Question

每次按下“添加客户端”按钮 - 减号按钮，客户端名称，客户端计数器和加号按钮都以水平线添加到gridLayout。我想在按下加号/减号按钮时更新计数（QLabel）。

这是我的代码：

#include "widget.h"
#include "ui_widget.h"
#include <QDebug>
#include <QGridLayout>
#include <QLabel>

int row = 0;

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_pushButton_clicked()
{
    QPushButton* minus_button = new QPushButton();
    QPushButton* plus_button = new QPushButton();
    minus_button->setText("-");
    plus_button->setText("+");

    QLabel* client_name = new QLabel(ui->lineEdit->text(), this);
    QLabel* client_count = new QLabel("", this);

    ui->gridLayout->addWidget(minus_button, row, 1, Qt::AlignTop|Qt::AlignHCenter);
    ui->gridLayout->addWidget(client_name, row, 2, Qt::AlignTop|Qt::AlignHCenter);
    ui->gridLayout->addWidget(client_count, row, 3, Qt::AlignTop|Qt::AlignHCenter);
    ui->gridLayout->addWidget(plus_button, row++, 4, Qt::AlignTop|Qt::AlignHCenter);

    connect(minus_button, SIGNAL(clicked(bool)), this, SLOT(minusCount()));
    connect(plus_button, SIGNAL(clicked(bool)), this, SLOT(plusCount()));
}

void Widget::minusCount(){
    //Here I want to somehow reference the client_count label which is in the same row
}
void Widget::plusCount(){
    //Here I want to somehow reference the client_count label which is in the same row
}

编辑：在Kevin的评论之后，这里是任何可能需要它的人的工作代码。

#include "widget.h"
#include "ui_widget.h"
#include <QDebug>
#include <QGridLayout>
#include <QLabel>
#include <QSignalMapper>

QSignalMapper* m_minusMapper;
QSignalMapper* m_plusMapper;

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    m_minusMapper = new QSignalMapper(this);
    connect(m_minusMapper, SIGNAL(mapped(QWidget*)), this, SLOT(minusCount(QWidget*)));

    m_plusMapper = new QSignalMapper(this);
    connect(m_plusMapper, SIGNAL(mapped(QWidget*)), this, SLOT(plusCount(QWidget*)));
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_pushButton_clicked()
{
    QPushButton* minus_button = new QPushButton();
    minus_button->setObjectName("minus" + QString::number(row));
    minus_button->setText("-");

    QPushButton* plus_button = new QPushButton();
    plus_button->setObjectName("plus" + QString::number(row));
    plus_button->setText("+");

    QLabel* client_name = new QLabel(ui->lineEdit->text(), this);
    QLabel* client_count = new QLabel("0", this);

    ui->gridLayout->addWidget(minus_button, row, 1, Qt::AlignVCenter|Qt::AlignHCenter);
    ui->gridLayout->addWidget(client_name, row, 2, Qt::AlignVCenter|Qt::AlignHCenter);
    ui->gridLayout->addWidget(client_count, row, 3, Qt::AlignVCenter|Qt::AlignHCenter);
    ui->gridLayout->addWidget(plus_button, row++, 4, Qt::AlignVCenter|Qt::AlignHCenter);

    connect(minus_button, SIGNAL(clicked()), m_minusMapper, SLOT(map()));
    connect(plus_button, SIGNAL(clicked()), m_plusMapper, SLOT(map()));

    m_minusMapper->setMapping(minus_button, client_count);
    m_plusMapper->setMapping(plus_button, client_count);
}

void Widget::minusCount(QWidget *widget)
{
    QLabel *client_count = qobject_cast<QLabel*>(widget);
    QString initCount = client_count->text();
    int newCount = initCount.toInt() - 1;
    client_count->setText(QString::number(newCount));
}

void Widget::plusCount(QWidget *widget)
{
    QLabel *client_count = qobject_cast<QLabel*>(widget);
    QString initCount = client_count->text();
    int newCount = initCount.toInt() + 1;
    client_count->setText(QString::number(newCount));
}

Answer 1

凯文原则上的答案很好，但是既然我们现在已经2016年了，MSVC2010，gcc 4.7和Clang 3.1（以及可能的早期版本）支持lambdas / C ++ 11，我＆＃39 ; d想添加一个没有QSignalMapper的版本：

static void minusCount(QLabel *label)
{
    QString initCount = label->text();
    int newCount = initCount.toInt() - 1;
    label->setText(QString::number(newCount));
}

static void plusCount(QLabel *label)
{
    QString initCount = label->text();
    int newCount = initCount.toInt() + 1;
    label->setText(QString::number(newCount));
}

void Widget::on_pushButton_clicked()
{
    // ... add the labels and buttons, then:
    connect(minus_button, &QPushButton::clicked,
            client_count, [client_count]() { minusCount(client_count); });
    connect(plus_button, &QPushButton::clicked,
            client_count, [client_count]() { plusCount(client_count); });
}

此处按钮单击应更改的client_count标签将在lambda中捕获，并直接传递给处理它的函数。

minusCount和plusCount也可以是静态函数，因为它们只对作为参数传递的标签进行操作，因此它们独立于任何Widget实例。 / p>

Answer 2

最简单的方法是使用QSignalMapper

// in the constructor of your class
m_minusSignalMapper = new QSignalMapper(this);
connect(m_minusSignalMapper, SIGNAL(mapped(QWidget*)), this, SLOT(minusCount(QWidget*)));

m_plusSignalMapper = new QSignalMapper(this);
connect(m_plusSignalMapper, SIGNAL(mapped(QWidget*)), this, SLOT(plusCount(QWidget*)));


// in your button slot you connect to the respective mapper instead
connect(minus_button, SIGNAL(clicked()), m_minusMapper, SLOT(map()));
connect(plus_button, SIGNAL(clicked()), m_plusMapper, SLOT(map()));

// and you set up the mapping
m_minusMapper->setMapping(minus_button, client_count);
m_plusMapper->setMapping(plus_button, client_count);

// in the the two receiver slots, the argument is the label
void Widget::minusCount(QWidget *widget)
{
    QLabel *client_count = qobject_cast<QLabel*>(widget);
}

如何在单击旁边的按钮时引用动态创建的标签[Qt]

2 个答案: