本文大部分内容学习自《Foundations of Qt Development》

notes

qt name rules

类的名字以大写字母开始，每一个新的词也以大写字母开头，也即骆驼拼写法 (CamelCasing)
方法的名字也遵从CamelCase，但是需要注意的是它以小写字母开头。

protected slots

被protect的slot只有被用作方法的时候才会被保护。私有的或者受保护的slots仍然能够用于connect sigals

meta-object和信号槽机制

meta-object自己知道signals和slots，meta-object compiler (moc) 会用c++实现相关的内容。

signals and slots

qt使用指针实现信号槽，当我们发出信号，实际上也就在调用信号方法，该方法被moc实现。signal方法随即调用slots。源对象和目标对象就是指向QObject或者它的子类的指针。

LIFO and FIFO

LIFO means “last in, first out”. 代表：栈
FIFO means “fist in, first out”. 代表：队列

Qt designer

命令行启动：shell> designer
qt4可能是shell> designer-qt4

widgets

QSlider and progressBar

下面的小应用由dialog, horizontalSlider, progressBar, pushButton, label构成。
第三个progressBar的范围是(0,0)，结果时不显示数值结果并不断运动的，第4个progressBar的范围我想设置成无穷大，但不确定这种方法setRange(-1,-1)是否正确。

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
/*
 *for QProgressBar format : QString
 *This property holds the string used to generate the current text.
 *%p - is replaced by the percentage completed. %v - is replaced by the current value. %m - is replaced
 *by the total number of steps. The default value is "%p%".
 */
    ui->progressBar->setFormat("%p%");  // default
    ui->progressBar_2->setFormat("%v out of %m"); //custom text
    ui->progressBar_3->setRange(0,0);   // hide text and keep moving.
    ui->progressBar_4->setRange(-1,-1); // static
    connect(ui->horizontalSlider,SIGNAL(valueChanged(int)),ui->progressBar,SLOT(setValue(int)));
    connect(ui->horizontalSlider,SIGNAL(valueChanged(int)),ui->progressBar_2,SLOT(setValue(int)));
    connect(ui->horizontalSlider,SIGNAL(valueChanged(int)),ui->progressBar_3,SLOT(setValue(int)));
    connect(ui->horizontalSlider,SIGNAL(valueChanged(int)),ui->progressBar_4,SLOT(setValue(int)));
    connect(ui->pushButton,SIGNAL(clicked()),this,SLOT(close()));
}

qt (2) —— 部分部件_ide

QLineEdit

LineEdit的echo mod可以设置成不同的格式，属性MaxLength则设定了能够填写的最大字符数。

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    ui->lineEdit_2->setEchoMode(QLineEdit::Password);
    ui->lineEdit_3->setMaxLength(9);
    connect(ui->lineEdit,SIGNAL(textChanged(QString)),ui->lineEdit_4,SLOT(setText(QString)));
    connect(ui->lineEdit_2,SIGNAL(textChanged(QString)),ui->lineEdit_5,SLOT(setText(QString)));
    connect(ui->lineEdit_3,SIGNAL(textChanged(QString)),ui->lineEdit_6,SLOT(setText(QString)));
}

qt (2) —— 部分部件_qt_02

QListWidget

将listWidget放进Dialog后，合理设置layout，我们可以在改变dialog的大小同时产生上下滑动条。
下面的例子对choose and click做了一些处理。
dialog.cpp:

#include "dialog.h"
#include "ui_dialog.h"

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    for(int i=0;i<10;i++){
        ui->listWidget->addItem(QString::number(i)+" item");
    }
}

Dialog::~Dialog()
{
    delete ui;
}

void Dialog::on_pushButton_clicked()
{
    QListWidgetItem *it = ui->listWidget->currentItem();
    it->setText("you click "+it->text());
    it->setBackground(Qt::black);
    it->setTextColor(Qt::red);
}

qt (2) —— 部分部件_应用_03


好好利用QListWidget，如takeItem, addItem等方法，我们可以创建出类似于管理书单的应用窗体。

dialog.h

#ifndef DIALOG_H
#define

#include <QDialog>
#include <QListWidget>
#include <QPushButton>

namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT
    QListWidget *listLeft, *listRight;
    QPushButton *buttonLeft, *buttonRight;
public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();

private:
    Ui::Dialog *ui;
public slots:
    void moveRight();
    void moveLeft();
};

