memory */ fb_munmap(fbmem, screensize); /* * close framebuffer device */ fb_close(fbdev); return (0); }void usage(char *msg) { fprintf(stderr, "%s\n", msg); printf("Usage: fv some-jpeg-file.jpg\n"); } /* * convert 24bit RGB888 to 16bit RGB565 color format */ unsigned short RGB888toRGB565(unsigned char red, unsigned char green, unsigned char blue) { unsigned short B = (blue >> 3) & 0x001F; unsigned short G = ((green >> 2) << 5) & 0x07E0; unsigned short R = ((red >> 3) << 11) & 0xF800; return (unsigned short) (R | G | B); } /* * open framebuffer device. * return positive file descriptor if success, * else return -1. */ int fb_open(char *fb_device) { int fd; if ((fd = open(fb_device, O_RDWR)) < 0) { perror(__func__); return (-1); } return (fd); } /* * get framebuffer's width,height,and depth. * return 0 if success, else return -1. */ int fb_stat(int fd, int *width, int *height, int *depth) { struct fb_fix_screeninfo fb_finfo; struct fb_var_screeninfo fb_vinfo; if (ioctl(fd, FBIOGET_FSCREENINFO, &fb_finfo)) { perror(__func__); return (-1); } if (ioctl(fd, FBIOGET_VSCREENINFO, &fb_vinfo)) { perror(__func__); return (-1); } *width = fb_vinfo.xres; *height = fb_vinfo.yres; *depth = fb_vinfo.bits_per_pixel; return (0); } /* * map shared memory to framebuffer device. * return maped memory if success, * else return -1, as mmap dose. */ void * fb_mmap(int fd, unsigned int screensize) { caddr_t fbmem; if ((fbmem = mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED) { perror(__func__); return (void *) (-1); } return (fbmem); } /* * unmap map memory for framebuffer device. */ int fb_munmap(void *start, size_t length) { return (munmap(start, length)); } /* * close framebuffer device */ int fb_close(int fd) { return (close(fd)); } /* * display a pixel on the framebuffer device. * fbmem is the starting memory of framebuffer, * width and height are dimension of framebuffer, * x and y are the coordinates to display, * color is the pixel's color value. * return 0 if success, otherwise return -1. */ int fb_pixel(void *fbmem, int width, int height, int x, int y, unsigned short color) { if ((x > width) || (y > height)) return (-1); unsigned short *dst = ((unsigned short *) fbmem + y * width + x); *dst = color; return 0; }
在ubuntu下通过命令：sudo apt-get install libjpeg-dev 安装libjpeg；
在g++编译时，加上-ljpeg
struct jpeg_decompress_struct cinfo; struct jpeg_error_mgr jerr; //指定要解压缩的图像文件
FILE *infile; unsigned char *buffer; /* * declaration for framebuffer device */ int fbdev; char *fb_device; unsigned char *fbmem; unsigned int screensize; unsigned int fb_width; unsigned int fb_height; unsigned int fb_depth; unsigned int x; unsigned int y; /* * check auguments */ if (argc != 2) { usage("insuffient auguments"); exit(-1); } /* * open framebuffer device */ if ((fb_device = getenv("FRAMEBUFFER")) == NULL) fb_device = FB_DEV; fbdev = fb_open(fb_device); /* * get status of framebuffer device */ fb_stat(fbdev, &fb_width, &fb_height, &fb_depth); /* * map framebuffer device to shared memory */ screensize = fb_width * fb_height * fb_depth / 8; fbmem = fb_mmap(fbdev, screensize); /* * open input jpeg file */ if ((infile = fopen(argv[1], "rb")) == NULL) { fprintf(stderr, "open %s failed\n", argv[1]); exit(-1); } /* * init jpeg decompress object error handler */ cinfo.err = jpeg_std_error(&jerr); jpeg_create_decompress(&cinfo); /* * bind jpeg decompress object to infile */ jpeg_stdio_src(&cinfo, infile); /* * read jpeg header */ jpeg_read_header(&cinfo, TRUE); /* * decompress