Viadeo Twitter Google Bookmarks ! Facebook Digg del.icio.us MySpace Yahoo MyWeb Blinklist Netvouz Reddit Simpy StumbleUpon Bookmarks Windows Live Favorites 
Logo Documentation Qt ·  Page d'accueil  ·  Toutes les classes  ·  Classes principales  ·  Annotées  ·  Classes groupées  ·  Modules  ·  Fonctions  · 

QGraphicsLinearLayout Class

The QGraphicsLinearLayout class provides a horizontal or vertical layout for managing widgets in Graphics View. More...

 #include <QGraphicsLinearLayout>

Inherits: QGraphicsLayout.

This class was introduced in Qt 4.4.

Public Functions

QGraphicsLayout(QGraphicsLayoutItem * parent = 0)
QGraphicsLayoutItem(QGraphicsLayoutItem * parent = 0, bool isLayout = false)
QGraphicsLinearLayout(QGraphicsLayoutItem * parent = 0)
QGraphicsLinearLayout(Qt::Orientation orientation, QGraphicsLayoutItem * parent = 0)
~QGraphicsLayout()
virtual ~QGraphicsLayoutItem()
virtual ~QGraphicsLinearLayout()
void activate()
void addItem(QGraphicsLayoutItem * item)
void addStretch(int stretch = 1)
Qt::Alignment alignment(QGraphicsLayoutItem * item) const
QRectF contentsRect() const
virtual int count() const = 0
QSizeF effectiveSizeHint(Qt::SizeHint which, const QSizeF & constraint = QSizeF()) const
QRectF geometry() const
virtual void getContentsMargins(qreal * left, qreal * top, qreal * right, qreal * bottom) const
QGraphicsItem * graphicsItem() const
void insertItem(int index, QGraphicsLayoutItem * item)
void insertStretch(int index, int stretch = 1)
virtual void invalidate()
bool isActivated() const
bool isLayout() const
virtual QGraphicsLayoutItem * itemAt(int i) const = 0
qreal itemSpacing(int index) const
qreal maximumHeight() const
QSizeF maximumSize() const
qreal maximumWidth() const
qreal minimumHeight() const
QSizeF minimumSize() const
qreal minimumWidth() const
Qt::Orientation orientation() const
bool ownedByLayout() const
QGraphicsLayoutItem * parentLayoutItem() const
qreal preferredHeight() const
QSizeF preferredSize() const
qreal preferredWidth() const
virtual void removeAt(int index) = 0
void removeItem(QGraphicsLayoutItem * item)
void setAlignment(QGraphicsLayoutItem * item, Qt::Alignment alignment)
void setContentsMargins(qreal left, qreal top, qreal right, qreal bottom)
virtual void setGeometry(const QRectF & rect)
void setItemSpacing(int index, qreal spacing)
void setMaximumHeight(qreal height)
void setMaximumSize(const QSizeF & size)
void setMaximumSize(qreal w, qreal h)
void setMaximumWidth(qreal width)
void setMinimumHeight(qreal height)
void setMinimumSize(const QSizeF & size)
void setMinimumSize(qreal w, qreal h)
void setMinimumWidth(qreal width)
void setOrientation(Qt::Orientation orientation)
void setParentLayoutItem(QGraphicsLayoutItem * parent)
void setPreferredHeight(qreal height)
void setPreferredSize(const QSizeF & size)
void setPreferredSize(qreal w, qreal h)
void setPreferredWidth(qreal width)
void setSizePolicy(const QSizePolicy & policy)
void setSizePolicy(QSizePolicy::Policy hPolicy, QSizePolicy::Policy vPolicy, QSizePolicy::ControlType controlType = QSizePolicy::DefaultType)
void setSpacing(qreal spacing)
void setStretchFactor(QGraphicsLayoutItem * item, int stretch)
QSizePolicy sizePolicy() const
qreal spacing() const
int stretchFactor(QGraphicsLayoutItem * item) const
virtual void updateGeometry()
virtual void widgetEvent(QEvent * e)

Reimplemented Public Functions

virtual int count() const
virtual void invalidate()
virtual QGraphicsLayoutItem * itemAt(int index) const
virtual void removeAt(int index)
virtual void setGeometry(const QRectF & rect)
virtual QSizeF sizeHint(Qt::SizeHint which, const QSizeF & constraint = QSizeF()) const

Protected Functions

void addChildLayoutItem(QGraphicsLayoutItem * layoutItem)
void setGraphicsItem(QGraphicsItem * item)
void setOwnedByLayout(bool ownership)
virtual QSizeF sizeHint(Qt::SizeHint which, const QSizeF & constraint = QSizeF()) const = 0

Detailed Description

The QGraphicsLinearLayout class provides a horizontal or vertical layout for managing widgets in Graphics View.

