// finddialog.h 头文件

#ifndef FINDDIALOG_H

#define FINDDIALOG_H#include <QDialog>class QCheckBox;
class QLabel;
class QLineEdit;
class QPushButton;class FindDialog : public QDialog
{Q_OBJECT  // Q_OBJECT为Qt的宏，定义了信号与槽的类必须含有该宏public:FindDialog(QWidget *parent = 0);signals:void findNext(const QString &str, Qt::CaseSensitivity cs);void findPrevious(const QString &str, Qt::CaseSensitivity cs);private slots:void findClicked();void enableFindButton(const QString &text);private:QLabel *label;QLineEdit *lineEdit;QCheckBox *caseCheckBox;QCheckBox *backwardCheckBox;QPushButton *findButton;QPushButton *closeButton;
};
#endif

// finddialog.cpp
#include <QLabel>
#include <QLineEdit>
#include <QCheckBox>
#include <QPushButton>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include "finddialog.h"FindDialog::FindDialog(QWidget *parent)
: QDialog(parent)
{label = new QLabel(tr("Find &what:")); // 设置快捷键 Alt+WlineEdit = new QLineEdit;// 设置lineEdit为label的伙伴，当按下快捷时，程序的焦点会转移到lineEdit上label->setBuddy(lineEdit);caseCheckBox = new QCheckBox(tr("Match &case"));  // 设置快捷键 Alt+CbackwardCheckBox = new QCheckBox(tr("Search &backward")); // 设置快捷键 Alt+B
findButton = new QPushButton(tr("&Find"));// 设置findButton为整个对话框(只有在对话框中才有默认按钮)的默认按钮// (那么如果用户在对话框中敲击回车键，这个推动按钮将被按下)findButton->setDefault(true);  // 禁用按钮，当禁用时不会与用户发生交换，显示为灰色findButton->setEnabled(false); closeButton = new QPushButton(tr("Close"));/* 设置信号与槽的连接 */// 设置lineEdit与findButton之间的通信connect(lineEdit, SIGNAL(textChanged(const QString &)),this, SLOT(enableFindButton(const QString &)));// 当findButton被点击时，调用findClicked()函数
    connect(findButton, SIGNAL(clicked()),this, SLOT(findClicked()));// 当点击closeButton按钮时调用close()函数，隐藏对话框
    connect(closeButton, SIGNAL(clicked()),this, SLOT(close()));/* 对话框的布局设置 */QHBoxLayout *topLeftLayout = new QHBoxLayout;topLeftLayout->addWidget(label);topLeftLayout->addWidget(lineEdit);QVBoxLayout *leftLayout = new QVBoxLayout;leftLayout->addLayout(topLeftLayout);leftLayout->addWidget(caseCheckBox);leftLayout->addWidget(backwardCheckBox);QVBoxLayout *rightLayout = new QVBoxLayout;rightLayout->addWidget(findButton);rightLayout->addWidget(closeButton);rightLayout->addStretch();QHBoxLayout *mainLayout = new QHBoxLayout;mainLayout->addLayout(leftLayout);mainLayout->addLayout(rightLayout);setLayout(mainLayout);setWindowTitle(tr("Find"));

    // 设置高度固定且高度为Qt建议的大小，在QtWidget类中含有建议大小属性 setFixedHeight(sizeHint().height()); 

}void FindDialog::findClicked()
{// 该函数获取lineEdit的text与caseCheckBox的选项设置，// 再根据backwardCheckBox的选项来选择发送向前查找或者// 向后查找信号QString text = lineEdit->text();Qt::CaseSensitivity cs =caseCheckBox->isChecked() ? Qt::CaseSensitive: Qt::CaseInsensitive;// emit为Qt的关键字，为Qt的扩展语法，表示发送信号的含义// 在这里可能会发送findPrevious或者findNext信号，但是// 由于没有设置相应的槽接受，所以不会调用其他函数if (backwardCheckBox->isChecked())emit findPrevious(text, cs);elseemit findNext(text, cs);
}void FindDialog::enableFindButton(const QString &text)
{findButton->setEnabled(!text.isEmpty());
}

// main.cpp
#include <QApplication>
#include "finddialog.h"int main(int argc, char *argv[])
{QApplication app(argc, argv);FindDialog *dialog = new FindDialog;dialog->show();return app.exec();
}