From 07e73475c18e129e18825426b3071b99f6b6871a Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Fri, 2 Apr 2021 12:00:50 +0100
Subject: [PATCH] make a patch for the libnsgif alloc delay

---
 .../libnsgif/patches/delay-alloc.patch        | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 libvips/foreign/libnsgif/patches/delay-alloc.patch

diff --git a/libvips/foreign/libnsgif/patches/delay-alloc.patch b/libvips/foreign/libnsgif/patches/delay-alloc.patch
new file mode 100644
index 00000000..d7d5f97d
--- /dev/null
+++ b/libvips/foreign/libnsgif/patches/delay-alloc.patch
@@ -0,0 +1,71 @@
+--- libnsgif-orig.c	2021-04-02 11:59:38.120048459 +0100
++++ libnsgif.c	2021-04-02 11:59:44.439972362 +0100
+@@ -79,34 +79,17 @@
+                       unsigned int width,
+                       unsigned int height)
+ {
+-        unsigned int max_width;
+-        unsigned int max_height;
+-        struct bitmap *buffer;
+-
+-        /* Check if we've changed */
+-        if ((width <= gif->width) && (height <= gif->height)) {
++	/* Already allocated? */
++	if (gif->frame_image) {
+                 return GIF_OK;
+         }
+ 
+-        /* Get our maximum values */
+-        max_width = (width > gif->width) ? width : gif->width;
+-        max_height = (height > gif->height) ? height : gif->height;
+-
+-        /* Allocate some more memory */
+         assert(gif->bitmap_callbacks.bitmap_create);
+-        buffer = gif->bitmap_callbacks.bitmap_create(max_width, max_height);
+-        if (buffer == NULL) {
++        gif->frame_image = gif->bitmap_callbacks.bitmap_create(width, height);
++        if (gif->frame_image == NULL) {
+                 return GIF_INSUFFICIENT_MEMORY;
+         }
+ 
+-        assert(gif->bitmap_callbacks.bitmap_destroy);
+-        gif->bitmap_callbacks.bitmap_destroy(gif->frame_image);
+-        gif->frame_image = buffer;
+-        gif->width = max_width;
+-        gif->height = max_height;
+-
+-        /* Invalidate our currently decoded image */
+-        gif->decoded_frame = GIF_INVALID_FRAME;
+         return GIF_OK;
+ }
+ 
+@@ -392,10 +375,12 @@
+         gif->frames[frame].redraw_required = ((gif->frames[frame].disposal_method == GIF_FRAME_CLEAR) ||
+                                                 (gif->frames[frame].disposal_method == GIF_FRAME_RESTORE));
+ 
+-        /* Boundary checking - shouldn't ever happen except with junk data */
+-        if (gif_initialise_sprite(gif, (offset_x + width), (offset_y + height))) {
+-                return GIF_INSUFFICIENT_MEMORY;
+-        }
++	/* Frame size may have grown.
++	 */
++        gif->width = (offset_x + width > gif->width) ? 
++		offset_x + width : gif->width;
++        gif->height = (offset_y + height > gif->height) ? 
++		offset_y + height : gif->height;
+ 
+         /* Decode the flags */
+         flags = gif_data[9];
+@@ -739,6 +724,12 @@
+                 goto gif_decode_frame_exit;
+         }
+ 
++	/* Make sure we have a buffer to decode to.
++	 */
++	if (gif_initialise_sprite(gif, gif->width, gif->height)) {
++                return GIF_INSUFFICIENT_MEMORY;
++        }
++
+         /* Decode the flags */
+         flags = gif_data[9];
+         colour_table_size = 2 << (flags & GIF_COLOUR_TABLE_SIZE_MASK);