The default orientation for a linear layout is Qt::Horizontal. You can choose a vertical orientation either by calling setOrientation(), or by passing Qt::Vertical to QGraphicsLinearLayout's constructor.

The most common way to use QGraphicsLinearLayout is to construct an object on the heap with no parent, add widgets and layouts by calling addItem(), and finally assign the layout to a widget by calling QGraphicsWidget::setLayout().

 QGraphicsScene scene;
 QGraphicsWidget *textEdit = scene.addWidget(new QTextEdit);
 QGraphicsWidget *pushButton = scene.addWidget(new QPushButton);

 QGraphicsLinearLayout *layout = new QGraphicsLinearLayout;
 layout->addItem(textEdit);
 layout->addItem(pushButton);

 QGraphicsWidget *form = new QGraphicsWidget;
 form->setLayout(layout);
 scene.addItem(form);

You can add widgets, layouts, stretches (addStretch(), insertStretch() or setStretchFactor()), and spacings (setItemSpacing()) to a linear layout. The layout takes ownership of the items. In some cases when the layout item also inherits from QGraphicsItem (such as QGraphicsWidget) there will be a ambiguity in ownership because the layout item belongs to two ownership hierarchies. See the documentation of QGraphicsLayoutItem::setOwnedByLayout() how to handle this. You can access each item in the layout by calling count() and itemAt(). Calling removeAt() or removeItem() will remove an item from the layout, without destroying it.

Size Hints and Size Policies in QGraphicsLinearLayout

QGraphicsLinearLayout respects each item's size hints and size policies, and when the layout contains more space than the items can fill, each item is arranged according to the layout's alignment for that item. You can set an alignment for each item by calling setAlignment(), and check the alignment for any item by calling alignment(). By default, items are aligned to the top left.

Spacing within QGraphicsLinearLayout

Between the items, the layout distributes some space. The actual amount of space depends on the managed widget's current style, but the common spacing is 4. You can also set your own spacing by calling setSpacing(), and get the current spacing value by calling spacing(). If you want to configure individual spacing for your items, you can call setItemSpacing().

Stretch Factor in QGraphicsLinearLayout

You can assign a stretch factor to each item to control how much space it will get compared to the other items. By default, two identical widgets arranged in a linear layout will have the same size, but if the first widget has a stretch factor of 1 and the second widget has a stretch factor of 2, the first widget will get 1/3 of the available space, and the second will get 2/3.

QGraphicsLinearLayout calculates the distribution of sizes by adding up the stretch factors of all items, and then dividing the available space accordingly. The default stretch factor is 0 for all items; a factor of 0 means the item does not have any defined stretch factor; effectively this is the same as setting the stretch factor to 1. The stretch factor only applies to the available space in the lengthwise direction of the layout (following its orientation). If you want to control both the item's horizontal and vertical stretch, you can use QGraphicsGridLayout instead.

QGraphicsLinearLayout Compared to Other Layouts

QGraphicsLinearLayout is very similar to QVBoxLayout and QHBoxLayout, but in contrast to these classes, it is used to manage QGraphicsWidget and QGraphicsLayout instead of QWidget and QLayout.

See also QGraphicsGridLayout and QGraphicsWidget.

Member Function Documentation

QGraphicsLinearLayout::QGraphicsLinearLayout(QGraphicsLayoutItem * parent = 0)

Constructs a QGraphicsLinearLayout instance using Qt::Horizontal orientation. parent is passed to QGraphicsLayout's constructor.

QGraphicsLinearLayout::QGraphicsLinearLayout(Qt::Orientation orientation, QGraphicsLayoutItem * parent = 0)

Constructs a QGraphicsLinearLayout instance. You can pass the orientation for the layout, either horizontal or vertical, and parent is passed to QGraphicsLayout's constructor.

QGraphicsLinearLayout::~QGraphicsLinearLayout() [virtual]

Destroys the QGraphicsLinearLayout object.

void QGraphicsLinearLayout::addItem(QGraphicsLayoutItem * item)

This convenience function is equivalent to calling insertItem(-1, item).

void QGraphicsLinearLayout::addStretch(int stretch = 1)

This convenience function is equivalent to calling insertStretch(-1, stretch).

Qt::Alignment QGraphicsLinearLayout::alignment(QGraphicsLayoutItem * item) const

Returns the alignment for item. The default alignment is Qt::AlignTop | Qt::AlignLeft.

