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- Log -----------------------------------------------------------------
commitdiff
http://git.netsurf-browser.org/libnsgif.git/commit/?id=8442a27c2bb8df48029ceea6e64c4930106a57fc
commit 8442a27c2bb8df48029ceea6e64c4930106a57fc
Author: Michael Drake <[email protected]>
Commit: Michael Drake <[email protected]>
Disposal Method: Handle Restore to previous with saved image.
Previously we decoded a previous frame over the current frame data
to handle resoration. However, the previous frame depended on its
own previous frame state for correct decode.
Now we just make a copy of the previous frame data and copy it
back to handle the GIF_FRAME_RESTORE case.
See: https://github.com/libvips/libvips/issues/1084#issuecomment-653497200
diff --git a/include/libnsgif.h b/include/libnsgif.h
index a819fec..50dc688 100644
--- a/include/libnsgif.h
+++ b/include/libnsgif.h
@@ -136,6 +136,15 @@ typedef struct gif_animation {
unsigned int *global_colour_table;
/** local colour table */
unsigned int *local_colour_table;
+
+ /** previous frame for GIF_FRAME_RESTORE */
+ void *prev_frame;
+ /** previous frame index */
+ int prev_index;
+ /** previous frame width */
+ unsigned prev_width;
+ /** previous frame height */
+ unsigned prev_height;
} gif_animation;
/**
diff --git a/src/libnsgif.c b/src/libnsgif.c
index 6bf9956..95bbbfb 100644
--- a/src/libnsgif.c
+++ b/src/libnsgif.c
@@ -570,6 +570,73 @@ static gif_result gif_error_from_lzw(lzw_result l_res)
return g_res[l_res];
}
+static void gif__record_previous_frame(gif_animation *gif)
+{
+ bool need_alloc = gif->prev_frame == NULL;
+ const uint32_t *frame_data;
+ uint32_t *prev_frame;
+
+ if (gif->decoded_frame == GIF_INVALID_FRAME ||
+ gif->decoded_frame == gif->prev_index) {
+ /* No frame to copy, or already have this frame recorded. */
+ return;
+ }
+
+ assert(gif->bitmap_callbacks.bitmap_get_buffer);
+ frame_data = (void
*)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
+ if (!frame_data) {
+ return;
+ }
+
+ if (gif->prev_frame != NULL &&
+ gif->width * gif->height < gif->prev_width * gif->prev_height) {
+ need_alloc = true;
+ }
+
+ if (need_alloc) {
+ prev_frame = realloc(gif->prev_frame,
+ gif->width * gif->height * 4);
+ if (prev_frame == NULL) {
+ return;
+ }
+ } else {
+ prev_frame = gif->prev_frame;
+ }
+
+ memcpy(prev_frame, frame_data, gif->width * gif->height * 4);
+
+ gif->prev_frame = prev_frame;
+ gif->prev_width = gif->width;
+ gif->prev_height = gif->height;
+ gif->prev_index = gif->decoded_frame;
+}
+
+static gif_result gif__recover_previous_frame(const gif_animation *gif)
+{
+ const uint32_t *prev_frame = gif->prev_frame;
+ unsigned height = gif->height < gif->prev_height ? gif->height :
gif->prev_height;
+ unsigned width = gif->width < gif->prev_width ? gif->width :
gif->prev_width;
+ uint32_t *frame_data;
+
+ if (prev_frame == NULL) {
+ return GIF_FRAME_DATA_ERROR;
+ }
+
+ assert(gif->bitmap_callbacks.bitmap_get_buffer);
+ frame_data = (void
*)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
+ if (!frame_data) {
+ return GIF_INSUFFICIENT_MEMORY;
+ }
+
+ for (unsigned y = 0; y < height; y++) {
+ memcpy(frame_data, prev_frame, width * 4);
+
+ frame_data += gif->width;
+ prev_frame += gif->prev_width;
+ }
+
+ return GIF_OK;
+}
/**
* decode a gif frame
@@ -583,6 +650,7 @@ gif_internal_decode_frame(gif_animation *gif,
unsigned int frame,
bool clear_image)
{
+ gif_result err;
unsigned int index = 0;
unsigned char *gif_data, *gif_end;
int gif_bytes;
@@ -612,6 +680,11 @@ gif_internal_decode_frame(gif_animation *gif,
return GIF_OK;
}
+ if (gif->frames[frame].disposal_method == GIF_FRAME_RESTORE) {
+ /* Store the previous frame for later restoration */
+ gif__record_previous_frame(gif);
+ }
+
/* Get the start of our frame data and the end of the GIF data */
gif_data = gif->gif_data + gif->frames[frame].frame_pointer;
gif_end = gif->gif_data + gif->buffer_size;
@@ -788,34 +861,16 @@ gif_internal_decode_frame(gif_animation *gif,
(gif->frames[frame - 1].disposal_method ==
GIF_FRAME_RESTORE)) {
/*
* If the previous frame's disposal method requires we
- * restore the previous image, find the last image set
- * to "do not dispose" and get that frame data
+ * restore the previous image, restore our saved image.