#endif

dialog.cpp

#include "dialog.h"
#include "ui_dialog.h"
#include <QGridLayout>
#include <QStringList>
#include <QList>
#include <QMessageBox>

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    listLeft = new QListWidget(this);
    listRight = new QListWidget(this);
    buttonLeft = new QPushButton(">>",this);
    buttonRight = new QPushButton("<<",this);
    QGridLayout *gLayout = new QGridLayout(this);
    gLayout->addWidget(listLeft,0,0);
    gLayout->addWidget(listRight,0,1);
    gLayout->addWidget(buttonLeft,1,0);
    gLayout->addWidget(buttonRight,1,1);
    QStringList items;
    items<<"apple"<<"pear"<<"banana"<<"peach";
    listLeft->addItems(items);

    connect(buttonLeft,SIGNAL(clicked()),this,SLOT(moveRight()));
    connect(buttonRight,SIGNAL(clicked()),this,SLOT(moveLeft()));
}

Dialog::~Dialog()
{
    delete ui;
}
void Dialog::moveLeft(){
    if(listRight->selectedItems().count()!=1) return;
    QListWidgetItem *item = listRight->takeItem(listRight->currentRow());
    listLeft->addItem(item);
}
void Dialog::moveRight(){
    if(listLeft->selectedItems().count()!=1) return;
    QListWidgetItem *item = listLeft->takeItem(listLeft->currentRow());
    listRight->addItem(item);
}

qt (2) —— 部分部件_应用_04

QPushButton

QPushButton可以被设置触发(pressed)，接着举一个例子，应用QMessageBox，QPushButton，QString.
工程ButtonDialog，程序运行后，点击toggle me按钮，直到下一次点击它，它一直处于pressed状态。
pro文件： 

#-------------------------------------------------
#
# Project created by QtCreator 2017-02-04T18:29:24
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = ButtonDialog
TEMPLATE = app


SOURCES += main.cpp\
        dialog.cpp

HEADERS  += dialog.h

FORMS

Dialog.h:

#ifndef DIALOG_H
#define

#include <QDialog>
#include <QPushButton>

namespace Ui {
class Dialog;
}

class Dialog : public QDialog
{
    Q_OBJECT
public:
    explicit Dialog(QWidget *parent = 0);
    ~Dialog();
 public slots:
    void buttonClicked();
    void buttonToggled();
private:
    Ui::Dialog *ui;
    QPushButton *clickButton;
    QPushButton *toggleButton;
};

#endif

Dialog.cpp

#include "dialog.h"
#include "ui_dialog.h"
#include <QVBoxLayout>
#include <QMessageBox>

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    clickButton = new QPushButton("click me",this);
    toggleButton = new QPushButton("toggle me",this);
    toggleButton->setCheckable(true);
    QVBoxLayout *vLayout = new QVBoxLayout(this);
    vLayout->addWidget(clickButton);
    vLayout->addWidget(toggleButton);
    connect(clickButton,SIGNAL(clicked()),this,SLOT(buttonClicked()));
    connect(toggleButton,SIGNAL(clicked()),this,SLOT(buttonToggled()));
}

Dialog::~Dialog()
{
    delete ui;
}
void Dialog::buttonClicked(){
    QMessageBox::information(this,"Clicked","the Button is cliecked.");
}
void Dialog::buttonToggled(){
    QMessageBox::information(this,"Toggled",QString("the button is %1!")\
                             .arg(toggleButton->isChecked()?"pressed":"released"));
}

main.cpp

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

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Dialog w;
    w.show();

    return

qt (2) —— 部分部件_ide_05

QLabel

QLabel可是设置shortCut，setBuddy。

在下面的例子中，按下”Alt+1”, 光标会聚焦于LineEdit1，按下”Alt +2”, 光标聚焦于LineEdit2。

qt (2) —— 部分部件_qt_06


dialog.cpp 

#include "dialog.h"
#include "ui_dialog.h"

