# HG changeset patch
# User Chris Cannam
# Date 1556718051 -3600
# Node ID ce5f80a7c697a6044f7228a5b788a88c4b939bf1
# Parent  4b7fc925a5ce7c6fc28b9fdb8393e0ff7b575018
Don't discard large wheel deltas; just clamp them

diff -r 4b7fc925a5ce -r ce5f80a7c697 view/Pane.cpp
--- a/view/Pane.cpp	Wed May 01 11:46:09 2019 +0100
+++ b/view/Pane.cpp	Wed May 01 14:40:51 2019 +0100
@@ -2298,11 +2298,19 @@
         // Coarse wheel information (or vertical zoom, which is
         // necessarily coarse itself)
 
-        // Sometimes on Linux we're seeing absurdly extreme angles on
-        // the first wheel event -- discard those entirely
-        if (abs(m_pendingWheelAngle) >= 600) {
-            m_pendingWheelAngle = 0;
-            return;
+        // Sometimes on Linux we're seeing very extreme angles on the
+        // first wheel event. They could be spurious, or they could be
+        // a result of the user frantically wheeling away while the
+        // pane was unresponsive for some reason. We don't want to
+        // discard them, as that makes the application feel even less
+        // responsive, but if we take them literally we risk changing
+        // the view so radically that the user won't recognise what
+        // has happened. Clamp them instead.
+        if (m_pendingWheelAngle > 600) {
+            m_pendingWheelAngle = 600;
+        }
+        if (m_pendingWheelAngle < -600) {
+            m_pendingWheelAngle = -600;
         }
 
         while (abs(m_pendingWheelAngle) >= 120) {