【qt学习006】Dialogs and MainWindows 小结
时间：2014-05-19 09:56:17
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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：
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// example1:#include "mainwindow.h"#include <QApplication>#include <QLabel>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, <span style="background-color: rgb(255, 0, 0);">container</span>, 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} |
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// example2:#include <QApplication>#include <QLabel>#include <QHBoxLayout>#include <QSlider>#include <QSpinBox>int main(int
argc, char
*argv[]){ QApplication app(argc, argv); QWidget *window = new
QWidget; // the application‘s <span style="background-color: rgb(255, 0, 0);">main window</span> 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);<br> // 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);<br> // 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 <QApplication>#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 <QDialog>// 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) providesclass
QCheckBox;class
QLabel;class
QLineEdit;class
QPushButton;class
FindDialog: public
QDialog{<br> // qt核心本质之一 // qt macro, is necessary for all classes that define signals or slots Q_OBJECTpublic: // 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 <QtGui>#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()); } |
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// 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<br>// 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。 |
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