Stop fighting over which mouse cursor to show on text editor

The BaseTextEditor was unconditionally setting the mouse cursor on each
mouse move event, after which the CPPEditor would set it as well when
the mouse was above a link. This caused some mouse cursor flickering, so
now the cursor is only set when it's supposed to change.

Also fixed an issue where the link wasn't removed when leaving the text
editor with the mouse while Ctrl was pressed.

src/plugins/cppeditor/cppeditor.cpp

@@ -183,13 +183,13 @@ CPPEditorEditable::CPPEditorEditable(CPPEditor *editor)
 
 CPPEditor::CPPEditor(QWidget *parent)
     : TextEditor::BaseTextEditor(parent)
+    , m_showingLink(false)
 {
     setParenthesesMatchingEnabled(true);
     setMarksVisible(true);
     setCodeFoldingSupported(true);
     setCodeFoldingVisible(true);
     baseTextDocument()->setSyntaxHighlighter(new CppHighlighter);
-//    new QShortcut(QKeySequence("Ctrl+Alt+M"), this, SLOT(foo()), 0, Qt::WidgetShortcut);
 
 #ifdef WITH_TOKEN_MOVE_POSITION
     new QShortcut(QKeySequence::MoveToPreviousWord, this, SLOT(moveToPreviousToken()),
@@ -808,8 +808,7 @@ void CPPEditor::contextMenuEvent(QContextMenuEvent *e)
 
 void CPPEditor::mouseMoveEvent(QMouseEvent *e)
 {
-    bool hasDestination = false;
-    Qt::CursorShape cursorShape;
+    bool linkFound = false;
 
     if (e->modifiers() & Qt::ControlModifier) {
         // Link emulation behaviour for 'go to definition'
@@ -826,30 +825,15 @@ void CPPEditor::mouseMoveEvent(QMouseEvent *e)
         const Link link = findLinkAt(cursor, false);
 
         if (onText && !link.fileName.isEmpty()) {
-            QTextEdit::ExtraSelection sel;
-            sel.cursor = cursor;
-            if (link.pos >= 0) {
-                sel.cursor.setPosition(link.pos);
-                sel.cursor.setPosition(link.pos + link.length, QTextCursor::KeepAnchor);
-            } else {
-                sel.cursor.select(QTextCursor::WordUnderCursor);
-            }
-            sel.format = m_linkFormat;
-            sel.format.setFontUnderline(true);
-            setExtraSelections(OtherSelection, QList<QTextEdit::ExtraSelection>() << sel);
-            hasDestination = true;
-            cursorShape = Qt::PointingHandCursor;
+            showLink(link);
+            linkFound = true;
         }
     }
 
-    if (!hasDestination) {
-        setExtraSelections(OtherSelection, QList<QTextEdit::ExtraSelection>());
-        cursorShape = Qt::IBeamCursor;
-    }
+    if (!linkFound)
+        clearLink();
 
     TextEditor::BaseTextEditor::mouseMoveEvent(e);
-
-    viewport()->setCursor(cursorShape);
 }
 
 void CPPEditor::mouseReleaseEvent(QMouseEvent *e)
@@ -859,8 +843,7 @@ void CPPEditor::mouseReleaseEvent(QMouseEvent *e)
 
         const QTextCursor cursor = cursorForPosition(e->pos());
         if (openCppEditorAt(findLinkAt(cursor))) {
-            setExtraSelections(OtherSelection, QList<QTextEdit::ExtraSelection>());
-            viewport()->setCursor(Qt::IBeamCursor);
+            clearLink();
             e->accept();
             return;
         }
@@ -869,17 +852,44 @@ void CPPEditor::mouseReleaseEvent(QMouseEvent *e)
     TextEditor::BaseTextEditor::mouseReleaseEvent(e);
 }
 
+void CPPEditor::leaveEvent(QEvent *e)
+{
+    clearLink();
+    TextEditor::BaseTextEditor::leaveEvent(e);
+}
+
 void CPPEditor::keyReleaseEvent(QKeyEvent *e)
 {
     // Clear link emulation when Ctrl is released
-    if (e->key() == Qt::Key_Control) {
-        setExtraSelections(OtherSelection, QList<QTextEdit::ExtraSelection>());
-        viewport()->setCursor(Qt::IBeamCursor);
-    }
+    if (e->key() == Qt::Key_Control)
+        clearLink();
 
