Fixed overlay selections

1. allow empty overlay selections
2. make it possible to bind a selection to a specified length

src/plugins/texteditor/basetexteditor.cpp

@@ -4219,7 +4219,7 @@ void BaseTextEditor::setExtraSelections(ExtraSelectionKind kind, const QList<QTe
     if (kind == CodeSemanticsSelection) {
         d->m_overlay->clear();
         foreach (const QTextEdit::ExtraSelection &selection, d->m_extraSelections[kind]) {
-            d->m_overlay->addOverlaySelection(selection.cursor, selection.format.background().color());
+            d->m_overlay->addOverlaySelection(selection.cursor, selection.format.background().color(), true);
         }
         d->m_overlay->setVisible(!d->m_overlay->isEmpty());
 

src/plugins/texteditor/texteditoroverlay.cpp

@@ -36,9 +36,9 @@ void TextEditorOverlay::clear()
     update();
 }
 
-void TextEditorOverlay::addOverlaySelection(int begin, int end, const QColor &color)
+void TextEditorOverlay::addOverlaySelection(int begin, int end, const QColor &color, bool lockSize)
 {
-    if (end <= begin)
+    if (end < begin)
         return;
 
     QTextDocument *document = m_editor->document();
@@ -52,16 +52,17 @@ void TextEditorOverlay::addOverlaySelection(int begin, int end, const QColor &co
     selection.m_cursor_end = QTextCursor(document);
     selection.m_cursor_end.setPosition(end);
 
+    if (lockSize)
+        selection.m_fixedLength = (end - begin);
+
     m_selections += selection;
     update();
 }
 
 
-void TextEditorOverlay::addOverlaySelection(const QTextCursor &cursor, const QColor &color)
+void TextEditorOverlay::addOverlaySelection(const QTextCursor &cursor, const QColor &color, bool lockSize)
 {
-    if (!cursor.hasSelection())
-        return;
-    addOverlaySelection(cursor.selectionStart(), cursor.selectionEnd(), color);
+    addOverlaySelection(cursor.selectionStart(), cursor.selectionEnd(), color, lockSize);
 }
 
 QRect TextEditorOverlay::rect() const
@@ -243,6 +244,11 @@ void TextEditorOverlay::paint(QPainter *painter, const QRect &clip)
     Q_UNUSED(clip);
     for (int i = 0; i < m_selections.size(); ++i) {
         const OverlaySelection &selection = m_selections.at(i);
+        if (selection.m_fixedLength >= 0
+            && selection.m_cursor_end.position() - selection.m_cursor_begin.position()
+            != selection.m_fixedLength)
+            continue;
+
         paintSelection(painter,
                        selection.m_cursor_begin,
                        selection.m_cursor_end,

src/plugins/texteditor/texteditoroverlay.h

@@ -8,9 +8,11 @@ namespace TextEditor {
 namespace Internal {
 
 struct TEXTEDITOR_EXPORT OverlaySelection {
+    OverlaySelection():m_fixedLength(-1){}
     QTextCursor m_cursor_begin;
     QTextCursor m_cursor_end;
     QColor m_color;
+    int m_fixedLength;
 };
 
 class TEXTEDITOR_EXPORT TextEditorOverlay : public QObject
@@ -38,8 +40,8 @@ public:
     void update();
 
     void clear();
-    void addOverlaySelection(const QTextCursor &cursor, const QColor &color);
-    void addOverlaySelection(int begin, int end, const QColor &color);
+    void addOverlaySelection(const QTextCursor &cursor, const QColor &color, bool lockSize = false);
+    void addOverlaySelection(int begin, int end, const QColor &color, bool lockSize = false);
 
     inline bool isEmpty() const { return m_selections.isEmpty(); }