From dabac3c61fe7758ece565bf2805a0bee7a22f14b Mon Sep 17 00:00:00 2001
From: Abdelrazak Younes <younes@lyx.org>
Date: Tue, 5 Jan 2010 13:33:29 +0000
Subject: [PATCH] Asynchronous preview: cancel too close preview or update
 calls.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@32769 a592a061-630c-0410-9148-cb99ea01b6c8
---
 src/frontends/qt4/GuiView.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/frontends/qt4/GuiView.cpp b/src/frontends/qt4/GuiView.cpp
index 13cb0c02e3..221af91f79 100644
--- a/src/frontends/qt4/GuiView.cpp
+++ b/src/frontends/qt4/GuiView.cpp
@@ -274,8 +274,11 @@ struct GuiView::GuiViewPrivate
 #if (QT_VERSION >= 0x040400)
 	void setPreviewFuture(QFuture<docstring> const & f)
 	{
-		if (preview_watcher_.isRunning())
-			preview_watcher_.waitForFinished();
+		if (preview_watcher_.isRunning()) {
+			// we prefer to cancel this preview in order to keep a snappy
+			// interface.
+			return;
+		}
 		preview_watcher_.setFuture(f);
 	}
 #endif
-- 
2.39.2