Add flag for showing document terminator in text

In 208496091d, the behavior of
QTextOption::ShowLineAndParagraphSeparators was changed to also
include a section symbol at the end of the document. This was
an unnecessary behavioral change. Instead we add a separate flag
for this marker.

[ChangeLog][QtGui][Text] Added QTextOption::ShowDocumentTerminator
flag.

Task-number: QTBUG-52048
Change-Id: I2f6f7e5c9c894f46525682f2c6520a7003fa09bc
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

src/gui/text/qtextengine.cpp

@@ -1569,8 +1569,12 @@ void QTextEngine::validate() const
     layoutData = new LayoutData();
     if (block.docHandle()) {
         layoutData->string = block.text();
-        if (option.flags() & QTextOption::ShowLineAndParagraphSeparators)
-            layoutData->string += QLatin1Char(block.next().isValid() ? 0xb6 : 0xA7);
+        if (block.next().isValid()) {
+            if (option.flags() & QTextOption::ShowLineAndParagraphSeparators)
+                layoutData->string += QChar(0xb6);
+        } else if (option.flags() & QTextOption::ShowDocumentTerminator) {
+            layoutData->string += QChar(0xA7);
+        }
     } else {
         layoutData->string = text;
     }

src/gui/text/qtextoption.cpp

@@ -309,6 +309,8 @@ QList<QTextOption::Tab> QTextOption::tabs() const
                                this width is excluded.
   \value ShowTabsAndSpaces Visualize spaces with little dots, and tabs with little arrows.
   \value ShowLineAndParagraphSeparators Visualize line and paragraph separators with appropriate symbol characters.
+  \value ShowDocumentTerminator Visualize the end of the document with a section sign. This enum value was added
+            in Qt 5.7.
   \value AddSpaceForLineAndParagraphSeparators While determining the line-break positions take into account the
             space added for drawing a separator character.
   \value SuppressColors Suppress all color changes in the character formats (except the main selection).

src/gui/text/qtextoption.h

@@ -109,6 +109,7 @@ public:
         ShowLineAndParagraphSeparators = 0x2,
         AddSpaceForLineAndParagraphSeparators = 0x4,
         SuppressColors = 0x8,
+        ShowDocumentTerminator = 0x10,
         IncludeTrailingSpaces = 0x80000000
     };
     Q_DECLARE_FLAGS(Flags, Flag)