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Update LibNSGIF to latest upstream #2791

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Merged
merged 2 commits into from
May 9, 2022
Merged

Update LibNSGIF to latest upstream #2791

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0121c74
libnsgif: Update to latest upstream
tlsa May 8, 2022
b4143ae
nsgifload: Add palette info to debug output.
tlsa May 8, 2022
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2 changes: 1 addition & 1 deletion libvips/foreign/libnsgif/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ but within the libvips build system.
Run `./update.sh` to update this copy of libnsgif from the upstream repo. It
will also patch libnsgif.c to prevent it modifying the input.

Last updated 15 Apr 2022.
Last updated 8 May 2022.

# To do

Expand Down
168 changes: 124 additions & 44 deletions libvips/foreign/libnsgif/gif.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,9 +17,6 @@
#include "lzw.h"
#include "nsgif.h"

/** Maximum colour table size */
#define NSGIF_MAX_COLOURS 256

/** Default minimum allowable frame delay in cs. */
#define NSGIF_FRAME_DELAY_MIN 2

Expand All @@ -35,7 +32,7 @@ typedef struct nsgif_frame {
struct nsgif_frame_info info;

/** offset (in bytes) to the GIF frame data */
uint32_t frame_pointer;
uint32_t frame_offset;
/** whether the frame has previously been decoded. */
bool decoded;
/** whether the frame is totally opaque */
Expand All @@ -46,6 +43,9 @@ typedef struct nsgif_frame {
/** the index designating a transparent pixel */
uint32_t transparency_index;

/** offset to frame colour table */
uint32_t colour_table_offset;

/* Frame flags */
uint32_t flags;
} nsgif_frame;
Expand All @@ -72,8 +72,11 @@ struct nsgif {
uint32_t frame;
/** current frame decoded to bitmap */
uint32_t decoded_frame;

/** currently decoded image; stored as bitmap from bitmap_create callback */
nsgif_bitmap_t *frame_image;
/** Row span of frame_image in pixels. */
uint32_t rowspan;

/** Minimum allowable frame delay. */
uint16_t delay_min;
Expand All @@ -100,11 +103,9 @@ struct nsgif {
uint32_t bg_index;
/** image aspect ratio (ignored) */
uint32_t aspect_ratio;
/** size of colour table (in entries) */
/** size of global colour table (in entries) */
uint32_t colour_table_size;

/** whether the GIF has a global colour table */
bool global_colours;
/** current colour table */
uint32_t *colour_table;
/** Client's colour component order. */
Expand Down Expand Up @@ -223,6 +224,11 @@ static inline uint32_t* nsgif__bitmap_get(
return NULL;
}

gif->rowspan = gif->info.width;
if (gif->bitmap.get_rowspan) {
gif->rowspan = gif->bitmap.get_rowspan(gif->frame_image);
}

/* Get the frame data */
assert(gif->bitmap.get_buffer);
return (void *)gif->bitmap.get_buffer(gif->frame_image);
Expand Down Expand Up @@ -463,7 +469,7 @@ static nsgif_error nsgif__decode_complex(
uint32_t *frame_scanline;

frame_scanline = frame_data + offset_x +
(y + offset_y) * gif->info.width;
(y + offset_y) * gif->rowspan;

x = width;
while (x > 0) {
Expand Down Expand Up @@ -594,7 +600,9 @@ static inline nsgif_error nsgif__decode(
uint32_t transparency_index = frame->transparency_index;
uint32_t *restrict colour_table = gif->colour_table;

if (interlace == false && width == gif->info.width && offset_x == 0) {
if (interlace == false && offset_x == 0 &&
width == gif->info.width &&
width == gif->rowspan) {
ret = nsgif__decode_simple(gif, height, offset_y,
data, transparency_index,
frame_data, colour_table);
Expand Down Expand Up @@ -1031,6 +1039,38 @@ static nsgif_error nsgif__parse_image_descriptor(
return NSGIF_OK;
}

/**
* Extract a GIF colour table into a LibNSGIF colour table buffer.
*
* \param[in] colour_table The colour table to populate.
* \param[in] layout la.
* \param[in] colour_table_entries The number of colour table entries.
* \param[in] Data Raw colour table data.
*/
static void nsgif__colour_table_decode(
uint32_t colour_table[NSGIF_MAX_COLOURS],
const struct nsgif_colour_layout *layout,
size_t colour_table_entries,
const uint8_t *data)
{
uint8_t *entry = (uint8_t *)colour_table;

while (colour_table_entries--) {
/* Gif colour map contents are r,g,b.
*
* We want to pack them bytewise into the colour table,
* according to the client colour layout.
*/

entry[layout->r] = *data++;
entry[layout->g] = *data++;
entry[layout->b] = *data++;
entry[layout->a] = 0xff;

entry += sizeof(uint32_t);
}
}

/**
* Extract a GIF colour table into a LibNSGIF colour table buffer.
*
Expand All @@ -1041,42 +1081,25 @@ static nsgif_error nsgif__parse_image_descriptor(
* \param[in] decode Whether to decode the colour table.
* \return NSGIF_OK on success, appropriate error otherwise.
*/
static nsgif_error nsgif__colour_table_extract(
struct nsgif *gif,
static inline nsgif_error nsgif__colour_table_extract(
uint32_t colour_table[NSGIF_MAX_COLOURS],
const struct nsgif_colour_layout *layout,
size_t colour_table_entries,
const uint8_t **pos,
const uint8_t *data,
size_t data_len,
size_t *used,
bool decode)
{
const uint8_t *data = *pos;
size_t len = gif->buf + gif->buf_len - data;

if (len < colour_table_entries * 3) {
if (data_len < colour_table_entries * 3) {
return NSGIF_ERR_END_OF_DATA;
}

if (decode) {
int count = colour_table_entries;
uint8_t *entry = (uint8_t *)colour_table;

while (count--) {
/* Gif colour map contents are r,g,b.
*
* We want to pack them bytewise into the colour table,
* according to the client colour layout.
*/

entry[layout->r] = *data++;
entry[layout->g] = *data++;
entry[layout->b] = *data++;
entry[layout->a] = 0xff;

entry += sizeof(uint32_t);
}
nsgif__colour_table_decode(colour_table, layout,
colour_table_entries, data);
}

*pos += colour_table_entries * 3;
*used = colour_table_entries * 3;
return NSGIF_OK;
}

Expand All @@ -1098,6 +1121,9 @@ static nsgif_error nsgif__parse_colour_table(
bool decode)
{
nsgif_error ret;
const uint8_t *data = *pos;
size_t len = gif->buf + gif->buf_len - data;
size_t used_bytes;

assert(gif != NULL);
assert(frame != NULL);
Expand All @@ -1107,15 +1133,25 @@ static nsgif_error nsgif__parse_colour_table(
return NSGIF_OK;
}

ret = nsgif__colour_table_extract(gif,
if (decode == false) {
frame->colour_table_offset = *pos - gif->buf;
}

ret = nsgif__colour_table_extract(
gif->local_colour_table, &gif->colour_layout,
2 << (frame->flags & NSGIF_COLOUR_TABLE_SIZE_MASK),
pos, decode);
data, len, &used_bytes, decode);
if (ret != NSGIF_OK) {
return ret;
}
*pos += used_bytes;

if (decode) {
gif->colour_table = gif->local_colour_table;
} else {
frame->info.local_palette = true;
}

gif->colour_table = gif->local_colour_table;
return NSGIF_OK;
}

Expand Down Expand Up @@ -1223,7 +1259,8 @@ static struct nsgif_frame *nsgif__get_frame(
frame = &gif->frames[frame_idx];

frame->transparency_index = NSGIF_NO_TRANSPARENCY;
frame->frame_pointer = gif->buf_pos;
frame->frame_offset = gif->buf_pos;
frame->info.local_palette = false;
frame->info.transparency = false;
frame->redraw_required = false;
frame->info.display = false;
Expand Down Expand Up @@ -1261,7 +1298,7 @@ static nsgif_error nsgif__process_frame(
end = gif->buf + gif->buf_len;

if (decode) {
pos = gif->buf + frame->frame_pointer;
pos = gif->buf + frame->frame_offset;

