TextEditor: handle syntax highlight in batches

Use an elapsed timer in the syntax highlighter to periodically return
from the highlight and push a continue highlight to the end of the event
loop.
This allows the user to interact with the editor in between those
batches. If the user modifies the document in between highlighting
batches, the area that still needs a rehighlight is increased if needed.

This also reverts 62ea85ee6ad15c8e4d9cb5e35b1f10bee3c49ac7 and the
related changes.

Task-number: QTCREATORBUG-28727
Change-Id: I7c394dbdff658330bb72f3b68b9928980947db75
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/plugins/glsleditor/glslhighlighter.cpp b/src/plugins/glsleditor/glslhighlighter.cpp
index eae8419a04..a6da1d6221 100644
--- a/src/plugins/glsleditor/glslhighlighter.cpp
+++ b/src/plugins/glsleditor/glslhighlighter.cpp
@@ -190,7 +190,8 @@ void GlslHighlighter::highlightBlock(const QString &text)
 
     // if the block is ifdefed out, we only store the parentheses, but
     // do not adjust the brace depth.
-    if (TextDocumentLayout::ifdefedOut(currentBlock())) {
+    if (TextBlockUserData *userData = TextDocumentLayout::textUserData(currentBlock());
+            userData && userData->ifdefedOut()) {
         braceDepth = initialBraceDepth;
         foldingIndent = initialBraceDepth;
     }