QLayoutItem(3qt)

📦 version 3.3.8b, in fedora 43, fedora 44

🎀 QLayoutItem(3qt) 🎀 the abstract item that a QLayout manipulates

okay bestie, welcome to QLayoutItem(3qt) — yes, the manual name is literally in the title, we're doing this 💅 this is the abstract item that a QLayout manipulates, and honestly? iconic behavior. let's get into it. ✨

🌸 NAME 🌸

QLayoutItem — the abstract item that a QLayout manipulates. that's the whole job description, and it's giving main character energy 👑

🦋 SYNOPSIS 🦋

#include <qlayout.h>

Inherited by QLayout, QSpacerItem, and QWidgetItem — so basically all the popular kids 💖

✨ Public Members ✨

QLayoutItem ( int alignment = 0 )
virtual ~QLayoutItem ()
virtual QSize sizeHint () const = 0
virtual QSize minimumSize () const = 0
virtual QSize maximumSize () const = 0
virtual QSizePolicy::ExpandData expanding () const = 0
virtual void setGeometry ( const QRect & r ) = 0
virtual QRect geometry () const = 0
virtual bool isEmpty () const = 0
virtual bool hasHeightForWidth () const
virtual int heightForWidth ( int w ) const
virtual void invalidate ()
virtual QWidget * widget ()
virtual QLayoutIterator iterator ()
virtual QLayout * layout ()
virtual QSpacerItem * spacerItem ()
int alignment () const
virtual void setAlignment ( int a )

💜 DESCRIPTION 💜

so. the QLayoutItem class provides an abstract item that a QLayout manipulates. periodt.

this is what you use for custom layouts — yes, when you wanna do your own thing instead of letting Qt handle the vibe.

there are pure virtual functions you gotta implement so the layout can get info about itself: sizeHint(), minimumSize(), maximumSize(), and expanding() 🫶

you can set and grab the layout's geometry with setGeometry() and geometry(), and its alignment with setAlignment() and alignment() — very much a two-way street, no cap.

isEmpty() tells you whether the layout is empty. iterator() hands you an iterator for the layout's children. and if the concrete item is a QWidget, you can grab it with widget() — same energy for layout() and spacerItem(), they're all doing the type-safe casting thing 🧚

See also QLayout, Widget Appearance and Style, and Layout Management.

👑 MEMBER FUNCTION DOCUMENTATION 👑

QLayoutItem::QLayoutItem ( int alignment = 0 )

Constructs a layout item, with an alignment that is a bitwise OR of the Qt::AlignmentFlags. heads up tho: not all subclasses support alignment 🙈

QLayoutItem::~QLayoutItem () [virtual]

Destroys the QLayoutItem. bye bestie 💀

int QLayoutItem::alignment () const

Returns the alignment of this item. simple as. ✨

QSizePolicy::ExpandData QLayoutItem::expanding () const [pure virtual]

Implemented in subclasses to return the direction(s) this item "wants" to expand in (if any). like, it has goals, okay? 💅

Reimplemented in QLayout, QSpacerItem, and QWidgetItem.

QRect QLayoutItem::geometry () const [pure virtual]

Returns the rectangle covered by this layout item. 📐

Example: customlayout/border.cpp.

bool QLayoutItem::hasHeightForWidth () const [virtual]

Returns TRUE if this layout's preferred height depends on its width; otherwise returns FALSE. the default implementation returns FALSE — lowkey the lazy option but it's valid.

reimplement this function in layout managers that support height for width, bestie. 🌈

See also heightForWidth() and QWidget::heightForWidth().

Examples: (the original man page lists examples right here but the filenames didn't render 🙈)

Reimplemented in QGridLayout and QBoxLayout.

int QLayoutItem::heightForWidth ( int w ) const [virtual]

Returns the preferred height for this layout item, given the width w.

the default implementation returns -1, which is code for "the preferred height is independent of the width of the item". and fr fr, using hasHeightForWidth() will typically be much faster than calling this function and then testing for -1. noted. 📝

reimplement this function in layout managers that support height for width. a typical implementation will look like this:

int MyLayout::heightForWidth( int w ) const
{
    if ( cache_dirty || cached_width != w ) {
        // not all C++ compilers support "mutable"
        MyLayout *that = (MyLayout*)this;
        int h = calculateHeightForWidth( w );
        that->cached_hfw = h;
        return h;
    }
    return cached_hfw;
}
caching is strongly recommended — without it, layout will take exponential time. exponential!! do not skip the cache, bestie, I am begging 😭

See also hasHeightForWidth().

