From 4bec59f1751d9d1e302465b68cceffb8df93a7be Mon Sep 17 00:00:00 2001
From: "Christoph M. Becker" <cmbecker69@gmx.de>
Date: Mon, 6 Jan 2020 10:33:47 +0100
Subject: Fix #79068: gdTransformAffineCopy() changes interpolation method

We port
<https://github.com/libgd/libgd/commit/9088591eae437358ee5b929adf82865e37e3001e>.
---
 NEWS                            |   2 ++
 ext/gd/libgd/gd_interpolation.c |   2 +-
 ext/gd/tests/bug79068.phpt      |  21 +++++++++++++++++++++
 ext/gd/tests/bug79068.png       | Bin 0 -> 798 bytes
 4 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 ext/gd/tests/bug79068.phpt
 create mode 100644 ext/gd/tests/bug79068.png

diff --git a/NEWS b/NEWS
index bb7dd649db..08f0f5b2db 100644
--- a/NEWS
+++ b/NEWS
@@ -25,6 +25,8 @@ PHP                                                                        NEWS
   . Fixed bug #78923 (Artifacts when convoluting image with transparency).
     (wilson chen)
   . Fixed bug #79067 (gdTransformAffineCopy() may use unitialized values). (cmb)
+  . Fixed bug #79068 (gdTransformAffineCopy() changes interpolation method).
+    (cmb)
 
 - Libxml:
   . Fixed bug #79029 (Use After Free's in XMLReader / XMLWriter). (Laruence)
diff --git a/ext/gd/libgd/gd_interpolation.c b/ext/gd/libgd/gd_interpolation.c
index 489f3c9694..d723e652a8 100644
--- a/ext/gd/libgd/gd_interpolation.c
+++ b/ext/gd/libgd/gd_interpolation.c
@@ -2351,7 +2351,7 @@ int gdTransformAffineCopy(gdImagePtr dst,
 	gdPointF pt, src_pt;
 	gdRect bbox;
 	int end_x, end_y;
-	gdInterpolationMethod interpolation_id_bak = GD_DEFAULT;
+	gdInterpolationMethod interpolation_id_bak = src->interpolation_id;
 	interpolation_method interpolation_bak;
 
 	/* These methods use special implementations */
diff --git a/ext/gd/tests/bug79068.phpt b/ext/gd/tests/bug79068.phpt
new file mode 100644
index 0000000000..391424b119
--- /dev/null
+++ b/ext/gd/tests/bug79068.phpt
@@ -0,0 +1,21 @@
+--TEST--
+Bug #79068 (gdTransformAffineCopy() changes interpolation method)
+--SKIPIF--
+<?php
+if (!extension_loaded('gd')) die('skip gd extension not available');
+?>
+--FILE--
+<?php
+require_once __DIR__ . '/func.inc';
+
+$src = imagecreatetruecolor(100, 100);
+imagefilledrectangle($src, 0, 0, 99, 99, 0xffffff);
+imageline($src, 10, 10, 90, 90, 0x000000);
+imagesetinterpolation($src, IMG_BSPLINE);
+imageaffine($src, [1, 1, 1, 1, 1, 1]);
+$dst = imagerotate($src, 80, 0xffffff);
+
+test_image_equals_file(__DIR__ . '/bug79068.png', $dst);
+?>
+--EXPECT--
+The images are equal.
diff --git a/ext/gd/tests/bug79068.png b/ext/gd/tests/bug79068.png
new file mode 100644
index 0000000000..805edc1c56
Binary files /dev/null and b/ext/gd/tests/bug79068.png differ
-- 
cgit v1.2.1