QDeclarativeText has new multiline properties

LineCount should return the number of lines currently being displayed.
Setting maximumLineCount limits the number of lines that will be shown
Truncated will return true if the text has been elided normally, or if
the lines have been limited due to maximumLineCount.

Task-number: QTBUG-12305
Reviewed-by: Michael Brasser

3 files changed, 185 insertions, 15 deletions

diff --git a/src/declarative/graphicsitems/qdeclarativetext.cpp b/src/declarative/graphicsitems/qdeclarativetext.cpp
index cf11be6..d61342e 100644
--- a/src/declarative/graphicsitems/qdeclarativetext.cpp
+++ b/src/declarative/graphicsitems/qdeclarativetext.cpp
@@ -54,6 +54,7 @@
 #include <QPainter>
 #include <QAbstractTextDocumentLayout>
 #include <qmath.h>
+#include <limits.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -84,12 +85,14 @@ private:
 
 DEFINE_BOOL_CONFIG_OPTION(enableImageCache, QML_ENABLE_TEXT_IMAGE_CACHE);
 
+QString QDeclarativeTextPrivate::elideChar = QString(0x2026);
+
 QDeclarativeTextPrivate::QDeclarativeTextPrivate()
 : color((QRgb)0), style(QDeclarativeText::Normal), hAlign(QDeclarativeText::AlignLeft), 
   vAlign(QDeclarativeText::AlignTop), elideMode(QDeclarativeText::ElideNone),
-  format(QDeclarativeText::AutoText), wrapMode(QDeclarativeText::NoWrap), imageCacheDirty(true), 
-  updateOnComponentComplete(true), richText(false), singleline(false), cacheAllTextAsImage(true), 
-  internalWidthUpdate(false), doc(0) 
+  format(QDeclarativeText::AutoText), wrapMode(QDeclarativeText::NoWrap), lineCount(1), truncated(false), maximumLineCount(INT_MAX),
+  maximumLineCountValid(false), imageCacheDirty(true), updateOnComponentComplete(true), richText(false), singleline(false),
+  cacheAllTextAsImage(true), internalWidthUpdate(false), doc(0)
 {
     cacheAllTextAsImage = enableImageCache();
     QGraphicsItemPrivate::acceptedMouseButtons = Qt::LeftButton;
@@ -192,9 +195,13 @@ void QDeclarativeTextPrivate::updateLayout()
             QString tmp = text;
             tmp.replace(QLatin1Char('\n'), QChar::LineSeparator);
             singleline = !tmp.contains(QChar::LineSeparator);
-            if (singleline && elideMode != QDeclarativeText::ElideNone && q->widthValid()) {
+            if (singleline && !maximumLineCountValid && elideMode != QDeclarativeText::ElideNone && q->widthValid()) {
                 QFontMetrics fm(font);
                 tmp = fm.elidedText(tmp,(Qt::TextElideMode)elideMode,q->width()); // XXX still worth layout...?
+                if (tmp != text && !truncated) {
+                    truncated = true;
+                    emit q->truncatedChanged();
+                }
             }
             layout.setText(tmp);
         } else {
@@ -291,6 +298,8 @@ QSize QDeclarativeTextPrivate::setupTextLayout()
     qreal height = 0;
     qreal widthUsed = 0;
     qreal lineWidth = 0;
+    int visibleTextLength = 0;
+    int visibleCount = 0;
 
     //set manual width
     if ((wrapMode != QDeclarativeText::NoWrap || elideMode != QDeclarativeText::ElideNone) && q->widthValid())
@@ -302,16 +311,71 @@ QSize QDeclarativeTextPrivate::setupTextLayout()
     textOption.setWrapMode(QTextOption::WrapMode(wrapMode));
     layout.setTextOption(textOption);
 
-    layout.beginLayout();
-    forever {
-        QTextLine line = layout.createLine();
-        if (!line.isValid())
-            break;
+    bool elideText = false;
+    bool truncate = false;
+
+    QFontMetrics fm(layout.font());
+    qreal elideWidth = fm.width(elideChar);
+    elidePos = QPointF();
+
+    if (maximumLineCountValid) {
+        layout.beginLayout();
+        int y = 0;
+        int linesLeft = maximumLineCount;
+        while (linesLeft > 0) {
+            QTextLine line = layout.createLine();
+            if (!line.isValid())
+                break;
+
+            visibleCount++;
+
+            if (lineWidth) {
+                if (--linesLeft == 0) {
+                    line.setLineWidth(q->width()*2); // Set out more than is required, but not too much.
+                    if (line.naturalTextWidth() > lineWidth)
+                        line.setLineWidth(lineWidth - elideWidth);
+                    visibleTextLength += line.textLength(); // Used to catch new lines that are shorter than the layout width.
+
+                    if (visibleTextLength < text.length()) {
+                        truncate = true;
+                        if (elideMode==QDeclarativeText::ElideRight) {
+                            // Need to correct for alignment
+                            int x = line.naturalTextWidth();
+                            if (hAlign == QDeclarativeText::AlignRight) {
+                                x = q->width()-elideWidth;
+                            } else if (hAlign == QDeclarativeText::AlignHCenter) {
+                                x = (q->width()+line.naturalTextWidth()-elideWidth)/2;
+                            }
+                            elidePos = QPointF(x, y + fm.ascent());
+                        }
+                    }
+                } else {
+                    line.setLineWidth(lineWidth);
+                    visibleTextLength += line.textLength();
+                }
+
+                y += line.height();
+            }
+        }
+        layout.endLayout();
 