Example: customlayout/flow.cpp.

Reimplemented in QGridLayout and QBoxLayout.

void QLayoutItem::invalidate () [virtual]

Invalidates any cached information in this layout item. it's giving "forget everything you thought you knew" 🧹

Reimplemented in QLayout.

bool QLayoutItem::isEmpty () const [pure virtual]

Implemented in subclasses to return whether this item is empty — i.e. whether it contains any widgets at all.

Reimplemented in QLayout, QSpacerItem, and QWidgetItem.

QLayoutIterator QLayoutItem::iterator () [virtual]

Returns an iterator over this item's QLayoutItem children. the default implementation returns an empty iterator (fair, it's the default).

reimplement this function in subclasses that can have children. 👶

Reimplemented in QLayout.

QLayout * QLayoutItem::layout () [virtual]

If this item is a QLayout, it is returned as a QLayout; otherwise 0 is returned. this function provides type-safe casting — no sketchy casting here, we're classy. 💅

QSize QLayoutItem::maximumSize () const [pure virtual]

Implemented in subclasses to return the maximum size of this item. dream big, but like, not too big. 📏

Reimplemented in QLayout, QSpacerItem, and QWidgetItem.

QSize QLayoutItem::minimumSize () const [pure virtual]

Implemented in subclasses to return the minimum size of this item. boundaries are healthy, bestie. 🛑

Examples: (the original man page lists examples right here but the filenames didn't render 🙈)

Reimplemented in QLayout, QSpacerItem, and QWidgetItem.

void QLayoutItem::setAlignment ( int a ) [virtual]

Sets the alignment of this item to a, which is a bitwise OR of the Qt::AlignmentFlags. and again: not all subclasses support alignment — check before you commit, iykyk.

Example: chart/optionsform.cpp.

void QLayoutItem::setGeometry ( const QRect & r ) [pure virtual]

Implemented in subclasses to set this item's geometry to r. put it where it belongs. 📍

Examples: (the original man page lists examples right here but the filenames didn't render 🙈)

Reimplemented in QLayout, QSpacerItem, and QWidgetItem.

QSize QLayoutItem::sizeHint () const [pure virtual]

Implemented in subclasses to return the preferred size of this item. it's a hint, not a command — a suggestion, a vibe check, if you will ✨

Examples: (the original man page lists examples right here but the filenames didn't render 🙈)

Reimplemented in QSpacerItem, QWidgetItem, QGridLayout, and QBoxLayout.

QSpacerItem * QLayoutItem::spacerItem () [virtual]

If this item is a QSpacerItem, it is returned as a QSpacerItem; otherwise 0 is returned. once again: type-safe casting, we love a safe cast 🫶

QWidget * QLayoutItem::widget () [virtual]

If this item is a QWidget, it is returned as a QWidget; otherwise 0 is returned. this function provides type-safe casting. 🦋

Reimplemented in QWidgetItem.

🌈 SEE ALSO 🌈

Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the license file included in the distribution for a complete license statement. 📜

🎀 AUTHOR 🎀

Generated automatically from the source code. so nobody hand-wrote this, it's a robot's baby and we respect it 🧚

💀 BUGS 💀

if you find a bug in Qt, please report it as described in http://doc.trolltech.com/bughowto.html. good bug reports help us to help you. thank you!! 🙏 (genuinely, they're being so nice about it)

the definitive Qt documentation is provided in HTML format; it is located at $QTDIR/doc/html and can be read using Qt Assistant or with a web browser. this man page is provided as a convenience for those users who prefer man pages, although this format is not officially supported by Trolltech 😭

if you find errors in this manual page, please report them to qt-bugs@trolltech.com. please include the name of the manual page (qlayoutitem.3qt) and the Qt version (3.3.8). be specific, bestie, it helps 💅

okay that's the whole page!! big slay, you made it to the bottom 🎉 this little beauty was brought to you by Trolltech AS, dated 2 February 2007, and the manual page itself is QLayoutItem(3qt) — take care of her, she's doing her best 💖✨🌸

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