如何在Qt中同时为QLineEdit设置输入掩码和QValidator？

Question

我希望有一个可以接受IP地址的行编辑。如果我输入掩码：

ui->lineEdit->setInputMask("000.000.000.000");

它正在接受大于255的值。如果我提供一个验证器，那么我们必须在每三个数字后面给出一个点(.)。最好的处理方法是什么？

- QtUser

Answer 1

它接受大于255的值。

'0'的含义是这个，所以完全可以。

ASCII digit permitted but not required.

正如你所看到的，这不是你的强项。至少有以下几种方法可以规避它：

• 编写自定义验证程序

• 使用正则表达式

• 将输入分成四个条目，并在每个条目之间仍然具有可视分隔符的情况下验证每个条目。

在我看来，正则表达式解决方案可能是最快的，但也是最丑陋的：

QString ipRange = "(?:[0-1]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])";
// You may want to use QRegularExpression for new code with Qt 5 (not mandatory).
QRegExp ipRegex ("^" + ipRange
                 + "\\." + ipRange
                 + "\\." + ipRange
                 + "\\." + ipRange + "$");
QRegExpValidator *ipValidator = new QRegExpValidator(ipRegex, this);
lineEdit->setValidator(ipValidator);

声明：这只能正确验证IP4地址，因此如果您将来需要IP6，则不适用。

- László Papp

Answer 2

更简单的方法是尝试使用inputmask选项。

ui->lineEdit_IP->setInputMask( "000.000.000.000" );

在您的验证代码中，请使用以下简单条件：

QHostAddress myIP;
   if( myIP.setAddress( ui->lineEdit_IP->text()) )
   qDebug()<<"Valid IP Address";
   else
   qDebug()<<"Invalid IP address";

- Arun Kumar K S

Answer 3

嗨，我几乎遇到了同样的问题。使用inputmask或regExp的解决方案并不令人满意。我决定自己动手。

标题：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QLineEdit>
#include <QFrame>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
};

//=============================================================================
class CustomIpEditor : public QFrame
{
    Q_OBJECT
public:
    explicit CustomIpEditor(QWidget *parent = 0);
    virtual ~CustomIpEditor() {}
};

//=============================================================================
class CustomLineEdit : public QLineEdit
{
    Q_OBJECT
public:
    explicit CustomLineEdit(const QString & contents = "", QWidget *parent = 0);
    virtual ~CustomLineEdit() {}

signals:
    void jumpForward();
    void jumpBackward();

public slots:
    void jumpIn();

protected:
    virtual void focusInEvent(QFocusEvent *event);
    virtual void keyPressEvent(QKeyEvent * event);
    virtual void mouseReleaseEvent(QMouseEvent *event);

private:
    bool selectOnMouseRelease;
};

#endif // MAINWINDOW_H

来源：

#include <QVBoxLayout>
#include <QKeyEvent>

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    centralWidget()->setLayout(new QVBoxLayout);

    CustomIpEditor *myed = new CustomIpEditor;
    centralWidget()->layout()->addWidget(myed);

}

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

//=============================================================================
CustomLineEdit::CustomLineEdit(const QString & contents, QWidget *parent) :
    QLineEdit(contents, parent), selectOnMouseRelease(false)
{
    QIntValidator *valid = new QIntValidator(0, 255, this);
    setValidator(valid);
}

void CustomLineEdit::jumpIn()
{
    setFocus();

    selectOnMouseRelease = false;
    selectAll();
}

void CustomLineEdit::focusInEvent(QFocusEvent *event)
{
    QLineEdit::focusInEvent(event);
    selectOnMouseRelease = true;
}

void CustomLineEdit::keyPressEvent(QKeyEvent * event)
{
    int key = event->key();
    int cursorPos = cursorPosition();

    // Jump forward by Space
    if (key == Qt::Key_Space) {
        emit jumpForward();
        event->accept();
        return;
    }

    // Jump Backward only from 0 cursor position
    if (cursorPos == 0) {
        if ((key == Qt::Key_Left) || (key == Qt::Key_Backspace)) {
            emit jumpBackward();
            event->accept();
            return;
        }
    }

