jpeg.rar_GetPixel_vc 像素坐标

CHRISDL@PAGESZ.NET 9/18/97 Note : GIF support has been removed as of 9/24/97. I am pursuing a license from Unisys to enable me to include GIF support in this package. Until then, no GIF. Sorry. -cdl My JpegLib2 library and JpegFile class I've been looking for a long time for a JPEG package that will allow me to do this : BYTE * RGBbuffer = ReadJPEGFile(filename,&width,&height); and this: SaveJPG(RGBbuf, width, height...); I never found one that didn't cost many hundreds of dollars, so I wrote my own. What is it? My class is called JpegFile.cpp. It is based on a Win32 compilation of the IJG V.6a JPEG source. It does two main things : it reads a JPEG file into an RGB buffer, it saves an RGB buffer as an RGB or grayscale JPEG file. There are some utility routines in it to do things like RGB -> BGR vertical flip DWORD-align un DWORD-align convert to grayscale Color quantize a 24-bit image to an 8-bit image It can also read 1, 4, 8 and 24 bit BMP files It can also write 1, 4, 8 and 24-bit BMP files There are no provisions for progressive reading, progress bars, partial reads/saves, extended error handling, etc.. I use a very small portion of what the IJG code is capable of doing. I tried to keep the IJG source as intact as possible, to ease debugging - I assume the IJG code works.perfectly and that anything going wrong is my fault. You should assume this is true, also. This code has worked in every application I've tried it in. This has only run (to my knowledge) on Win 95, VC++ 4.x and VC++5.0 . I have heard, however, that one person successfully modified it to work on a Borland compiler to create a DLL for use in Visual BASIC - I don't have his code. Color quantization code is based on Dennis Lee's DL1Quant. If you don't like MFC, or would prefer to have your JPG and BMP code all wrapped up in a DLL, with dozens of handy image processing utilities ( resize, zoom, rotate, matrix, LUT, crop, draw, etc.) then check out my ImgDLL package. http://www.pagesz.net/software/imgdll.htm Non-MFC support I do offer a Win32 DLL that does everything this package does, for those of you who don't have access to VC++ or would rather not mess with VC++ (all you Borland or Visual BASIC types, for instance). Check out my ImgDLL page for more info. Terms of use 1: I've decided to make this class, as well as my compilation of the IJG library available to the public. This is entirely free - no royalties, no time bombs, no annoyance screens. All I ask is that you mention me in your software, especially if it's commercial software - and, if possible, add a link to my page . I just want some acknowledgment... :) 2: Because it is free, however, there are no guarantees - use at your own risk! If you want software that comes with someone you can point your finger at if it fails, spend the money on a commercial package from a company with a legal department. I'm just sharing. 3: The main reason for this package is to provide simple C++ JPG support. The BMP functions are in there only so that I won't have to answer the question "I got your JPG stuff, do you do BMP ?" 4: Come to me first for help with this code. Troubleshooting This package is not the responsibility of the people who's code I have used here - the IJG people, for example. Let me rephrase that. Come to me first with any problems you are having with this package. If you run into any problems with this software, please feel free to contact me. If it turns out that the problem is in my code, I will fix it. Please do not ask the IJG people, or any of the other people who's code I have included here for help unless we've first determined that the problem is not in my code. If you feel the problem is with the IJG code that I have included, I recommend you get a full copy of the official IJG source. The full IJG source comes with excellent documentation and should be able to help you. You can get the IJG code at the simtel archives. MSVC 5.0 Dialog App Problem + BOOL redefinition problem Problem : There is some serious type conflict associated with the IJG code's use of the name "boolean" and MSVC 5.0's use of the name "boolean". In MSVC 5.0, "boolean" is a different size than it is in the IJG code (one is a char and one is an int). You typically run into this if you start using OLE stuff, which Dialog Apps come with by default. You will see lots of "struct mismatch" errors and your code won't run. It doesn't seem to happen in MSVC 4.x dialog apps. This is new. Fix method #1 - Specific to MSVC 5.0 Dialog Apps 1. Compile the Jpeglib2.lib as-is. 2. In your app, stdafx.h, remove the line: #include <afxdisp.h> // MFC OLE automation classes 3. In your main app class InitInstance() remove the line : AfxEnableControlContainer(); 4. In jpegfile.cpp, be sure not to : #define HAVE_BOOLEAN This might break a whole bunch of OLE things. But, if you're not using OLE, I think this is safe. Fix method #2 - General fix. 1. In the Jpeglib2.lib files, change jmorecfg.h : from (line 228): #ifndef HAVE_BOOLEAN typedef int boolean; #endif to: #ifndef HAVE_BOOLEAN typedef char boolean; #endif 2. Compile Jpeglib2.lib as usual - ignore the warnings... 3. In your app, in jpegfile.cpp, add #define HAVE_BOOLEAN before #include "jpeglib.h" This method allows you to use OLE. But makes a change in the IJG code. This is something I've tried to avoid doing. All of my tests have worked, though I'm unsure of what effect this change could have. I include a file dlgvc5.zip, which contains a tiny sample MSVC 5.0 dialog app example. It simply loads and displays JPEG files. I used the steps outlined in method #1 above in creating it. Thanks to Bryce Burrows, Brian Krisler and Alexandre Maltais for taking the time to point out the problem to me. The Package JPEGLIB2 This is the VC++ 4.x project (JPEGLIB2.MDP) for my compilation of the IJG source for Win95. Most of the IJG source is included here - everything but the example programs and the documentation. This is what does the actual work. It is absolutely necessary that this library is compiled and linked to the application using the JpegFile class. Fortunately, it should be a matter of unZipping the project into it own directory and aiming VC++ 4.x at it. It is possible to use this library (or the source for the library) on its own, if you know the IJG codebase. I really don't. I know that it works for my JpegFile class, though. I have changed only two lines of the original source. I commented out the exit(..) in jerror.c and replaced the fprintf(stderr,..) with a MessageBox(...). That's right, it launches a message box on warnings. It's certainly possible to remove this line if you absolutely can not have message boxes popping up. It is also possible for you to write your own error handler. The biggest benefit of using my JPEG package is that I've managed to get the IJG codebase into a VC++ 4.x (Win32) project. The other part of my package is really a thin wrapper. MFCAPP This is a small MFC C++ sample application using a class called JpegFile. JpegFile is a wrapper around the JPEGLIB2 library. If you know what you're doing, you can certainly ignore my class. If you want simple functionality for reading and writing JPEG files, JpegFile does it very well. If nothing else, this class is a gr