📄 ximajpg.cpp
字号:
/* * File: ximajpg.cpp * Purpose: Platform Independent JPEG Image Class Loader and Writer * 07/Aug/2001 Davide Pizzolato - www.xdp.it * CxImage version 5.99c 17/Oct/2004 */ #include "ximajpg.h"#if CXIMAGE_SUPPORT_JPG#include "../jpeg/jmorecfg.h"#include "ximaiter.h" #include <setjmp.h>struct jpg_error_mgr { struct jpeg_error_mgr pub; /* "public" fields */ jmp_buf setjmp_buffer; /* for return to caller */ char* buffer; /* error message <CSC>*/};typedef jpg_error_mgr *jpg_error_ptr;////////////////////////////////////////////////////////////////////////////////// Here's the routine that will replace the standard error_exit method:////////////////////////////////////////////////////////////////////////////////static voidima_jpeg_error_exit (j_common_ptr cinfo){ /* cinfo->err really points to a my_error_mgr struct, so coerce pointer */ jpg_error_ptr myerr = (jpg_error_ptr) cinfo->err; /* Create the message */ myerr->pub.format_message (cinfo, myerr->buffer); /* Send it to stderr, adding a newline */ /* Return control to the setjmp point */ longjmp(myerr->setjmp_buffer, 1);}////////////////////////////////////////////////////////////////////////////////CxImageJPG::CxImageJPG(): CxImage(CXIMAGE_FORMAT_JPG){#if CXIMAGEJPG_SUPPORT_EXIF m_exif = NULL; memset(&m_exifinfo, 0, sizeof(EXIFINFO));#endif}////////////////////////////////////////////////////////////////////////////////CxImageJPG::~CxImageJPG(){#if CXIMAGEJPG_SUPPORT_EXIF if (m_exif) delete m_exif;#endif}bool CxImageJPG::CheckFormat(BYTE * buffer, DWORD size, basic_image_information *basic_info){ CxImageJPG img; CxMemFile hFile(buffer,size); img.SetEscape(-1); if (img.Decode(&hFile) == true) { create_basic_image_information(CXIMAGE_FORMAT_JPG,img.GetWidth(),img.GetHeight(),basic_info); return true; } else { return false; }}////////////////////////////////////////////////////////////////////////////////#if CXIMAGEJPG_SUPPORT_EXIFbool CxImageJPG::DecodeExif(CxFile * hFile){ m_exif = new CxExifInfo(&m_exifinfo); if (m_exif){ long pos=hFile->Tell(); m_exif->DecodeExif(hFile); hFile->Seek(pos,SEEK_SET); return m_exif->m_exifinfo->IsExif; } else { return false; }}#endif //CXIMAGEJPG_SUPPORT_EXIF////////////////////////////////////////////////////////////////////////////////bool CxImageJPG::Decode(CxFile * hFile){ bool is_exif = false;#if CXIMAGEJPG_SUPPORT_EXIF is_exif = DecodeExif(hFile);#endif CImageIterator iter(this); /* This struct contains the JPEG decompression parameters and pointers to * working space (which is allocated as needed by the JPEG library). */ struct jpeg_decompress_struct cinfo; /* We use our private extension JPEG error handler. <CSC> */ struct jpg_error_mgr jerr; jerr.buffer=info.szLastError; /* More stuff */ JSAMPARRAY buffer; /* Output row buffer */ int row_stride; /* physical row width in output buffer */ /* In this example we want to open the input file before doing anything else, * so that the setjmp() error recovery below can assume the file is open. * VERY IMPORTANT: use "b" option to fopen() if you are on a machine that * requires it in order to read binary files. */ /* Step 1: allocate and initialize JPEG decompression object */ /* We set up the normal JPEG error routines, then override error_exit. */ cinfo.err = jpeg_std_error(&jerr.pub); jerr.pub.error_exit = ima_jpeg_error_exit; /* Establish the setjmp return context for my_error_exit to use. */ if (setjmp(jerr.setjmp_buffer)) { /* If we get here, the JPEG code has signaled an error. * We need to clean up the JPEG object, close the input file, and return. */ jpeg_destroy_decompress(&cinfo); return 0; } /* Now we can initialize the JPEG decompression object. */ jpeg_create_decompress(&cinfo); /* Step 2: specify data source (eg, a file) */ //jpeg_stdio_src(&cinfo, infile); CxFileJpg src(hFile); cinfo.src = &src; /* Step 3: read file parameters with jpeg_read_header() */ (void) jpeg_read_header(&cinfo, TRUE); /* Step 4 <chupeev> handle decoder options*/ if ((GetCodecOption(CXIMAGE_FORMAT_JPG) & DECODE_GRAYSCALE) != 0) cinfo.out_color_space = JCS_GRAYSCALE; if ((GetCodecOption(CXIMAGE_FORMAT_JPG) & DECODE_QUANTIZE) != 0) { cinfo.quantize_colors = TRUE; cinfo.desired_number_of_colors = info.nQuality; } if ((GetCodecOption(CXIMAGE_FORMAT_JPG) & DECODE_DITHER) != 0) cinfo.dither_mode = m_nDither; if ((GetCodecOption(CXIMAGE_FORMAT_JPG) & DECODE_ONEPASS) != 0) cinfo.two_pass_quantize = FALSE; if ((GetCodecOption(CXIMAGE_FORMAT_JPG) & DECODE_NOSMOOTH) != 0) cinfo.do_fancy_upsampling = FALSE;//<DP>: Load true color images as RGB (no quantize) /* Step 4: set parameters for decompression *//* if (cinfo.jpeg_color_space!=JCS_GRAYSCALE) { * cinfo.quantize_colors = TRUE; * cinfo.desired_number_of_colors = 128; *} */ //</DP> // Set the scale <ignacio> cinfo.scale_denom = GetJpegScale(); // Borrowed the idea from GIF implementation <ignacio> if (info.nEscape == -1) { // Return output dimensions only jpeg_calc_output_dimensions(&cinfo); head.biWidth = cinfo.output_width; head.biHeight = cinfo.output_height; jpeg_destroy_decompress(&cinfo); return true; } /* Step 5: Start decompressor */ jpeg_start_decompress(&cinfo); /* We may need to do some setup of our own at this point before reading * the data. After jpeg_start_decompress() we have the correct scaled * output image dimensions available, as well as the output colormap * if we asked for color quantization. */ //Create the image using output dimensions <ignacio> //Create(cinfo.image_width, cinfo.image_height, 8*cinfo.output_components, CXIMAGE_FORMAT_JPG); Create(cinfo.output_width, cinfo.output_height, 8*cinfo.output_components, CXIMAGE_FORMAT_JPG); if (!pDib) longjmp(jerr.setjmp_buffer, 1); //<DP> check if the image has been created if (is_exif){#if CXIMAGEJPG_SUPPORT_EXIF if ((m_exifinfo.Xresolution != 0.0) && (m_exifinfo.ResolutionUnit != 0)) SetXDPI((long)(m_exifinfo.Xresolution/m_exifinfo.ResolutionUnit)); if ((m_exifinfo.Yresolution != 0.0) && (m_exifinfo.ResolutionUnit != 0)) SetYDPI((long)(m_exifinfo.Yresolution/m_exifinfo.ResolutionUnit));#endif } else { if (cinfo.density_unit==2){ SetXDPI((long)floor(cinfo.X_density * 254.0 / 10000.0 + 0.5)); SetYDPI((long)floor(cinfo.Y_density * 254.0 / 10000.0 + 0.5)); } else { SetXDPI(cinfo.X_density); SetYDPI(cinfo.Y_density); } } if (cinfo.out_color_space==JCS_GRAYSCALE){ SetGrayPalette(); head.biClrUsed =256; } else { if (cinfo.quantize_colors==TRUE){ SetPalette(cinfo.actual_number_of_colors, cinfo.colormap[0], cinfo.colormap[1], cinfo.colormap[2]); head.biClrUsed=cinfo.actual_number_of_colors; } else { head.biClrUsed=0; } } /* JSAMPLEs per row in output buffer */ row_stride = cinfo.output_width * cinfo.output_components; /* Make a one-row-high sample array that will go away when done with image */ buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1); /* Step 6: while (scan lines remain to be read) */ /* jpeg_read_scanlines(...); */ /* Here we use the library's state variable cinfo.output_scanline as the * loop counter, so that we don't have to keep track ourselves. */ iter.Upset(); while (cinfo.output_scanline < cinfo.output_height) { if (info.nEscape) longjmp(jerr.setjmp_buffer, 1); // <vho> - cancel decoding (void) jpeg_read_scanlines(&cinfo, buffer, 1); // info.nProgress = (long)(100*cinfo.output_scanline/cinfo.output_height); //<DP> Step 6a: CMYK->RGB */ if ((cinfo.num_components==4)&&(cinfo.quantize_colors==FALSE)){ BYTE k,*dst,*src; dst=iter.GetRow(); src=buffer[0];
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -