QLayout

The QLayout class is the base class of geometry managers. More…

Inheritance diagram of PySide2.QtWidgets.QLayout

Inherited by: QBoxLayout, QFormLayout, QGridLayout, QHBoxLayout, QStackedLayout, QVBoxLayout

Synopsis

Functions

Virtual functions

Static functions

Detailed Description

This is an abstract base class inherited by the concrete classes QBoxLayout , QGridLayout , QFormLayout , and QStackedLayout .

For users of QLayout subclasses or of QMainWindow there is seldom any need to use the basic functions provided by QLayout , such as setSizeConstraint() or setMenuBar() . See Layout Management for more information.

To make your own layout manager, implement the functions addItem() , sizeHint() , setGeometry() , itemAt() and takeAt() . You should also implement minimumSize() to ensure your layout isn’t resized to zero size if there is too little space. To support children whose heights depend on their widths, implement hasHeightForWidth() and heightForWidth() . See the Border Layout and Flow Layout examples for more information about implementing custom layout managers.

Geometry management stops when the layout manager is deleted.

See also

QLayoutItem Layout Management Basic Layouts Example Border Layout Example Flow Layout Example

class QLayout

QLayout(parent)

param parent

QWidget

Constructs a new child QLayout .

This layout has to be inserted into another layout before geometry management will work.

Constructs a new top-level QLayout , with parent parent . parent may not be a nullptr .

The layout is set directly as the top-level layout for parent . There can be only one top-level layout for a widget. It is returned by layout() .

PySide2.QtWidgets.QLayout.SizeConstraint

The possible values are:

Constant

Description

QLayout.SetDefaultConstraint

The main widget’s minimum size is set to minimumSize() , unless the widget already has a minimum size.

QLayout.SetFixedSize

The main widget’s size is set to sizeHint() ; it cannot be resized at all.

QLayout.SetMinimumSize

The main widget’s minimum size is set to minimumSize() ; it cannot be smaller.

QLayout.SetMaximumSize

The main widget’s maximum size is set to maximumSize() ; it cannot be larger.

QLayout.SetMinAndMaxSize

The main widget’s minimum size is set to minimumSize() and its maximum size is set to maximumSize() .

QLayout.SetNoConstraint

The widget is not constrained.

See also

setSizeConstraint()

PySide2.QtWidgets.QLayout.activate()
Return type

bool

Redoes the layout for parentWidget() if necessary.

You should generally not need to call this because it is automatically called at the most appropriate times. It returns true if the layout was redone.

See also

update() updateGeometry()

PySide2.QtWidgets.QLayout.addChildLayout(l)
Parameters

l – QLayout

This function is called from addLayout() or insertLayout() functions in subclasses to add layout l as a sub-layout.

The only scenario in which you need to call it directly is if you implement a custom layout that supports nested layouts.

See also

addLayout() insertLayout() addLayout()

PySide2.QtWidgets.QLayout.addChildWidget(w)
Parameters

w – QWidget

This function is called from addWidget() functions in subclasses to add w as a managed widget of a layout.

If w is already managed by a layout, this function will give a warning and remove w from that layout. This function must therefore be called before adding w to the layout’s data structure.

PySide2.QtWidgets.QLayout.addItem(arg__1)
Parameters

arg__1 – QLayoutItem

Implemented in subclasses to add an item . How it is added is specific to each subclass.

This function is not usually called in application code. To add a widget to a layout, use the addWidget() function; to add a child layout, use the addLayout() function provided by the relevant QLayout subclass.

Note

The ownership of item is transferred to the layout, and it’s the layout’s responsibility to delete it.

See also

addWidget() addLayout() addLayout()

PySide2.QtWidgets.QLayout.addWidget(w)
Parameters

w – QWidget

Adds widget w to this layout in a manner specific to the layout. This function uses addItem() .

PySide2.QtWidgets.QLayout.adoptLayout(layout)
Parameters

layout – QLayout

Return type

bool

PySide2.QtWidgets.QLayout.alignmentRect(arg__1)
Parameters

arg__1 – QRect

Return type

QRect

Returns the rectangle that should be covered when the geometry of this layout is set to r , provided that this layout supports setAlignment() .

