Add line spacing to QTextBlockFormat, get/set functions, CSS support

The patch adds line spacing options to Qt, as in all modern word
processors. I primarily checked OpenOffice as a reference for how to
position the lines based on the various types of line spacing as well
as where to do the page breaks. The following functions were added:

void QTextBlockFormat::setLineHeight(qreal height, int heightType)
qreal QTextBlockFormat::lineHeight()
int QTextBlockFormat::lineHeightType()
qreal QTextBlockFormat::lineHeight(qreal scriptLineHeight, qreal scaling)

Here are the HeightTypes available:
QTextBlockFormat::SingleHeight
QTextBlockFormat::ProportionalHeight
QTextBlockFormat::FixedHeight
QTextBlockFormat::AtLeastHeight
QTextBlockFormat::LineDistanceHeight

The following CSS syntax was added:
line-height:150%
line-height:40px
line-height:normal
line-height:40al
line-height:40ld

Merge-request: 2305
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>

6 files changed, 154 insertions, 6 deletions

diff --git a/src/gui/text/qcssparser.cpp b/src/gui/text/qcssparser.cpp
index dafc8e7..edb08ae 100644
--- a/src/gui/text/qcssparser.cpp
+++ b/src/gui/text/qcssparser.cpp
@@ -122,6 +122,7 @@ static const QCssKnownValue properties[NumProperties - 1] = {
     { "image", QtImage },
     { "image-position", QtImageAlignment },
     { "left", Left },
+    { "line-height", LineHeight },
     { "list-style", ListStyle },
     { "list-style-type", ListStyleType },
     { "margin" , Margin },
diff --git a/src/gui/text/qcssparser_p.h b/src/gui/text/qcssparser_p.h
index ca9688e..6bcbdab 100644
--- a/src/gui/text/qcssparser_p.h
+++ b/src/gui/text/qcssparser_p.h
@@ -180,6 +180,7 @@ enum Property {
     TextTransform,
     QtListNumberPrefix,
     QtListNumberSuffix,
+    LineHeight,
     NumProperties
 };
 
diff --git a/src/gui/text/qtextdocumentlayout.cpp b/src/gui/text/qtextdocumentlayout.cpp
index ff14490..5334ae8 100644
--- a/src/gui/text/qtextdocumentlayout.cpp
+++ b/src/gui/text/qtextdocumentlayout.cpp
@@ -2506,6 +2506,23 @@ void QTextDocumentLayoutPrivate::layoutFlow(QTextFrame::Iterator it, QTextLayout
     fd->currentLayoutStruct = 0;
 }
 
+static inline void getLineHeightParams(const QTextBlockFormat &blockFormat, const QTextLine &line, qreal scaling,
+                                       QFixed *lineAdjustment, QFixed *lineBreakHeight, QFixed *lineHeight)
+{
+    *lineHeight = QFixed::fromReal(blockFormat.lineHeight(line.height(), scaling));
+    if (blockFormat.lineHeightType() == QTextBlockFormat::FixedHeight || blockFormat.lineHeightType() == QTextBlockFormat::AtLeastHeight) {
+        *lineBreakHeight = *lineHeight;
+        if (blockFormat.lineHeightType() == QTextBlockFormat::FixedHeight)
+            *lineAdjustment = QFixed::fromReal(line.ascent() + qMax(line.leading(), 0.0)) - ((*lineHeight * 4) / 5);
+        else
+            *lineAdjustment = QFixed::fromReal(line.height()) - *lineHeight;
+    }
+    else {
+        *lineBreakHeight = QFixed::fromReal(line.height());
+        *lineAdjustment = 0;
+    }
+}
+
 void QTextDocumentLayoutPrivate::layoutBlock(const QTextBlock &bl, int blockPosition, const QTextBlockFormat &blockFormat,
                                              QTextLayoutStruct *layoutStruct, int layoutFrom, int layoutTo, const QTextBlockFormat *previousBlockFormat)
 {
@@ -2639,8 +2656,12 @@ void QTextDocumentLayoutPrivate::layoutBlock(const QTextBlock &bl, int blockPosi
 
             }
 
-            QFixed lineHeight = QFixed::fromReal(line.height());
-            if (layoutStruct->pageHeight > 0 && layoutStruct->absoluteY() + lineHeight > layoutStruct->pageBottom) {
+            QFixed lineBreakHeight, lineHeight, lineAdjustment;
+            qreal scaling = (q->paintDevice() && q->paintDevice()->logicalDpiY() != qt_defaultDpi()) ?
+                            qreal(q->paintDevice()->logicalDpiY()) / qreal(qt_defaultDpi()) : 1;
+            getLineHeightParams(blockFormat, line, scaling, &lineAdjustment, &lineBreakHeight, &lineHeight);
+
+            if (layoutStruct->pageHeight > 0 && layoutStruct->absoluteY() + lineBreakHeight > layoutStruct->pageBottom) {
                 layoutStruct->newPage();
 
                 floatMargins(layoutStruct->y, layoutStruct, &left, &right);
@@ -2652,7 +2673,7 @@ void QTextDocumentLayoutPrivate::layoutBlock(const QTextBlock &bl, int blockPosi
                     right -= text_indent;
             }
 
-            line.setPosition(QPointF((left - layoutStruct->x_left).toReal(), (layoutStruct->y - cy).toReal()));
+            line.setPosition(QPointF((left - layoutStruct->x_left).toReal(), (layoutStruct->y - cy - lineAdjustment).toReal()));
             layoutStruct->y += lineHeight;
             layoutStruct->contentsWidth
                 = qMax<QFixed>(layoutStruct->contentsWidth, QFixed::fromReal(line.x() + line.naturalTextWidth()) + totalRightMargin);
@@ -2672,11 +2693,16 @@ void QTextDocumentLayoutPrivate::layoutBlock(const QTextBlock &bl, int blockPosi
             QTextLine line = tl->lineAt(i);
             layoutStruct->contentsWidth
                 = qMax(layoutStruct->contentsWidth, QFixed::fromReal(line.x() + tl->lineAt(i).naturalTextWidth()) + totalRightMargin);
-            const QFixed lineHeight = QFixed::fromReal(line.height());
+
+            QFixed lineBreakHeight, lineHeight, lineAdjustment;
+            qreal scaling = (q->paintDevice() && q->paintDevice()->logicalDpiY() != qt_defaultDpi()) ?
+                            qreal(q->paintDevice()->logicalDpiY()) / qreal(qt_defaultDpi()) : 1;
+            getLineHeightParams(blockFormat, line, scaling, &lineAdjustment, &lineBreakHeight, &lineHeight);
+
             if (layoutStruct->pageHeight != QFIXED_MAX) {
-                if (layoutStruct->absoluteY() + lineHeight > layoutStruct->pageBottom)
+                if (layoutStruct->absoluteY() + lineBreakHeight > layoutStruct->pageBottom)
                     layoutStruct->newPage();
-                line.setPosition(QPointF(line.position().x(), layoutStruct->y.toReal() - tl->position().y()));
+                line.setPosition(QPointF(line.position().x(), (layoutStruct->y - lineAdjustment).toReal() - tl->position().y()));
             }
             layoutStruct->y += lineHeight;
         }
diff --git a/src/gui/text/qtextformat.cpp b/src/gui/text/qtextformat.cpp
index 945b012..719db7a 100644
--- a/src/gui/text/qtextformat.cpp
+++ b/src/gui/text/qtextformat.cpp
@@ -541,6 +541,8 @@ Q_GUI_EXPORT QDataStream &operator>>(QDataStream &stream, QTextFormat &fmt)
     \value TabPositions     Specifies the tab positions.  The tab positions are structs of QTextOption::Tab which are stored in
                             a QList (internally, in a QList<QVariant>).
     \value BlockIndent
+    \value LineHeight
+    \value LineHeightType
     \value BlockNonBreakableLines
     \value BlockTrailingHorizontalRulerWidth The width of a horizontal ruler element.
 
