昨天晚上，读了C++之父的《C++程序设计原理与实践》一书的第12~16章，其中介绍了图形用户界面编程用到一些基本技术，读完之后大呼过瘾。为了实践书中介绍的方法，今天在ubuntu上把需要用到的GUI库fltk安装一下，如下是安装的记录。
安装必须的支持库
sudo apt-get install build-essential xorg-dev libx11-dev libcairo2-dev
如果支持库不全，可能在configure阶段遇到以下错误：
checking for pthread_create using -lpthread... yes
checking for X... no
./configure: line 410: test: aborting.: integer expression expected
configure: error: Configure could not find required X11 libraries
./configure: line 299: return: aborting.: numeric argument required
./configure: line 309: exit: aborting.: numeric argument required
make阶段遇到以下错误：
=== making src ===
Compiling Fl.cxx...
make[1]: g++: Command not found
make[1]: *** [Fl.o] Error 127
make: *** [all] Error 1
从[官网](http://www.fltk.org/index.php)下载安装包，目前的稳定版是1.3.3，所以决定使用这个版本。
解压源代码包
tar xvzf fltk-1.3.3-source-tar.gz
首先打开README，看看configure都支持一些什么选项。
You can run configure yourself to get the exact setup you need. Type "./configure". Options include:
--enable-cygwin - Enable the Cygwin libraries (WIN32)
--enable-debug - Enable debugging code & symbols
--disable-gl - Disable OpenGL support
--enable-shared - Enable generation of shared libraries
--enable-threads - Enable multithreading support
--enable-xdbe - Enable the X double-buffer extension
--enable-xft - Enable the Xft library (anti-aliased fonts)
--bindir=/path - Set the location for executables
[default = /usr/local/bin]
--libdir=/path - Set the location for libraries
[default = /usr/local/lib]
--includedir=/path - Set the location for include files.
[default = /usr/local/include]
--prefix=/dir - Set the directory prefix for files
[default = /usr/local]
configure、make、make install安装三部曲，安装软件。为了好管理，不适用默认的路径，我把所有文件都装到了HOME目录下
mkdir -p ~/fltk/{bin, lib, include}
./configure --enable-debug --disable-gl --enable-shared --enable-threads --enable-xdbe --enable-xft --bindir=/home/xlee/fltk/bin --libdir=/home/xlee/fltk/lib --includedir=/home/xlee/fltk/include --prefix=/home/xlee/fltk
make
make install
如果在make过程中遇到以下错误：
Compiling filename_list.cxx...
filename_list.cxx: In function ‘int fl_filename_list(const char*, dirent***, int (*)(dirent**, dirent**))’:
filename_list.cxx:121:73: error: invalid conversion from ‘int (*)(const void*, const void*)’ to ‘int (*)(const dirent**, const dirent**)’ [-fpermissive]
int n = scandir(dirloc, list, 0, (int(*)(const void*,const void*))sort);
^
In file included from ../FL/filename.H:101:0,
from filename_list.cxx:21:
/usr/include/dirent.h:254:12: error: initializing argument 4 of ‘int scandir(const char*, dirent***, int (*)(const dirent*), int (*)(const dirent**, const dirent**))’ [-fpermissive]
extern int scandir (const char *__restrict __dir,
^
make[1]: *** [filename_list.o] Error 1
make: *** [all] Error 1
则修改src/filename_list.cxx文件的第121行为
int n = scandir(dirloc, list, 0, (int (*)(const dirent**, const dirent**))sort);
至此，编译安装完成。
