Question

我正在创建的程序包括Dim tempLong As Double tempLong = Radians(longD) + ArcTan2(Sin(bearingR) * sinAngDistance * Cos(latR), cosAngDistance - Sin(latR) * Sin(latlong(0))) ' set longitude if calculated value less than 1 If tempLong < 1 Then latlong(1) = tempLong ' if greater than 1, add decimal part back to modulus result Else Dim decLong As Double decLong = tempLong While decLong > 1 decLong = decLong - 1 Wend latlong(1) = ((tempLong + 540) Mod 360 - 180) + decLong End If部分。我要执行以下功能：

当我尝试按扮演{strong>撤消角色的QTextEdit项目时，撤消的跟踪历史记录的结尾时，必须返回具体值（QAction或bool）。我猜想成功执行完上述命令后，将执行另一个命令。
重做必须执行相同的操作。

谢谢。

Answer 1

在Qt QTextEdit documentation中，您可以找到redo和undo动作。您还可以通过redo和undo信号测试redoAvailable或undoAvailable是否可用。

要执行操作，您可以使用信号/插槽注册。

例如：

#include <QVBoxLayout>
#include <QPushButton>
#include <QTextEdit>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent)
{
    QPushButton *poUndo     = new QPushButton("Undo", this);
    QPushButton *poRedo     = new QPushButton("Redo", this);
    QTextEdit   *poTextEdit = new QTextEdit(this);
    QHBoxLayout *poHlayout  = new QHBoxLayout;

    QLabel * poLabelRedoAvaliable = new QLabel(this);
    QLabel * poLabelUndoAvaliable = new QLabel(this);


    // add undo/redo buttons
    poHlayout->addWidget(poRedo);
    poHlayout->addWidget(poUndo);

    QVBoxLayout *poVLayout  = new QVBoxLayout;
    poVLayout->addWidget(poTextEdit); // add text edit
    poVLayout->addLayout(poHlayout);

    // redo/undo avaliable status
    poVLayout->addWidget(poLabelRedoAvaliable);
    poVLayout->addWidget(poLabelUndoAvaliable);

    // main central widget
    QWidget *poCentral  = new QWidget(this);
    poCentral->setLayout(poVLayout);
    this->setCentralWidget(poCentral);

    // register the undo/redo actions actions
    connect(poUndo, &QPushButton::clicked,  poTextEdit, &QTextEdit::undo);
    connect(poRedo, &QPushButton::clicked,  poTextEdit, &QTextEdit::redo);

    connect(poTextEdit, &QTextEdit::redoAvailable,
            [poLabelRedoAvaliable](bool bAvailable)
    {
        if (bAvailable)
        {
            poLabelRedoAvaliable->setText("redo available");
        }
        else {
            poLabelRedoAvaliable->setText("redo not available");
        }
    });

    connect(poTextEdit, &QTextEdit::undoAvailable,
            [poLabelUndoAvaliable](bool bAvailable)
    {
        if (bAvailable)
        {
            poLabelUndoAvaliable->setText("undo available");
        }
        else {
            poLabelUndoAvaliable->setText("undo not available");
        }
    });

}

在QTextEdit中撤消/重做

1 个答案: