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>

5 files changed, 404 insertions, 5 deletions

diff --git a/src/quick/util/qquickfontmetrics.cpp b/src/quick/util/qquickfontmetrics.cpp
index bf533995a5..47e4fc1c7e 100644
--- a/src/quick/util/qquickfontmetrics.cpp
+++ b/src/quick/util/qquickfontmetrics.cpp
@@ -65,12 +65,12 @@ QT_BEGIN_NAMESPACE
     }
 
     Rectangle {
-        width: fontMetrics.height() * 4
-        height: fontMetrics.height() * 2
+        width: fontMetrics.height * 4
+        height: fontMetrics.height * 2
     }
     \endcode
 
-    \sa QFontMetricsF
+    \sa QFontMetricsF, TextMetrics
 */
 QQuickFontMetrics::QQuickFontMetrics(QObject *parent) :
     QObject(parent),
@@ -280,6 +280,10 @@ qreal QQuickFontMetrics::lineWidth() const
     This is the distance from the position of the string to where the next
     string should be drawn.
 
+    This method is offered as an imperative alternative to the
+    \l {QQuickTextMetrics::advanceWidth}{advanceWidth} property of
+    \l {QQuickTextMetrics::advanceWidth}{TextMetrics}.
+
     \sa {QFontMetricsF::width()}, height()
 */
 qreal QQuickFontMetrics::advanceWidth(const QString &text) const
@@ -293,6 +297,10 @@ qreal QQuickFontMetrics::advanceWidth(const QString &text) const
     This method returns the bounding rectangle of the characters in the string
     specified by \a text.
 
+    This method is offered as an imperative alternative to the
+    \l {QQuickTextMetrics::boundingRect}{boundingRect} property of
+    \l {QQuickTextMetrics::boundingRect}{TextMetrics}.
+
     \sa {QFontMetricsF::boundingRect()}, tightBoundingRect()
 */
 QRectF QQuickFontMetrics::boundingRect(const QString &text) const
@@ -306,6 +314,10 @@ QRectF QQuickFontMetrics::boundingRect(const QString &text) const
     This method returns a tight bounding rectangle around the characters in the
     string specified by \a text.
 
+    This method is offered as an imperative alternative to the
+    \l {QQuickTextMetrics::tightBoundingRect}{tightBoundingRect} property of
+    \l {QQuickTextMetrics::tightBoundingRect}{TextMetrics}.
+
     \sa {QFontMetricsF::tightBoundingRect()}, boundingRect()
 */
 QRectF QQuickFontMetrics::tightBoundingRect(const QString &text) const
@@ -324,6 +336,10 @@ QRectF QQuickFontMetrics::tightBoundingRect(const QString &text) const
     The \a flags argument is optional and currently only supports
     \l {Qt::TextShowMnemonic}.
 
+    This method is offered as an imperative alternative to the
+    \l {QQuickTextMetrics::elidedText}{elidedText} property of
+    \l {QQuickTextMetrics::elidedText}{TextMetrics}.
+
     \sa {QFontMetricsF::elidedText()}
 */
 QString QQuickFontMetrics::elidedText(const QString &text, Qt::TextElideMode mode, qreal width, int flags) const
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
diff --git a/src/quick/util/qquicktextmetrics_p.h b/src/quick/util/qquicktextmetrics_p.h
new file mode 100644
index 0000000000..ec993229e5
--- /dev/null
+++ b/src/quick/util/qquicktextmetrics_p.h
@@ -0,0 +1,111 @@
+/****************************************************************************
+**
+** 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.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQUICKTEXTMETRICS_H
+#define QQUICKTEXTMETRICS_H
+
+#include <qqml.h>
+
+#include <QtGui/QFontMetricsF>
+#include <QtCore/QObject>
+
+QT_BEGIN_NAMESPACE
+
+class QFont;
+
+class Q_AUTOTEST_EXPORT QQuickTextMetrics : public QObject
+{
+    Q_OBJECT
+
+    Q_PROPERTY(QFont font READ font WRITE setFont NOTIFY fontChanged FINAL)
+    Q_PROPERTY(QString text READ text WRITE setText NOTIFY textChanged FINAL)
+    Q_PROPERTY(qreal advanceWidth READ advanceWidth NOTIFY metricsChanged FINAL)
+    Q_PROPERTY(QRectF boundingRect READ boundingRect NOTIFY metricsChanged FINAL)
+    Q_PROPERTY(qreal width READ width NOTIFY metricsChanged FINAL)
+    Q_PROPERTY(qreal height READ height NOTIFY metricsChanged FINAL)
+    Q_PROPERTY(QRectF tightBoundingRect READ tightBoundingRect NOTIFY metricsChanged FINAL)
+    Q_PROPERTY(QString elidedText READ elidedText NOTIFY metricsChanged FINAL)
+    Q_PROPERTY(Qt::TextElideMode elide READ elide WRITE setElide NOTIFY elideChanged FINAL)
+    Q_PROPERTY(qreal elideWidth READ elideWidth WRITE setElideWidth NOTIFY elideWidthChanged FINAL)
+
+public:
+    explicit QQuickTextMetrics(QObject *parent = 0);
+    ~QQuickTextMetrics();
+
+    QFont font() const;
+    void setFont(const QFont &font);
+
+    QString text() const;
+    void setText(const QString &text);
+
+    Qt::TextElideMode elide() const;
+    void setElide(Qt::TextElideMode elide);
+
+    qreal elideWidth() const;
+    void setElideWidth(qreal elideWidth);
+
+    qreal advanceWidth() const;
+    QRectF boundingRect() const;
+    qreal width() const;
+    qreal height() const;
+    QRectF tightBoundingRect() const;
+    QString elidedText() const;
+
+Q_SIGNALS:
+    void fontChanged();
+    void textChanged();
+    void elideChanged();
+    void elideWidthChanged();
+    void metricsChanged();
+
+private:
+    QString m_text;
+    QFont m_font;
+    QFontMetricsF m_metrics;
+    Qt::TextElideMode m_elide;
+    qreal m_elideWidth;
+};
+
+QT_END_NAMESPACE
+
+QML_DECLARE_TYPE(QQuickTextMetrics)
+
+#endif // QQUICKTEXTMETRICS_H
diff --git a/src/quick/util/qquickutilmodule.cpp b/src/quick/util/qquickutilmodule.cpp
index 1d82cfca43..8ea903b010 100644
--- a/src/quick/util/qquickutilmodule.cpp
+++ b/src/quick/util/qquickutilmodule.cpp
@@ -53,6 +53,7 @@
 #include "qquickstate_p.h"
 #include "qquickstate_p_p.h"
 #include "qquicksystempalette_p.h"
+#include "qquicktextmetrics_p.h"
 #include "qquicktransition_p.h"
 #include "qquickanimator_p.h"
 #include <qqmlinfo.h>
@@ -109,4 +110,5 @@ void QQuickUtilModule::defineModule()
     qmlRegisterUncreatableType<QKeySequence, 2>("QtQuick", 2, 2, "StandardKey", QStringLiteral("Cannot create an instance of StandardKey."));
 
     qmlRegisterType<QQuickFontMetrics>("QtQuick", 2, 4, "FontMetrics");
+    qmlRegisterType<QQuickTextMetrics>("QtQuick", 2, 4, "TextMetrics");
 }
diff --git a/src/quick/util/util.pri b/src/quick/util/util.pri
index 35553070dc..76cf1996bc 100644
--- a/src/quick/util/util.pri
+++ b/src/quick/util/util.pri
@@ -27,7 +27,8 @@ SOURCES += \
     $$PWD/qquickanimatorjob.cpp \
     $$PWD/qquickanimatorcontroller.cpp \
     $$PWD/qquickprofiler.cpp \
-    $$PWD/qquickfontmetrics.cpp
+    $$PWD/qquickfontmetrics.cpp \
+    $$PWD/qquicktextmetrics.cpp
 
 HEADERS += \
     $$PWD/qquickapplication_p.h\
@@ -62,4 +63,5 @@ HEADERS += \
     $$PWD/qquickanimatorjob_p.h \
     $$PWD/qquickanimatorcontroller_p.h \
     $$PWD/qquickprofiler_p.h \
-    $$PWD/qquickfontmetrics_p.h
+    $$PWD/qquickfontmetrics_p.h \
+    $$PWD/qquicktextmetrics_p.h