The result is derived from sizeHint() and expanding(). It is never larger than r .

static PySide2.QtWidgets.QLayout.closestAcceptableSize(w, s)
Parameters
Return type

QSize

Returns a size that satisfies all size constraints on widget , including heightForWidth() and that is as close as possible to size .

PySide2.QtWidgets.QLayout.contentsMargins()
Return type

QMargins

Returns the margins used around the layout.

By default, QLayout uses the values provided by the style. On most platforms, the margin is 11 pixels in all directions.

See also

setContentsMargins()

PySide2.QtWidgets.QLayout.contentsRect()
Return type

QRect

Returns the layout’s geometry() rectangle, but taking into account the contents margins.

See also

setContentsMargins() getContentsMargins()

PySide2.QtWidgets.QLayout.count()
Return type

int

Must be implemented in subclasses to return the number of items in the layout.

See also

itemAt()

PySide2.QtWidgets.QLayout.getContentsMargins()

Extracts the left, top, right, and bottom margins used around the layout, and assigns them to *``left`` , *``top`` , *``right`` , and *``bottom`` (unless they are null pointers).

By default, QLayout uses the values provided by the style. On most platforms, the margin is 11 pixels in all directions.

See also

setContentsMargins() pixelMetric() PM_LayoutLeftMargin PM_LayoutTopMargin PM_LayoutRightMargin PM_LayoutBottomMargin

PySide2.QtWidgets.QLayout.indexOf(arg__1)
Parameters

arg__1 – QLayoutItem

Return type

int

Searches for layout item layoutItem in this layout (not including child layouts).

Returns the index of layoutItem , or -1 if layoutItem is not found.

PySide2.QtWidgets.QLayout.indexOf(arg__1)
Parameters

arg__1 – QWidget

Return type

int

Searches for widget widget in this layout (not including child layouts).

Returns the index of widget , or -1 if widget is not found.

The default implementation iterates over all items using itemAt()

PySide2.QtWidgets.QLayout.isEnabled()
Return type

bool

Returns true if the layout is enabled; otherwise returns false .

See also

setEnabled()

PySide2.QtWidgets.QLayout.itemAt(index)
Parameters

index – int

Return type

QLayoutItem

Must be implemented in subclasses to return the layout item at index . If there is no such item, the function must return 0. Items are numbered consecutively from 0. If an item is deleted, other items will be renumbered.

This function can be used to iterate over a layout. The following code will draw a rectangle for each layout item in the layout structure of the widget.

def paintLayout(self, painter, item):
    layout = item.layout()

    if layout:
        for layout_item in layout:
            self.paintLayout(painter, layout_item)

    painter.drawRect(item.geometry())

def paintEvent(self, event):
    painter = QPainter(self)
    if self.layout():
        self.paintLayout(painter, self.layout())

See also

count() takeAt()

PySide2.QtWidgets.QLayout.margin()
Return type

int

See also

setMargin()

PySide2.QtWidgets.QLayout.menuBar()
Return type

QWidget

Returns the menu bar set for this layout, or 0 if no menu bar is set.

See also

setMenuBar()

PySide2.QtWidgets.QLayout.parentWidget()
Return type

QWidget

Returns the parent widget of this layout, or 0 if this layout is not installed on any widget.

If the layout is a sub-layout, this function returns the parent widget of the parent layout.

See also

parent()

PySide2.QtWidgets.QLayout.removeItem(arg__1)
Parameters

arg__1 – QLayoutItem

Removes the layout item item from the layout. It is the caller’s responsibility to delete the item.

Notice that item can be a layout (since QLayout inherits QLayoutItem ).

See also

removeWidget() addItem()

PySide2.QtWidgets.QLayout.removeWidget(w)
Parameters

w – QWidget

Removes the widget widget from the layout. After this call, it is the caller’s responsibility to give the widget a reasonable geometry or to put the widget back into a layout or to explicitly hide it if necessary.

Note

The ownership of widget remains the same as when it was added.

See also

removeItem() setGeometry() addWidget()

PySide2.QtWidgets.QLayout.replaceWidget(from, to[, options=Qt.FindChildrenRecursively])
Parameters
Return type

QLayoutItem

Searches for widget from and replaces it with widget to if found. Returns the layout item that contains the widget from on success. Otherwise 0 is returned. If options contains Qt::FindChildrenRecursively (the default), sub-layouts are searched for doing the replacement. Any other flag in options is ignored.

Notice that the returned item therefore might not belong to this layout, but to a sub-layout.

The returned layout item is no longer owned by the layout and should be either deleted or inserted to another layout. The widget from is no longer managed by the layout and may need to be deleted or hidden. The parent of widget from is left unchanged.

This function works for the built-in Qt layouts, but might not work for custom layouts.

See also

indexOf()

PySide2.QtWidgets.QLayout.setAlignment(l, alignment)
Parameters

  • l – QLayout

  • alignment – Alignment

Return type

bool

This is an overloaded function.

Sets the alignment for the layout l to alignment and returns true if l is found in this layout (not including child layouts); otherwise returns false .

PySide2.QtWidgets.QLayout.setAlignment(w, alignment)
Parameters

  • w – QWidget

  • alignment – Alignment

Return type

bool

Sets the alignment for widget w to alignment and returns true if w is found in this layout (not including child layouts); otherwise returns false .

PySide2.QtWidgets.QLayout.setContentsMargins(margins)
Parameters

margins – QMargins

Sets the margins to use around the layout.

By default, QLayout uses the values provided by the style. On most platforms, the margin is 11 pixels in all directions.

See also

contentsMargins()

PySide2.QtWidgets.QLayout.setContentsMargins(left, top, right, bottom)
Parameters

  • left – int

  • top – int

  • right – int

  • bottom – int

Sets the left , top , right , and bottom margins to use around the layout.

By default, QLayout uses the values provided by the style. On most platforms, the margin is 11 pixels in all directions.

See also

contentsMargins() getContentsMargins() pixelMetric() PM_LayoutLeftMargin PM_LayoutTopMargin PM_LayoutRightMargin PM_LayoutBottomMargin

PySide2.QtWidgets.QLayout.setEnabled(arg__1)
Parameters

arg__1 – bool

Enables this layout if enable is true, otherwise disables it.

An enabled layout adjusts dynamically to changes; a disabled layout acts as if it did not exist.

By default all layouts are enabled.

See also

isEnabled()

PySide2.QtWidgets.QLayout.setMargin(arg__1)
Parameters

arg__1 – int

See also

margin()

PySide2.QtWidgets.QLayout.setMenuBar(w)
Parameters

w – QWidget

Tells the geometry manager to place the menu bar widget at the top of parentWidget() , outside contentsMargins() . All child widgets are placed below the bottom edge of the menu bar.

See also

menuBar()

PySide2.QtWidgets.QLayout.setSizeConstraint(arg__1)
Parameters

arg__1 – SizeConstraint

See also

sizeConstraint()

PySide2.QtWidgets.QLayout.setSpacing(arg__1)
Parameters

arg__1 – int

See also

spacing()

PySide2.QtWidgets.QLayout.sizeConstraint()
Return type

SizeConstraint

See also

setSizeConstraint()

PySide2.QtWidgets.QLayout.spacing()
Return type

int

See also

setSpacing()

PySide2.QtWidgets.QLayout.takeAt(index)
Parameters

index – int

Return type

QLayoutItem

Must be implemented in subclasses to remove the layout item at index from the layout, and return the item. If there is no such item, the function must do nothing and return 0. Items are numbered consecutively from 0. If an item is removed, other items will be renumbered.

The following code fragment shows a safe way to remove all items from a layout:

child = layout.takeAt(0)
while child:
    ...
    del child

See also

itemAt() count()

PySide2.QtWidgets.QLayout.totalHeightForWidth(w)
Parameters

w – int

Return type

int

Also takes contentsMargins and menu bar into account.

PySide2.QtWidgets.QLayout.totalMaximumSize()
Return type

QSize

Also takes contentsMargins and menu bar into account.

PySide2.QtWidgets.QLayout.totalMinimumSize()
Return type

QSize

Also takes contentsMargins and menu bar into account.

PySide2.QtWidgets.QLayout.totalSizeHint()
Return type

QSize

Also takes contentsMargins and menu bar into account.

PySide2.QtWidgets.QLayout.update()

Updates the layout for parentWidget() .

You should generally not need to call this because it is automatically called at the most appropriate times.

See also

activate() invalidate()

PySide2.QtWidgets.QLayout.widgetEvent(arg__1)
Parameters

arg__1 – QEvent

Performs child widget layout when the parent widget is resized. Also handles removal of widgets. e is the event