qtdeclarative/src/quicktemplates2/qquicklabel.cpp

/****************************************************************************
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** Copyright (C) 2016 The Qt Company Ltd.
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** This file is part of the Qt Quick Templates 2 module of the Qt Toolkit.
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#include "qquicklabel_p.h"
#include "qquicklabel_p_p.h"
#include "qquickcontrol_p.h"
#include "qquickcontrol_p_p.h"

#include <QtQuick/private/qquickitem_p.h>
#include <QtQuick/private/qquicktext_p.h>
#include <QtQuick/private/qquickclipnode_p.h>

#ifndef QT_NO_ACCESSIBILITY
#include <QtQuick/private/qquickaccessibleattached_p.h>
#endif

QT_BEGIN_NAMESPACE

/*!
    \qmltype Label
    \inherits Text
    \instantiates QQuickLabel
    \inqmlmodule QtQuick.Controls
    \since 5.7
    \ingroup text
    \brief A text label with inherited styling and font.

    Label extends \l Text with styling and \l {Control::font}{font}
    inheritance. The default colors and font are style specific. Label
    can also have a visual \l background item.

    \image qtquickcontrols2-label.png

    \snippet qtquickcontrols2-label.qml 1

    You can use the properties of Text to change the appearance of the text as desired:

    \qml
     Label {
         text: "Hello world"
         font.pixelSize: 22
         font.italic: true
     }
    \endqml

    \sa {Customizing Label}
*/

QQuickLabel::QQuickLabel(QQuickItem *parent) :
    QQuickText(*(new QQuickLabelPrivate), parent)
{
    Q_D(QQuickLabel);
    QObjectPrivate::connect(this, &QQuickText::textChanged,
                            d, &QQuickLabelPrivate::_q_textChanged);
}

QQuickLabel::~QQuickLabel()
{
}

QQuickLabelPrivate::QQuickLabelPrivate()
    : background(nullptr), accessibleAttached(nullptr)
{
#ifndef QT_NO_ACCESSIBILITY
    QAccessible::installActivationObserver(this);
#endif
}

QQuickLabelPrivate::~QQuickLabelPrivate()
{
#ifndef QT_NO_ACCESSIBILITY
    QAccessible::removeActivationObserver(this);
#endif
}

/*!
    \internal

    Determine which font is implicitly imposed on this control by its ancestors
    and QGuiApplication::font, resolve this against its own font (attributes from
    the implicit font are copied over). Then propagate this font to this
    control's children.
*/
void QQuickLabelPrivate::resolveFont()
{
    Q_Q(QQuickLabel);
    inheritFont(QQuickControlPrivate::parentFont(q));
}

void QQuickLabelPrivate::inheritFont(const QFont &f)
{
    Q_Q(QQuickLabel);
    QFont parentFont = font.resolve(f);
    parentFont.resolve(font.resolve() | f.resolve());

    const QFont defaultFont = QQuickControlPrivate::themeFont(QPlatformTheme::LabelFont);
    const QFont resolvedFont = parentFont.resolve(defaultFont);

    const bool changed = resolvedFont != sourceFont;
    q->QQuickText::setFont(resolvedFont);
    if (changed)
        emit q->fontChanged();
}

void QQuickLabelPrivate::_q_textChanged(const QString &text)
{
#ifndef QT_NO_ACCESSIBILITY
    if (accessibleAttached)
        accessibleAttached->setName(text);
#else
    Q_UNUSED(text)
#endif
}

#ifndef QT_NO_ACCESSIBILITY
void QQuickLabelPrivate::accessibilityActiveChanged(bool active)
{
    if (accessibleAttached || !active)
        return;

    Q_Q(QQuickLabel);
    accessibleAttached = qobject_cast<QQuickAccessibleAttached *>(qmlAttachedPropertiesObject<QQuickAccessibleAttached>(q, true));
    if (accessibleAttached) {
        accessibleAttached->setRole(accessibleRole());
        accessibleAttached->setName(text);
    } else {
        qWarning() << "QQuickLabel: " << q << " QQuickAccessibleAttached object creation failed!";
    }
}

QAccessible::Role QQuickLabelPrivate::accessibleRole() const
{
    return QAccessible::StaticText;
}
#endif

/*
   Deletes "delegate" if Component.completed() has been emitted,
   otherwise stores it in pendingDeletions.
*/
void QQuickLabelPrivate::deleteDelegate(QObject *delegate)
{
    if (componentComplete)
        delete delegate;
    else
        pendingDeletions.append(delegate);
}

QFont QQuickLabel::font() const
{
    return QQuickText::font();
}

void QQuickLabel::setFont(const QFont &font)
{
    Q_D(QQuickLabel);
    if (d->font.resolve() == font.resolve() && d->font == font)
        return;

    d->font = font;
    d->resolveFont();
}

/*!
    \qmlproperty Item QtQuick.Controls::Label::background

    This property holds the background item.

    \note If the background item has no explicit size specified, it automatically
          follows the control's size. In most cases, there is no need to specify
          width or height for a background item.

    \sa {Customizing Label}
*/
QQuickItem *QQuickLabel::background() const
{
    Q_D(const QQuickLabel);
    return d->background;
}

void QQuickLabel::setBackground(QQuickItem *background)
{
    Q_D(QQuickLabel);
    if (d->background == background)
        return;

    d->deleteDelegate(d->background);
    d->background = background;
    if (background) {
        background->setParentItem(this);
        if (qFuzzyIsNull(background->z()))
            background->setZ(-1);
    }
    emit backgroundChanged();
}

void QQuickLabel::classBegin()
{
    Q_D(QQuickLabel);
    QQuickText::classBegin();
    d->resolveFont();
}

void QQuickLabel::componentComplete()
{
    Q_D(QQuickLabel);
    QQuickText::componentComplete();
#ifndef QT_NO_ACCESSIBILITY
    if (!d->accessibleAttached && QAccessible::isActive())
        d->accessibilityActiveChanged(true);
#endif

    qDeleteAll(d->pendingDeletions);
    d->pendingDeletions.clear();
}

void QQuickLabel::itemChange(QQuickItem::ItemChange change, const QQuickItem::ItemChangeData &value)
{
    Q_D(QQuickLabel);
    QQuickText::itemChange(change, value);
    if (change == ItemParentHasChanged && value.item)
        d->resolveFont();
}

void QQuickLabel::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_D(QQuickLabel);
    QQuickText::geometryChanged(newGeometry, oldGeometry);
    if (d->background) {
        QQuickItemPrivate *p = QQuickItemPrivate::get(d->background);
        if (!p->widthValid) {
            d->background->setWidth(newGeometry.width());
            p->widthValid = false;
        }
        if (!p->heightValid) {
            d->background->setHeight(newGeometry.height());
            p->heightValid = false;
        }
    }
}

QT_END_NAMESPACE