QT学习笔记3--创建对话框

1. 对话框子类

finddialog.h

#ifndef FINDDIALOG_H
#define FINDDIALOG_H#include <QLabel>
#include <QDialog>
#include <QCheckBox>
#include <QLineEdit>
#include <QPushButton>#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QGridLayout>class FindDialog: public QDialog
{Q_OBJECT
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_H

finddialog.cpp

#include "finddialog.h"FindDialog::FindDialog(QWidget *parent):QDialog(parent)
{label = new QLabel(tr("Find &what:"));lineEdit = new QLineEdit;label->setBuddy(parent);caseCheckBox = new QCheckBox(tr("Match &case:"));backwardCheckBox = new QCheckBox(tr("Search &backward"));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();QHBoxLayout *mainLayout = new QHBoxLayout;mainLayout->addLayout(leftLayout);mainLayout->addLayout(rightLayout);setLayout(mainLayout);setWindowTitle(tr("Find"));setFixedHeight(sizeHint().height());}
void FindDialog::findClicked()
{QString text = lineEdit->text();Qt::CaseSensitivity cs = caseCheckBox->isChecked() ? Qt::CaseSensitive:Qt::CaseInsensitive;if (backwardCheckBox->isChecked()) {emit findPrevious(text,cs);}else {emit 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 a(argc, argv);FindDialog *dialog = new FindDialog;dialog->show();return a.exec();
}

2. 再探信号与槽

绑定函数

connect(sender, SIGNAL(signal),receiver,SLOT(slot))

sender与receiver都是QObject *;
信号与槽都是不带参数名的函数原型。

2.1 不同信号绑定不同槽

 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()));

2.2 一个信号绑定多个槽

connect(slider, SIGNAL(valuedChanged(int)), spinBox, SLOT(setValue(int)));
connect(slider, SIGNAL(valuedChanged(int)), this, SLOT(updateStatusBarIndicator(int)));

2.3 多个信号绑定一个槽

connect( lcd, SIGNAL(overflow()), this, SLOT(handleMathError()));
connect( caculator, SIGNAL(divisionByZero()), this, SLOT(handleMathError()));

2.4 信号绑定信号

connect(lineEdit, SIGNAL(textChanged(const QString &)), this, SLOT(updateRecord(const QString &));

2.5 信号槽绑定可以被移除

disconnect( lcd, SIGNAL(overflow()), this, SLOT(handleMathError()));

2.6信号函数与槽函数要求

槽函数与信号函数需要参数对应，或者信号函数参数个数多于槽函数。

connect(ftp, SIGNAL(rawCommandReply(int, const QString &)),this, SLOT(processReply(int,const QString &)))；connect(ftp, SIGNAL(rawCommandReply(int, const QString &)),this, SLOT(checkErrorCode(int)))