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LIBPNG读写PNG图像_png_get_text

作者：小丑西瓜9 | 2024-03-07 00:28:25

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png_get_text
  1. //file:pngtest.c
  2. //changed from the libpng,对照libpng中源码阅读
  3. //myers
  4. #include "png.h"
  5. #include <stdio.h>
  6. #include "zlib.h"
  7. #include "png.h"
  8. #include <stdlib.h>
  9. #include <string.h>
  10. #include <stdio.h>
  11.  
  12. int main(int argc,char* argv[])
  13. {
  14.     static png_FILE_p fpin;
  15.     static png_FILE_p fpout;
  16.     //输入文件名
  17.     char *inname = "/home/mingming/graph/1.png";
  18.     char *outname = "/home/mingming/graph/1_like.png";
  19.     //读：
  20.     png_structp read_ptr;
  21.     png_infop read_info_ptr, end_info_ptr;
  22.     //写
  23.     png_structp write_ptr;
  24.     png_infop write_info_ptr,write_end_info_ptr;
  25.     //
  26.     png_bytep row_buf;
  27.     png_uint_32 y;
  28.     int num_pass, pass;
  29.     png_uint_32 width, height;//宽度，高度
  30.     int bit_depth, color_type;//位深，颜色类型
  31.     int interlace_type, compression_type, filter_type;//扫描方式，压缩方式，滤波方式
  32.     //读
  33.     row_buf = NULL;
  34.     //打开读文件
  35.     if ((fpin = fopen(inname, "rb")) == NULL)
  36.     {
  37.         fprintf(stderr,"Could not find input file %s\n", inname);
  38.         return (1);
  39.     }
  40.     //打开写文件
  41.     if ((fpout = fopen(outname, "wb")) == NULL)
  42.     {
  43.         printf("Could not open output file %s\n", outname);
  44.         fclose(fpin);
  45.         return (1);
  46.     }
  47.     //我们这里不处理未知的块unknown chunk
  48.     //初始化1
  49.     read_ptr =
  50.               png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  51.     write_ptr =
  52.           png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  53.     read_info_ptr = png_create_info_struct(read_ptr);
  54.        end_info_ptr = png_create_info_struct(read_ptr);
  55.     write_info_ptr = png_create_info_struct(write_ptr);
  56.        write_end_info_ptr = png_create_info_struct(write_ptr);
  57.     //初始化2
  58.     png_init_io(read_ptr, fpin);
  59.     png_init_io(write_ptr, fpout);
  60.     //读文件有high level(高层）和low level两种，我们选择从底层具体信息中读取。
  61.     //这里我们读取所有可选。
  62.     png_read_info(read_ptr, read_info_ptr);    
  63.     //（1）IHDR
  64.       //读取图像宽度(width)，高度(height)，位深(bit_depth)，颜色类型(color_type)，压缩方法(compression_type)
  65.     //滤波器方法(filter_type),隔行扫描方式(interlace_type)
  66.     if (png_get_IHDR(read_ptr, read_info_ptr, &width, &height, &bit_depth,
  67.       &color_type, &interlace_type, &compression_type, &filter_type))
  68.     {
  69.     //我们采用默认扫描方式
  70.      png_set_IHDR(write_ptr, write_info_ptr, width, height, bit_depth,
  71.         color_type, PNG_INTERLACE_NONE, compression_type, filter_type);
  72.     }
  73.     //（2）cHRM
  74.     //读取白色度信息  白/红/绿/蓝 点的x,y坐标，这里采用整形，不采用浮点数
  75.     png_fixed_point white_x, white_y, red_x, red_y, green_x, green_y, blue_x,blue_y;
  76.  
  77.     if (png_get_cHRM_fixed(read_ptr, read_info_ptr, &white_x, &white_y,
  78.      &red_x, &red_y, &green_x, &green_y, &blue_x, &blue_y))
  79.     {
  80.      png_set_cHRM_fixed(write_ptr, write_info_ptr, white_x, white_y, red_x,
  81.         red_y, green_x, green_y, blue_x, blue_y);
  82.     }
  83.         //（3）gAMA
  84.       png_fixed_point gamma;
  85.  
