From ce31c04cd28ab4d2c2872dd94d69b8e337ad0738 Mon Sep 17 00:00:00 2001
From: Sergey Alexandrovich <DarthSim@users.noreply.github.com>
Date: Fri, 9 Sep 2022 00:05:42 +0600
Subject: [PATCH] nsgifload: choose tile-height based on page height (#2996)

---
 libvips/foreign/nsgifload.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/libvips/foreign/nsgifload.c b/libvips/foreign/nsgifload.c
index dc915af1..ac6deaac 100644
--- a/libvips/foreign/nsgifload.c
+++ b/libvips/foreign/nsgifload.c
@@ -487,6 +487,26 @@ vips_foreign_load_nsgif_generate( VipsRegion *or,
 	return( 0 );
 }
 
+int
+vips_foreign_load_nsgif_tile_height(VipsForeignLoadNsgif *gif) {
+	int i;
+	int height = gif->info->height;
+
+	// First, check the perfect size
+	if (height % 16 == 0)
+		return 16;
+
+	// Next, check larger and smaller sizes
+	for (i = 1; i < 16; i++) {
+		if (height % (16 + i) == 0)
+			return (16 + i);
+		if (height % (16 - i) == 0)
+			return (16 - i);
+	}
+
+	return 1;
+}
+
 static int
 vips_foreign_load_nsgif_load( VipsForeignLoad *load )
 {
@@ -507,7 +527,7 @@ vips_foreign_load_nsgif_load( VipsForeignLoad *load )
 	if( vips_image_generate( t[0],
 		NULL, vips_foreign_load_nsgif_generate, NULL, gif, NULL ) ||
 		vips_sequential( t[0], &t[1],
-			"tile_height", VIPS__FATSTRIP_HEIGHT,
+			"tile_height", vips_foreign_load_nsgif_tile_height(gif),
 			NULL ) ||
 		vips_image_write( t[1], load->real ) )
 		return( -1 );