【qt学习006】Dialogs and MainWindows 小结

2020-11-27 08:40

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学习《c++GUI Programming with Qt 4》已有一段时间，非常享受这本书的阅读过程，内容简洁清晰，让人一目了然。

马上要学习更难的内容，所以先做个总结，然后再继续前进。

总结的形式尽量简洁，以代码为主，再将一些我认为重要的笔记作为注释添加在代码中。内容大多是摘抄自书本，但也有一些地方属于个人理解。

闲话少谈，下面列出代码：

// example1:

#include "mainwindow.h"

#include

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

{

QApplication app(argc, argv); // The QApplication constructor requires argc and argv because Qt supports a few command-line arguments of its own.

QLabel *label = new QLabel("Hello Qt!"); // Widget: control, container, a user interface in a user interface,容器的意思。

// Buttons, menus, scroll bars, and frames are all examples of widgets. Widgets can contain other widgets

label->show();

return app.exec(); // passes control of the application on to Qt.

// At this point, the program enters the event loop. 开始执行，进入事件队列，由操作系统接管

}

// example2:

#include

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

{

QApplication app(argc, argv);

QWidget *window = new QWidget; // the application‘s main window

window->setWindowTitle("Enter your age");

// We could pass window to the QSpinBox and QSlider constructors, specifying that these widgets should have window as their parent

QSpinBox * spinBox = new QSpinBox;

QSlider *slider = new QSlider(Qt::Horizontal);

spinBox->setRange(0, 130);

slider->setRange(0, 130);

// 信号槽机制，qt核心本质之一

QObject::connect(spinBox, SIGNAL(valueChanged(int)),

slider, SLOT(setValue(int)));

QObject::connect(slider, SIGNAL(valueChanged(int)),

spinBox, SLOT(setValue(int)));

spinBox->setValue(35);

// a layout manager，多控件时需要有布局管理器来管理各个控件的位置，qt的布局管理器类可以自动化布局，无需用户关心，写复杂的应用程序时可能会需要自己来布局。

QHBoxLayout *layout = new QHBoxLayout;

layout->addWidget(spinBox);

layout->addWidget(slider);

QVBoxLayout *layout1 = new QVBoxLayout;

layout1->addWidget(spinBox); // automatically assigns reasonable positions and sizes to the widgets for which it is responsible, based on their needs

layout1->addWidget(slider);

// 此处可以将Layout1设置为layout，体验一下不同的布局形式

window->setLayout(layout1); // an object that sets the size and position of the widgets that lie under its responsibility

// installs the layout manager on the window

window->show();

return app.exec();

}

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// dialog boxes

// example 3

//  学习有感，学一样东西，未必要从最新的地方入手，应该从资料最丰富的地方入手，如学qt4比qt5容易些，因为qt5刚发布，有很多新特性，新手容易混淆，并且遇见问题，因为资料少，无从下手解决。

// main.cpp

#include "mainwindow.h"

#include

#include "finddialog.h"

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

{

QApplication app(argc, argv);

FindDialog *dialog = new FindDialog;

dialog->show();

return app.exec();

}

// finddialog.h

#ifndef FINDDIALOG_H

#define FINDDIALOG_H

#include

// A forward declaration tells the C++ compiler that a class exists, without giving all the detail that a class definition (usually located in a header file of its own) provides

class QCheckBox;

class QLabel;

class QLineEdit;

class QPushButton;

class FindDialog: public QDialog

// qt核心本质之一

// qt macro, is necessary for all classes that define signals or slots

Q_OBJECT

public:

// The default is a null pointer, meaning that the dialog has no parent.

FindDialog(QWidget *parent = 0);

signals: // qt macro

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

// Including this header saves us the bother of including every class individually

// contains the definition of Qt‘s GUI classes

// bad style to include such a big header file from another header file, especially in larger applications.

#include

#include "finddialog.h"

FindDialog::FindDialog(QWidget *parent)

: QDialog(parent) // ??? we pass on the parent parameter to the base class constructor

{

label = new QLabel(tr("Find &what:")); // ??? ampersands (‘&‘) to indicate shortcut keys

lineEdit = new QLineEdit;

// we set the label‘s buddy to be the line editor.

// A buddy is a widget that accepts the focus when the label‘s shortcut key is pressed.

// So when the user presses Alt+W (the label‘s shortcut), the focus goes to the line editor (the label‘s buddy).

label->setBuddy(lineEdit);

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(); // a spacer item (or "stretch").

QHBoxLayout *mainLayout = new QHBoxLayout;

mainLayout->addLayout(leftLayout);

mainLayout->addLayout(rightLayout);

setLayout(mainLayout); // the main layout is installed on the dialog

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); //The emit keyword is specific to Qt

}

void FindDialog::enableFindButton(const QString &text)

{

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

}

// example 4

// signals and slots

//

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

// sender and receiver are POINTERS to QObjects and where signal and slot are function // signatures WITHOUT PARAMETER names

// To successfully connect a signal to a slot (or to another signal), they must have the // same parameter types in the same order:

// connect(ftp, SIGNAL(rawCommandReply(int, const QString &)),

// this, SLOT(processReply(int, const QString &)));

// signals and slots mechanism don‘t limit to qt gui programming.

// example 5

// 跳过了qt designer 几小节

// Qt‘s container widgets are widgets that contain other widgets, such as QFrame, // QGroupBox

// QFrame can also be used on its own to simply draw lines and serves as the base class // for many other widget classes, including QToolBox and QLabel.

// example 6: main windows

// complete with menus, toolbars, status bar, and as many dialogs as the application requires

// mainWdinows（Chapter3）这一章有点难度，比起之前的章节，这一章的知识点有些跳跃，需要写出一个完整的程序，包括布局、对象之间的继承、信号与槽的设置以及一些特殊的函数使用等等一些内容
// 另外章节的设置也有问题，这一章需要使用的类，在前两章由qt designer实现，无法直接在本章使用，需要自己去完善。

//　如果学懂了这一章，应该可以独立设计一个记事本。

【qt学习006】Dialogs and MainWindows 小结,搜素材,soscw.com

【qt学习006】Dialogs and MainWindows 小结

标签：des style blog class code c

原文地址：http://www.cnblogs.com/xy-kidult/p/3731923.html

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