    // Jump forward from last postion by right arrow
    if (cursorPos == text().count()) {
        if (key == Qt::Key_Right) {
            emit jumpForward();
            event->accept();
            return;
        }
    }

    // After key is placed cursor has new position
    QLineEdit::keyPressEvent(event);
    int freshCurPos = cursorPosition();

    if ((freshCurPos == 3) && (key != Qt::Key_Right))
        emit jumpForward();
}

void CustomLineEdit::mouseReleaseEvent(QMouseEvent *event)
{
    if(!selectOnMouseRelease)
        return;

    selectOnMouseRelease = false;
    selectAll();

    QLineEdit::mouseReleaseEvent(event);
}

//=============================================================================
void makeCommonStyle(QLineEdit* line) {
    line->setContentsMargins(0, 0, 0, 0);
    line->setAlignment(Qt::AlignCenter);
    line->setStyleSheet("QLineEdit { border: 0px none; }");
    line->setFrame(false);
    line->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Preferred);
}

QLineEdit* makeIpSpliter() {
    QLineEdit *spliter = new QLineEdit(".");
    makeCommonStyle(spliter);

    spliter->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
    spliter->setMaximumWidth(10);
    spliter->setReadOnly(true);
    spliter->setFocusPolicy(Qt::NoFocus);
    return spliter;
}

CustomIpEditor::CustomIpEditor(QWidget *parent) :
    QFrame(parent)
{
    setContentsMargins(0, 0, 0, 0);
    setStyleSheet("QFrame { background-color: white;  border: 1px solid white; border-radius: 15px; }");

    QList <CustomLineEdit *>  lines;
    QList <CustomLineEdit *>::iterator linesIterator;

    lines.append(new CustomLineEdit);
    lines.append(new CustomLineEdit);
    lines.append(new CustomLineEdit);
    lines.append(new CustomLineEdit);

    QHBoxLayout *mainLayout = new QHBoxLayout;
    mainLayout->setSpacing(0);
    setLayout(mainLayout);

    for (linesIterator = lines.begin(); linesIterator != lines.end(); ++linesIterator) {
        makeCommonStyle(*linesIterator);
        mainLayout->addWidget(*linesIterator);

        if (*linesIterator != lines.last()) {
            connect(*linesIterator, &CustomLineEdit::jumpForward,
                    *(linesIterator+1), &CustomLineEdit::jumpIn);
            mainLayout->addWidget(makeIpSpliter());
        }
        if (*linesIterator != lines.first()) {
            connect(*linesIterator, &CustomLineEdit::jumpBackward,
                    *(linesIterator-1), &CustomLineEdit::jumpIn);
        }
    }

}

- AGo

Answer 4

对于那些对QT文档中以下提示感到困惑的人：doku:

为了获得范围控制（例如IP地址），请将掩码与验证器一起使用。

在这种情况下，验证器需要处理空格。我的解决方案改编自lpapp的答案和这个Qt论坛帖子，因此如下：

QString ipRange = "(([ 0]+)|([ 0]*[0-9] *)|([0-9][0-9] )|([ 0][0-9][0-9])|(1[0-9][0-9])|([2][0-4][0-9])|(25[0-5]))";
// You may want to use QRegularExpression for new code with Qt 5 (not mandatory).
QRegExp ipRegex ("^" + ipRange
                 + "\\." + ipRange
                 + "\\." + ipRange
                 + "\\." + ipRange + "$");
QRegExpValidator *ipValidator = new QRegExpValidator(ipRegex, this);
lineEdit->setValidator(ipValidator);
lineEdit->setInputMask("000.000.000.000");
// Avoid having to move cursor before typing
linEdit->setCursorPosition(0);

我是一个正则表达式的初学者，所以请随意推荐改进。

- Gesalat

Answer 5

根据Arun Kumar K S的回答：

如果myIP.setAddress()成功了，你可以将IP以格式化字符串的形式写回到行编辑器中：

ui->lineEdit->setText(myIP->toString());

因此，您不一定需要设置掩码（也不需要验证器或正则表达式）。

注意：如果setAddress()无法读取IP，则会写入/覆盖myIP。因此，在这种情况下调用toString()将导致一个空字符串。

- ElvisIsAlive