QSyntaxHighlighter: cancel delayed highlight if done manually

It was an implicit effect before which stopped working after
dec7961709c90f6977d2447f7fa6c6625af41cb2. Reintroduce it as some
projects used this side-effect as a way to abort the initial
highlighting.

Change-Id: I5340ee9882a242bc8b5f7f843f1cfe793a65d357
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@qt.io>

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/auto/gui/text/qsyntaxhighlighter/tst_qsyntaxhighlighter.cpp b/tests/auto/gui/text/qsyntaxhighlighter/tst_qsyntaxhighlighter.cpp
index 9d6ce78b24..c683ecd424 100644
--- a/tests/auto/gui/text/qsyntaxhighlighter/tst_qsyntaxhighlighter.cpp
+++ b/tests/auto/gui/text/qsyntaxhighlighter/tst_qsyntaxhighlighter.cpp
@@ -82,6 +82,7 @@ private slots:
     void preservePreeditArea();
     void task108530();
     void avoidUnnecessaryRehighlight();
+    void avoidUnnecessaryDelayedRehighlight();
     void noContentsChangedDuringHighlight();
     void rehighlight();
     void rehighlightBlock();
@@ -478,6 +479,24 @@ void tst_QSyntaxHighlighter::avoidUnnecessaryRehighlight()
     QTRY_VERIFY(!hl->highlighted);
 }
 
+void tst_QSyntaxHighlighter::avoidUnnecessaryDelayedRehighlight()
+{
+    // Having text in the document before creating the highlighter starts the delayed rehighlight
+    cursor.insertText("Hello World");
+
+    TestHighlighter *hl = new TestHighlighter(doc);
+    QVERIFY(!hl->highlighted);
+
+    hl->rehighlight();
+    QVERIFY(hl->highlighted);
+
+    hl->highlighted = false;
+    // Process events, including delayed rehighlight emission
+    QCoreApplication::processEvents();
+    // Should be cancelled and no extra rehighlight should be done
+    QVERIFY(!hl->highlighted);
+}
+
 void tst_QSyntaxHighlighter::noContentsChangedDuringHighlight()
 {
     QVector<QTextLayout::FormatRange> formats;