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- // Copyright 2012 Google Inc. All Rights Reserved.
- //
- // Use of this source code is governed by a BSD-style license
- // that can be found in the COPYING file in the root of the source
- // tree. An additional intellectual property rights grant can be found
- // in the file PATENTS. All contributing project authors may
- // be found in the AUTHORS file in the root of the source tree.
- // -----------------------------------------------------------------------------
- //
- // main entry for the decoder
- //
- // Authors: Vikas Arora (vikaas.arora@gmail.com)
- // Jyrki Alakuijala (jyrki@google.com)
- #include <stdlib.h>
- #include "./alphai.h"
- #include "./vp8li.h"
- #include "../dsp/dsp.h"
- #include "../dsp/lossless.h"
- #include "../dsp/yuv.h"
- #include "../utils/huffman.h"
- #include "../utils/utils.h"
- #define NUM_ARGB_CACHE_ROWS 16
- static const int kCodeLengthLiterals = 16;
- static const int kCodeLengthRepeatCode = 16;
- static const int kCodeLengthExtraBits[3] = { 2, 3, 7 };
- static const int kCodeLengthRepeatOffsets[3] = { 3, 3, 11 };
- // -----------------------------------------------------------------------------
- // Five Huffman codes are used at each meta code:
- // 1. green + length prefix codes + color cache codes,
- // 2. alpha,
- // 3. red,
- // 4. blue, and,
- // 5. distance prefix codes.
- typedef enum {
- GREEN = 0,
- RED = 1,
- BLUE = 2,
- ALPHA = 3,
- DIST = 4
- } HuffIndex;
- static const uint16_t kAlphabetSize[HUFFMAN_CODES_PER_META_CODE] = {
- NUM_LITERAL_CODES + NUM_LENGTH_CODES,
- NUM_LITERAL_CODES, NUM_LITERAL_CODES, NUM_LITERAL_CODES,
- NUM_DISTANCE_CODES
- };
- #define NUM_CODE_LENGTH_CODES 19
- static const uint8_t kCodeLengthCodeOrder[NUM_CODE_LENGTH_CODES] = {
- 17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
- };
- #define CODE_TO_PLANE_CODES 120
- static const uint8_t kCodeToPlane[CODE_TO_PLANE_CODES] = {
- 0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a,
- 0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a,
- 0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b,
- 0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03,
- 0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c,
- 0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e,
- 0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b,
- 0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f,
- 0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b,
- 0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41,
- 0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f,
- 0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70
- };
- static int DecodeImageStream(int xsize, int ysize,
- int is_level0,
- VP8LDecoder* const dec,
- uint32_t** const decoded_data);
- //------------------------------------------------------------------------------
- int VP8LCheckSignature(const uint8_t* const data, size_t size) {
- return (size >= VP8L_FRAME_HEADER_SIZE &&
- data[0] == VP8L_MAGIC_BYTE &&
- (data[4] >> 5) == 0); // version
- }
- static int ReadImageInfo(VP8LBitReader* const br,
- int* const width, int* const height,
- int* const has_alpha) {
- if (VP8LReadBits(br, 8) != VP8L_MAGIC_BYTE) return 0;
- *width = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1;
- *height = VP8LReadBits(br, VP8L_IMAGE_SIZE_BITS) + 1;
- *has_alpha = VP8LReadBits(br, 1);
- if (VP8LReadBits(br, VP8L_VERSION_BITS) != 0) return 0;
- return 1;
- }
- int VP8LGetInfo(const uint8_t* data, size_t data_size,
- int* const width, int* const height, int* const has_alpha) {
- if (data == NULL || data_size < VP8L_FRAME_HEADER_SIZE) {
- return 0; // not enough data
- } else if (!VP8LCheckSignature(data, data_size)) {
- return 0; // bad signature
- } else {
- int w, h, a;
- VP8LBitReader br;
- VP8LInitBitReader(&br, data, data_size);
- if (!ReadImageInfo(&br, &w, &h, &a)) {
- return 0;
- }
- if (width != NULL) *width = w;
- if (height != NULL) *height = h;
- if (has_alpha != NULL) *has_alpha = a;
- return 1;
- }
- }
- //------------------------------------------------------------------------------
- static WEBP_INLINE int GetCopyDistance(int distance_symbol,
- VP8LBitReader* const br) {
- int extra_bits, offset;
- if (distance_symbol < 4) {
- return distance_symbol + 1;
- }
- extra_bits = (distance_symbol - 2) >> 1;
- offset = (2 + (distance_symbol & 1)) << extra_bits;
- return offset + VP8LReadBits(br, extra_bits) + 1;
- }
- static WEBP_INLINE int GetCopyLength(int length_symbol,
- VP8LBitReader* const br) {
- // Length and distance prefixes are encoded the same way.
- return GetCopyDistance(length_symbol, br);
- }
- static WEBP_INLINE int PlaneCodeToDistance(int xsize, int plane_code) {
- if (plane_code > CODE_TO_PLANE_CODES) {
- return plane_code - CODE_TO_PLANE_CODES;
- } else {
- const int dist_code = kCodeToPlane[plane_code - 1];
- const int yoffset = dist_code >> 4;
- const int xoffset = 8 - (dist_code & 0xf);
- const int dist = yoffset * xsize + xoffset;
- return (dist >= 1) ? dist : 1; // dist<1 can happen if xsize is very small
- }
- }
- //------------------------------------------------------------------------------
- // Decodes the next Huffman code from bit-stream.
- // FillBitWindow(br) needs to be called at minimum every second call
- // to ReadSymbol, in order to pre-fetch enough bits.
- static WEBP_INLINE int ReadSymbol(const HuffmanTree* tree,
- VP8LBitReader* const br) {
- const HuffmanTreeNode* node = tree->root_;
- uint32_t bits = VP8LPrefetchBits(br);
- int bitpos = br->bit_pos_;
- // Check if we find the bit combination from the Huffman lookup table.
- const int lut_ix = bits & (HUFF_LUT - 1);
- const int lut_bits = tree->lut_bits_[lut_ix];
- if (lut_bits <= HUFF_LUT_BITS) {
- VP8LSetBitPos(br, bitpos + lut_bits);
- return tree->lut_symbol_[lut_ix];
- }
- node += tree->lut_jump_[lut_ix];
- bitpos += HUFF_LUT_BITS;
- bits >>= HUFF_LUT_BITS;
- // Decode the value from a binary tree.