@@ -1856,6 +1858,10 @@ QFont QTextCharFormat::font() const
     indentation is set with setIndent(), the indentation of the first
     line with setTextIndent().
 
+    Line spacing is set with setLineHeight() and retreived via lineHeight()
+    and lineHeightType(). The types of line spacing available are in the
+    LineHeightTypes enum.
+
     Line breaking can be enabled and disabled with setNonBreakableLines().
 
     The brush used to paint the paragraph's background
@@ -1872,6 +1878,22 @@ QFont QTextCharFormat::font() const
 */
 
 /*!
+    \since 4.7
+    \enum QTextBlockFormat::LineHeightTypes
+
+    This enum describes the various types of line spacing support paragraphs can have.
+
+    \value SingleHeight This is the default line height: single spacing.
+    \value ProportionalHeight This sets the spacing proportional to the line (in percentage).
+                              For example, set to 200 for double spacing.
+    \value FixedHeight This sets the line height to a fixed line height (in pixels).
+    \value AtLeastHeight This sets the minimum line height (in pixels).
+    \value LineDistanceHeight This adds the specified height between lines (in pixels).
+
+    \sa lineHeight(), lineHeightType(), setLineHeight()
+*/
+
+/*!
     \fn QTextBlockFormat::QTextBlockFormat()
 
     Constructs a new QTextBlockFormat.
@@ -2089,6 +2111,51 @@ QList<QTextOption::Tab> QTextBlockFormat::tabPositions() const
 
 
 /*!
+    \fn void QTextBlockFormat::setLineHeight(qreal height, int heightType)
+    \since 4.7
+
+    This sets the line height for the paragraph to the value in height
+    which is dependant on heightType, described by the LineHeightTypes enum.
+
+    \sa LineHeightTypes, lineHeight(), lineHeightType()
+*/
+
+
+/*!
+    \fn qreal QTextBlockFormat::lineHeight(qreal scriptLineHeight, qreal scaling) const
+    \since 4.7
+
+    This returns what the height of the lines in the paragraph will be depending
+    on the given height of the script line and the scaling. The value that is returned
+    is also dependant on the given LineHeightType of the paragraph as well as the LineHeight
+    setting that has been set for the paragraph. The scaling is needed for the heights
+    that include a fixed number of pixels, to scale them appropriately for printing.
+
+    \sa LineHeightTypes, setLineHeight(), lineHeightType()
+*/
+
+
+/*!
+    \fn qreal QTextBlockFormat::lineHeight() const
+    \since 4.7
+
+    This returns the LineHeight property for the paragraph.
+
+    \sa LineHeightTypes, setLineHeight(), lineHeightType()
+*/
+
+
+/*!
+    \fn qreal QTextBlockFormat::lineHeightType() const
+    \since 4.7
+
+    This returns the LineHeightType property of the paragraph.
+
+    \sa LineHeightTypes, setLineHeight(), lineHeight()
+*/
+
+
+/*!
     \fn void QTextBlockFormat::setNonBreakableLines(bool b)
 
     If \a b is true, the lines in the paragraph are treated as
diff --git a/src/gui/text/qtextformat.h b/src/gui/text/qtextformat.h
index bb6e71d..41cc1d9 100644
--- a/src/gui/text/qtextformat.h
+++ b/src/gui/text/qtextformat.h
@@ -164,6 +164,8 @@ public:
         TextIndent = 0x1034,
         TabPositions = 0x1035,
         BlockIndent = 0x1040,
+        LineHeight = 0x1048,
+        LineHeightType = 0x1049,
         BlockNonBreakableLines = 0x1050,
         BlockTrailingHorizontalRulerWidth = 0x1060,
 