-        if (lineWidth)
-            line.setLineWidth(lineWidth);
+        //Update truncated
+        if (truncated != truncate) {
+            truncated = truncate;
+            emit q->truncatedChanged();
+        }
+    } else {
+        layout.beginLayout();
+        forever {
+            QTextLine line = layout.createLine();
+            if (!line.isValid())
+                break;
+            visibleCount++;
+            if (lineWidth)
+                line.setLineWidth(lineWidth);
+        }
+        layout.endLayout();
     }
-    layout.endLayout();
 
     for (int i = 0; i < layout.lineCount(); ++i) {
         QTextLine line = layout.lineAt(i);
@@ -331,13 +395,23 @@ QSize QDeclarativeTextPrivate::setupTextLayout()
                 x = 0;
             } else if (hAlign == QDeclarativeText::AlignRight) {
                 x = layoutWidth - line.naturalTextWidth();
+                if (elideText && i == layout.lineCount()-1)
+                    x -= elideWidth; // Correct for when eliding multilines
             } else if (hAlign == QDeclarativeText::AlignHCenter) {
                 x = (layoutWidth - line.naturalTextWidth()) / 2;
+                if (elideText && i == layout.lineCount()-1)
+                    x -= elideWidth/2; // Correct for when eliding multilines
             }
             line.setPosition(QPointF(x, line.y()));
         }
     }
 
+    //Update the number of visible lines
+    if (lineCount != visibleCount) {
+        lineCount = visibleCount;
+        emit q->lineCountChanged();
+    }
+
     return layout.boundingRect().toAlignedRect().size();
 }
 
@@ -391,7 +465,9 @@ void QDeclarativeTextPrivate::drawTextLayout(QPainter *painter, const QPointF &p
     else
         painter->setPen(color);
     painter->setFont(font);
-    layout.draw(painter, pos); 
+    layout.draw(painter, pos);
+    if (!elidePos.isNull())
+        painter->drawText(elidePos, elideChar);
 }
 
 /*!
@@ -979,6 +1055,76 @@ void QDeclarativeText::setWrapMode(WrapMode mode)
     emit wrapModeChanged();
 }
 
+/*!
+    \qmlproperty int Text::lineCount
+
+    Returns the number of lines visible in the text item.
+
+    This property is not supported for rich text.
+
+    \sa maximumLineCount
+*/
+int QDeclarativeText::lineCount() const
+{
+    Q_D(const QDeclarativeText);
+    return d->lineCount;
+}
+
+/*!
+    \qmlproperty bool Text::truncated
+
+    Returns if the text has been truncated due to \l maximumLineCount
+    or \l elide.
+
+    This property is not supported for rich text.
+
+    \sa maximumLineCount, elide
+*/
+bool QDeclarativeText::truncated() const
+{
+    Q_D(const QDeclarativeText);
+    return d->truncated;
+}
+
+/*!
+    \qmlproperty int Text::maximumLineCount
+
+    Set this property to limit the number of lines that the text item will show.
+    If elide is set to Text.ElideRight, the text will be elided appropriately.
+    By default, this is the value of the largest possible integer.
+
+    This property is not supported for rich text.
+
+    \sa lineCount, elide
+*/
+int QDeclarativeText::maximumLineCount() const
+{
+    Q_D(const QDeclarativeText);
+    return d->maximumLineCount;
+}
+
+void QDeclarativeText::setMaximumLineCount(int lines)
+{
+    Q_D(QDeclarativeText);
+
+    d->maximumLineCountValid = lines==INT_MAX ? false : true;
+    if (d->maximumLineCount != lines) {
+        d->maximumLineCount = lines;
+        d->updateLayout();
+        emit maximumLineCountChanged();
+    }
+}
+
+void QDeclarativeText::resetMaximumLineCount()
+{
+    Q_D(QDeclarativeText);
+    setMaximumLineCount(INT_MAX);
+    d->elidePos = QPointF();
+    if (d->truncated != false) {
+        d->truncated = false;
+        emit truncatedChanged();
+    }
+}
 
 /*!
     \qmlproperty enumeration Text::textFormat
@@ -1066,7 +1212,7 @@ void QDeclarativeText::setTextFormat(TextFormat format)
     Set this property to elide parts of the text fit to the Text item's width.
     The text will only elide if an explicit width has been set.
 