- assert(node != NULL);
- do {
- node = HuffmanTreeNextNode(node, bits & 1);
- bits >>= 1;
- ++bitpos;
- } while (HuffmanTreeNodeIsNotLeaf(node));
- VP8LSetBitPos(br, bitpos);
- return node->symbol_;
- }
- static int ReadHuffmanCodeLengths(
- VP8LDecoder* const dec, const int* const code_length_code_lengths,
- int num_symbols, int* const code_lengths) {
- int ok = 0;
- VP8LBitReader* const br = &dec->br_;
- int symbol;
- int max_symbol;
- int prev_code_len = DEFAULT_CODE_LENGTH;
- HuffmanTree tree;
- int huff_codes[NUM_CODE_LENGTH_CODES] = { 0 };
- if (!VP8LHuffmanTreeBuildImplicit(&tree, code_length_code_lengths,
- huff_codes, NUM_CODE_LENGTH_CODES)) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- return 0;
- }
- if (VP8LReadBits(br, 1)) { // use length
- const int length_nbits = 2 + 2 * VP8LReadBits(br, 3);
- max_symbol = 2 + VP8LReadBits(br, length_nbits);
- if (max_symbol > num_symbols) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- goto End;
- }
- } else {
- max_symbol = num_symbols;
- }
- symbol = 0;
- while (symbol < num_symbols) {
- int code_len;
- if (max_symbol-- == 0) break;
- VP8LFillBitWindow(br);
- code_len = ReadSymbol(&tree, br);
- if (code_len < kCodeLengthLiterals) {
- code_lengths[symbol++] = code_len;
- if (code_len != 0) prev_code_len = code_len;
- } else {
- const int use_prev = (code_len == kCodeLengthRepeatCode);
- const int slot = code_len - kCodeLengthLiterals;
- const int extra_bits = kCodeLengthExtraBits[slot];
- const int repeat_offset = kCodeLengthRepeatOffsets[slot];
- int repeat = VP8LReadBits(br, extra_bits) + repeat_offset;
- if (symbol + repeat > num_symbols) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- goto End;
- } else {
- const int length = use_prev ? prev_code_len : 0;
- while (repeat-- > 0) code_lengths[symbol++] = length;
- }
- }
- }
- ok = 1;
- End:
- VP8LHuffmanTreeFree(&tree);
- if (!ok) dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- return ok;
- }
- // 'code_lengths' is pre-allocated temporary buffer, used for creating Huffman
- // tree.
- static int ReadHuffmanCode(int alphabet_size, VP8LDecoder* const dec,
- int* const code_lengths, int* const huff_codes,
- HuffmanTree* const tree) {
- int ok = 0;
- VP8LBitReader* const br = &dec->br_;
- const int simple_code = VP8LReadBits(br, 1);
- if (simple_code) { // Read symbols, codes & code lengths directly.
- int symbols[2];
- int codes[2];
- const int num_symbols = VP8LReadBits(br, 1) + 1;
- const int first_symbol_len_code = VP8LReadBits(br, 1);
- // The first code is either 1 bit or 8 bit code.
- symbols[0] = VP8LReadBits(br, (first_symbol_len_code == 0) ? 1 : 8);
- codes[0] = 0;
- code_lengths[0] = num_symbols - 1;
- // The second code (if present), is always 8 bit long.
- if (num_symbols == 2) {
- symbols[1] = VP8LReadBits(br, 8);
- codes[1] = 1;
- code_lengths[1] = num_symbols - 1;
- }
- ok = VP8LHuffmanTreeBuildExplicit(tree, code_lengths, codes, symbols,
- alphabet_size, num_symbols);
- } else { // Decode Huffman-coded code lengths.
- int i;
- int code_length_code_lengths[NUM_CODE_LENGTH_CODES] = { 0 };
- const int num_codes = VP8LReadBits(br, 4) + 4;
- if (num_codes > NUM_CODE_LENGTH_CODES) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- return 0;
- }
- memset(code_lengths, 0, alphabet_size * sizeof(*code_lengths));
- for (i = 0; i < num_codes; ++i) {
- code_length_code_lengths[kCodeLengthCodeOrder[i]] = VP8LReadBits(br, 3);
- }
- ok = ReadHuffmanCodeLengths(dec, code_length_code_lengths, alphabet_size,
- code_lengths);
- ok = ok && VP8LHuffmanTreeBuildImplicit(tree, code_lengths, huff_codes,
- alphabet_size);
- }
- ok = ok && !br->error_;
- if (!ok) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- return 0;
- }
- return 1;
- }
- static int ReadHuffmanCodes(VP8LDecoder* const dec, int xsize, int ysize,
- int color_cache_bits, int allow_recursion) {
- int i, j;
- VP8LBitReader* const br = &dec->br_;
- VP8LMetadata* const hdr = &dec->hdr_;
- uint32_t* huffman_image = NULL;
- HTreeGroup* htree_groups = NULL;
- int num_htree_groups = 1;
- int max_alphabet_size = 0;
- int* code_lengths = NULL;
- int* huff_codes = NULL;
- if (allow_recursion && VP8LReadBits(br, 1)) {
- // use meta Huffman codes.
- const int huffman_precision = VP8LReadBits(br, 3) + 2;
- const int huffman_xsize = VP8LSubSampleSize(xsize, huffman_precision);
- const int huffman_ysize = VP8LSubSampleSize(ysize, huffman_precision);
- const int huffman_pixs = huffman_xsize * huffman_ysize;
- if (!DecodeImageStream(huffman_xsize, huffman_ysize, 0, dec,
- &huffman_image)) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- goto Error;
- }
- hdr->huffman_subsample_bits_ = huffman_precision;
- for (i = 0; i < huffman_pixs; ++i) {
- // The huffman data is stored in red and green bytes.
- const int group = (huffman_image[i] >> 8) & 0xffff;
- huffman_image[i] = group;
- if (group >= num_htree_groups) {
- num_htree_groups = group + 1;
- }
- }
- }
- if (br->error_) goto Error;
- // Find maximum alphabet size for the htree group.
- for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
- int alphabet_size = kAlphabetSize[j];
- if (j == 0 && color_cache_bits > 0) {
- alphabet_size += 1 << color_cache_bits;
- }
- if (max_alphabet_size < alphabet_size) {
- max_alphabet_size = alphabet_size;
- }
- }
- htree_groups = VP8LHtreeGroupsNew(num_htree_groups);
- code_lengths =
- (int*)WebPSafeCalloc((uint64_t)max_alphabet_size, sizeof(*code_lengths));
- huff_codes =
- (int*)WebPSafeMalloc((uint64_t)max_alphabet_size, sizeof(*huff_codes));
- if (htree_groups == NULL || code_lengths == NULL || huff_codes == NULL) {
- dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
- goto Error;
- }
- for (i = 0; i < num_htree_groups; ++i) {
- HuffmanTree* const htrees = htree_groups[i].htrees_;
- for (j = 0; j < HUFFMAN_CODES_PER_META_CODE; ++j) {
- int alphabet_size = kAlphabetSize[j];
- HuffmanTree* const htree = htrees + j;
- if (j == 0 && color_cache_bits > 0) {
- alphabet_size += 1 << color_cache_bits;
- }
- if (!ReadHuffmanCode(alphabet_size, dec, code_lengths, huff_codes,
- htree)) {
- goto Error;
- }
- }
- }
- WebPSafeFree(huff_codes);
- WebPSafeFree(code_lengths);
- // All OK. Finalize pointers and return.
