macOS Monterey下Perl Imager::File::PNG安装失败：libpng库/头文件未找到

问题背景 #

我在MacBook（macOS Monterey系统）上运行Perl脚本生成“魔法笔”OID图片（image.png）时持续报错。我不是程序员，谷歌排查一个多月没解决，已完成以下操作：

• 安装Homebrew
• 通过brew install perl安装Perl
• 通过brew install libpng安装libpng
• 在perl -MCPAN -eshell中安装Imager、YAML及MP3::Info，均无报错

旧款MacBook按这些步骤能正常运行脚本，但这台Mac安装Homebrew时做过修改，不确定Imager能否调用libpng。尝试安装Imager::File::PNG时出现如下错误：

Running install for module 'Imager::File::PNG'
Checksum for /Users/darina/.cpan/sources/authors/id/T/TO/TONYC/Imager-File-PNG-0.99.tar.gz ok
Scanning cache /Users/darina/.cpan/build for sizes
............................................................................DONE
Configuring T/TO/TONYC/Imager-File-PNG-0.99.tar.gz with Makefile.PL
PNG: building independently
PNG: Generic: includes not found - libraries found
PNG: v1.6: includes not found - libraries found
PNG: v1.5: includes not found - libraries not found
PNG: v1.4: includes not found - libraries not found
PNG: v1.2: includes not found - libraries not found
PNG: v1.0: includes not found - libraries not found
PNG: base (+libz): includes not found - libraries not found
PNG: v1.6 (+libz): includes not found - libraries not found
PNG: v1.5 (+libz): includes not found - libraries not found
PNG: v1.4 (+libz): includes not found - libraries not found
PNG: v1.2 (+libz): includes not found - libraries not found
PNG: v1.0 (+libz): includes not found libraries not found
PNG: Checking if the compiler can find them on its own
PNG: Test code failed: Can't link/include 'png.h', 'stdio.h', 'png'
OS unsupported: PNG libraries or headers not found
Warning: No success on command[/usr/local/Homebrew/Cellar/perl/5.34.0/bin/perl Makefile.PL]
TONYC/Imager-File-PNG-0.99.tar.gz /usr/local/Homebrew/Cellar/perl/5.34.0/bin/perl Makefile.PL -- NOT OK
Failed during this command:
TONYC/Imager-File-PNG-0.99.tar.gz : writemakefile NO '/usr/local/Homebrew/Cellar/perl/5.34.0/bin/perl Makefile.PL' returned status 512

详细解决步骤（一步步操作） #

步骤1：找到libpng的安装路径 #

打开终端，输入以下命令并按回车：

brew --prefix libpng

终端会输出一串路径（比如/usr/local/Cellar/libpng/1.6.40），用鼠标选中路径后按Command+C复制。

步骤2：安装cpanm（如果没装过） #

如果之前没安装过cpanm，在终端输入以下命令安装：

brew install cpanm

等待安装完成后继续下一步。

步骤3：手动指定路径安装Imager::File::PNG #

在终端输入以下命令，把[刚才复制的libpng路径]替换成你实际复制的路径：

cpanm --configure-args="--png-inc=[刚才复制的libpng路径]/include --png-lib=[刚才复制的libpng路径]/lib" Imager::File::PNG

举个例子，如果复制的路径是/usr/local/Cellar/libpng/1.6.40，完整命令就是：

cpanm --configure-args="--png-inc=/usr/local/Cellar/libpng/1.6.40/include --png-lib=/usr/local/Cellar/libpng/1.6.40/lib" Imager::File::PNG

输入完按回车，等待安装完成。

步骤4：验证安装是否成功 #

安装完成后，在终端输入以下命令：

perl -MImager::File::PNG -e 'print "安装成功\n"'

如果终端输出安装成功，说明安装没问题；如果还是报错，继续下一步。

步骤5：设置环境变量后重试 #

如果步骤3失败，在终端依次输入以下3条命令，每条输完按回车：

export C_INCLUDE_PATH=$(brew --prefix libpng)/include:$C_INCLUDE_PATH
export LIBRARY_PATH=$(brew --prefix libpng)/lib:$LIBRARY_PATH
export LD_LIBRARY_PATH=$(brew --prefix libpng)/lib:$LD_LIBRARY_PATH

然后再次运行安装命令：

cpanm Imager::File::PNG

安装完成后，再用步骤4的命令验证。

步骤6：测试脚本 #

回到你的Perl脚本所在文件夹，运行脚本，检查是否能正常生成image.png。

内容的提问来源于stack exchange，提问作者Darina