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[devel] VisualC/GCC warning fixes, VisualC build fixes

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The changes include support for function attributes in VC in addition to
    those already present in GCC - necessary because without these some
    warnings are unavoidable.  Fixes include signed/unsigned fixes in
    pngvalid and checks with gcc -Wall -Wextra -Wunused.
  VC requires function attributes on function definitions as well as
    declarations, PNG_FUNCTION has been added to enable this and the
    relevant function definitions changed.
This commit is contained in:
Glenn Randers-Pehrson
2010-08-02 08:00:10 -05:00
parent 21c1f06ef9
commit 77396b63f9
18 changed files with 678 additions and 313 deletions
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63
projects/vstudio/readme.txt
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@@ -1,7 +1,7 @@
VisualStudio instructions
libpng version 1.5.0beta39 - July 31, 2010
libpng version 1.5.0beta39 - August 2, 2010
Copyright (c) 1998-2010 Glenn Randers-Pehrson
@@ -15,21 +15,11 @@ You should be familiar with VisualStudio before using this directory.
Initial preparations
====================
You should install the 'official' build of zlib on your system - follow the
instructions provided on http://www.zlib.net. When a new release is being
made of zlib the instructions disappear for a while until the new official
build is available. You will have to wait.
You must enter some information in zlib.props before attempting to build
with this 'solution'. Please read and edit zlib.props first. You will
probably not be familiar with the contents of zlib.props - do not worry,
it is mostly harmless.
Make sure that your official build layout matches the requirements listed
in zlib.props. Prior to zlib-1.2.4 the official build (1.2.3) placed
include and library files in different directories - if you find this
has happened just put them all in the same directory.
This is all you need to do to build the 'release' and 'release library'
configurations.
@@ -40,6 +30,25 @@ information is produced (in the .pdb), but if you encounter a problem the
optimization may make it difficult to debug. Simply rebuild with a lower
optimization level (e.g. /Od.)
Linking your application
========================
Normally you should link against the 'release' configuration. This builds a
DLL for libpng 1.5 with the default runtime options used by Visual Studio
2010. In particular the runtime library is the "MultiThreaded DLL" version.
If you use Visual Studio defaults to build your application you will have no
problems.
If you don't use the Visual Studio defaults your application must still be built
with the default runtime option (/MD). If, for some reason, it is not then your
application will crash inside libpng15.dll as soon as libpng tries to read
from a file handle you pass in.
If you do not want to use the DLL, for example for a very small application,
the 'release library' configuration may be more appropriate. This is built
with a non-standard runtime library - the "MultiThreaded" version. When you
build your application it must be compiled with this option (/MT), otherwise
it will not build (if you are lucky) or crash (if you are not.)
Stop reading here
=================
You have enough information to build a working application.
@@ -51,37 +60,5 @@ do not need these unless your own solution itself uses debug builds (it is
far more effective to debug on the release builds, there is no point building
a special debug build.)
If, despite the previous paragraph, you still feel you need a debug build you
will have to download the zlib source as well (http://www.zlib.net) and include
the directory where you unpack it in zlib.props. This solution will then be
able to build a minimal zlib sufficient for libpng. This build is only
suitable for making a debug libpng.
The debug build of libpng is minimally supported. Support for debug builds of
zlib is also minimal. You really don't want to do this.
This solution only supports the Multi-Threaded DLL C Runtime
============================================================
If you examine the solution you will find that it very deliberately lists
exactly which MicroSoft DLLs it is linking against. It explicitly links
against msvcrt.lib. The debug version links against msvcrtd.lib (this is
why it is a debug version - it's nothing to do with having any special
debug support, it doesn't).
These versions of the MicroSoft C runtime correspond to the compiler flags
/MD (release) and /MDd (debug) - the "Multi-Threaded DLL" implementation of the
C runtime library.
If you need to change this then you will have to make sure that both the
compiler flags and the ".lib" in the linker dependences match up. Fortunately
neither zlib nor libpng require libraries other than a C runtime and
kernel32.
You cannot pass (FILE*) objects from a different runtime (including msvcrtd
to msvcrt) to libpng. If you do then your program will crash within libpng
when it first makes a file read or write call.
It is likely if you have read this far that you have found you can't avoid
having multiple C runtimes in your program. This is OK, it does work, but
you will have to implement the libpng file read/write callbacks rather than
using the internal libpng default. This is easy.