The alignment decides how the item is positioned within its assigned space in the case where there's more space available in the layout than the widgets can occupy.

See also setAlignment().

int QGraphicsLinearLayout::count() const [virtual]

Reimplemented from QGraphicsLayout::count().

void QGraphicsLinearLayout::insertItem(int index, QGraphicsLayoutItem * item)

Inserts item into the layout at index, or before any item that is currently at index.

See also addItem(), itemAt(), insertStretch(), and setItemSpacing().

void QGraphicsLinearLayout::insertStretch(int index, int stretch = 1)

Inserts a stretch of stretch at index, or before any item that is currently at index.

See also addStretch(), setStretchFactor(), setItemSpacing(), and insertItem().

void QGraphicsLinearLayout::invalidate() [virtual]

Reimplemented from QGraphicsLayout::invalidate().

QGraphicsLayoutItem * QGraphicsLinearLayout::itemAt(int index) const [virtual]

Reimplemented from QGraphicsLayout::itemAt().

When iterating from 0 and up, it will return the items in the visual arranged order.

qreal QGraphicsLinearLayout::itemSpacing(int index) const

Returns the spacing after item at index.

See also setItemSpacing().

Qt::Orientation QGraphicsLinearLayout::orientation() const

Returns the layout orientation.

See also setOrientation().

void QGraphicsLinearLayout::removeAt(int index) [virtual]

Reimplemented from QGraphicsLayout::removeAt().

Removes the item at index without destroying it. Ownership of the item is transferred to the caller.

See also removeItem() and insertItem().

void QGraphicsLinearLayout::removeItem(QGraphicsLayoutItem * item)

Removes item from the layout without destroying it. Ownership of item is transferred to the caller.

See also removeAt() and insertItem().

void QGraphicsLinearLayout::setAlignment(QGraphicsLayoutItem * item, Qt::Alignment alignment)

Sets the alignment of item to alignment. If item's alignment changes, the layout is automatically invalidated.

See also alignment() and invalidate().

void QGraphicsLinearLayout::setGeometry(const QRectF & rect) [virtual]

Reimplemented from QGraphicsLayoutItem::setGeometry().

void QGraphicsLinearLayout::setItemSpacing(int index, qreal spacing)

Sets the spacing after item at index to spacing.

See also itemSpacing().

void QGraphicsLinearLayout::setOrientation(Qt::Orientation orientation)

Change the layout orientation to orientation. Changing the layout orientation will automatically invalidate the layout.

See also orientation().

void QGraphicsLinearLayout::setSpacing(qreal spacing)

Sets the layout's spacing to spacing. Spacing refers to the vertical and horizontal distances between items.

See also spacing(), setItemSpacing(), setStretchFactor(), and QGraphicsGridLayout::setSpacing().

void QGraphicsLinearLayout::setStretchFactor(QGraphicsLayoutItem * item, int stretch)

Sets the stretch factor for item to stretch. If an item's stretch factor changes, this function will invalidate the layout.

Setting stretch to 0 removes the stretch factor from the item, and is effectively equivalent to setting stretch to 1.

See also stretchFactor().

QSizeF QGraphicsLinearLayout::sizeHint(Qt::SizeHint which, const QSizeF & constraint = QSizeF()) const [virtual]

Reimplemented from QGraphicsLayoutItem::sizeHint().

qreal QGraphicsLinearLayout::spacing() const

Returns the layout's spacing. Spacing refers to the vertical and horizontal distances between items.

See also setSpacing().

int QGraphicsLinearLayout::stretchFactor(QGraphicsLayoutItem * item) const

Returns the stretch factor for item. The default stretch factor is 0, meaning that the item has no assigned stretch factor.

See also setStretchFactor().

Cette page est une traduction d'une page de la documentation de Qt, écrite par Nokia Corporation and/or its subsidiary(-ies). Les éventuels problèmes résultant d'une mauvaise traduction ne sont pas imputables à Nokia. Qt 5.0-snapshot
Copyright © 2012 Developpez LLC. Tous droits réservés Developpez LLC. Aucune reproduction, même partielle, ne peut être faite de ce site et de l'ensemble de son contenu : textes, documents et images sans l'autorisation expresse de Developpez LLC. Sinon, vous encourez selon la loi jusqu'à 3 ans de prison et jusqu'à 300 000 E de dommages et intérêts. Cette page est déposée à la SACD.
Vous avez déniché une erreur ? Un bug ? Une redirection cassée ? Ou tout autre problème, quel qu'il soit ? Ou bien vous désirez participer à ce projet de traduction ? N'hésitez pas à nous contacter ou par MP !
 
 
 
 
Partenaires

Hébergement Web