process. * note: after jpeg_start_decompress() is called * the dimension infomation will be known, * so allocate memory buffer for scanline immediately */ jpeg_start_decompress(&cinfo); if ((cinfo.output_width > fb_width) || (cinfo.output_height > fb_height)) { printf("too large JPEG file,cannot display\n"); return (-1); } buffer = (unsigned char *) malloc(cinfo.output_width * cinfo.output_components); y = 0; while (cinfo.output_scanline < cinfo.output_height) { jpeg_read_scanlines(&cinfo, &buffer, 1); if (fb_depth == 16) { unsigned short color; for (x = 0; x < cinfo.output_width; x++) { color = RGB888toRGB565(buffer[x * 3], buffer[x * 3 + 1], buffer[x * 3 + 2]); fb_pixel(fbmem, fb_width, fb_height, x, y, color); } } else if (fb_depth == 24) { memcpy((unsigned char *) fbmem + y * fb_width * 3, buffer, cinfo.output_width * cinfo.output_components); } y++; // next scanline } /* * finish decompress, destroy decompress object */ jpeg_finish_decompress(&cinfo); jpeg_destroy_decompress(&cinfo); /* * release memory buffer */ free(buffer); /* * close jpeg inputing file */ fclose(infile); /* * unmap framebuffer's shared memory */ fb_munmap(fbmem, screensize); /* * close framebuffer device */ fb_close(fbdev); return (0); }void usage(char *msg) { fprintf(stderr, "%s\n", msg); printf("Usage: fv some-jpeg-file.jpg\n"); } /* * convert 24bit RGB888 to 16bit RGB565 color format */ unsigned short RGB888toRGB565(unsigned char red, unsigned char green, unsigned char blue) { unsigned short B = (blue >> 3) & 0x001F; unsigned short G = ((green >> 2) << 5) & 0x07E0; unsigned short R = ((red >> 3) << 11) & 0xF800; return (unsigned short) (R | G | B); } /* * open framebuffer device. * return positive file descriptor if success, * else return -1. */ int fb_open(char *fb_device) { int fd; if ((fd = open(fb_device, O_RDWR)) < 0) { perror(__func__); return (-1); } return (fd); } /* * get framebuffer's width,height,and depth. * return 0 if success, else return -1. */ int fb_stat(int fd, int *width, int *height, int *depth) { struct fb_fix_screeninfo fb_finfo; struct fb_var_screeninfo fb_vinfo; if (ioctl(fd, FBIOGET_FSCREENINFO, &fb_finfo)) { perror(__func__); return (-1); } if (ioctl(fd, FBIOGET_VSCREENINFO, &fb_vinfo)) { perror(__func__); return (-1); } *width = fb_vinfo.xres; *height = fb_vinfo.yres; *depth = fb_vinfo.bits_per_pixel; return (0); } /* * map shared memory to framebuffer device. * return maped memory if success, * else return -1, as mmap dose. */ void * fb_mmap(int fd, unsigned int screensize) { caddr_t fbmem; if ((fbmem = mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED) { perror(__func__); return (void *) (-1); } return (fbmem); } /* * unmap map memory for framebuffer device. */ int fb_munmap(void *start, size_t length) { return (munmap(start, length)); } /* * close framebuffer device */ int fb_close(int fd) { return (close(fd)); } /* * display a pixel on the framebuffer device. * fbmem is the starting memory of framebuffer, * width and height are dimension of framebuffer, * x and y are the coordinates to display, * color is the pixel's color value. * return 0 if success, otherwise return -1. */ int fb_pixel(void *fbmem, int width, int height, int x, int y, unsigned short color) { if ((x > width) || (y > height)) return (-1); unsigned short *dst = ((unsigned short *) fbmem + y * width + x); *dst = color; return 0; }
在ubuntu下通过命令：sudo apt-get install libjpeg-dev 安装libjpeg；
在g++编译时，加上-ljpeg
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