From d6996452e5bfd80673f47f8e78c72c42dd7f76a2 Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Mon, 13 Aug 2018 14:12:45 -0700
Subject: [PATCH] Make sure cairo transform accounts for frame center

---
 camera/camera.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/camera/camera.py b/camera/camera.py
index 701dd64f..03e2b658 100644
--- a/camera/camera.py
+++ b/camera/camera.py
@@ -301,6 +301,7 @@ class Camera(object):
         ph = self.get_pixel_height()
         fw = self.get_frame_width()
         fh = self.get_frame_height()
+        fc = self.get_frame_center()
         surface = cairo.ImageSurface.create_for_data(
             pixel_array,
             cairo.FORMAT_ARGB32,
@@ -311,7 +312,8 @@ class Camera(object):
         ctx.set_matrix(cairo.Matrix(
             fdiv(pw, fw), 0,
             0, -fdiv(ph, fh),
-            pw / 2, ph / 2,
+            (pw / 2) + fc[0] * fdiv(pw, fw),
+            (ph / 2) + fc[1] * fdiv(ph, fh),
         ))
         self.cache_cairo_context(pixel_array, ctx)
         return ctx