- hdr->huffman_image_ = huffman_image;
- hdr->num_htree_groups_ = num_htree_groups;
- hdr->htree_groups_ = htree_groups;
- return 1;
- Error:
- WebPSafeFree(huff_codes);
- WebPSafeFree(code_lengths);
- WebPSafeFree(huffman_image);
- VP8LHtreeGroupsFree(htree_groups, num_htree_groups);
- return 0;
- }
- //------------------------------------------------------------------------------
- // Scaling.
- static int AllocateAndInitRescaler(VP8LDecoder* const dec, VP8Io* const io) {
- const int num_channels = 4;
- const int in_width = io->mb_w;
- const int out_width = io->scaled_width;
- const int in_height = io->mb_h;
- const int out_height = io->scaled_height;
- const uint64_t work_size = 2 * num_channels * (uint64_t)out_width;
- int32_t* work; // Rescaler work area.
- const uint64_t scaled_data_size = num_channels * (uint64_t)out_width;
- uint32_t* scaled_data; // Temporary storage for scaled BGRA data.
- const uint64_t memory_size = sizeof(*dec->rescaler) +
- work_size * sizeof(*work) +
- scaled_data_size * sizeof(*scaled_data);
- uint8_t* memory = (uint8_t*)WebPSafeCalloc(memory_size, sizeof(*memory));
- if (memory == NULL) {
- dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
- return 0;
- }
- assert(dec->rescaler_memory == NULL);
- dec->rescaler_memory = memory;
- dec->rescaler = (WebPRescaler*)memory;
- memory += sizeof(*dec->rescaler);
- work = (int32_t*)memory;
- memory += work_size * sizeof(*work);
- scaled_data = (uint32_t*)memory;
- WebPRescalerInit(dec->rescaler, in_width, in_height, (uint8_t*)scaled_data,
- out_width, out_height, 0, num_channels,
- in_width, out_width, in_height, out_height, work);
- return 1;
- }
- //------------------------------------------------------------------------------
- // Export to ARGB
- // We have special "export" function since we need to convert from BGRA
- static int Export(WebPRescaler* const rescaler, WEBP_CSP_MODE colorspace,
- int rgba_stride, uint8_t* const rgba) {
- uint32_t* const src = (uint32_t*)rescaler->dst;
- const int dst_width = rescaler->dst_width;
- int num_lines_out = 0;
- while (WebPRescalerHasPendingOutput(rescaler)) {
- uint8_t* const dst = rgba + num_lines_out * rgba_stride;
- WebPRescalerExportRow(rescaler, 0);
- WebPMultARGBRow(src, dst_width, 1);
- VP8LConvertFromBGRA(src, dst_width, colorspace, dst);
- ++num_lines_out;
- }
- return num_lines_out;
- }
- // Emit scaled rows.
- static int EmitRescaledRowsRGBA(const VP8LDecoder* const dec,
- uint8_t* in, int in_stride, int mb_h,
- uint8_t* const out, int out_stride) {
- const WEBP_CSP_MODE colorspace = dec->output_->colorspace;
- int num_lines_in = 0;
- int num_lines_out = 0;
- while (num_lines_in < mb_h) {
- uint8_t* const row_in = in + num_lines_in * in_stride;
- uint8_t* const row_out = out + num_lines_out * out_stride;
- const int lines_left = mb_h - num_lines_in;
- const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left);
- assert(needed_lines > 0 && needed_lines <= lines_left);
- WebPMultARGBRows(row_in, in_stride,
- dec->rescaler->src_width, needed_lines, 0);
- WebPRescalerImport(dec->rescaler, lines_left, row_in, in_stride);
- num_lines_in += needed_lines;
- num_lines_out += Export(dec->rescaler, colorspace, out_stride, row_out);
- }
- return num_lines_out;
- }
- // Emit rows without any scaling.
- static int EmitRows(WEBP_CSP_MODE colorspace,
- const uint8_t* row_in, int in_stride,
- int mb_w, int mb_h,
- uint8_t* const out, int out_stride) {
- int lines = mb_h;
- uint8_t* row_out = out;
- while (lines-- > 0) {
- VP8LConvertFromBGRA((const uint32_t*)row_in, mb_w, colorspace, row_out);
- row_in += in_stride;
- row_out += out_stride;
- }
- return mb_h; // Num rows out == num rows in.
- }
- //------------------------------------------------------------------------------
- // Export to YUVA
- // TODO(skal): should be in yuv.c
- static void ConvertToYUVA(const uint32_t* const src, int width, int y_pos,
- const WebPDecBuffer* const output) {
- const WebPYUVABuffer* const buf = &output->u.YUVA;
- // first, the luma plane
- {
- int i;
- uint8_t* const y = buf->y + y_pos * buf->y_stride;
- for (i = 0; i < width; ++i) {
- const uint32_t p = src[i];
- y[i] = VP8RGBToY((p >> 16) & 0xff, (p >> 8) & 0xff, (p >> 0) & 0xff,
- YUV_HALF);
- }
- }
- // then U/V planes
- {
- uint8_t* const u = buf->u + (y_pos >> 1) * buf->u_stride;
- uint8_t* const v = buf->v + (y_pos >> 1) * buf->v_stride;
- const int uv_width = width >> 1;
- int i;
- for (i = 0; i < uv_width; ++i) {
- const uint32_t v0 = src[2 * i + 0];
- const uint32_t v1 = src[2 * i + 1];
- // VP8RGBToU/V expects four accumulated pixels. Hence we need to
- // scale r/g/b value by a factor 2. We just shift v0/v1 one bit less.
- const int r = ((v0 >> 15) & 0x1fe) + ((v1 >> 15) & 0x1fe);
- const int g = ((v0 >> 7) & 0x1fe) + ((v1 >> 7) & 0x1fe);
- const int b = ((v0 << 1) & 0x1fe) + ((v1 << 1) & 0x1fe);
- if (!(y_pos & 1)) { // even lines: store values
- u[i] = VP8RGBToU(r, g, b, YUV_HALF << 2);
- v[i] = VP8RGBToV(r, g, b, YUV_HALF << 2);
- } else { // odd lines: average with previous values
- const int tmp_u = VP8RGBToU(r, g, b, YUV_HALF << 2);
- const int tmp_v = VP8RGBToV(r, g, b, YUV_HALF << 2);
- // Approximated average-of-four. But it's an acceptable diff.