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    ui->label->setText("Line&1");
    ui->label_2->setText("Line&2");
    ui->label->setBuddy(ui->lineEdit);
    ui->label_2->setBuddy(ui->lineEdit_2);
}

Dialog::~Dialog()
{
    delete ui;
}

QComboBox

假设在类中声明了slot，我们一定要在cpp中定义。
comboBox.h

#ifndef COMBOBOX_H
#define

#include <QDialog>

namespace Ui {
class ComboBox;
}

class ComboBox : public QDialog
{
    Q_OBJECT

public:
    explicit ComboBox(QWidget *parent = 0);
    ~ComboBox();
public slots:
    void myshow();  //show is key word, care about it.
private:
    Ui::ComboBox *ui;
};

#endif

comboBox.cpp

#include "combobox.h"
#include "ui_combobox.h"
#include <QFontComboBox>
#include <QMessageBox>

ComboBox::ComboBox(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::ComboBox)
{
    ui->setupUi(this);
    QFont font("KaiTi_GB2312",16);
    ui->comboBox->setFont(font);
    int i;
    for(i=0;i<10;i++){
        ui->comboBox->addItem(QString::number(i)+" item");
    }

    connect(ui->pushButton,SIGNAL(clicked(bool)),this,SLOT(myshow()));
}
void ComboBox::myshow(){
    QMessageBox::information(this,"choosed",ui->comboBox->currentText());
}

ComboBox::~ComboBox()
{
    delete ui;
}

main.cpp

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

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    ComboBox w;
    w.show();

    return

qt (2) —— 部分部件_ide_07

QSPinBox + LCD Number

在designer中进行connect设置，连接spinBox的valueChanged()和LCD number的display()。QDoubleSpinBox相比QSpinBox提供了更高的精度。

qt (2) —— 部分部件_ide_08


qt (2) —— 部分部件_ide_09

QCalender + QDateTime

QCalender和QDateTime(QDate)均可表示日期。前者更加直观，后者更加精确，容易修改。

qt (2) —— 部分部件_应用_10

)

qt (2) —— 部分部件_#include_11

QGridLayout

GridLayout很强大，因为它灵活，坐标定位，所以用起来很方便。

#include <QApplication>
#include <QGridLayout>
#include <QLabel>
#include <QDialog>
#include <QString>

int main(int argc,char *argv[]){
    QApplication app(argc,argv);
    QDialog dlg;
    dlg.resize(400,400);
    dlg.show();
    QGridLayout *grid = new QGridLayout(&dlg);
    int i,j;
    int counter = 1;
    for(i=0;i<10;i++){
        for(j=0;j<10;j++){
            QLabel *label = new QLabel(QString::number(counter));
            label->setFrameStyle(QFrame::Panel | QFrame::Sunken);
            grid->addWidget(label,i,j);
            counter++;
        }
    }
    grid->setMargin(2);
    return

qt (2) —— 部分部件_qt_12

QVBoxLayout

.pro

SOURCES += \
    main.cpp
QT

main.cpp

#include <QApplication>
#include <QLabel>
#include <QDialog>
#include <QVBoxLayout>
#include <QDialogButtonBox>
#include <QPushButton>
#include <QGridLayout>
#include <QDebug>

int main(int argc,char *argv[]){
    QApplication app(argc,argv);
    QDialog dlg;
    dlg.resize(100,200);
    dlg.show();
    QLabel *label = new QLabel("hello world.");
    label->show();
    QDialogButtonBox *buttons = new QDialogButtonBox(QDialogButtonBox::Ok
                                                     |QDialogButtonBox::Cancel);
    QVBoxLayout *vLayout = new QVBoxLayout(&dlg);
    vLayout->addWidget(label);
    vLayout->addStretch();
    vLayout->addWidget(buttons);
    return

qt (2) —— 部分部件_ide_13