QTextDocument: add css-styling of table cell borders to HTML import/export

Supported style attributes:

<table>
style: supports "border-collapse: collapse" and "border-color".
border: width of the outer border
bordercolor: basic color for all borders

<tr>
style: not supported

<td>/</th>
style: supports the "border", "border-[top|left|bottom|right]]"
       shorthand styles and the "border-width", "border-color"
       and "border-style" (and the top/left/bottom/right variants)
       attributes

<table border=1 style="border-collapse: collapse"> will render
a simple 1px table grid.

Notes:

The QTextDocument table model is much simpler than the HTML table model.
It basically only has <table> and <td> support. So the HTML parser is
forced to map markup and styling to the QTextDocument model which
is not without loss.

In other words: While QTextDocument -> HTML -> QTextDocument should
preserve the QTextDocument structure, HTML -> QTextDocument -> HTML
does not preserve the HTML DOM at all.

So for now the HTML importer and writer only support border styles on
the <td> and <th> nodes. In future updates, the HTML parser might be
enhanced to map <tr> and <table> CSS styles to the cells.

Change-Id: If9e7312fa6cbf270cf8f7b3c72ba1fa094107517
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 51 insertions, 29 deletions

diff --git a/src/gui/text/qtextdocument.cpp b/src/gui/text/qtextdocument.cpp
index dc34a96918..c80617f929 100644
--- a/src/gui/text/qtextdocument.cpp
+++ b/src/gui/text/qtextdocument.cpp
@@ -2593,51 +2593,43 @@ void QTextHtmlExporter::emitFloatStyle(QTextFrameFormat::Position pos, StyleMode
         html += QLatin1Char('\"');
 }
 
-void QTextHtmlExporter::emitBorderStyle(QTextFrameFormat::BorderStyle style)
+static QLatin1String richtextBorderStyleToHtmlBorderStyle(QTextFrameFormat::BorderStyle style)
 {
-    Q_ASSERT(style <= QTextFrameFormat::BorderStyle_Outset);
-
-    html += QLatin1String(" border-style:");
-
     switch (style) {
     case QTextFrameFormat::BorderStyle_None:
-        html += QLatin1String("none");
-        break;
+        return QLatin1String("none");
     case QTextFrameFormat::BorderStyle_Dotted:
-        html += QLatin1String("dotted");
-        break;
+        return QLatin1String("dotted");
     case QTextFrameFormat::BorderStyle_Dashed:
-        html += QLatin1String("dashed");
-        break;
+        return QLatin1String("dashed");
     case QTextFrameFormat::BorderStyle_Solid:
-        html += QLatin1String("solid");
-        break;
+        return QLatin1String("solid");
     case QTextFrameFormat::BorderStyle_Double:
-        html += QLatin1String("double");
-        break;
+        return QLatin1String("double");
     case QTextFrameFormat::BorderStyle_DotDash:
-        html += QLatin1String("dot-dash");
-        break;
+        return QLatin1String("dot-dash");
     case QTextFrameFormat::BorderStyle_DotDotDash:
-        html += QLatin1String("dot-dot-dash");
-        break;
+        return QLatin1String("dot-dot-dash");
     case QTextFrameFormat::BorderStyle_Groove:
-        html += QLatin1String("groove");
-        break;
+        return QLatin1String("groove");
     case QTextFrameFormat::BorderStyle_Ridge:
-        html += QLatin1String("ridge");
-        break;
+        return QLatin1String("ridge");
     case QTextFrameFormat::BorderStyle_Inset:
-        html += QLatin1String("inset");
-        break;
+        return QLatin1String("inset");
     case QTextFrameFormat::BorderStyle_Outset:
-        html += QLatin1String("outset");
-        break;
+        return QLatin1String("outset");
     default:
-        Q_ASSERT(false);
-        break;
+        Q_UNREACHABLE();
     };
+    return QLatin1String("");
+}
+
+void QTextHtmlExporter::emitBorderStyle(QTextFrameFormat::BorderStyle style)
+{
+    Q_ASSERT(style <= QTextFrameFormat::BorderStyle_Outset);
 
