Optimize QQuickTextEdit for larger documents.

The rationale is to not end up re-processing the whole document on each update
Since we know where the editing takes place, we can break down the text edit's
contents in several text nodes and only re-create the affected text nodes upon
editing.

This requires ripping out the SelectionEngine helper class from QQuickTextNode
so that QQuickTextEdit can tap into its functionality directly.

A positive side-effect of this exercise is that it should be much harder to
to come across GlyphNodes packing more than 16300 glyphs or so.

Task-number: QTBUG-29596
Change-Id: Id29b0709baa43f5b29c44ab02398ba996be3e28a
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/src/quick/items/qquicktextedit_p.h b/src/quick/items/qquicktextedit_p.h
index 8a2d9b1e92..4e09eafcac 100644
--- a/src/quick/items/qquicktextedit_p.h
+++ b/src/quick/items/qquicktextedit_p.h
@@ -313,17 +313,19 @@ public Q_SLOTS:
 
 private Q_SLOTS:
     void q_textChanged();
-    void updateSelectionMarkers();
+    void q_contentsChange(int, int, int);
+    void updateSelection();
     void moveCursorDelegate();
     void createCursor();
     void q_canPasteChanged();
-    void updateDocument();
+    void updateWholeDocument();
     void updateCursor();
     void q_updateAlignment();
     void updateSize();
     void triggerPreprocess();
 
 private:
+    void markDirtyNodesForRange(int start, int end, int charDelta);
     void updateTotalLines();
 
 protected: