qt (2) —— 部分部件

qt (2) —— 部分部件

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()));}

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)));}

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);}

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 #include #include 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 #include #include #include 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);}

QPushButton

#-------------------------------------------------## Project created by QtCreator 2017-02-04T18:29:24##-------------------------------------------------QT += core guigreaterThan(QT_MAJOR_VERSION, 4): QT += widgetsTARGET = ButtonDialogTEMPLATE = appSOURCES += main.cpp\ dialog.cppHEADERS += dialog.hFORMS

Dialog.h:

#ifndef DIALOG_H#define#include #include namespace Ui {class Dialog;}class Dialog : public QDialog{ Q_OBJECTpublic: 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 #include 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 int main(int argc, char *argv[]){ QApplication a(argc, argv); Dialog w; w.show(); return

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。

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

#ifndef COMBOBOX_H#define#include namespace Ui {class ComboBox;}class ComboBox : public QDialog{ Q_OBJECTpublic: 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 #include 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 int main(int argc, char *argv[]){ QApplication a(argc, argv); ComboBox w; w.show(); return

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。

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。

)

QGridLayout

GridLayout很强大，因为它灵活，坐标定位，所以用起来很方便。

#include #include #include #include #include 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

QVBoxLayout

.pro

SOURCES += \ main.cppQT

main.cpp

#include #include #include #include #include #include #include #include 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

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。