*/
- int last_undisposed_frame = frame - 2;
- while ((last_undisposed_frame >= 0) &&
-
(gif->frames[last_undisposed_frame].disposal_method == GIF_FRAME_RESTORE)) {
- last_undisposed_frame--;
- }
-
- /* If we don't find one, clear the frame data */
- if (last_undisposed_frame == -1) {
+ err = gif__recover_previous_frame(gif);
+ if (err != GIF_OK) {
/* see notes above on transparency
* vs. background color
*/
memset((char*)frame_data,
GIF_TRANSPARENT_COLOUR,
gif->width * gif->height * sizeof(int));
- } else {
- return_value = gif_internal_decode_frame(gif,
last_undisposed_frame, false);
- if (return_value != GIF_OK) {
- goto gif_decode_frame_exit;
- }
- /* Get this frame's data */
-
assert(gif->bitmap_callbacks.bitmap_get_buffer);
- frame_data = (void
*)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
- if (!frame_data) {
- return GIF_INSUFFICIENT_MEMORY;
- }
}
}
gif->decoded_frame = frame;
@@ -923,6 +978,7 @@ void gif_create(gif_animation *gif, gif_bitmap_callback_vt
*bitmap_callbacks)
memset(gif, 0, sizeof(gif_animation));
gif->bitmap_callbacks = *bitmap_callbacks;
gif->decoded_frame = GIF_INVALID_FRAME;
+ gif->prev_index = GIF_INVALID_FRAME;
}
@@ -1164,6 +1220,9 @@ void gif_finalise(gif_animation *gif)
free(gif->global_colour_table);
gif->global_colour_table = NULL;
+ free(gif->prev_frame);
+ gif->prev_frame = NULL;
+
lzw_context_destroy(gif->lzw_ctx);
gif->lzw_ctx = NULL;
}
-----------------------------------------------------------------------
Summary of changes:
include/libnsgif.h | 9 +++++
src/libnsgif.c | 101 +++++++++++++++++++++++++++++++++++++++++-----------
2 files changed, 89 insertions(+), 21 deletions(-)
diff --git a/include/libnsgif.h b/include/libnsgif.h
index a819fec..50dc688 100644
--- a/include/libnsgif.h
+++ b/include/libnsgif.h
@@ -136,6 +136,15 @@ typedef struct gif_animation {
unsigned int *global_colour_table;
/** local colour table */
unsigned int *local_colour_table;
+
+ /** previous frame for GIF_FRAME_RESTORE */
+ void *prev_frame;
+ /** previous frame index */
+ int prev_index;
+ /** previous frame width */
+ unsigned prev_width;
+ /** previous frame height */
+ unsigned prev_height;
} gif_animation;
/**
diff --git a/src/libnsgif.c b/src/libnsgif.c
index 6bf9956..95bbbfb 100644
--- a/src/libnsgif.c
+++ b/src/libnsgif.c
@@ -570,6 +570,73 @@ static gif_result gif_error_from_lzw(lzw_result l_res)
return g_res[l_res];
}
+static void gif__record_previous_frame(gif_animation *gif)
+{
+ bool need_alloc = gif->prev_frame == NULL;
+ const uint32_t *frame_data;
+ uint32_t *prev_frame;
+
+ if (gif->decoded_frame == GIF_INVALID_FRAME ||
+ gif->decoded_frame == gif->prev_index) {
+ /* No frame to copy, or already have this frame recorded. */
+ return;
+ }
+
+ assert(gif->bitmap_callbacks.bitmap_get_buffer);
+ frame_data = (void
*)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
+ if (!frame_data) {
+ return;
+ }
+
+ if (gif->prev_frame != NULL &&
+ gif->width * gif->height < gif->prev_width * gif->prev_height) {
+ need_alloc = true;
+ }
+
+ if (need_alloc) {
+ prev_frame = realloc(gif->prev_frame,
+ gif->width * gif->height * 4);
+ if (prev_frame == NULL) {
+ return;
+ }
+ } else {
+ prev_frame = gif->prev_frame;
+ }
+
+ memcpy(prev_frame, frame_data, gif->width * gif->height * 4);
+
+ gif->prev_frame = prev_frame;
