From 7b4ff5d82328911017efd70fbb0e2134dc9ab7a6 Mon Sep 17 00:00:00 2001
From: Matthias Koefferlein <matthias@klayout.de>
Date: Sat, 6 May 2023 21:40:36 +0200
Subject: [PATCH] Zoom in/out menu functions now use mouse position for zoom
 center instead of center (if mouse is inside window)

---
 src/laybasic/laybasic/layLayoutViewBase.cc | 17 +++++++++++++++--
 src/laybasic/laybasic/layLayoutViewBase.h  |  2 ++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/laybasic/laybasic/layLayoutViewBase.cc b/src/laybasic/laybasic/layLayoutViewBase.cc
index b59495ef3..9d9e58598 100644
--- a/src/laybasic/laybasic/layLayoutViewBase.cc
+++ b/src/laybasic/laybasic/layLayoutViewBase.cc
@@ -3852,13 +3852,26 @@ LayoutViewBase::pan_center (const db::DPoint &p)
 void
 LayoutViewBase::zoom_in ()
 {
-  shift_window (zoom_factor, 0.0, 0.0);
+  zoom_by (zoom_factor);
 }
 
 void
 LayoutViewBase::zoom_out ()
 {
-  shift_window (1.0 / zoom_factor, 0.0, 0.0);
+  zoom_by (1.0 / zoom_factor);
+}
+
+void
+LayoutViewBase::zoom_by (double f)
+{
+  db::DBox b = mp_canvas->viewport ().box ();
+
+  db::DPoint c = b.center ();
+  if (mp_canvas->mouse_in_window ()) {
+    c = mp_canvas->mouse_position_um ();
+  }
+
+  zoom_box ((b.moved (db::DPoint () - c) * f).moved (c - db::DPoint ()));
 }
 
 void
diff --git a/src/laybasic/laybasic/layLayoutViewBase.h b/src/laybasic/laybasic/layLayoutViewBase.h
index 0f8281458..d3328384b 100644
--- a/src/laybasic/laybasic/layLayoutViewBase.h
+++ b/src/laybasic/laybasic/layLayoutViewBase.h
@@ -2881,6 +2881,8 @@ private:
   bool has_max_hier () const;
   int max_hier_level () const;
 
+  void zoom_by (double f);
+
   void update_event_handlers ();
   void viewport_changed ();
   void cellview_changed (unsigned int index);