- u[i] = (u[i] + tmp_u + 1) >> 1;
- v[i] = (v[i] + tmp_v + 1) >> 1;
- }
- }
- if (width & 1) { // last pixel
- const uint32_t v0 = src[2 * i + 0];
- const int r = (v0 >> 14) & 0x3fc;
- const int g = (v0 >> 6) & 0x3fc;
- const int b = (v0 << 2) & 0x3fc;
- if (!(y_pos & 1)) { // even lines
- u[i] = VP8RGBToU(r, g, b, YUV_HALF << 2);
- v[i] = VP8RGBToV(r, g, b, YUV_HALF << 2);
- } else { // odd lines (note: we could just skip this)
- const int tmp_u = VP8RGBToU(r, g, b, YUV_HALF << 2);
- const int tmp_v = VP8RGBToV(r, g, b, YUV_HALF << 2);
- u[i] = (u[i] + tmp_u + 1) >> 1;
- v[i] = (v[i] + tmp_v + 1) >> 1;
- }
- }
- }
- // Lastly, store alpha if needed.
- if (buf->a != NULL) {
- int i;
- uint8_t* const a = buf->a + y_pos * buf->a_stride;
- for (i = 0; i < width; ++i) a[i] = (src[i] >> 24);
- }
- }
- static int ExportYUVA(const VP8LDecoder* const dec, int y_pos) {
- WebPRescaler* const rescaler = dec->rescaler;
- uint32_t* const src = (uint32_t*)rescaler->dst;
- const int dst_width = rescaler->dst_width;
- int num_lines_out = 0;
- while (WebPRescalerHasPendingOutput(rescaler)) {
- WebPRescalerExportRow(rescaler, 0);
- WebPMultARGBRow(src, dst_width, 1);
- ConvertToYUVA(src, dst_width, y_pos, dec->output_);
- ++y_pos;
- ++num_lines_out;
- }
- return num_lines_out;
- }
- static int EmitRescaledRowsYUVA(const VP8LDecoder* const dec,
- uint8_t* in, int in_stride, int mb_h) {
- int num_lines_in = 0;
- int y_pos = dec->last_out_row_;
- while (num_lines_in < mb_h) {
- const int lines_left = mb_h - num_lines_in;
- const int needed_lines = WebPRescaleNeededLines(dec->rescaler, lines_left);
- WebPMultARGBRows(in, in_stride, dec->rescaler->src_width, needed_lines, 0);
- WebPRescalerImport(dec->rescaler, lines_left, in, in_stride);
- num_lines_in += needed_lines;
- in += needed_lines * in_stride;
- y_pos += ExportYUVA(dec, y_pos);
- }
- return y_pos;
- }
- static int EmitRowsYUVA(const VP8LDecoder* const dec,
- const uint8_t* in, int in_stride,
- int mb_w, int num_rows) {
- int y_pos = dec->last_out_row_;
- while (num_rows-- > 0) {
- ConvertToYUVA((const uint32_t*)in, mb_w, y_pos, dec->output_);
- in += in_stride;
- ++y_pos;
- }
- return y_pos;
- }
- //------------------------------------------------------------------------------
- // Cropping.
- // Sets io->mb_y, io->mb_h & io->mb_w according to start row, end row and
- // crop options. Also updates the input data pointer, so that it points to the
- // start of the cropped window. Note that pixels are in ARGB format even if
- // 'in_data' is uint8_t*.
- // Returns true if the crop window is not empty.
- static int SetCropWindow(VP8Io* const io, int y_start, int y_end,
- uint8_t** const in_data, int pixel_stride) {
- assert(y_start < y_end);
- assert(io->crop_left < io->crop_right);
- if (y_end > io->crop_bottom) {
- y_end = io->crop_bottom; // make sure we don't overflow on last row.
- }
- if (y_start < io->crop_top) {
- const int delta = io->crop_top - y_start;
- y_start = io->crop_top;
- *in_data += delta * pixel_stride;
- }
- if (y_start >= y_end) return 0; // Crop window is empty.
- *in_data += io->crop_left * sizeof(uint32_t);
- io->mb_y = y_start - io->crop_top;
- io->mb_w = io->crop_right - io->crop_left;
- io->mb_h = y_end - y_start;
- return 1; // Non-empty crop window.
- }
- //------------------------------------------------------------------------------
- static WEBP_INLINE int GetMetaIndex(
- const uint32_t* const image, int xsize, int bits, int x, int y) {
- if (bits == 0) return 0;
- return image[xsize * (y >> bits) + (x >> bits)];
- }
- static WEBP_INLINE HTreeGroup* GetHtreeGroupForPos(VP8LMetadata* const hdr,
- int x, int y) {
- const int meta_index = GetMetaIndex(hdr->huffman_image_, hdr->huffman_xsize_,
- hdr->huffman_subsample_bits_, x, y);
- assert(meta_index < hdr->num_htree_groups_);
- return hdr->htree_groups_ + meta_index;
- }
- //------------------------------------------------------------------------------
- // Main loop, with custom row-processing function
- typedef void (*ProcessRowsFunc)(VP8LDecoder* const dec, int row);
- static void ApplyInverseTransforms(VP8LDecoder* const dec, int num_rows,
- const uint32_t* const rows) {
- int n = dec->next_transform_;
- const int cache_pixs = dec->width_ * num_rows;
- const int start_row = dec->last_row_;
- const int end_row = start_row + num_rows;
- const uint32_t* rows_in = rows;
- uint32_t* const rows_out = dec->argb_cache_;
- // Inverse transforms.
- // TODO: most transforms only need to operate on the cropped region only.
- memcpy(rows_out, rows_in, cache_pixs * sizeof(*rows_out));
- while (n-- > 0) {
- VP8LTransform* const transform = &dec->transforms_[n];
- VP8LInverseTransform(transform, start_row, end_row, rows_in, rows_out);
- rows_in = rows_out;
- }
- }
- // Special method for paletted alpha data.
- static void ApplyInverseTransformsAlpha(VP8LDecoder* const dec, int num_rows,
- const uint8_t* const rows) {
- const int start_row = dec->last_row_;
- const int end_row = start_row + num_rows;
- const uint8_t* rows_in = rows;
- uint8_t* rows_out = (uint8_t*)dec->io_->opaque + dec->io_->width * start_row;
- VP8LTransform* const transform = &dec->transforms_[0];
- assert(dec->next_transform_ == 1);
- assert(transform->type_ == COLOR_INDEXING_TRANSFORM);
- VP8LColorIndexInverseTransformAlpha(transform, start_row, end_row, rows_in,
- rows_out);
- }
- // Processes (transforms, scales & color-converts) the rows decoded after the
- // last call.