/* Ensure this frame is supposed to be decoded */
if (frame->info.display == false) {
Expand Down Expand Up @@ -1536,7 +1573,7 @@ static nsgif_error nsgif__parse_logical_screen_descriptor(

gif->info.width = data[0] | (data[1] << 8);
gif->info.height = data[2] | (data[3] << 8);
gif->global_colours = data[4] & NSGIF_COLOUR_TABLE_MASK;
gif->info.global_palette = data[4] & NSGIF_COLOUR_TABLE_MASK;
gif->colour_table_size = 2 << (data[4] & NSGIF_COLOUR_TABLE_SIZE_MASK);
gif->bg_index = data[5];
gif->aspect_ratio = data[6];
Expand Down Expand Up @@ -1630,16 +1667,20 @@ nsgif_error nsgif_data_scan(
*/
if (gif->global_colour_table[0] == NSGIF_PROCESS_COLOURS) {
/* Check for a global colour map signified by bit 7 */
if (gif->global_colours) {
ret = nsgif__colour_table_extract(gif,
if (gif->info.global_palette) {
size_t remaining = gif->buf + gif->buf_len - nsgif_data;
size_t used;

ret = nsgif__colour_table_extract(
gif->global_colour_table,
&gif->colour_layout,
gif->colour_table_size,
&nsgif_data, true);
nsgif_data, remaining, &used, true);
if (ret != NSGIF_OK) {
return ret;
}

nsgif_data += used;
gif->buf_pos = (nsgif_data - gif->buf);
} else {
/* Create a default colour table with the first two
Expand All @@ -1659,9 +1700,11 @@ nsgif_error nsgif_data_scan(
entry[gif->colour_layout.g] = 0xFF;
entry[gif->colour_layout.b] = 0xFF;
entry[gif->colour_layout.a] = 0xFF;

gif->colour_table_size = 2;
}

if (gif->global_colours &&
if (gif->info.global_palette &&
gif->bg_index < gif->colour_table_size) {
size_t bg_idx = gif->bg_index;
gif->info.background = gif->global_colour_table[bg_idx];
Expand Down Expand Up @@ -1895,6 +1938,43 @@ const nsgif_frame_info_t *nsgif_get_frame_info(
return &gif->frames[frame].info;
}

/* exported function documented in nsgif.h */
void nsgif_global_palette(
const nsgif_t *gif,
uint32_t table[NSGIF_MAX_COLOURS],
size_t *entries)
{
size_t len = sizeof(*table) * NSGIF_MAX_COLOURS;

memcpy(table, gif->global_colour_table, len);
*entries = gif->colour_table_size;
}

/* exported function documented in nsgif.h */
bool nsgif_local_palette(
const nsgif_t *gif,
uint32_t frame,
uint32_t table[NSGIF_MAX_COLOURS],
size_t *entries)
{
const nsgif_frame *f;

if (frame >= gif->frame_count_partial) {
return false;
}

f = &gif->frames[frame];
if (f->info.local_palette == false) {
return false;
}

*entries = 2 << (f->flags & NSGIF_COLOUR_TABLE_SIZE_MASK);
nsgif__colour_table_decode(table, &gif->colour_layout,
*entries, gif->buf + f->colour_table_offset);

return true;
}

/* exported function documented in nsgif.h */
const char *nsgif_strerror(nsgif_error err)
{
Expand Down
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