Optimize calculating lines of range to redraw when whole range is on one line.

SciLineFromPosition is a binary search over the line indices but LineStart is
just indexing so is less expensive.
This code may limit performance when updating many positions.

1 files changed, 8 insertions, 4 deletions

diff --git a/src/Editor.cxx b/src/Editor.cxx
index 1c3437b7e..bd5a0b2c1 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -516,10 +516,14 @@ void Editor::RedrawSelMargin(Sci::Line line, bool allAfter) {
 }
 
 PRectangle Editor::RectangleFromRange(Range r, int overlap) {
-	const Sci::Line minLine = pcs->DisplayFromDoc(
-		pdoc->SciLineFromPosition(r.First()));
-	const Sci::Line maxLine = pcs->DisplayLastFromDoc(
-		pdoc->SciLineFromPosition(r.Last()));
+	const Sci::Line docLineFirst = pdoc->SciLineFromPosition(r.First());
+	const Sci::Line minLine = pcs->DisplayFromDoc(docLineFirst);
+	Sci::Line docLineLast = docLineFirst;	// Common case where range is wholly in one document line
+	if (r.Last() >= pdoc->LineStart(docLineFirst + 1)) {
+		// Range covers multiple lines so need last line
+		docLineLast = pdoc->SciLineFromPosition(r.Last());
+	}
+	const Sci::Line maxLine = pcs->DisplayLastFromDoc(docLineLast);
 	const PRectangle rcClientDrawing = GetClientDrawingRectangle();
 	PRectangle rc;
 	const int leftTextOverlap = ((xOffset == 0) && (vs.leftMarginWidth > 0)) ? 1 : 0;