- static void ProcessRows(VP8LDecoder* const dec, int row) {
- const uint32_t* const rows = dec->pixels_ + dec->width_ * dec->last_row_;
- const int num_rows = row - dec->last_row_;
- if (num_rows <= 0) return; // Nothing to be done.
- ApplyInverseTransforms(dec, num_rows, rows);
- // Emit output.
- {
- VP8Io* const io = dec->io_;
- uint8_t* rows_data = (uint8_t*)dec->argb_cache_;
- const int in_stride = io->width * sizeof(uint32_t); // in unit of RGBA
- if (!SetCropWindow(io, dec->last_row_, row, &rows_data, in_stride)) {
- // Nothing to output (this time).
- } else {
- const WebPDecBuffer* const output = dec->output_;
- if (output->colorspace < MODE_YUV) { // convert to RGBA
- const WebPRGBABuffer* const buf = &output->u.RGBA;
- uint8_t* const rgba = buf->rgba + dec->last_out_row_ * buf->stride;
- const int num_rows_out = io->use_scaling ?
- EmitRescaledRowsRGBA(dec, rows_data, in_stride, io->mb_h,
- rgba, buf->stride) :
- EmitRows(output->colorspace, rows_data, in_stride,
- io->mb_w, io->mb_h, rgba, buf->stride);
- // Update 'last_out_row_'.
- dec->last_out_row_ += num_rows_out;
- } else { // convert to YUVA
- dec->last_out_row_ = io->use_scaling ?
- EmitRescaledRowsYUVA(dec, rows_data, in_stride, io->mb_h) :
- EmitRowsYUVA(dec, rows_data, in_stride, io->mb_w, io->mb_h);
- }
- assert(dec->last_out_row_ <= output->height);
- }
- }
- // Update 'last_row_'.
- dec->last_row_ = row;
- assert(dec->last_row_ <= dec->height_);
- }
- // Row-processing for the special case when alpha data contains only one
- // transform (color indexing), and trivial non-green literals.
- static int Is8bOptimizable(const VP8LMetadata* const hdr) {
- int i;
- if (hdr->color_cache_size_ > 0) return 0;
- // When the Huffman tree contains only one symbol, we can skip the
- // call to ReadSymbol() for red/blue/alpha channels.
- for (i = 0; i < hdr->num_htree_groups_; ++i) {
- const HuffmanTree* const htrees = hdr->htree_groups_[i].htrees_;
- if (htrees[RED].num_nodes_ > 1) return 0;
- if (htrees[BLUE].num_nodes_ > 1) return 0;
- if (htrees[ALPHA].num_nodes_ > 1) return 0;
- }
- return 1;
- }
- static void ExtractPalettedAlphaRows(VP8LDecoder* const dec, int row) {
- const int num_rows = row - dec->last_row_;
- const uint8_t* const in =
- (uint8_t*)dec->pixels_ + dec->width_ * dec->last_row_;
- if (num_rows > 0) {
- ApplyInverseTransformsAlpha(dec, num_rows, in);
- }
- dec->last_row_ = dec->last_out_row_ = row;
- }
- static int DecodeAlphaData(VP8LDecoder* const dec, uint8_t* const data,
- int width, int height, int last_row) {
- int ok = 1;
- int row = dec->last_pixel_ / width;
- int col = dec->last_pixel_ % width;
- VP8LBitReader* const br = &dec->br_;
- VP8LMetadata* const hdr = &dec->hdr_;
- const HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row);
- int pos = dec->last_pixel_; // current position
- const int end = width * height; // End of data
- const int last = width * last_row; // Last pixel to decode
- const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES;
- const int mask = hdr->huffman_mask_;
- assert(htree_group != NULL);
- assert(pos < end);
- assert(last_row <= height);
- assert(Is8bOptimizable(hdr));
- while (!br->eos_ && pos < last) {
- int code;
- // Only update when changing tile.
- if ((col & mask) == 0) {
- htree_group = GetHtreeGroupForPos(hdr, col, row);
- }
- VP8LFillBitWindow(br);
- code = ReadSymbol(&htree_group->htrees_[GREEN], br);
- if (code < NUM_LITERAL_CODES) { // Literal
- data[pos] = code;
- ++pos;
- ++col;
- if (col >= width) {
- col = 0;
- ++row;
- if (row % NUM_ARGB_CACHE_ROWS == 0) {
- ExtractPalettedAlphaRows(dec, row);
- }
- }
- } else if (code < len_code_limit) { // Backward reference
- int dist_code, dist;
- const int length_sym = code - NUM_LITERAL_CODES;
- const int length = GetCopyLength(length_sym, br);
- const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br);
- VP8LFillBitWindow(br);
- dist_code = GetCopyDistance(dist_symbol, br);
- dist = PlaneCodeToDistance(width, dist_code);
- if (pos >= dist && end - pos >= length) {
- int i;
- for (i = 0; i < length; ++i) data[pos + i] = data[pos + i - dist];
- } else {
- ok = 0;
- goto End;
- }
- pos += length;
- col += length;
- while (col >= width) {
- col -= width;
- ++row;
- if (row % NUM_ARGB_CACHE_ROWS == 0) {
- ExtractPalettedAlphaRows(dec, row);
- }
- }
- if (pos < last && (col & mask)) {
- htree_group = GetHtreeGroupForPos(hdr, col, row);
- }
- } else { // Not reached
- ok = 0;
- goto End;
- }
- assert(br->eos_ == VP8LIsEndOfStream(br));
- ok = !br->error_;
- if (!ok) goto End;
- }
- // Process the remaining rows corresponding to last row-block.
- ExtractPalettedAlphaRows(dec, row);
- End:
- if (br->error_ || !ok || (br->eos_ && pos < end)) {
- ok = 0;
- dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED
- : VP8_STATUS_BITSTREAM_ERROR;
- } else {
- dec->last_pixel_ = (int)pos;
- if (pos == end) dec->state_ = READ_DATA;
- }
- return ok;
- }
- static int DecodeImageData(VP8LDecoder* const dec, uint32_t* const data,
- int width, int height, int last_row,
- ProcessRowsFunc process_func) {
- int ok = 1;
- int row = dec->last_pixel_ / width;
- int col = dec->last_pixel_ % width;
- VP8LBitReader* const br = &dec->br_;
- VP8LMetadata* const hdr = &dec->hdr_;
- HTreeGroup* htree_group = GetHtreeGroupForPos(hdr, col, row);
- uint32_t* src = data + dec->last_pixel_;
- uint32_t* last_cached = src;
- uint32_t* const src_end = data + width * height; // End of data
- uint32_t* const src_last = data + width * last_row; // Last pixel to decode
- const int len_code_limit = NUM_LITERAL_CODES + NUM_LENGTH_CODES;
- const int color_cache_limit = len_code_limit + hdr->color_cache_size_;
- VP8LColorCache* const color_cache =
- (hdr->color_cache_size_ > 0) ? &hdr->color_cache_ : NULL;
- const int mask = hdr->huffman_mask_;
- assert(htree_group != NULL);
- assert(src < src_end);
- assert(src_last <= src_end);
- while (!br->eos_ && src < src_last) {
- int code;
- // Only update when changing tile. Note we could use this test:
- // if "((((prev_col ^ col) | prev_row ^ row)) > mask)" -> tile changed
- // but that's actually slower and needs storing the previous col/row.
