MacOSX下libpng的链接器错误 [英] Linker error with libpng under MacOSX

问题描述

我正在使用MacOSX 10.7.2和Xcode 4.2.1.我使用端口安装了libpng，试图在应用程序中加载PNG图像，但出现链接器错误:

I'm working on MacOSX 10.7.2 and Xcode 4.2.1. I installed libpng using port and I was trying to load a PNG image in my application, but I get linker errors:

Undefined symbols for architecture x86_64:
  "_png_create_read_struct", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_create_info_struct", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_destroy_read_struct", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_set_longjmp_fn", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_init_io", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_set_sig_bytes", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_read_png", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_get_IHDR", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_get_rowbytes", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
  "_png_get_rows", referenced from:
      loadPngImage(char*, int&, int&, bool&, unsigned char**) in test.o
ld: symbol(s) not found for architecture x86_64

我使用

#include "/usr/X11/include/png.h"

我知道libpng是基于zlib的，因此我已将-lz包含在其他链接器标志"中，但没有任何更改.

I know libpng is based on zlib, thus I have included -lz in "Other linker flags" but nothing changed.

关于如何使其工作的任何建议?

Any suggestions on how to make it work?

推荐答案

我通过手动安装libpng解决了问题:

I solved with a manual installation of libpng:

• 从官方网站
下载源代码

• 在终端中，进入下载的文件夹并启动

• download the source from official web site

• in Terminal, go in the downloaded folder and launch

cp ./scripts/makefile.darwin makefile
make 
sudo make install
make clean

如果它不起作用(如我的情况)，请使用TextEdit(或同等功能)打开makefile并更改行

if it doesn't work (as in my case) open makefile with TextEdit (or equivalent) and change line

ARCH="-arch i386 -arch x86_64"

在

ARCH=-arch x86_64

(当然，假设您的系统是64位).

(assuming, of course, your system is 64 bit).

可能还不够. Xcode仍然找不到该库.我解决了使用

It may not be enough. Xcode was still unable to find the library. I solved using

cd /usr/local/lib
sudo ln -s libpng15.dylib ./libpng15.15.dylib

就成功了.现在可以正常工作了.

That did the trick. Now it works fine.

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