Add declarative QQuickTextMetrics API from QQuickFontMetrics invokables

This allows use of a declarative API for the functions in QFontMetricsF
which take parameters. This solves the problem of QML expressions that
use QML methods not being re-evaluated when the internal data changes,
by allowing the user to set the arguments as properties of a
TextMetrics object, that would otherwise have to be passed to QML
methods.

For example:

    FontMetrics {
        id: fontMetrics
    }

    property rect r: fontMetrics.boundingRect("Blah")

At some point, the font of the FontMetrics object is changed, but r
will still represent the original bounding rect. Instead, the user will
now write:

    TextMetrics {
        id: textMetrics
        text: "Blah"
    }

    property rect r: textMetrics.boundingRect

The QML methods remain in QQuickFontMetrics for those who need an
imperative API.

[ChangeLog][QtQuick] Added QQuickTextMetrics, which provides a
declarative API for the functions in QFontMetricsF which take
arguments.

Change-Id: I019dc4639531906fc751ba61281cc1c695742287
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>

1 files changed, 268 insertions, 0 deletions

diff --git a/src/quick/util/qquicktextmetrics.cpp b/src/quick/util/qquicktextmetrics.cpp
new file mode 100644
index 0000000000..09af99b82b
--- /dev/null
+++ b/src/quick/util/qquicktextmetrics.cpp
@@ -0,0 +1,268 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qquicktextmetrics_p.h"
+
+#include <QFont>
+
+QT_BEGIN_NAMESPACE
+
+/*!
+    \qmltype TextMetrics
+    \instantiates QQuickTextMetrics
+    \inqmlmodule QtQuick
+    \ingroup qtquick-text-utility
+    \brief Provides metrics for a given font and text
+
+    TextMetrics calculates various properties of a given string of text for a
+    particular font.
+
+    It provides a declarative API for the functions in \l QFontMetricsF which
+    take arguments.
+
+    \code
+    TextMetrics {
+        id: textMetrics
+        font.family: "Arial"
+        elide: Text.ElideMiddle
+        elideWidth: 100
+        text: "Hello World"
+    }
+
+    MyItem {
+        text: textMetrics.elidedText
+    }
+    \endcode
+
+    \sa QFontMetricsF, FontMetrics
+*/
+QQuickTextMetrics::QQuickTextMetrics(QObject *parent) :
+    QObject(parent),
+    m_metrics(m_font),
+    m_elide(Qt::ElideNone),
+    m_elideWidth(0)
+{
+}
+
+QQuickTextMetrics::~QQuickTextMetrics()
+{
+}
+
+/*!
+    \qmlproperty font QtQuick::TextMetrics::font
+
+    This property holds the font used for the metrics calculations.
+*/
+QFont QQuickTextMetrics::font() const
+{
+    return m_font;
+}
+
+void QQuickTextMetrics::setFont(const QFont &font)
+{
+    if (m_font != font) {
+        m_font = font;
+        m_metrics = QFontMetricsF(m_font);
+        emit fontChanged();
+        emit metricsChanged();
+    }
+}
+
+/*!
+    \qmlproperty string QtQuick::TextMetrics::text
+
+    This property holds the text used for the metrics calculations.
+*/
+QString QQuickTextMetrics::text() const
+{
+    return m_text;
+}
+
+void QQuickTextMetrics::setText(const QString &text)
+{
+    if (m_text != text) {
+        m_text = text;
+        emit textChanged();
+        emit metricsChanged();
+    }
+}
+
+/*!
+    \qmlproperty enumeration QtQuick::TextMetrics::elide
+
+    This property holds the elide mode of the text. This determines the
+    position in which the string is elided. The possible values are:
+
+    \list
+        \li \c Qt::ElideNone - No eliding; this is the default value.
+        \li \c Qt::ElideLeft - For example: "...World"
+        \li \c Qt::ElideMiddle - For example: "He...ld"
+        \li \c Qt::ElideRight - For example: "Hello..."
+    \endlist
+
+    \sa elideWidth, elidedText
+*/
+Qt::TextElideMode QQuickTextMetrics::elide() const
+{
+    return m_elide;
+}
+
+void QQuickTextMetrics::setElide(Qt::TextElideMode elide)
+{
+    if (m_elide != elide) {
+        m_elide = elide;
+        emit elideChanged();
+        emit metricsChanged();
+    }
+}
+
+/*!
+    \qmlproperty real QtQuick::TextMetrics::elideWidth
+
+    This property holds the largest width the text can have (in pixels) before
+    eliding will occur.
+
+    \sa elide, elidedText
+*/
+qreal QQuickTextMetrics::elideWidth() const
+{
+    return m_elideWidth;
+}
+
+void QQuickTextMetrics::setElideWidth(qreal elideWidth)
+{
+    if (m_elideWidth != elideWidth) {
+        m_elideWidth = elideWidth;
+        emit elideWidthChanged();
+        emit metricsChanged();
+    }
+}
+
+/*!
+    \qmlproperty real QtQuick::TextMetrics::advanceWidth
+
+    This property holds the advance in pixels of the characters in \l text.
+    This is the distance from the position of the string to where the next
+    string should be drawn.
+
+    \sa {QFontMetricsF::width()}
+*/
+qreal QQuickTextMetrics::advanceWidth() const
+{
+    return m_metrics.width(m_text);
+}
+
+/*!
+    \qmlproperty rect QtQuick::TextMetrics::boundingRect
+
+    This property holds the bounding rectangle of the characters in the string
+    specified by \l text.
+
+    \sa {QFontMetricsF::boundingRect()}, tightBoundingRect
+*/
+QRectF QQuickTextMetrics::boundingRect() const
+{
+    return m_metrics.boundingRect(m_text);
+}
+
+/*!
+    \qmlproperty real QtQuick::TextMetrics::width
+
+    This property holds the width of the bounding rectangle of the characters
+    in the string specified by \l text. It is equivalent to:
+
+    \code
+    textMetrics.boundingRect.width
+    \endcode
+
+    \sa boundingRect
+*/
+qreal QQuickTextMetrics::width() const
+{
+    return boundingRect().width();
+}
+
+/*!
+    \qmlproperty real QtQuick::TextMetrics::height
+
+    This property holds the height of the bounding rectangle of the characters
+    in the string specified by \l text. It is equivalent to:
+
+    \code
+    textMetrics.boundingRect.height
+    \endcode
+
+    \sa boundingRect
+*/
+qreal QQuickTextMetrics::height() const
+{
+    return boundingRect().height();
+}
+
+/*!
+    \qmlproperty rect QtQuick::TextMetrics::tightBoundingRect
+
+    This property holds a tight bounding rectangle around the characters in the
+    string specified by \l text.
+
+    \sa {QFontMetricsF::tightBoundingRect()}, boundingRect
+*/
+QRectF QQuickTextMetrics::tightBoundingRect() const
+{
+    return m_metrics.tightBoundingRect(m_text);
+}
+
+/*!
+    \qmlmethod string QtQuick::TextMetrics::elidedText
+
+    This property holds an elided version of the string (i.e., a string with
+    "..." in it) if the string \l text is wider than \l elideWidth. If the
+    text is not wider than \l elideWidth, or \l elide is set to
+    \c Qt::ElideNone, this property will be equal to the original string.
+
+    \sa {QFontMetricsF::elidedText()}
+*/
+QString QQuickTextMetrics::elidedText() const
+{
+    return m_metrics.elidedText(m_text, m_elide, m_elideWidth);
+}
+
+QT_END_NAMESPACE