From 6ba4b3bfdb1799d2426225192d11040032dc8619 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Mon, 17 Dec 2018 20:29:31 +0000
Subject: [PATCH] fix clipping with new mapim cods

we had the clip in the wrong place

see https://github.com/libvips/libvips/issues/1180
---
 libvips/resample/mapim.c         | 14 ++++++++------
 test/test-suite/test_resample.py |  6 ++----
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/libvips/resample/mapim.c b/libvips/resample/mapim.c
index b82960fa..b582b8ad 100644
--- a/libvips/resample/mapim.c
+++ b/libvips/resample/mapim.c
@@ -231,8 +231,8 @@ vips_mapim_region_minmax( VipsRegion *region, VipsRect *r, VipsRect *bounds )
 	TYPE * restrict p1 = (TYPE *) p; \
 	\
 	for( x = 0; x < r->width; x++ ) { \
-		TYPE px = p1[0] + window_offset; \
-		TYPE py = p1[1] + window_offset; \
+		TYPE px = p1[0]; \
+		TYPE py = p1[1]; \
 		\
 		if( px >= clip_width || \
 			py >= clip_height ) { \
@@ -240,7 +240,8 @@ vips_mapim_region_minmax( VipsRegion *region, VipsRect *r, VipsRect *bounds )
 				q[z] = 0; \
 		} \
 		else \
-			interpolate( mapim->interpolate, q, ir[0], px, py ); \
+			interpolate( mapim->interpolate, q, ir[0], \
+				px + window_offset, py + window_offset ); \
 		\
 		p1 += 2; \
 		q += ps; \
@@ -251,8 +252,8 @@ vips_mapim_region_minmax( VipsRegion *region, VipsRect *r, VipsRect *bounds )
 	TYPE * restrict p1 = (TYPE *) p; \
 	\
 	for( x = 0; x < r->width; x++ ) { \
-		TYPE px = p1[0] + window_offset; \
-		TYPE py = p1[1] + window_offset; \
+		TYPE px = p1[0]; \
+		TYPE py = p1[1]; \
 		\
 		if( px < 0 || \
 			px >= clip_width || \
@@ -262,7 +263,8 @@ vips_mapim_region_minmax( VipsRegion *region, VipsRect *r, VipsRect *bounds )
 				q[z] = 0; \
 		} \
 		else \
-			interpolate( mapim->interpolate, q, ir[0], px, py ); \
+			interpolate( mapim->interpolate, q, ir[0], \
+				px + window_offset, py + window_offset ); \
 		\
 		p1 += 2; \
 		q += ps; \
diff --git a/test/test-suite/test_resample.py b/test/test-suite/test_resample.py
index 1375718b..791a30c7 100644
--- a/test/test-suite/test_resample.py
+++ b/test/test-suite/test_resample.py
@@ -200,11 +200,9 @@ class TestResample:
 
         # this was a bug at one point, strangely, if executed with debug
         # enabled
-        mp = pyvips.Image.xyz(100, 100)
+        mp = pyvips.Image.xyz(im.width, im.height)
         interp = pyvips.Interpolate.new('bicubic')
-        assert im.mapim(mp, interpolate=interp).avg() == \
-                   im.crop(0, 0, 100, 100).avg()
-
+        assert im.mapim(mp, interpolate=interp).avg() == im.avg()
 
 
 if __name__ == '__main__':