preface

Qt provides many auxiliary tools for visiting controls

1, Five layout managers

QVBoxLayout vertical layout

1. VBox layout
   

QVBoxLayout();
QVBoxLayout(QWidget* parent);

1. Simple use method

//1. Main window
QWidget wid；
wid.setWindowTitle("Vertical layout");
//2.new QVBoxLayout 
QVBoxLayout *layout = new QVBoxLayout();
layout->setDirection(QBoxLayout::BottomToTop);
//3 window contains layout
wid.setLayout(layout );
//4. layout contains controls
layout->addStretch(2);
layout->addWidget(&lab1,1)
layout->addWidget(&lab2,1)
layout->addStretch(1); 

1. function

Member function	function
add controls	- state -
addWidget	Add widget control to layout
	addWidget(QWidget*,int stretch)
	stretch = is the future share
Add blank	- state -
addStretch(int strech)	Add blank line
addSpacing(int size)	Add a fixed size spacing
Set distance	- state -
setMargin(int margin)	Set your own boundaries
setContentsMargins	Sets the boundary of the internal control
factor	- state -
setStretchFactor(QWidget *widget, int stretch)	Set control ratio column
setStretchFactor(QLayout *layout, int stretch)	Set internal layout ratio column

1. qtCreator settings
   4.1 setting layout
   On the qtCreator designer, you can set the window layout = wid - > setlayout (& layout);

Editor settings layout	Main layout code setLayout
	QWidget widget; QVBoxLayout *layout = new QVBoxLayout(); widget.setLayout(layout );

In addition, QVBoxLayout on the control panel is actually a child layout

Main layout widLayout	Child layout
wid->setLayout(widLayout)	widLayout->addLayout(childLayout);

4.2 setting stretch
Here, a total of 5 controls are arranged in the main layout QVBoxLayout
Set in the property to

control	proportion	other
v-spacer	0	Fixed height 45 see the following figure for details
label	1	TextLabel1
label	2	TextLabel2
label	3	TextLabel3
OK-CANCEL	1

window	Property set ratio column
a. The first control: the fixed height of the spacer is set to 45 and its stretch = 0	Special: if stretch is not set for others, the spacer will occupy unlimited space
b. Second control: Lab, stretch = 1
c. Third control: Lab, stretch = 2
c. Fourth control: buttons, stretch = 1	For button, the booth is enlarged, but it will not expand up and down

Spacer settings	Spacer control list
Spacer = fixed size occupancy, stretch=0

4.3 examples

 //Create a Lab and use setStyleSheet to set the style
 //Create three text boxes in succession and set their background and font size
    QLabel lab1("Label1");
    lab1.setStyleSheet("QLabel{background:#dddddd;font:20px;}");
    lab1.setAlignment(Qt::AlignCenter);
    QLabel lab2("Label2");
    lab2.setStyleSheet("QLabel{background:#cccccc;font:20px;}");
    lab2.setAlignment(Qt::AlignCenter);
    QLabel lab3("Label3");
    lab3.setStyleSheet("QLabel{background:#ffffff;font:20px;}");
    lab3.setAlignment(Qt::AlignCenter);
    
  //Add 3 text boxes and 2 blank columns to the manager with a stretch factor ratio of 2:1:2:3:3
    layout->addStretch(2);
    layout->addWidget(&lab1,1);
    layout->addWidget(&lab2,2);
    layout->addWidget(&lab3,3);
    layout->addStretch(3);
    widget.setLayout(layout);
    widget.show();

4.4 setting of qlabel

1. setStyleSheet use

Change background color	qtCreator + code
	lab.setStyleSheet("QLable{background:rgb(170,0,0);}")
	Difference: Is QLabel{XXX} required

QHBoxLayout horizontal layout

1. The main functions are the same as VBox
   function

hbox.addWidget(QWidget*);
hbox.addStretch(int );
Window.setLayout(hbox);

QGridLayout layout

function

QGridLayout member function	function
Query function	-----Explain------
rowCount()	Number of rows
columnCount()	Number of columns
add controls	-----Explain------
addWidget()	(QWidget *widget, int row, int column) add a control at the row col umn position
addWidget()	fromRow, int fromColumn, int rowSpan, int columnSpan, cross column
Add sub layout	-----Explain------
addLayout()	QLayout *layout, int row, int column, int rowSpan, int columnSpan, add sub layout
Set stretch	-----Explain------
setColumnStretch(int column, int stretch)	Sets the stretch of the column
setRowStretch(int row, int stretch)	Sets the stretch of the row

addWidget(ctrl,row,column); Directly specify the location without setting the number of rows and columns first

 QGridLayout *layout = new QGridLayout;
   //Add controls to the layout and specify the location of each control
   layout->addWidget(but1, 0, 0);
   layout->addWidget(but2, 0, 2);
   layout->addWidget(lab3, 1, 0, 3, 3);
   layout->addWidget(but3, 4, 0);
   layout->addWidget(but4, 4, 2);
   //Add layout to widget window
   widget.setLayout(layout);

QFormLayout form layout

1. QLabel on the left and controls on the right
2. function

function	explain
add to	-----Explain-----
addRow(QWidget *label, QWidget *field)	Left label right field
addRow(const QString &labelText, QWidget *field)	Left label right field
insertRow(int row, const QString &labelText, QWidget *field)	Left label right field
delete	-----Explain-----
removeRow(int row)
Line feed strategy	-----Explain-----
setRowWrapPolicy(RowWrapPolicy policy)	The DontWrapRows tag is always on the left WrapLongRows tags can be left or top WrapAllRows tag is always on

1. Example description

function	explain
	The tag is always above setRowWrapPolicy(QFormLayout::WrapAllRows) Add a line layout - > addrow ("Name:", new QLineEdit()); Spacing (10);

    QFormLayout* layout = new QFormLayout();
    //Set all labels in the form above the control
    layout->setRowWrapPolicy(QFormLayout::WrapAllRows);
    //Add 3 lines of input boxes and labels
    layout->addRow("Name:",new QLineEdit());
    layout->addRow("Email:",new QLineEdit());
    layout->addRow("Adress:",new QLineEdit());
    //Set row and column spacing to 10
    layout->setSpacing(10);
    //Add the layout form to the widget window
    widget.setLayout(layout);

QStackedLayout group layout

 QHBoxLayout *layout=new QHBoxLayout;
   
    //Create a list
    QListWidget listWidget(&widget);
    listWidget.setMinimumWidth(150);
    listWidget.setFont(QFont("Song typeface",14));
    listWidget.addItem("QPushButton");
    listWidget.addItem("QLabel");
    listWidget.addItem("QLineEdit");
   
    //Create three new windows to place text boxes, buttons and single line input boxes respectively
    QWidget widget1;
    widget1.setMinimumSize(400,400);
    QPushButton but1("This is a button",&widget1);
    QWidget widget2;
    widget2.setMinimumSize(400,400);
    QLabel lab1("This is a text box",&widget2);
    QWidget widget3;
    widget3.setMinimumSize(400,400);
    QLineEdit edit("This is a single line input box",&widget3);
   
    //Create a grouping layout and add 3 windows to the grouping control
    QStackedLayout *stackedLayout = new QStackedLayout;
    stackedLayout->addWidget(&widget1);
    stackedLayout->addWidget(&widget2);
    stackedLayout->addWidget(&widget3);
   
    //The QListWidget control is added to the first column of layout, and the grouping layout control is added to the second column. Set their expansion factor ratio to 1:4
    layout->addWidget(&listWidget,1);
    layout->addLayout(stackedLayout,4);
    //Add the layout horizontal layout control to the widget window
    widget.setLayout(layout);
    widget.show();