@@ -531,6 +533,14 @@ inline void QTextCharFormat::setTableCellColumnSpan(int _tableCellColumnSpan)
 class Q_GUI_EXPORT QTextBlockFormat : public QTextFormat
 {
 public:
+    enum LineHeightTypes {
+        SingleHeight = 0,
+        ProportionalHeight = 1,
+        FixedHeight = 2,
+        AtLeastHeight = 3,
+        LineDistanceHeight = 4
+    };
+
     QTextBlockFormat();
 
     bool isValid() const { return isBlockFormat(); }
@@ -568,6 +578,14 @@ public:
     inline int indent() const
     { return intProperty(BlockIndent); }
 
+    inline void setLineHeight(qreal height, int heightType)
+    { setProperty(LineHeight, height); setProperty(LineHeightType, heightType); }
+    inline qreal lineHeight(qreal scriptLineHeight, qreal scaling) const;
+    inline qreal lineHeight() const
+    { return doubleProperty(LineHeight); }
+    inline int lineHeightType() const
+    { return intProperty(LineHeightType); }
+
     inline void setNonBreakableLines(bool b)
     { setProperty(BlockNonBreakableLines, b); }
     inline bool nonBreakableLines() const
@@ -592,6 +610,23 @@ inline void QTextBlockFormat::setAlignment(Qt::Alignment aalignment)
 inline void QTextBlockFormat::setIndent(int aindent)
 { setProperty(BlockIndent, aindent); }
 
+inline qreal QTextBlockFormat::lineHeight(qreal scriptLineHeight, qreal scaling = 1.0) const
+{
+  switch(intProperty(LineHeightType)) {
+    case SingleHeight:
+      return(scriptLineHeight);
+    case ProportionalHeight:
+      return(scriptLineHeight * doubleProperty(LineHeight) / 100.0);
+    case FixedHeight:
+      return(doubleProperty(LineHeight) * scaling);
+    case AtLeastHeight:
+      return(qMax(scriptLineHeight, doubleProperty(LineHeight) * scaling));
+    case LineDistanceHeight:
+      return(scriptLineHeight + doubleProperty(LineHeight) * scaling);
+  }
+  return(0);
+}
+
 class Q_GUI_EXPORT QTextListFormat : public QTextFormat
 {
 public:
diff --git a/src/gui/text/qtexthtmlparser.cpp b/src/gui/text/qtexthtmlparser.cpp
index 5b9ab90..769a509 100644
--- a/src/gui/text/qtexthtmlparser.cpp
+++ b/src/gui/text/qtexthtmlparser.cpp
@@ -1250,6 +1250,24 @@ void QTextHtmlParserNode::applyCssDeclarations(const QVector<QCss::Declaration>
         case QCss::QtBlockIndent:
             blockFormat.setIndent(decl.d->values.first().variant.toInt());
             break;
+       case QCss::LineHeight: {
+            qreal lineHeight;
+            if (decl.realValue(&lineHeight, "px"))
+                blockFormat.setLineHeight(lineHeight, QTextBlockFormat::FixedHeight);
+            else if (decl.realValue(&lineHeight, "al"))
+                blockFormat.setLineHeight(lineHeight, QTextBlockFormat::AtLeastHeight);
+            else if (decl.realValue(&lineHeight, "ld"))
+                blockFormat.setLineHeight(lineHeight, QTextBlockFormat::LineDistanceHeight);
+            else {
+                bool ok;
+                QString value = decl.d->values.first().toString();
+                lineHeight = value.toDouble(&ok);
+                if (ok)
+                    blockFormat.setLineHeight(lineHeight, QTextBlockFormat::ProportionalHeight);
+                else
+                    blockFormat.setLineHeight(0, QTextBlockFormat::SingleHeight);
+            }
+            break; }
         case QCss::TextIndent: {
             qreal indent = 0;
             if (decl.realValue(&indent, "px"))