Qt学习（002-1）

从这一节开始做一个通讯录。基本还是分析已有的代码。
Qt5.1.1下creator建立addressbook项目。

建立头文件addressbook.h：

#ifndef ADDRESSBOOK_H
#define ADDRESSBOOK_H

#include <QWidget>
#include <QLineEdit>
#include <QTextEdit>

class AddressBook : public QWidget
{
    Q_OBJECT

public:
    AddressBook(QWidget *parent = 0);

private:
    QLineEdit *nameLine;
    QTextEdit *addressText;
};


#endif // ADDRESSBOOK_H

建立源文件addressbook.cpp：

#include "addressbook.h"

#include <QLabel>
#include <QGridLayout>

AddressBook::AddressBook(QWidget *parent)
    : QWidget(parent)
{
    QLabel *nameLabel = new QLabel(tr("Name:"));
    nameLine = new QLineEdit;

    QLabel *addressLabel = new QLabel(tr("Address:"));
    addressText = new QTextEdit;

    QGridLayout *mainLayout = new QGridLayout;
    mainLayout->addWidget(nameLabel, 0, 0);
    mainLayout->addWidget(nameLine, 0, 1);
    mainLayout->addWidget(addressLabel, 1, 0, Qt::AlignTop);
    mainLayout->addWidget(addressText, 1, 1);
    setLayout(mainLayout);
    setWindowTitle(tr("Simple Address Book"));
}

AddressBook类继承自QWidget，“:QWidget(parent)”用来初始化父类。

这里使用了网格布局。其addWidget函数有两个原型：

void QGridLayout::addWidget(QWidget * widget, int row, int column, Qt::Alignment alignment = 0)

void QGridLayout::addWidget(QWidget * widget, int fromRow, int fromColumn, int rowSpan, int columnSpan, Qt::Alignment alignment = 0)

参数含义显而易见。alignment需要多解释一下：

其默认值为0，说明添加的部件会填充满指定的网格。 Qt::AlignTop指明会将部件放在网格的上部。这些指定位置的常量还有：

The horizontal flags are:

Qt::AlignLeft ： Aligns with the left edge.
Qt::AlignRight  ：  Aligns with the right edge.
Qt::AlignHCenter  ：  Centers horizontally in the available space.
Qt::AlignJustify  ：  Justifies the text in the available space.

--------
The vertical flags are:

Constant  Value Description
Qt::AlignTop  ：  Aligns with the top.
Qt::AlignBottom ：  Aligns with the bottom.
Qt::AlignVCenter  ：  Centers vertically in the available space.

--------
You can use only one of the horizontal flags at a time. There is one two-dimensional flag:

Qt::AlignCenter  ： Centers in both dimensions（AlignVCenter | AlignHCenter）.

修改main.cpp：

#include "addressbook.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    AddressBook addressBook;
    addressBook.show();

    return a.exec();
}

运行结果：

参考：

http://qt-project.org/doc/qt-4.8/tutorials-addressbook-part1.html