Operation of QT controls

QComboBox control

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1. Add content:

 //不带图标写法
    ui->comboBox->addItem("A1");
    ui->comboBox->addItem("A2");
    ui->comboBox->addItem("A3");
    ui->comboBox->addItem("A4");
    ui->comboBox->addItem("A5");
    ui->comboBox->addItem("A6");
    //带图标写法
    ui->comboBox->addItem(icon,QString::asprintf("Item %d",i)); 
    //可以使用QStringList 一次写入多个数据
    QStringList strList;
    strList<<"A1"<<"A2"<<"A3"<<"A4"<<"A5"<<"A6";
    ui->comboBox->addItems(strList);

2. Default display

ui->comboBox->setCurrentIndex(2);	//后面的数字是显示第几个，从零开始

3. Get the currently selected index of the comboBox control

    //索引为0-5
    int index = ui->comboBox->currentIndex();//获得索引
    QString StrIntN=QString::number(index);
    QMessageBox::information(this, "comboBox", StrIntN, QMessageBox::Ok);

4. Get the current content

QMessageBox::information(this, "comboBox", ui->comboBox->currentText(), QMessageBox::Ok);

5. Clear the list

ui->comboBox->clear(); //清除列表

QLineedit

1. QLineedit’s 6 signals and slot functions
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void cursorPositionChanged(int old, int new)	The cursor position changes and a signal is emitted. The previous position is old, and the new position is new.
void editingFinished( )	When editing is completed, click Enter to emit a signal.
oid returnPressed( )	The cursor clicks Enter in the line editing box to emit a signal.
void selectionChanged( )	Emits a signal when the selected text changes.
void textChanged(const QString & text)	Emit a signal when the text content changes.
void textEdited(const QString & text)	This signal is emitted when text is edited. When the text is changed using setText(), the textEdited() signal is also emitted.

2. Commonly used class member functions

void setPlaceholderText(QString)	Set placeholder
void setText(QString)	Set the text in the edit box
void setReadOnly(bool)	Set the edit box to read-only mode and cannot edit it.
void setEnabled(bool)	Set whether to activate the line edit box, the function is similar to 3
bool isModified()	Determine whether the text has been modified
void selectAll()	Select all text in the box
QString displayText()	Returns the displayed text
QString selectedText()	Returns the selected text
QString text() const	Returns the current text of the input box
void setMaxLength(int)	Set the maximum allowed length of text

3. Set text alignment

lineedit->setAlignment(Qt::AlignLeft)//左对齐 
lineedit->setAlignment(Qt::AlignRight)//右对齐  
lineedit->setAlignment(Qt::AlignCenter)//居中对齐

4. Get the input value

ui->lineEdit->text();//获取输入的值

5. Settings cannot be edited

setReadOnly(false); 
//或 
setEnabled(false); 
//或  
setFocusPolicy(Qt::NoFocus);//无法获得焦点，自然无法输入，其他文本控件类似 
//或 
hasAcceptableInput(false);

6. Set the maximum number of characters that can be entered

setMaxLength()

QTabWidget control

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1. Set the page name

    ui->tabWidget->setTabText(0,"常规");
    ui->tabWidget->setTabText(1,"安全");
    ui->tabWidget->setTabText(2,"属性修改");
    ui->tabWidget->setTabText(3,"详细信息");
    ui->tabWidget->setTabText(4,"以前的版本");

2. Set prompt information

    ui->tabWidget->setTabToolTip(0,"常规页面提示信息");
    ui->tabWidget->setTabToolTip(1,"安全页面提示信息");
    ui->tabWidget->setTabToolTip(2,"属性修改页面提示信息");
    ui->tabWidget->setTabToolTip(3,"详细信息页面提示信息");
    ui->tabWidget->setTabToolTip(4,"以前的版本提示信息");

3. Setting page activation

    ui->tabWidget->setTabEnabled(0, true);
    ui->tabWidget->setTabEnabled(1, true);
    ui->tabWidget->setTabEnabled(2, true);
    ui->tabWidget->setTabEnabled(3, true);
    ui->tabWidget->setTabEnabled(4, false);

4. Set the title bar position

//设置标题栏位置 North, South, West, East
ui->tabWidget->setTabPosition(QTabWidget::West);

5. Set the close button

//设置页面关闭按钮。
ui->tabWidget->setTabsClosable(true);

6. Clear all pages

qDebug() << "清空所有页面!";
ui->tabWidget->clear();

7. Delete a page

qDebug() << "删除页面!";
ui->tabWidget->removeTab(4);

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