-    This property cannot be used with multi-line text or with rich text.
+    This property cannot be used with rich text.
 
     Eliding can be:
     \list
@@ -1076,6 +1222,9 @@ void QDeclarativeText::setTextFormat(TextFormat format)
     \o Text.ElideRight
     \endlist
 
+    If this property is set to Text.ElideRight, it can be used with multiline
+    text. The text will only elide if maximumLineCount has been set.
+
     If the text is a multi-length string, and the mode is not \c Text.ElideNone,
     the first string that fits will be used, otherwise the last will be elided.
 
@@ -1153,7 +1302,7 @@ void QDeclarativeText::geometryChanged(const QRectF &newGeometry, const QRectF &
             && (d->wrapMode != QDeclarativeText::NoWrap
                 || d->elideMode != QDeclarativeText::ElideNone
                 || d->hAlign != QDeclarativeText::AlignLeft)) {
-        if (d->singleline && d->elideMode != QDeclarativeText::ElideNone && widthValid()) {
+        if ((d->singleline || d->maximumLineCountValid) && d->elideMode != QDeclarativeText::ElideNone && widthValid()) {
             // We need to re-elide
             d->updateLayout();
         } else {
diff --git a/src/declarative/graphicsitems/qdeclarativetext_p.h b/src/declarative/graphicsitems/qdeclarativetext_p.h
index 49bff14..2e19910 100644
--- a/src/declarative/graphicsitems/qdeclarativetext_p.h
+++ b/src/declarative/graphicsitems/qdeclarativetext_p.h
@@ -71,6 +71,10 @@ class Q_DECLARATIVE_PRIVATE_EXPORT QDeclarativeText : public QDeclarativeItem
     Q_PROPERTY(HAlignment horizontalAlignment READ hAlign WRITE setHAlign NOTIFY horizontalAlignmentChanged)
     Q_PROPERTY(VAlignment verticalAlignment READ vAlign WRITE setVAlign NOTIFY verticalAlignmentChanged)
     Q_PROPERTY(WrapMode wrapMode READ wrapMode WRITE setWrapMode NOTIFY wrapModeChanged)
+    Q_PROPERTY(int lineCount READ lineCount NOTIFY lineCountChanged)
+    Q_PROPERTY(bool truncated READ truncated NOTIFY truncatedChanged)
+    Q_PROPERTY(int maximumLineCount READ maximumLineCount WRITE setMaximumLineCount NOTIFY maximumLineCountChanged RESET resetMaximumLineCount)
+
     Q_PROPERTY(TextFormat textFormat READ textFormat WRITE setTextFormat NOTIFY textFormatChanged)
     Q_PROPERTY(TextElideMode elide READ elideMode WRITE setElideMode NOTIFY elideModeChanged) //### elideMode?
     Q_PROPERTY(qreal paintedWidth READ paintedWidth NOTIFY paintedSizeChanged)
@@ -131,6 +135,13 @@ public:
     WrapMode wrapMode() const;
     void setWrapMode(WrapMode w);
 
+    int lineCount() const;
+    bool truncated() const;
+
+    int maximumLineCount() const;
+    void setMaximumLineCount(int lines);
+    void resetMaximumLineCount();
+
     TextFormat textFormat() const;
     void setTextFormat(TextFormat format);
 
@@ -158,6 +169,9 @@ Q_SIGNALS:
     void horizontalAlignmentChanged(HAlignment alignment);
     void verticalAlignmentChanged(VAlignment alignment);
     void wrapModeChanged();
+    void lineCountChanged();
+    void truncatedChanged();
+    void maximumLineCountChanged();
     void textFormatChanged(TextFormat textFormat);
     void elideModeChanged(TextElideMode mode);
     void paintedSizeChanged();
diff --git a/src/declarative/graphicsitems/qdeclarativetext_p_p.h b/src/declarative/graphicsitems/qdeclarativetext_p_p.h
index e37f477..42c815b 100644
--- a/src/declarative/graphicsitems/qdeclarativetext_p_p.h
+++ b/src/declarative/graphicsitems/qdeclarativetext_p_p.h
@@ -88,6 +88,13 @@ public:
     QDeclarativeText::TextElideMode elideMode;
     QDeclarativeText::TextFormat format;
     QDeclarativeText::WrapMode wrapMode;
+    int lineCount;
+    bool truncated;
+    int maximumLineCount;
+    int maximumLineCountValid;
+    QPointF elidePos;
+
+    static QString elideChar;
 
     void invalidateImageCache();
     void checkImageCache();