c++ - 从 QGraphicsScene 上的 QGraphicsLinearLayout 中删除 QGraphics 项目

Question

我遇到了一个非常令人沮丧的问题，试图删除我的应用程序中的 qgraphicsitems。我有一个菜单 Controller ，负责将按钮添加到布局并将它们添加到场景中。这些按钮都与自定义信号和槽相连。当我改变状态时，我想删除这个 Controller 并删除所有这些 qgraphicsitems。

下面是我如何将它们添加到我的 menu_controller.cpp 中:

QGraphicsWidget * temp;//this is used during iteration to add to the layout

    this->layout = new QGraphicsLinearLayout(Qt::Vertical);//q graphics view layout
    this->menu = new QGraphicsWidget;//holds the layout


    // initialize the proper buttons
    (this->game_state->is_logged_in()) ? (this->logged_in()) : (this->not_logged_in());//test whether or not the user is logged in to generate the correct menu

    // now iterate through each button and add to the layout
    for (int i = 0, z = this->buttons.size(); i < z; i++) {

        temp = this->scene->addWidget(this->buttons[i]);//add widget to the scene
        this->layout->addItem(temp);//add this widget to the layou
        connect(this->buttons[i], SIGNAL(menu_selection(QString)), this, SLOT(set_menu_option(QString)));//connect the button to this
    }

    // set menu layout as the layout and then add the menu to the scene
    this->menu->setLayout(this->layout);
    this->position();
    this->scene->addItem(this->menu);

最后，我的析构函数看起来像这样:

QGraphicsScene * scene = this->game_state->get_scene();

    QList<QGraphicsItem *> list = scene->items();
    QList<QGraphicsItem *>::Iterator it = list.begin();

    for (; it != list.end(); ++it)
        if (*it)
            scene->removeItem(*it);

    for (int i = 0, z = this->buttons.size(); i < z; i++)
        disconnect(this->buttons[i], 0, 0, 0);//button not connected to anything

    // for each deletes each place in memory
    for_each(this->buttons.begin(), this->buttons.end(), utilities::delete_ptr());

    delete this->layout;//delete the layout container
    delete this->menu;//delete the menu

我从场景中移除每个按钮，断开连接的按钮，然后尝试对它们调用 delete。

我每次都会遇到段错误。场景项目删除正常，断开连接正常工作，但由于某种原因，当我删除项目时，它会抛出段错误并使程序崩溃。

Answer 1

我猜你的 utilities::delete_ptr() 有问题。

但无论如何。如果您要删除发送者或接收者，则无需断开信号。当其中一个被删除时，这会自动完成。

也无需遍历场景中的整个项目列表并删除它们。来电 QGraphicsScene::clear()会做。即使那样也没有必要，因为您无论如何都要删除场景。