- if ((col & mask) == 0) {
- htree_group = GetHtreeGroupForPos(hdr, col, row);
- }
- VP8LFillBitWindow(br);
- code = ReadSymbol(&htree_group->htrees_[GREEN], br);
- if (code < NUM_LITERAL_CODES) { // Literal
- int red, green, blue, alpha;
- red = ReadSymbol(&htree_group->htrees_[RED], br);
- green = code;
- VP8LFillBitWindow(br);
- blue = ReadSymbol(&htree_group->htrees_[BLUE], br);
- alpha = ReadSymbol(&htree_group->htrees_[ALPHA], br);
- *src = ((uint32_t)alpha << 24) | (red << 16) | (green << 8) | blue;
- AdvanceByOne:
- ++src;
- ++col;
- if (col >= width) {
- col = 0;
- ++row;
- if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) {
- process_func(dec, row);
- }
- if (color_cache != NULL) {
- while (last_cached < src) {
- VP8LColorCacheInsert(color_cache, *last_cached++);
- }
- }
- }
- } else if (code < len_code_limit) { // Backward reference
- int dist_code, dist;
- const int length_sym = code - NUM_LITERAL_CODES;
- const int length = GetCopyLength(length_sym, br);
- const int dist_symbol = ReadSymbol(&htree_group->htrees_[DIST], br);
- VP8LFillBitWindow(br);
- dist_code = GetCopyDistance(dist_symbol, br);
- dist = PlaneCodeToDistance(width, dist_code);
- if (src - data < (ptrdiff_t)dist || src_end - src < (ptrdiff_t)length) {
- ok = 0;
- goto End;
- } else {
- int i;
- for (i = 0; i < length; ++i) src[i] = src[i - dist];
- src += length;
- }
- col += length;
- while (col >= width) {
- col -= width;
- ++row;
- if ((row % NUM_ARGB_CACHE_ROWS == 0) && (process_func != NULL)) {
- process_func(dec, row);
- }
- }
- if (src < src_last) {
- if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row);
- if (color_cache != NULL) {
- while (last_cached < src) {
- VP8LColorCacheInsert(color_cache, *last_cached++);
- }
- }
- }
- } else if (code < color_cache_limit) { // Color cache
- const int key = code - len_code_limit;
- assert(color_cache != NULL);
- while (last_cached < src) {
- VP8LColorCacheInsert(color_cache, *last_cached++);
- }
- *src = VP8LColorCacheLookup(color_cache, key);
- goto AdvanceByOne;
- } else { // Not reached
- ok = 0;
- goto End;
- }
- assert(br->eos_ == VP8LIsEndOfStream(br));
- ok = !br->error_;
- if (!ok) goto End;
- }
- // Process the remaining rows corresponding to last row-block.
- if (process_func != NULL) process_func(dec, row);
- End:
- if (br->error_ || !ok || (br->eos_ && src < src_end)) {
- ok = 0;
- dec->status_ = br->eos_ ? VP8_STATUS_SUSPENDED
- : VP8_STATUS_BITSTREAM_ERROR;
- } else {
- dec->last_pixel_ = (int)(src - data);
- if (src == src_end) dec->state_ = READ_DATA;
- }
- return ok;
- }
- // -----------------------------------------------------------------------------
- // VP8LTransform
- static void ClearTransform(VP8LTransform* const transform) {
- WebPSafeFree(transform->data_);
- transform->data_ = NULL;
- }
- // For security reason, we need to remap the color map to span
- // the total possible bundled values, and not just the num_colors.
- static int ExpandColorMap(int num_colors, VP8LTransform* const transform) {
- int i;
- const int final_num_colors = 1 << (8 >> transform->bits_);
- uint32_t* const new_color_map =
- (uint32_t*)WebPSafeMalloc((uint64_t)final_num_colors,
- sizeof(*new_color_map));
- if (new_color_map == NULL) {
- return 0;
- } else {
- uint8_t* const data = (uint8_t*)transform->data_;
- uint8_t* const new_data = (uint8_t*)new_color_map;
- new_color_map[0] = transform->data_[0];
- for (i = 4; i < 4 * num_colors; ++i) {
- // Equivalent to AddPixelEq(), on a byte-basis.
- new_data[i] = (data[i] + new_data[i - 4]) & 0xff;
- }
- for (; i < 4 * final_num_colors; ++i)
- new_data[i] = 0; // black tail.
- WebPSafeFree(transform->data_);
- transform->data_ = new_color_map;
- }
- return 1;
- }
- static int ReadTransform(int* const xsize, int const* ysize,
- VP8LDecoder* const dec) {
- int ok = 1;
- VP8LBitReader* const br = &dec->br_;
- VP8LTransform* transform = &dec->transforms_[dec->next_transform_];
- const VP8LImageTransformType type =
- (VP8LImageTransformType)VP8LReadBits(br, 2);
- // Each transform type can only be present once in the stream.
- if (dec->transforms_seen_ & (1U << type)) {
- return 0; // Already there, let's not accept the second same transform.
- }
- dec->transforms_seen_ |= (1U << type);
- transform->type_ = type;
- transform->xsize_ = *xsize;
- transform->ysize_ = *ysize;
- transform->data_ = NULL;
- ++dec->next_transform_;
- assert(dec->next_transform_ <= NUM_TRANSFORMS);
- switch (type) {
- case PREDICTOR_TRANSFORM:
- case CROSS_COLOR_TRANSFORM:
- transform->bits_ = VP8LReadBits(br, 3) + 2;
- ok = DecodeImageStream(VP8LSubSampleSize(transform->xsize_,
- transform->bits_),
- VP8LSubSampleSize(transform->ysize_,
- transform->bits_),
- 0, dec, &transform->data_);
- break;
- case COLOR_INDEXING_TRANSFORM: {
- const int num_colors = VP8LReadBits(br, 8) + 1;
- const int bits = (num_colors > 16) ? 0
- : (num_colors > 4) ? 1
- : (num_colors > 2) ? 2
- : 3;
- *xsize = VP8LSubSampleSize(transform->xsize_, bits);
- transform->bits_ = bits;
- ok = DecodeImageStream(num_colors, 1, 0, dec, &transform->data_);
- ok = ok && ExpandColorMap(num_colors, transform);
- break;
- }
- case SUBTRACT_GREEN:
- break;
- default:
- assert(0); // can't happen
- break;
- }
- return ok;
- }
- // -----------------------------------------------------------------------------
- // VP8LMetadata
- static void InitMetadata(VP8LMetadata* const hdr) {
- assert(hdr);
- memset(hdr, 0, sizeof(*hdr));
- }
- static void ClearMetadata(VP8LMetadata* const hdr) {
- assert(hdr);
- WebPSafeFree(hdr->huffman_image_);
- VP8LHtreeGroupsFree(hdr->htree_groups_, hdr->num_htree_groups_);
- VP8LColorCacheClear(&hdr->color_cache_);
- InitMetadata(hdr);
- }
- // -----------------------------------------------------------------------------
- // VP8LDecoder
- VP8LDecoder* VP8LNew(void) {
- VP8LDecoder* const dec = (VP8LDecoder*)WebPSafeCalloc(1ULL, sizeof(*dec));
- if (dec == NULL) return NULL;
- dec->status_ = VP8_STATUS_OK;
- dec->action_ = READ_DIM;
- dec->state_ = READ_DIM;
- VP8LDspInit(); // Init critical function pointers.
- return dec;
- }
- void VP8LClear(VP8LDecoder* const dec) {
- int i;
- if (dec == NULL) return;
- ClearMetadata(&dec->hdr_);
- WebPSafeFree(dec->pixels_);
- dec->pixels_ = NULL;
- for (i = 0; i < dec->next_transform_; ++i) {
- ClearTransform(&dec->transforms_[i]);
- }
- dec->next_transform_ = 0;
- dec->transforms_seen_ = 0;
- WebPSafeFree(dec->rescaler_memory);
- dec->rescaler_memory = NULL;
- dec->output_ = NULL; // leave no trace behind
- }
- void VP8LDelete(VP8LDecoder* const dec) {
- if (dec != NULL) {
- VP8LClear(dec);
- WebPSafeFree(dec);
- }
- }
- static void UpdateDecoder(VP8LDecoder* const dec, int width, int height) {
- VP8LMetadata* const hdr = &dec->hdr_;
- const int num_bits = hdr->huffman_subsample_bits_;
- dec->width_ = width;
- dec->height_ = height;
- hdr->huffman_xsize_ = VP8LSubSampleSize(width, num_bits);
- hdr->huffman_mask_ = (num_bits == 0) ? ~0 : (1 << num_bits) - 1;
- }
- static int DecodeImageStream(int xsize, int ysize,
- int is_level0,
- VP8LDecoder* const dec,
- uint32_t** const decoded_data) {
- int ok = 1;
- int transform_xsize = xsize;
- int transform_ysize = ysize;
- VP8LBitReader* const br = &dec->br_;
- VP8LMetadata* const hdr = &dec->hdr_;
- uint32_t* data = NULL;
- int color_cache_bits = 0;
- // Read the transforms (may recurse).
- if (is_level0) {
- while (ok && VP8LReadBits(br, 1)) {
- ok = ReadTransform(&transform_xsize, &transform_ysize, dec);
- }
- }
- // Color cache
- if (ok && VP8LReadBits(br, 1)) {
- color_cache_bits = VP8LReadBits(br, 4);
- ok = (color_cache_bits >= 1 && color_cache_bits <= MAX_CACHE_BITS);
- if (!ok) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- goto End;
- }
- }
- // Read the Huffman codes (may recurse).
- ok = ok && ReadHuffmanCodes(dec, transform_xsize, transform_ysize,
- color_cache_bits, is_level0);
- if (!ok) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- goto End;
- }
- // Finish setting up the color-cache
- if (color_cache_bits > 0) {
- hdr->color_cache_size_ = 1 << color_cache_bits;
- if (!VP8LColorCacheInit(&hdr->color_cache_, color_cache_bits)) {
- dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
- ok = 0;
- goto End;
- }
- } else {
- hdr->color_cache_size_ = 0;
- }
- UpdateDecoder(dec, transform_xsize, transform_ysize);
- if (is_level0) { // level 0 complete
- dec->state_ = READ_HDR;
- goto End;
- }
- {
- const uint64_t total_size = (uint64_t)transform_xsize * transform_ysize;
- data = (uint32_t*)WebPSafeMalloc(total_size, sizeof(*data));
- if (data == NULL) {
- dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
- ok = 0;
- goto End;
- }
- }
- // Use the Huffman trees to decode the LZ77 encoded data.
- ok = DecodeImageData(dec, data, transform_xsize, transform_ysize,
- transform_ysize, NULL);
- ok = ok && !br->error_;
- End:
- if (!ok) {
- WebPSafeFree(data);
- ClearMetadata(hdr);
- // If not enough data (br.eos_) resulted in BIT_STREAM_ERROR, update the
- // status appropriately.
- if (dec->status_ == VP8_STATUS_BITSTREAM_ERROR && dec->br_.eos_) {
- dec->status_ = VP8_STATUS_SUSPENDED;
- }
- } else {
- if (decoded_data != NULL) {
- *decoded_data = data;
- } else {
- // We allocate image data in this function only for transforms. At level 0
- // (that is: not the transforms), we shouldn't have allocated anything.
- assert(data == NULL);
- assert(is_level0);
- }
- dec->last_pixel_ = 0; // Reset for future DECODE_DATA_FUNC() calls.
- if (!is_level0) ClearMetadata(hdr); // Clean up temporary data behind.
- }
- return ok;
- }
- //------------------------------------------------------------------------------
- // Allocate internal buffers dec->pixels_ and dec->argb_cache_.
- static int AllocateInternalBuffers32b(VP8LDecoder* const dec, int final_width) {
- const uint64_t num_pixels = (uint64_t)dec->width_ * dec->height_;
- // Scratch buffer corresponding to top-prediction row for transforming the
- // first row in the row-blocks. Not needed for paletted alpha.
- const uint64_t cache_top_pixels = (uint16_t)final_width;
- // Scratch buffer for temporary BGRA storage. Not needed for paletted alpha.
- const uint64_t cache_pixels = (uint64_t)final_width * NUM_ARGB_CACHE_ROWS;
- const uint64_t total_num_pixels =
- num_pixels + cache_top_pixels + cache_pixels;
- assert(dec->width_ <= final_width);
- dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint32_t));
- if (dec->pixels_ == NULL) {
- dec->argb_cache_ = NULL; // for sanity check
- dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
- return 0;
- }
- dec->argb_cache_ = dec->pixels_ + num_pixels + cache_top_pixels;
- return 1;
- }
- static int AllocateInternalBuffers8b(VP8LDecoder* const dec) {
- const uint64_t total_num_pixels = (uint64_t)dec->width_ * dec->height_;
- dec->argb_cache_ = NULL; // for sanity check
- dec->pixels_ = (uint32_t*)WebPSafeMalloc(total_num_pixels, sizeof(uint8_t));
- if (dec->pixels_ == NULL) {
- dec->status_ = VP8_STATUS_OUT_OF_MEMORY;
- return 0;
- }
- return 1;
- }
- //------------------------------------------------------------------------------
- // Special row-processing that only stores the alpha data.
- static void ExtractAlphaRows(VP8LDecoder* const dec, int row) {
- const int num_rows = row - dec->last_row_;
- const uint32_t* const in = dec->pixels_ + dec->width_ * dec->last_row_;
- if (num_rows <= 0) return; // Nothing to be done.
- ApplyInverseTransforms(dec, num_rows, in);
- // Extract alpha (which is stored in the green plane).
- {
- const int width = dec->io_->width; // the final width (!= dec->width_)
- const int cache_pixs = width * num_rows;
- uint8_t* const dst = (uint8_t*)dec->io_->opaque + width * dec->last_row_;
- const uint32_t* const src = dec->argb_cache_;
- int i;
- for (i = 0; i < cache_pixs; ++i) dst[i] = (src[i] >> 8) & 0xff;
- }
- dec->last_row_ = dec->last_out_row_ = row;
- }
- int VP8LDecodeAlphaHeader(ALPHDecoder* const alph_dec,
- const uint8_t* const data, size_t data_size,
- uint8_t* const output) {
- int ok = 0;
- VP8LDecoder* dec;
- VP8Io* io;
- assert(alph_dec != NULL);
- alph_dec->vp8l_dec_ = VP8LNew();
- if (alph_dec->vp8l_dec_ == NULL) return 0;
- dec = alph_dec->vp8l_dec_;
- dec->width_ = alph_dec->width_;
- dec->height_ = alph_dec->height_;
- dec->io_ = &alph_dec->io_;
- io = dec->io_;
- VP8InitIo(io);
- WebPInitCustomIo(NULL, io); // Just a sanity Init. io won't be used.
- io->opaque = output;
- io->width = alph_dec->width_;
- io->height = alph_dec->height_;
- dec->status_ = VP8_STATUS_OK;
- VP8LInitBitReader(&dec->br_, data, data_size);
- dec->action_ = READ_HDR;
- if (!DecodeImageStream(alph_dec->width_, alph_dec->height_, 1, dec, NULL)) {
- goto Err;
- }
- // Special case: if alpha data uses only the color indexing transform and
- // doesn't use color cache (a frequent case), we will use DecodeAlphaData()
- // method that only needs allocation of 1 byte per pixel (alpha channel).
- if (dec->next_transform_ == 1 &&
- dec->transforms_[0].type_ == COLOR_INDEXING_TRANSFORM &&
- Is8bOptimizable(&dec->hdr_)) {
- alph_dec->use_8b_decode = 1;
- ok = AllocateInternalBuffers8b(dec);
- } else {
- // Allocate internal buffers (note that dec->width_ may have changed here).
- alph_dec->use_8b_decode = 0;
- ok = AllocateInternalBuffers32b(dec, alph_dec->width_);
- }
- if (!ok) goto Err;
- dec->action_ = READ_DATA;
- return 1;
- Err:
- VP8LDelete(alph_dec->vp8l_dec_);
- alph_dec->vp8l_dec_ = NULL;
- return 0;
- }
- int VP8LDecodeAlphaImageStream(ALPHDecoder* const alph_dec, int last_row) {
- VP8LDecoder* const dec = alph_dec->vp8l_dec_;
- assert(dec != NULL);
- assert(dec->action_ == READ_DATA);
- assert(last_row <= dec->height_);
- if (dec->last_pixel_ == dec->width_ * dec->height_) {
- return 1; // done
- }
- // Decode (with special row processing).
- return alph_dec->use_8b_decode ?
- DecodeAlphaData(dec, (uint8_t*)dec->pixels_, dec->width_, dec->height_,
- last_row) :
- DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_,
- last_row, ExtractAlphaRows);
- }
- //------------------------------------------------------------------------------
- int VP8LDecodeHeader(VP8LDecoder* const dec, VP8Io* const io) {
- int width, height, has_alpha;
- if (dec == NULL) return 0;
- if (io == NULL) {
- dec->status_ = VP8_STATUS_INVALID_PARAM;
- return 0;
- }
- dec->io_ = io;
- dec->status_ = VP8_STATUS_OK;
- VP8LInitBitReader(&dec->br_, io->data, io->data_size);
- if (!ReadImageInfo(&dec->br_, &width, &height, &has_alpha)) {
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- goto Error;
- }
- dec->state_ = READ_DIM;
- io->width = width;
- io->height = height;
- dec->action_ = READ_HDR;
- if (!DecodeImageStream(width, height, 1, dec, NULL)) goto Error;
- return 1;
- Error:
- VP8LClear(dec);
- assert(dec->status_ != VP8_STATUS_OK);
- return 0;
- }
- int VP8LDecodeImage(VP8LDecoder* const dec) {
- VP8Io* io = NULL;
- WebPDecParams* params = NULL;
- // Sanity checks.
- if (dec == NULL) return 0;
- dec->status_ = VP8_STATUS_BITSTREAM_ERROR;
- assert(dec->hdr_.htree_groups_ != NULL);
- assert(dec->hdr_.num_htree_groups_ > 0);
- io = dec->io_;
- assert(io != NULL);
- params = (WebPDecParams*)io->opaque;
- assert(params != NULL);
- dec->output_ = params->output;
- assert(dec->output_ != NULL);
- // Initialization.
- if (!WebPIoInitFromOptions(params->options, io, MODE_BGRA)) {
- dec->status_ = VP8_STATUS_INVALID_PARAM;
- goto Err;
- }
- if (!AllocateInternalBuffers32b(dec, io->width)) goto Err;
- if (io->use_scaling && !AllocateAndInitRescaler(dec, io)) goto Err;
- if (io->use_scaling || WebPIsPremultipliedMode(dec->output_->colorspace)) {
- // need the alpha-multiply functions for premultiplied output or rescaling
- WebPInitAlphaProcessing();
- }
- // Decode.
- dec->action_ = READ_DATA;
- if (!DecodeImageData(dec, dec->pixels_, dec->width_, dec->height_,
- dec->height_, ProcessRows)) {
- goto Err;
- }
- // Cleanup.
- params->last_y = dec->last_out_row_;
- VP8LClear(dec);
- return 1;
- Err:
- VP8LClear(dec);
- assert(dec->status_ != VP8_STATUS_OK);
- return 0;
- }
- //------------------------------------------------------------------------------
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