+    html += QLatin1String(" border-style:");
+    html += richtextBorderStyleToHtmlBorderStyle(style);
     html += QLatin1Char(';');
 }
 
@@ -3204,6 +3196,33 @@ void QTextHtmlExporter::emitTable(const QTextTable *table)
             if (cellFormat.hasProperty(QTextFormat::TableCellBottomPadding))
                 styleString += QLatin1String(" padding-bottom:") + QString::number(cellFormat.bottomPadding()) + QLatin1Char(';');
 
+            if (cellFormat.hasProperty(QTextFormat::TableCellTopBorder))
+                styleString += QLatin1String(" border-top:") + QString::number(cellFormat.topBorder()) + QLatin1String("px;");
+            if (cellFormat.hasProperty(QTextFormat::TableCellRightBorder))
+                styleString += QLatin1String(" border-right:") + QString::number(cellFormat.rightBorder()) + QLatin1String("px;");
+            if (cellFormat.hasProperty(QTextFormat::TableCellBottomBorder))
+                styleString += QLatin1String(" border-bottom:") + QString::number(cellFormat.bottomBorder()) + QLatin1String("px;");
+            if (cellFormat.hasProperty(QTextFormat::TableCellLeftBorder))
+                styleString += QLatin1String(" border-left:") + QString::number(cellFormat.leftBorder()) + QLatin1String("px;");
+
+            if (cellFormat.hasProperty(QTextFormat::TableCellTopBorderBrush))
+                styleString += QLatin1String(" border-top-color:") + cellFormat.topBorderBrush().color().name() + QLatin1Char(';');
+            if (cellFormat.hasProperty(QTextFormat::TableCellRightBorderBrush))
+                styleString += QLatin1String(" border-right-color:") + cellFormat.rightBorderBrush().color().name() + QLatin1Char(';');
+            if (cellFormat.hasProperty(QTextFormat::TableCellBottomBorderBrush))
+                styleString += QLatin1String(" border-bottom-color:") + cellFormat.bottomBorderBrush().color().name() + QLatin1Char(';');
+            if (cellFormat.hasProperty(QTextFormat::TableCellLeftBorderBrush))
+                styleString += QLatin1String(" border-left-color:") + cellFormat.leftBorderBrush().color().name() + QLatin1Char(';');
+
+            if (cellFormat.hasProperty(QTextFormat::TableCellTopBorderStyle))
+                styleString += QLatin1String(" border-top-style:") + richtextBorderStyleToHtmlBorderStyle(cellFormat.topBorderStyle()) + QLatin1Char(';');
+            if (cellFormat.hasProperty(QTextFormat::TableCellRightBorderStyle))
+                styleString += QLatin1String(" border-right-style:") + richtextBorderStyleToHtmlBorderStyle(cellFormat.rightBorderStyle()) + QLatin1Char(';');
+            if (cellFormat.hasProperty(QTextFormat::TableCellBottomBorderStyle))
+                styleString += QLatin1String(" border-bottom-style:") + richtextBorderStyleToHtmlBorderStyle(cellFormat.bottomBorderStyle()) + QLatin1Char(';');
+            if (cellFormat.hasProperty(QTextFormat::TableCellLeftBorderStyle))
+                styleString += QLatin1String(" border-left-style:") + richtextBorderStyleToHtmlBorderStyle(cellFormat.leftBorderStyle()) + QLatin1Char(';');
+
             if (!styleString.isEmpty())
                 html += QLatin1String(" style=\"") + styleString + QLatin1Char('\"');
 
@@ -3310,6 +3329,9 @@ void QTextHtmlExporter::emitFrameStyle(const QTextFrameFormat &format, FrameType
                     QString::number(format.leftMargin()),
                     QString::number(format.rightMargin()));
 
+    if (format.property(QTextFormat::TableBorderCollapse).toBool())
+        html += QLatin1String(" border-collapse:collapse;");
+
     if (html.length() == originalHtmlLength) // nothing emitted?
         html.chop(styleAttribute.size());
     else