用cmake构建gtk程序

情况说明

先前已经在windows下基于GDI实现了一个简陋的imshow：基于GDI的imshow：使用stb_image读取图像并修正绘制。考虑跨平台，也考虑万一某天M$不让我们用盗版系统了，还是需要实现一个Linux/Mac下的imshow。

GTK相当于GDI在Linux下的一个替代。我用的是GTK-3

官方GTK文档的tutorial给出了一个能运行的例子，不过构建工具用的非常raw的gcc和pkg-config，未免过于刀耕火种。用CMake改造一下也是可以的。这里简单记录。

依赖项

ubuntu下的依赖项

• pkg-config

sudo apt install pkg-config

• gtk3

sudo apt-get install libgtk-3-dev 

• cmake

手动下载解压配置最新的cmake，例如3.14

mac OSX下的依赖项

mac下也可以使用gtk-3.0。依赖问题解决如下：

brew install pkg-config gtk+3 libffi

然后还需要手动解决下libffi无法被cmake找到的问题，第一种办法是在_/.bashrc或/.zshrc中添加：

export PKG_CONFIG_PATH="(brew --prefix libffi)/lib/pkgconfig/"

不过这个办法略显ugly，另一种ugly的做法是在CMake中临时修改PKG_CONFIG_PATH环境变量。考虑到gtk库本身的链接目录在Mac OSX下也不能被cmake找到，还是需要另行写一段cmake的，因此不如都放到cmake脚本中处理。

目录结构

CMakeLists.txt

src/main.c

build/

代码

CMakeLists.txt

试了下直接find_package(GTK)不行。需要搭配pkg-config，cmake已经对此做出封装。

cmake_minimum_required (VERSION 3.14)
project (hello-gtk)

if (CMAKE_SYSTEM_NAME MATCHES "Linux")
    find_package(PkgConfig REQUIRED)
	pkg_check_modules(GTK3 REQUIRED gtk+-3.0)
    message(STATUS "----- GTK3_INCLUDE_DIRS: ${GTK3_INCLUDE_DIRS}")
    message(STATUS "----- GKT3_LIBRARIES: ${GTK3_LIBRARIES}")
    message(STATUS "----- GTK3_LINK_LIBRARIES: ${GTK3_LINK_LIBRARIES}")
	include_directories(${GTK3_INCLUDE_DIRS})
	link_directories(${GTK3_LIBRARY_DIRS})
	list(APPEND FC_DEP_LIBS ${GTK3_LIBRARIES})
elseif (CMAKE_SYSTEM_NAME MATCHES "Darwin")
    #export PKG_CONFIG_PATH="$(brew --prefix libffi)/lib/pkgconfig/"
    set(ENV{PKG_CONFIG_PATH} /usr/local/opt/libffi/lib/pkgconfig)
    find_package(PkgConfig REQUIRED)
	pkg_check_modules(GTK3 REQUIRED gtk+-3.0)
    message(STATUS "----- GKT3_LIBRARIES: ${GTK3_LIBRARIES}")
    message(STATUS "----- GTK3_LINK_LIBRARIES: ${GTK3_LINK_LIBRARIES}")
	include_directories(${GTK3_INCLUDE_DIRS})
    list(APPEND FC_DEP_LIBS ${GTK3_LINK_LIBRARIES})
endif()

add_executable (gtk-test src/main.c)

#add_definitions (${GTK3_CFLAGS_OTHER})
message(STATUS "----- ${GTK3_CFLAGS_OTHER}")
# -pthread

target_link_libraries (gtk-test ${FC_DEP_LIBS})

main.c

#include <gtk/gtk.h>

static void activate(GtkApplication* app, gpointer user_data)
{
    GtkWidget *window;

    window = gtk_application_window_new (app);
    gtk_window_set_title (GTK_WINDOW (window), "Window");
    gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);
    gtk_widget_show_all (window);
}

int main(int argc, char** argv)
{
    GtkApplication *app;
    int status;

    app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
    g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
    status = g_application_run (G_APPLICATION (app), argc, argv);
    g_object_unref (app);

    return status;
}

Linux下cmake ..执行结果：

-- The C compiler identification is GNU 5.4.0
-- The CXX compiler identification is GNU 5.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1") 
-- Checking for module 'gtk+-3.0'
--   Found gtk+-3.0, version 3.18.9
-- ----- -pthread
-- Configuring done
-- Generating done
-- Build files have been written to: /home/chris/dev/libfc/gtk/build

make之后运行得到窗口：

reference
How do I link gtk library more easily with cmake in windows?