From e407f6e79aea4398d9d5626ca32655162ef72951 Mon Sep 17 00:00:00 2001
From: Ingo <heckflosse@i-weyrich.de>
Date: Mon, 18 May 2015 21:39:12 +0200
Subject: [PATCH] image processing 1000 times slower if image in portrait
 orientation, Issue 2783

---
 rtgui/previewhandler.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rtgui/previewhandler.cc b/rtgui/previewhandler.cc
index 0452db0c2..42b48b879 100644
--- a/rtgui/previewhandler.cc
+++ b/rtgui/previewhandler.cc
@@ -206,8 +206,8 @@ Glib::RefPtr<Gdk::Pixbuf> PreviewHandler::getRoughImage (int desiredW, int desir
     Glib::RefPtr<Gdk::Pixbuf> resPixbuf;
 
     if (previewImg) {
-        double zoom1 = (double)desiredW / previewImg->get_width();
-        double zoom2 = (double)desiredH / previewImg->get_height();
+        double zoom1 = (double)max(desiredW,20) / previewImg->get_width();  // too small values lead to extremely increased processing time in scale function, Issue 2783
+        double zoom2 = (double)max(desiredH,20) / previewImg->get_height(); // ""
         double zoom = zoom1<zoom2 ? zoom1 : zoom2;
         
         resPixbuf = Gdk::Pixbuf::create (Gdk::COLORSPACE_RGB, false, 8, image->getWidth()*zoom, image->getHeight()*zoom);