From 5cd4bad136878af59d368b1749a76b9cbbd246ec Mon Sep 17 00:00:00 2001
From: Richard Moe Gustavsen <richard.gustavsen@nokia.com>
Date: Mon, 7 Dec 2009 15:02:01 +0100
Subject: Fix performance issue with live resize

Calling [NSView addTrackingArea] is slow. So doing this for
views that are not even visible on screen is unnecesary. This
patch will greatly improve the speed for some (perhaps extreme)
cases.

Task-number: QT-1610
Reviewed-by: MortenS
---
 src/gui/kernel/qcocoaview_mac.mm | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/gui/kernel/qcocoaview_mac.mm b/src/gui/kernel/qcocoaview_mac.mm
index 212684b..1039a75 100644
--- a/src/gui/kernel/qcocoaview_mac.mm
+++ b/src/gui/kernel/qcocoaview_mac.mm
@@ -555,6 +555,10 @@ extern "C" {
 
 - (void)updateTrackingAreas
 {
+    // [NSView addTrackingArea] is slow, so bail out early if we can:
+    if (NSIsEmptyRect([self visibleRect]))
+        return;
+
     QMacCocoaAutoReleasePool pool;
     if (NSArray *trackingArray = [self trackingAreas]) {
         NSUInteger size = [trackingArray count];
-- 
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