+ gif->prev_width = gif->width;
+ gif->prev_height = gif->height;
+ gif->prev_index = gif->decoded_frame;
+}
+
+static gif_result gif__recover_previous_frame(const gif_animation *gif)
+{
+ const uint32_t *prev_frame = gif->prev_frame;
+ unsigned height = gif->height < gif->prev_height ? gif->height :
gif->prev_height;
+ unsigned width = gif->width < gif->prev_width ? gif->width :
gif->prev_width;
+ uint32_t *frame_data;
+
+ if (prev_frame == NULL) {
+ return GIF_FRAME_DATA_ERROR;
+ }
+
+ assert(gif->bitmap_callbacks.bitmap_get_buffer);
+ frame_data = (void
*)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
+ if (!frame_data) {
+ return GIF_INSUFFICIENT_MEMORY;
+ }
+
+ for (unsigned y = 0; y < height; y++) {
+ memcpy(frame_data, prev_frame, width * 4);
+
+ frame_data += gif->width;
+ prev_frame += gif->prev_width;
+ }
+
+ return GIF_OK;
+}
/**
* decode a gif frame
@@ -583,6 +650,7 @@ gif_internal_decode_frame(gif_animation *gif,
unsigned int frame,
bool clear_image)
{
+ gif_result err;
unsigned int index = 0;
unsigned char *gif_data, *gif_end;
int gif_bytes;
@@ -612,6 +680,11 @@ gif_internal_decode_frame(gif_animation *gif,
return GIF_OK;
}
+ if (gif->frames[frame].disposal_method == GIF_FRAME_RESTORE) {
+ /* Store the previous frame for later restoration */
+ gif__record_previous_frame(gif);
+ }
+
/* Get the start of our frame data and the end of the GIF data */
gif_data = gif->gif_data + gif->frames[frame].frame_pointer;
gif_end = gif->gif_data + gif->buffer_size;
@@ -788,34 +861,16 @@ gif_internal_decode_frame(gif_animation *gif,
(gif->frames[frame - 1].disposal_method ==
GIF_FRAME_RESTORE)) {
/*
* If the previous frame's disposal method requires we
- * restore the previous image, find the last image set
- * to "do not dispose" and get that frame data
+ * restore the previous image, restore our saved image.
*/
- int last_undisposed_frame = frame - 2;
- while ((last_undisposed_frame >= 0) &&
-
(gif->frames[last_undisposed_frame].disposal_method == GIF_FRAME_RESTORE)) {
- last_undisposed_frame--;
- }
-
- /* If we don't find one, clear the frame data */
- if (last_undisposed_frame == -1) {
+ err = gif__recover_previous_frame(gif);
+ if (err != GIF_OK) {
/* see notes above on transparency
* vs. background color
*/
memset((char*)frame_data,
GIF_TRANSPARENT_COLOUR,
gif->width * gif->height * sizeof(int));
- } else {
- return_value = gif_internal_decode_frame(gif,
last_undisposed_frame, false);
- if (return_value != GIF_OK) {
- goto gif_decode_frame_exit;
- }
- /* Get this frame's data */
-
assert(gif->bitmap_callbacks.bitmap_get_buffer);
- frame_data = (void
*)gif->bitmap_callbacks.bitmap_get_buffer(gif->frame_image);
- if (!frame_data) {
- return GIF_INSUFFICIENT_MEMORY;
- }
}
}
gif->decoded_frame = frame;
@@ -923,6 +978,7 @@ void gif_create(gif_animation *gif, gif_bitmap_callback_vt
*bitmap_callbacks)
memset(gif, 0, sizeof(gif_animation));
gif->bitmap_callbacks = *bitmap_callbacks;
gif->decoded_frame = GIF_INVALID_FRAME;
+ gif->prev_index = GIF_INVALID_FRAME;
}
@@ -1164,6 +1220,9 @@ void gif_finalise(gif_animation *gif)
free(gif->global_colour_table);
gif->global_colour_table = NULL;
+ free(gif->prev_frame);
+ gif->prev_frame = NULL;
+
lzw_context_destroy(gif->lzw_ctx);
gif->lzw_ctx = NULL;
}
--
NetSurf GIF Decoder
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