From e2f312f8f0495ed30ee64b6078f2749158c58325 Mon Sep 17 00:00:00 2001
From: Stefan Schimanski <sts@lyx.org>
Date: Sat, 15 Nov 2008 18:17:20 +0000
Subject: [PATCH] * save one redraw on each change of the scrollbar.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@27471 a592a061-630c-0410-9148-cb99ea01b6c8
---
 src/BufferView.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/BufferView.cpp b/src/BufferView.cpp
index 0bb341ac30..8d8c7e6975 100644
--- a/src/BufferView.cpp
+++ b/src/BufferView.cpp
@@ -549,9 +549,14 @@ docstring BufferView::contextMenu(int x, int y) const
 void BufferView::scrollDocView(int value)
 {
 	int const offset = value - d->scrollbarParameters_.position;
+
+	// No scrolling at all? No need to redraw anything
+	if (offset == 0)
+		return;
+
 	// If the offset is less than 2 screen height, prefer to scroll instead.
 	if (abs(offset) <= 2 * height_) {
-		scroll(offset);
+		d->anchor_ypos_ -= offset;
 		updateMetrics();
 		buffer_.changed();
 		return;
@@ -2192,6 +2197,7 @@ void BufferView::draw(frontend::Painter & pain)
 	if (height_ == 0 || width_ == 0)
 		return;
 	LYXERR(Debug::PAINTING, "\t\t*** START DRAWING ***");
+
 	Text & text = buffer_.text();
 	TextMetrics const & tm = d->text_metrics_[&text];
 	int const y = tm.first().second->position();