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>

2 files changed, 171 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicktextmetrics/qquicktextmetrics.pro b/tests/auto/quick/qquicktextmetrics/qquicktextmetrics.pro
new file mode 100644
index 0000000000..6ef68db8e2
--- /dev/null
+++ b/tests/auto/quick/qquicktextmetrics/qquicktextmetrics.pro
@@ -0,0 +1,10 @@
+CONFIG += testcase
+TARGET = tst_qquicktextmetrics
+osx:CONFIG -= app_bundle
+
+SOURCES += tst_qquicktextmetrics.cpp
+
+CONFIG += parallel_test
+
+QT += core gui qml quick-private testlib
+DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0
diff --git a/tests/auto/quick/qquicktextmetrics/tst_qquicktextmetrics.cpp b/tests/auto/quick/qquicktextmetrics/tst_qquicktextmetrics.cpp
new file mode 100644
index 0000000000..733b3d06b3
--- /dev/null
+++ b/tests/auto/quick/qquicktextmetrics/tst_qquicktextmetrics.cpp
@@ -0,0 +1,161 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtQml 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 <QFont>
+#include <QString>
+#include <QtTest>
+#include <QCoreApplication>
+#include <QQmlComponent>
+#include <QQmlEngine>
+#include <QQuickItem>
+
+#include <QtQuick/private/qquicktextmetrics_p.h>
+
+#include <QFontMetricsF>
+
+class tst_QQuickTextMetrics : public QObject
+{
+    Q_OBJECT
+
+public:
+    tst_QQuickTextMetrics();
+
+private Q_SLOTS:
+    void font();
+    void functionsWithArguments_data();
+    void functionsWithArguments();
+};
+
+tst_QQuickTextMetrics::tst_QQuickTextMetrics()
+{
+}
+
+void tst_QQuickTextMetrics::font()
+{
+    QQuickTextMetrics metrics;
+
+    QSignalSpy fontSpy(&metrics, SIGNAL(fontChanged()));
+    QSignalSpy metricsSpy(&metrics, SIGNAL(metricsChanged()));
+    QFont font;
+    font.setPointSize(font.pointSize() + 1);
+    metrics.setFont(font);
+    QCOMPARE(fontSpy.count(), 1);
+    QCOMPARE(metricsSpy.count(), 1);
+}
+
+Q_DECLARE_METATYPE(Qt::TextElideMode)
+
+void tst_QQuickTextMetrics::functionsWithArguments_data()
+{
+    QTest::addColumn<QString>("text");
+    QTest::addColumn<Qt::TextElideMode>("mode");
+    QTest::addColumn<qreal>("width");
+
+    QStringList strings;
+    strings << QString()
+            << QString::fromLatin1("")
+            << QString::fromLatin1("0")
+            << QString::fromLatin1("@@@@@@@")
+            << QString::fromLatin1("Hello");
+
+    QVector<Qt::TextElideMode> elideModes;
+    elideModes << Qt::ElideLeft << Qt::ElideMiddle << Qt::ElideRight << Qt::ElideNone;
+
+    for (int stringIndex = 0; stringIndex < strings.size(); ++stringIndex) {
+        const QString string = strings.at(stringIndex);
+
+        for (int elideModeIndex = 0; elideModeIndex < elideModes.size(); ++elideModeIndex) {
+            Qt::TextElideMode elideMode = static_cast<Qt::TextElideMode>(elideModes.at(elideModeIndex));
+
+            for (qreal width = 0; width < 100; width += 20) {
+                const QString tag = QString::fromLatin1("string=%1, mode=%2, width=%3").arg(string).arg(elideMode).arg(width);
+                QTest::newRow(qPrintable(tag)) << QString() << elideMode << width;
+            }
+        }
+    }
+}
+
+void tst_QQuickTextMetrics::functionsWithArguments()
+{
+    QFETCH(QString, text);
+    QFETCH(Qt::TextElideMode, mode);
+    QFETCH(qreal, width);
+
+    QQuickTextMetrics metrics;
+    // Ensures that the values actually change.
+    metrics.setText(text + "extra");
+    metrics.setElideWidth(width + 1);
+    switch (mode) {
+        case Qt::ElideNone: metrics.setElide(Qt::ElideMiddle); break;
+        case Qt::ElideLeft: metrics.setElide(Qt::ElideRight); break;
+        case Qt::ElideMiddle: metrics.setElide(Qt::ElideNone); break;
+        case Qt::ElideRight: metrics.setElide(Qt::ElideLeft); break;
+    }
+
+    QSignalSpy textSpy(&metrics, SIGNAL(textChanged()));
+    QSignalSpy metricsSpy(&metrics, SIGNAL(metricsChanged()));
+    metrics.setText(text);
+    QCOMPARE(textSpy.count(), 1);
+    QCOMPARE(metricsSpy.count(), 1);
+
+    QSignalSpy elideSpy(&metrics, SIGNAL(elideChanged()));
+    metrics.setElide(mode);
+    QCOMPARE(elideSpy.count(), 1);
+    QCOMPARE(metricsSpy.count(), 2);
+
+    QSignalSpy elideWidthSpy(&metrics, SIGNAL(elideWidthChanged()));
+    metrics.setElideWidth(width);
+    QCOMPARE(elideWidthSpy.count(), 1);
+    QCOMPARE(metricsSpy.count(), 3);
+
+    QFontMetricsF expected = QFontMetricsF(QFont());
+
+    QCOMPARE(metrics.elidedText(), expected.elidedText(text, mode, width, 0));
+    QCOMPARE(metrics.advanceWidth(), expected.width(text));
+    QCOMPARE(metrics.boundingRect(), expected.boundingRect(text));
+    QCOMPARE(metrics.width(), expected.boundingRect(text).width());
+    QCOMPARE(metrics.height(), expected.boundingRect(text).height());
+    QCOMPARE(metrics.tightBoundingRect(), expected.tightBoundingRect(text));
+}
+
+QTEST_MAIN(tst_QQuickTextMetrics)
+
+#include "tst_qquicktextmetrics.moc"