     TextEditor::BaseTextEditor::keyReleaseEvent(e);
 }
 
+void CPPEditor::showLink(const Link &link)
+{
+    QTextEdit::ExtraSelection sel;
+    sel.cursor = textCursor();
+    sel.cursor.setPosition(link.pos);
+    sel.cursor.setPosition(link.pos + link.length, QTextCursor::KeepAnchor);
+    sel.format = m_linkFormat;
+    sel.format.setFontUnderline(true);
+    setExtraSelections(OtherSelection, QList<QTextEdit::ExtraSelection>() << sel);
+    viewport()->setCursor(Qt::PointingHandCursor);
+    m_showingLink = true;
+}
+
+void CPPEditor::clearLink()
+{
+    if (!m_showingLink)
+        return;
+
+    setExtraSelections(OtherSelection, QList<QTextEdit::ExtraSelection>());
+    viewport()->setCursor(Qt::IBeamCursor);
+    m_showingLink = false;
+}
+
 QList<int> CPPEditorEditable::context() const
 {
     return m_context;

src/plugins/cppeditor/cppeditor.h

@@ -99,6 +99,7 @@ protected:
     void contextMenuEvent(QContextMenuEvent *);
     void mouseMoveEvent(QMouseEvent *);
     void mouseReleaseEvent(QMouseEvent *);
+    void leaveEvent(QEvent *);
     void keyReleaseEvent(QKeyEvent *);
 
     TextEditor::BaseTextEditorEditable *createEditableInterface();
@@ -148,6 +149,10 @@ private:
         int column;        // Target column
     };
 
+    void showLink(const Link &);
+    void clearLink();
+    bool m_showingLink;
+
     Link findLinkAt(const QTextCursor &, bool lookupDefinition = true);
     static Link linkToSymbol(CPlusPlus::Symbol *symbol);
     bool openCppEditorAt(const Link &);

src/plugins/texteditor/basetexteditor.cpp

@@ -1255,6 +1255,7 @@ BaseTextEditorPrivate::BaseTextEditorPrivate()
     m_document(new BaseTextDocument()),
     m_parenthesesMatchingEnabled(false),
     m_extraArea(0),
+    m_mouseOnCollapsedMarker(false),
     m_marksVisible(false),
     m_codeFoldingVisible(false),
     m_codeFoldingSupported(false),
@@ -2421,22 +2422,30 @@ void BaseTextEditorPrivate::clearVisibleCollapsedBlock()
 void BaseTextEditor::mouseMoveEvent(QMouseEvent *e)
 {
     d->m_lastEventWasBlockSelectionEvent = (e->modifiers() & Qt::AltModifier);
-    if (e->buttons() == 0) {
-        QTextBlock collapsedBlock = collapsedBlockAt(e->pos());
-        int blockNumber = collapsedBlock.next().blockNumber();
+    if (e->buttons() == Qt::NoButton) {
+        const QTextBlock collapsedBlock = collapsedBlockAt(e->pos());
+        const int blockNumber = collapsedBlock.next().blockNumber();
         if (blockNumber < 0) {
             d->clearVisibleCollapsedBlock();
         } else if (blockNumber != d->visibleCollapsedBlockNumber) {
             d->suggestedVisibleCollapsedBlockNumber = blockNumber;
             d->collapsedBlockTimer.start(40, this);
         }
-        viewport()->setCursor(collapsedBlock.isValid() ? Qt::PointingHandCursor : Qt::IBeamCursor);
+
+        // Update the mouse cursor
+        if (collapsedBlock.isValid() && !d->m_mouseOnCollapsedMarker) {
+            d->m_mouseOnCollapsedMarker = true;
+            viewport()->setCursor(Qt::PointingHandCursor);
+        } else if (!collapsedBlock.isValid() && d->m_mouseOnCollapsedMarker) {
+            d->m_mouseOnCollapsedMarker = false;
+            viewport()->setCursor(Qt::IBeamCursor);
+        }
     } else {
         QPlainTextEdit::mouseMoveEvent(e);
     }
     if (d->m_lastEventWasBlockSelectionEvent && d->m_inBlockSelectionMode) {
         if (textCursor().atBlockEnd()) {
-            d->m_blockSelectionExtraX = qMax(0, e->pos().x() - cursorRect().center().x()) / fontMetrics().width(QLatin1Char('x'));
+            d->m_blockSelectionExtraX = qMax(0, e->pos().x() - cursorRect().center().x()) / fontMetrics().averageCharWidth();
         } else {
             d->m_blockSelectionExtraX = 0;
         }

src/plugins/texteditor/basetexteditor_p.h

@@ -175,6 +175,7 @@ public:
     int visibleCollapsedBlockNumber;
     int suggestedVisibleCollapsedBlockNumber;
     void clearVisibleCollapsedBlock();
+    bool m_mouseOnCollapsedMarker;
 
     QBasicTimer autoScrollTimer;
     void updateMarksLineNumber();