学步园

QMessageBox类提供了常用的弹出式对话框：提示、警告、错误、询问、关于对话框

原型如下：

void	about ( QWidget * parent, const QString & title, const QString & text )
void	aboutQt ( QWidget * parent, const QString & title = QString() )
StandardButton	critical ( QWidget * parent, const QString & title, const QString & text, StandardButtons buttons = Ok, StandardButton defaultButton = NoButton )
StandardButton	information ( QWidget * parent, const QString & title, const QString & text, StandardButtons buttons = Ok, StandardButton defaultButton = NoButton )
StandardButton	question ( QWidget * parent, const QString & title, const QString & text, StandardButtons buttons = Ok, StandardButton defaultButton = NoButton )
StandardButton	warning ( QWidget * parent, const QString & title, const QString & text, StandardButtons buttons = Ok, StandardButton defaultButton = NoButton )

（1）title表示标题

（2）text是对话框中的内容信息

（3）buttons是要显示的按钮，它可以是：

        NoButton           = 0x00000000,
        Ok                 = 0x00000400,
        Save               = 0x00000800,
        SaveAll            = 0x00001000,
        Open               = 0x00002000,
        Yes                = 0x00004000,
        YesToAll           = 0x00008000,
        No                 = 0x00010000,
        NoToAll            = 0x00020000,
        Abort              = 0x00040000,
        Retry              = 0x00080000,
        Ignore             = 0x00100000,
        Close              = 0x00200000,
        Cancel             = 0x00400000,
        Discard            = 0x00800000,
        Help               = 0x01000000,
        Apply              = 0x02000000,
        Reset              = 0x04000000,
        RestoreDefaults    = 0x08000000,

（4）defaultButton是默认激活的按钮

（5）对话框的返回值即是用户最终点击的按钮。

示例：

void Dialog::criticalMessage()
{
    QMessageBox::StandardButton reply;
    reply = QMessageBox::critical(this, tr("QMessageBox::critical()"),
                                    MESSAGE,
                                    QMessageBox::Abort | QMessageBox::Retry | QMessageBox::Ignore);
    if (reply == QMessageBox::Abort)
        criticalLabel->setText(tr("Abort"));
    else if (reply == QMessageBox::Retry)
        criticalLabel->setText(tr("Retry"));
    else
        criticalLabel->setText(tr("Ignore"));
}

void Dialog::informationMessage()
{
    QMessageBox::StandardButton reply;
    reply = QMessageBox::information(this, tr("QMessageBox::information()"), MESSAGE);
    if (reply == QMessageBox::Ok)
        informationLabel->setText(tr("OK"));
    else
        informationLabel->setText(tr("Escape"));
}

void Dialog::questionMessage()
{
    QMessageBox::StandardButton reply;
    reply = QMessageBox::question(this, tr("QMessageBox::question()"),
                                    MESSAGE,
                                    QMessageBox::Yes | QMessageBox::No | QMessageBox::Cancel);
    if (reply == QMessageBox::Yes)
        questionLabel->setText(tr("Yes"));
    else if (reply == QMessageBox::No)
        questionLabel->setText(tr("No"));
    else
        questionLabel->setText(tr("Cancel"));
}

void Dialog::warningMessage()
{
    QMessageBox msgBox(QMessageBox::Warning, tr("QMessageBox::warning()"),
                       MESSAGE, 0, this);
    msgBox.addButton(tr("Save &Again"), QMessageBox::AcceptRole);
    msgBox.addButton(tr("&Continue"), QMessageBox::RejectRole);
    if (msgBox.exec() == QMessageBox::AcceptRole)
        warningLabel->setText(tr("Save Again"));
    else
        warningLabel->setText(tr("Continue"));

}

界面：