  86.       if (png_get_gAMA_fixed(read_ptr, read_info_ptr, &gamma))
  87.          png_set_gAMA_fixed(write_ptr, write_info_ptr, gamma);
  88.         //（4）iCCP
  89.     png_charp name;
  90.     png_bytep profile;
  91.     png_uint_32 proflen;
  92.  
  93.     if (png_get_iCCP(read_ptr, read_info_ptr, &name, &compression_type,
  94.               &profile, &proflen))
  95.     {
  96.      png_set_iCCP(write_ptr, write_info_ptr, name, compression_type,
  97.               profile, proflen);
  98.     }
  99.     //(5)sRGB
  100.       int intent;
  101.       if (png_get_sRGB(read_ptr, read_info_ptr, &intent))
  102.          png_set_sRGB(write_ptr, write_info_ptr, intent);
  103.     //(7)PLTE
  104.       png_colorp palette;
  105.       int num_palette;
  106.  
  107.       if (png_get_PLTE(read_ptr, read_info_ptr, &palette, &num_palette))
  108.          png_set_PLTE(write_ptr, write_info_ptr, palette, num_palette);
  109.     //(8)bKGD
  110.       png_color_16p background;
  111.  
  112.       if (png_get_bKGD(read_ptr, read_info_ptr, &background))
  113.       {
  114.          png_set_bKGD(write_ptr, write_info_ptr, background);
  115.       }
  116.     //(9)hist
  117.  
  118.       png_uint_16p hist;
  119.  
  120.       if (png_get_hIST(read_ptr, read_info_ptr, &hist))
  121.          png_set_hIST(write_ptr, write_info_ptr, hist);
  122.        //(10)oFFs
  123.       png_int_32 offset_x, offset_y;
  124.       int unit_type;
  125.  
  126.       if (png_get_oFFs(read_ptr, read_info_ptr, &offset_x, &offset_y,
  127.           &unit_type))
  128.       {
  129.          png_set_oFFs(write_ptr, write_info_ptr, offset_x, offset_y, unit_type);
  130.       }
  131.     //(11)pCAL
  132.       png_charp purpose, units;
  133.       png_charpp params;
  134.       png_int_32 X0, X1;
  135.       int type, nparams;
  136.  
  137.       if (png_get_pCAL(read_ptr, read_info_ptr, &purpose, &X0, &X1, &type,
  138.          &nparams, &units, ¶ms))
  139.       {
  140.          png_set_pCAL(write_ptr, write_info_ptr, purpose, X0, X1, type,
  141.             nparams, units, params);
  142.       }
  143.        //(12)pHYs
  144.    
  145.       png_uint_32 res_x, res_y;
  146.  
  147.       if (png_get_pHYs(read_ptr, read_info_ptr, &res_x, &res_y, &unit_type))
  148.          png_set_pHYs(write_ptr, write_info_ptr, res_x, res_y, unit_type);
  149.    //(13)sBIT
  150.       png_color_8p sig_bit;
  151.  
  152.       if (png_get_sBIT(read_ptr, read_info_ptr, &sig_bit))
  153.          png_set_sBIT(write_ptr, write_info_ptr, sig_bit);
  154.     //（14）sCAL
  155.       int unit;
  156.       png_charp scal_width, scal_height;
  157.  
  158.       if (png_get_sCAL_s(read_ptr, read_info_ptr, &unit, &scal_width,
  159.           &scal_height))
  160.       {
  161.          png_set_sCAL_s(write_ptr, write_info_ptr, unit, scal_width,
  162.              scal_height);
  163.       }
  164.         //(15)iTXt
  165.       png_textp text_ptr;
  166.       int num_text;
  167.  
  168.       if (png_get_text(read_ptr, read_info_ptr, &text_ptr, &num_text) > 0)
  169.       {
  170.          png_set_text(write_ptr, write_info_ptr, text_ptr, num_text);
  171.       }
  172.     //(16)tIME,这里我们不支持RFC1123
  173.       png_timep mod_time;
  174.  
  175.       if (png_get_tIME(read_ptr, read_info_ptr, &mod_time))
  176.       {
  177.          png_set_tIME(write_ptr, write_info_ptr, mod_time);
  178.       }
  179.     //(17)tRNS
  180.       png_bytep trans_alpha;
  181.       int num_trans;
  182.       png_color_16p trans_color;
  183.  
  184.       if (png_get_tRNS(read_ptr, read_info_ptr, &trans_alpha, &num_trans,
  185.          &trans_color))
  186.       {
  187.          int sample_max = (1 << bit_depth);
  188.          /* libpng doesn't reject a tRNS chunk with out-of-range samples */
  189.          if (!((color_type == PNG_COLOR_TYPE_GRAY &&
  190.              (int)trans_color->gray > sample_max) ||
  191.              (color_type == PNG_COLOR_TYPE_RGB &&
  192.              ((int)trans_color->red > sample_max ||
  193.              (int)trans_color->green > sample_max ||
  194.              (int)trans_color->blue > sample_max))))
  195.             png_set_tRNS(write_ptr, write_info_ptr, trans_alpha, num_trans,
  196.                trans_color);
  197.       }
  198.     
  199.     //写进新的png文件中
  200.     png_write_info(write_ptr, write_info_ptr);
  201.     //读真正的图像数据
  202.     num_pass = 1;
  203.    for (pass = 0; pass < num_pass; pass++)
  204.    {
  205.       for (y = 0; y < height; y++)
  206.       {
  207.     //分配内存
  208.          row_buf = (png_bytep)png_malloc(read_ptr,
  209.             png_get_rowbytes(read_ptr, read_info_ptr));
  210.     png_read_rows(read_ptr, (png_bytepp)&row_buf, NULL, 1);
  211.     png_write_rows(write_ptr, (png_bytepp)&row_buf, 1);
  212.          png_free(read_ptr, row_buf);
  213.          row_buf = NULL;
  214.       }
  215.    }
  216.     //结束
  217.    png_read_end(read_ptr, end_info_ptr);
  218.     //
  219.     //tTXt
  220.       if (png_get_text(read_ptr, end_info_ptr, &text_ptr, &num_text) > 0)
  221.       {
  222.          png_set_text(write_ptr, write_end_info_ptr, text_ptr, num_text);
  223.       }
  224.     //tIME
  225.       if (png_get_tIME(read_ptr, end_info_ptr, &mod_time))
  226.       {
  227.          png_set_tIME(write_ptr, write_end_info_ptr, mod_time);
  228.       }
  229.     //
  230.     png_write_end(write_ptr, write_end_info_ptr);
  231.     //回收
  232.     png_free(read_ptr, row_buf);
  233.     row_buf = NULL;
  234.     png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
  235.     png_destroy_info_struct(write_ptr, &write_end_info_ptr);
  236.     png_destroy_write_struct(&write_ptr, &write_info_ptr);
  237.     //
  238.    fclose(fpin);
  239.    fclose(fpout);
  240.     //测试，比较两个PNG文件是否相同
  241.    if ((fpin = fopen(inname, "rb")) == NULL)
  242.    {
  243.       printf("Could not find file %s\n", inname);
  244.       return (1);
  245.    }
  246.  
  247.    if ((fpout = fopen(outname, "rb")) == NULL)
  248.    {
  249.       printf("Could not find file %s\n", outname);
  250.       fclose(fpin);
  251.       return (1);
  252.    }
  253.    char inbuf[256], outbuf[256];
  254.    for (;;)
  255.    {
  256.       png_size_t num_in, num_out;
  257.  
  258.          num_in = fread(inbuf, 1, 1, fpin);
  259.          num_out = fread(outbuf, 1, 1, fpout);
  260.  
  261.       if (num_in != num_out)
  262.       {
  263.          printf("\nFiles %s and %s 大小不同\n",
  264.                  inname, outname);
  265.  
  266.          fclose(fpin);
  267.          fclose(fpout);
  268.          return (0);
  269.       }
  270.  
  271.       if (!num_in)
  272.          break;
  273.  
  274.       if (memcmp(inbuf, outbuf, num_in))
  275.       {
  276.          printf("\nFiles %s and %s 内容不同\n", inname, outname);
  277.          fclose(fpin);
  278.          fclose(fpout);
  279.          return (0);
  280.       }
  281.    }
  282.  
  283.    fclose(fpin);
  284.    fclose(fpout);
  285.  
  286.    return (0);
  287. }

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