Question

所以，我刚开始在我的SFML项目中使用SFGUI，而且我很难理解一切是如何工作的。我一直在阅读hello world教程以及图书馆本身在其文件夹中提供的一些示例。

我现在正在尝试创建一个简单的按钮，当它检测到左键单击时会执行某些操作，但我甚至无法正常工作。错误窗口显示我的button方法中未定义OnClick变量，如果我尝试使用button的参数发送std::bind，我会得到典型的＆＃34 ;没有匹配功能...＆＃34;。

在大多数库的示例中，通过在函数名称旁边使用this作为第二个参数来解决此问题，但这对我来说似乎不起作用。

应该怎么做？

我的代码：

void pressEnter(){
    button->SetLabel("Tocado"); // FIRST ERROR IN THIS LINE
}

int main(){

    sfg::SFGUI sfgui;

    sf::VideoMode video_mode( 800, 600 );
    sf::RenderWindow rwindow( video_mode, "In-joked - Menu Principal");
    sf::Event event;

    auto button = sfg::Button::Create("Status");
    button->GetSignal(sfg::Button::OnLeftClick).Connect(
            std::bind(&pressEnter, button)); //SECOND ERROR IN THIS LINE

    ...
}

NetBeans显示的第一行错误：＆＃34;无法解析标识符＆＃34;按钮＆＃34;。＆＃34;按钮＆＃34;未在此范围内宣布＆＃34;

第二行：

＆＃34;来自

的文件

错误：没有匹配函数来调用'sfg :: Signal :: Connect（std :: _ Bind_helper＆amp;＆gt; :: type）' std :: bind（＆amp; pressEnter，button））;＆＃34;

运行控制台输出中的完整错误：

main.cpp: In function ‘void pressEnter()’:
main.cpp:7:5: error: ‘button’ was not declared in this scope
     button->SetLabel("Tocado");
     ^
In file included from /usr/include/c++/5/memory:79:0,
                 from /usr/local/include/SFGUI/Signal.hpp:6,
                 from /usr/local/include/SFGUI/Object.hpp:4,
                 from /usr/local/include/SFGUI/Adjustment.hpp:3,
                 from /usr/local/include/SFGUI/Widgets.hpp:6,
                 from main.cpp:2:
/usr/include/c++/5/functional: In instantiation of ‘struct std::_Bind_check_arity<void (*)(), std::shared_ptr<sfg::Button>&>’:
/usr/include/c++/5/functional:1439:12:   required from ‘struct std::_Bind_helper<false, void (*)(), std::shared_ptr<sfg::Button>&>’
/usr/include/c++/5/functional:1462:5:   required by substitution of ‘template<class _Func, class ... _BoundArgs> typename std::_Bind_helper<std::__is_socketlike<_Func>::value, _Func, _BoundArgs ...>::type std::bind(_Func&&, _BoundArgs&& ...) [with _Func = void (*)(); _BoundArgs = {std::shared_ptr<sfg::Button>&}]’
main.cpp:20:42:   required from here
/usr/include/c++/5/functional:1410:7: error: static assertion failed: Wrong number of arguments for function
       static_assert(sizeof...(_BoundArgs) == sizeof...(_Args),
       ^
main.cpp: In function ‘int main()’:
main.cpp:20:43: error: no matching function for call to ‘sfg::Signal::Connect(std::_Bind_helper<false, void (*)(), std::shared_ptr<sfg::Button>&>::type)’
             std::bind(&pressEnter, button));
                                           ^
In file included from /usr/local/include/SFGUI/Object.hpp:4:0,
                 from /usr/local/include/SFGUI/Adjustment.hpp:3,
                 from /usr/local/include/SFGUI/Widgets.hpp:6,
                 from main.cpp:2:
/usr/local/include/SFGUI/Signal.hpp:40:16: note: candidate: unsigned int sfg::Signal::Connect(std::function<void()>)
   unsigned int Connect( std::function<void()> delegate );
                ^
/usr/local/include/SFGUI/Signal.hpp:40:16: note:   no known conversion for argument 1 from ‘std::_Bind_helper<false, void (*)(), std::shared_ptr<sfg::Button>&>::type {aka std::_Bind<void (*(std::shared_ptr<sfg::Button>))()>}’ to ‘std::function<void()>’
nbproject/Makefile-Debug.mk:78: recipe for target 'build/Debug/GNU-Linux/main.o' failed
make[2]: *** [build/Debug/GNU-Linux/main.o] Error 1
make[2]: Leaving directory '/home/manu/NetBeansProjects/GameMenu'
nbproject/Makefile-Debug.mk:59: recipe for target '.build-conf' failed
make[1]: *** [.build-conf] Error 2
make[1]: Leaving directory '/home/manu/NetBeansProjects/GameMenu'
nbproject/Makefile-impl.mk:39: recipe for target '.build-impl' failed
make: *** [.build-impl] Error 2

BUILD FAILED (exit value 2, total time: 953ms)

Answer 1

一种选择是将变量放在可以访问它的范围内。

sfg::Button::Ptr button;

void pressEnter(){
    button->SetLabel("Tocado");
}

int main(){

    sfg::SFGUI sfgui;

    sf::VideoMode video_mode( 800, 600 );
    sf::RenderWindow rwindow( video_mode, "In-joked - Menu Principal");
    sf::Event event;

    button = sfg::Button::Create("Status");
    button->GetSignal(sfg::Button::OnLeftClick).Connect(&pressEnter);

    ...
}

这是一个全局变量，可能不是最好的方法，但它会起作用。如何将程序结构化为没有全局变量对于Q＆amp; A来说有点过于宽泛。

尝试将简单按钮绑定到SFGUI中的OnClick函数

1 个答案: