Qt学习之路(4)：创建一个对话框

#ifndef FINDDIALOG_H

#define FINDDIALOG_H

#include <QtGui/QDialog>

class QCheckBox;//前向声明，告诉编译器我要用到这几个类，而且这几个类存在

class QLabel;

class QLineEdit;

class QPushButton;

class FindDialog:public QDialog

{

Q_OBJECT//凡是定义信号槽的类都必须声明这个宏

public:

FindDialog(QWidget *parent = 0);

~FindDialog();

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_H

#include <QtGui>

#include "finddialog.h"

FindDialog::FindDialog(QWidget *parent):QDialog(parent)

{

label = new QLabel(tr("Find &what:"));

lineEdit = new QLineEdit;

label->setBuddy(lineEdit);

caseCheckBox = new QCheckBox(tr("Match &case"));

backwardCheckBox = new QCheckBox(tr("Search &backford"));

findButton = new QPushButton(tr("&Find"));

findButton->setDefault(true);

findButton->setEnabled(false);

closeButton = new QPushButton(tr("close"));

connect(lineEdit, SIGNAL(textChanged(const QString&)), this,

SLOT(enableFindButton(const QString&)));

connect(findButton, SIGNAL(clicked()), this,

SLOT(findClicked()));

connect(closeButton, SIGNAL(clicked()), this, SLOT(close()));

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();//暂时没搞懂这个是干什么用的

QHBoxLayout *mainLayout = new QHBoxLayout;

mainLayout->addLayout(leftLayout);

mainLayout->addLayout(rightLayout);

setLayout(mainLayout);

setWindowTitle(tr("Find"));

setFixedHeight(sizeHint().height());

}

FindDialog::~FindDialog()

{

}

void FindDialog::findClicked()

{

QString text = lineEdit->text();

Qt::CaseSensitivity cs = caseCheckBox->isChecked()?Qt::CaseInsensitive : Qt::CaseInsensitive;//判断checkbox是不是被选中，暂时不是很了解，据说是用于大小写敏感的查找

if(backwardCheckBox->isChecked()) {

emit findPrevious(text, cs);

} else {

emit findNext(text, cs);

}

}

void FindDialog::enableFindButton(const QString &text)

{

findButton->setEnabled(!text.isEmpty());

}

#include <QApplication>

#include "finddialog.h"

int main(int argc,char *argv[])

{

QApplication app(argc,argv);

FindDialog *dialog = new FindDialog;

dialog->show();

return app.exec();

}

(1)tr()函数。被它处理的字符串可以使用工具提取出来翻译成其他语言，也就是做国际化使用。

(2)findButton = new QPushButton(tr("&Find"));&代表快捷键。当按下Alt+f的时候就相当于被点击。

(3)setBuddy()函数。当按下Alt+w时候，会选中QLineEdit控件里面的内容。

(4)共有4个布局，分别时左上布局，左边布局，右边布局，总布局。把2个组件以水平布局的方式放入到左上布局之中，然后把左上布局，和2个组件以垂直布局的方式放入到左边布局，以垂直布局的方式把2个组件放入到右边布局，最后以水平布局的方式把左边布局和右边布局放入到总布局当中。说明布局可以嵌套。

(5)FindDialog::FindDialog(QWidget *parent):QDialog(parent)初始化父类，相当于new QPutton(0，“hello”)之类的。