Question

我创建了一个自定义QWidget（下面的代码）[内有QHBoxLayout和两个QPushButtons]并将其添加到GUI中的QVBoxLayout。此自定义QWidget - 对象将被多次创建和删除（代码如下）。

当我在控制台（嵌入式Linux）中输入top时，每次添加新的QWidget时都会增加RAM。没关系！但是在删除时我看不到内存减少。

我的代码出了什么问题？我想，删除自定义QWidgets后RAM会减少。

myCustomWidget.h

class QCustomPushButton_withinIcon_LeftAndRight : public QWidget {
    Q_OBJECT

public:
    //functions
    QCustomPushButton_withinIcon_LeftAndRight(QWidget *parent = 0);
    ~QCustomPushButton_withinIcon_LeftAndRight();

    //other slots like:
    // - virtual void mousePressEvent();
    // - virtual void mouseReleaseEvent();
    //other signals like:
    // - void clicked();
    //other functions like:
    // - virtual void setEnabled(bool a);
    // - virtual void paintEvent(QPaintEvent *);
    // - ...

private:
    //variables
    QLayout *innerLayout;           //!< Layout for two buttons
    QPushButton *buttonLeft;        //!< Button left
    QPushButton *buttonRight;       //!< Button right

    //other variables like:
    // - bool enabled;
    // - ...
};

myCustomWidget.cpp

QCustomPushButton_withinIcon_LeftAndRight::QCustomPushButton_withinIcon_LeftAndRight(QWidget *parent) :
    QWidget(parent),
    mSVG (new svg),
    mGradient (new gradient)
{
    enabled = true;

    //create innerLayout
    innerLayout = new QHBoxLayout();
    this->setLayout(innerLayout);

    //create buttons
    buttonLeft = new QPushButton();
    buttonRight = new QPushButton();
    innerLayout->addWidget(buttonLeft);
    innerLayout->addWidget(buttonRight);

    //create connections like:
    // - connect (buttonLeft, SIGNAL(pressed()), this, SLOT(mousePressEvent()));
    // - ...

    //set some stylesheets
    // - buttonLeft->setStyleSheet("...");
}
QCustomPushButton_withinIcon_LeftAndRight::~QCustomPushButton_withinIcon_LeftAndRight()
{
    //I think, that this is right. If not, correct me.
    delete buttonLeft;
    delete buttonRight;
    delete innerLayout;
}

//void QCustomPushButton_withinIcon_LeftAndRight::mousePressEvent() {}
//void QCustomPushButton_withinIcon_LeftAndRight::mouseReleaseEvent() {}
//void QCustomPushButton_withinIcon_LeftAndRight::setEnabled(bool a) {}
//void QCustomPushButton_withinIcon_LeftAndRight::paintEvent(QPaintEvent *) {} ...

gui.cpp（将QWidgets添加到GUI中的QLayout）

    QCustomPushButton_withinIcon_LeftAndRight *button = new QCustomPushButton_withinIcon_LeftAndRight();
    //add button to layout
    parentUiWindow->aLayoutNameInGui->addWidget(button);
    //aLayoutNameInGui is type of QVBoxLayout

gui.cpp（在GUI中的QWidgets中删除QLayout）

    //delete all buttons in layout
    QLayoutItem *child;
    while((child = parentUiWindow->aLayoutNameInGui->layout()->takeAt(0)) != 0) {
        //parentUiWindow->aLayoutNameInGui->removeWidget(child->widget()); //already removed by ->takeAt()
        //child->widget()->setParent(NULL);
        delete child->widget();
        delete child;
    }

Answer 1

使用top命令查看内存使用情况时，可能会出现误报。正如某些程序员dude 所述，当您在某些对象上调用delete时，操作系统并不总是从您的进程中释放已分配的内存。

但是，您使用QCustomPushButton_withinIcon_LeftAndRight在new构造函数中创建了两个对象：

mSVG (new svg),
mGradient (new gradient)

但你似乎永远不会破坏这些物体。所以你可能会在那里发生内存泄漏。

在QLayout

1 个答案: