通过访问容器的父级来使用sigc::mem_fun

Question

我正在尝试用Gtkmm3制作一个简单的软件。

我想要一扇窗户，里面有格子。单击该网格内的按钮，就会触发一个窗口方法来删除当前网格并用另一个网格替换它。

我可以使用这样的网格方法：

button.signal_clicked().connect(sigc::mem_fun(*this, &MyGrid::someMethod));

"这个"；是MyGrid。

我想做这样的事情：

button.signal_clicked().connect(sigc::mem_fun(*this->get_parent(), &MyWindow::someMethod));

其中该->get_parent((将是MyWindow 的一个实例

我的.h:

#ifndef MINIPROJECT_GUI_H
#define MINIPROJECT_GUI_H
#include <gtkmm/button.h>
#include <gtkmm/window.h>
#include <gtkmm/grid.h>
#include <iostream>
#include <string>
#include <map>
#include <vector>
#include <gtkmm/label.h>

class WelcomeGrid: public Gtk::Grid
{
Gtk::Label message;
Gtk::Button nextButton; // This button should be connected to Fenetre::infoView()
public:
WelcomeGrid();
void display();
};

class InfoGrid : public Gtk::Grid
{
Gtk::Button button2;// This button should be connected to Fenetre::welcomeView()
Gtk::Label label2;
public:
InfoGrid();
void display();
};

class Fenetre : public Gtk::Window
{
public:
Fenetre();
virtual ~Fenetre(); // Setup window
void welcomeView();
protected:
//Member widgets:
WelcomeGrid welcome;
InfoGrid info;
void infoView(); // Remove the current grid from the window and replace it by infoGrid
void welcomeView(); // Remove the current grid from the window and replace it by WelcomeGrid
};

#endif //MINIPROJECT_GUI_H

我的.cpp:

#include "GUI.h"
Fenetre::Fenetre()
{
// Sets the border width of the window.
set_border_width(10);
this->add(welcome);
}
Fenetre::~Fenetre()
{
}
void Fenetre::welcomeView() {
this->remove();
this->add(welcome);
}
void Fenetre::infoView() {
this->remove();
this->add(info);
}

InfoGrid::InfoGrid() {
button2.set_label("Hello.");
button2.signal_clicked().connect(sigc::mem_fun(*this,
&InfoGrid::display));
label2.set_label("Welcome on the Vampire creation interface.");
this->attach(label2, 0, 0, 1, 1);
this->attach(button2,1,1,1,1);
button2.show();
this->show_all();
}

WelcomeGrid::WelcomeGrid() {
nextButton.set_label("Create new character.");
auto a = this->get_parent();
nextButton.signal_clicked().connect(sigc::mem_fun(*this,
&WelcomeGrid::display));
message.set_label("Welcome on the Vampire creation interface.");
this->attach(message, 0, 0, 1, 1);
this->attach(nextButton,1,1,1,1);
// This packs the button into the Window (a container);
this->show_all();
}
void WelcomeGrid::display() {
auto a = this->get_parent();
std::cout << typeid(a).name();
}
void InfoGrid::display() {
std::cout << "coucou";
}

Answer 1

如果没有任何代码，很难知道您到底在寻找什么。以下是我的操作方法：我将在网格中保留对父窗口的引用。例如：

#include <iostream>
#include <memory>
#include <sstream>
#include <gtkmm.h>
class MyWindow : public Gtk::Window
{
public:
MyWindow()
: m_grid{std::make_unique<MyGrid>(*this, m_count)}
{
add(*m_grid);
}
// This is called when the grid's button is pressed:
void ReplaceGrid()
{
++m_count; 

// Remove the grid from the window:
remove();
// Destroy current grid:
m_grid = nullptr;
// Create a new grid:
m_grid = std::make_unique<MyGrid>(*this, m_count);
// Add it to the window:
add(*m_grid);
show_all();
}
private:
class MyGrid : public Gtk::Grid
{

public:

MyGrid(MyWindow& p_parent, int p_count)
: m_parent{p_parent}
{
// Create button:
std::ostringstream ss;
ss << "Replace me #" << p_count;
m_replaceButton = Gtk::Button(ss.str());

// Attach it to the grid:
attach(m_replaceButton, 0, 0, 1, 1);

// Connect replacement signal, using the parent window:
m_replaceButton.signal_clicked().connect([this]()
{
// Call the parent (the window):
m_parent.ReplaceGrid();
});
}
~MyGrid()
{
std::cout << "Grid destroyed" << std::endl;
}

private:

Gtk::Button m_replaceButton;
// Keep a reference to the parent window in the grid:
MyWindow&   m_parent;
};
int                     m_count = 0;
std::unique_ptr<MyGrid> m_grid;
};
int main(int argc, char *argv[]) 
{
auto app = Gtk::Application::create(argc, argv, "so.question.q64594709");
MyWindow w;
w.show_all();

return app->run(w);
}

如果运行此代码，您将看到一个窗口，其中有一个包含一个按钮的网格。每当你点击按钮，窗口：

1. 更新计数器
2. 破坏当前电网
3. 使用更新的计数器值创建新网格

您将在新网格的按钮标签上看到更新的计数器值。在终端中，网格析构函数将打印一条消息，证明网格确实被切换了。

注意，我在这里使用了lambdas来清理语法。我建议你也这样做。如果您真的想使用sigc::men_fun，可以将lambda的内容封装到问题中提到的MyGrid::someMethod方法中。

还要注意，网格是窗口的私有嵌套类(没有其他人需要知道…(

用GCC编译：

g++ main.cpp -o example.out `pkg-config gtkmm-3.0 --cflags --libs`