diff options
Diffstat (limited to 'thirdparty/libwebp/src/demux/anim_decode.c')
| -rw-r--r-- | thirdparty/libwebp/src/demux/anim_decode.c | 454 |
1 files changed, 454 insertions, 0 deletions
diff --git a/thirdparty/libwebp/src/demux/anim_decode.c b/thirdparty/libwebp/src/demux/anim_decode.c new file mode 100644 index 0000000000..05dd707371 --- /dev/null +++ b/thirdparty/libwebp/src/demux/anim_decode.c @@ -0,0 +1,454 @@ +// Copyright 2015 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. +// ----------------------------------------------------------------------------- +// +// AnimDecoder implementation. +// + +#ifdef HAVE_CONFIG_H +#include "src/webp/config.h" +#endif + +#include <assert.h> +#include <string.h> + +#include "src/utils/utils.h" +#include "src/webp/decode.h" +#include "src/webp/demux.h" + +#define NUM_CHANNELS 4 + +typedef void (*BlendRowFunc)(uint32_t* const, const uint32_t* const, int); +static void BlendPixelRowNonPremult(uint32_t* const src, + const uint32_t* const dst, int num_pixels); +static void BlendPixelRowPremult(uint32_t* const src, const uint32_t* const dst, + int num_pixels); + +struct WebPAnimDecoder { + WebPDemuxer* demux_; // Demuxer created from given WebP bitstream. + WebPDecoderConfig config_; // Decoder config. + // Note: we use a pointer to a function blending multiple pixels at a time to + // allow possible inlining of per-pixel blending function. + BlendRowFunc blend_func_; // Pointer to the chose blend row function. + WebPAnimInfo info_; // Global info about the animation. + uint8_t* curr_frame_; // Current canvas (not disposed). + uint8_t* prev_frame_disposed_; // Previous canvas (properly disposed). + int prev_frame_timestamp_; // Previous frame timestamp (milliseconds). + WebPIterator prev_iter_; // Iterator object for previous frame. + int prev_frame_was_keyframe_; // True if previous frame was a keyframe. + int next_frame_; // Index of the next frame to be decoded + // (starting from 1). +}; + +static void DefaultDecoderOptions(WebPAnimDecoderOptions* const dec_options) { + dec_options->color_mode = MODE_RGBA; + dec_options->use_threads = 0; +} + +int WebPAnimDecoderOptionsInitInternal(WebPAnimDecoderOptions* dec_options, + int abi_version) { + if (dec_options == NULL || + WEBP_ABI_IS_INCOMPATIBLE(abi_version, WEBP_DEMUX_ABI_VERSION)) { + return 0; + } + DefaultDecoderOptions(dec_options); + return 1; +} + +static int ApplyDecoderOptions(const WebPAnimDecoderOptions* const dec_options, + WebPAnimDecoder* const dec) { + WEBP_CSP_MODE mode; + WebPDecoderConfig* config = &dec->config_; + assert(dec_options != NULL); + + mode = dec_options->color_mode; + if (mode != MODE_RGBA && mode != MODE_BGRA && + mode != MODE_rgbA && mode != MODE_bgrA) { + return 0; + } + dec->blend_func_ = (mode == MODE_RGBA || mode == MODE_BGRA) + ? &BlendPixelRowNonPremult + : &BlendPixelRowPremult; + WebPInitDecoderConfig(config); + config->output.colorspace = mode; + config->output.is_external_memory = 1; + config->options.use_threads = dec_options->use_threads; + // Note: config->output.u.RGBA is set at the time of decoding each frame. + return 1; +} + +WebPAnimDecoder* WebPAnimDecoderNewInternal( + const WebPData* webp_data, const WebPAnimDecoderOptions* dec_options, + int abi_version) { + WebPAnimDecoderOptions options; + WebPAnimDecoder* dec = NULL; + if (webp_data == NULL || + WEBP_ABI_IS_INCOMPATIBLE(abi_version, WEBP_DEMUX_ABI_VERSION)) { + return NULL; + } + + // Note: calloc() so that the pointer members are initialized to NULL. + dec = (WebPAnimDecoder*)WebPSafeCalloc(1ULL, sizeof(*dec)); + if (dec == NULL) goto Error; + + if (dec_options != NULL) { + options = *dec_options; + } else { + DefaultDecoderOptions(&options); + } + if (!ApplyDecoderOptions(&options, dec)) goto Error; + + dec->demux_ = WebPDemux(webp_data); + if (dec->demux_ == NULL) goto Error; + + dec->info_.canvas_width = WebPDemuxGetI(dec->demux_, WEBP_FF_CANVAS_WIDTH); + dec->info_.canvas_height = WebPDemuxGetI(dec->demux_, WEBP_FF_CANVAS_HEIGHT); + dec->info_.loop_count = WebPDemuxGetI(dec->demux_, WEBP_FF_LOOP_COUNT); + dec->info_.bgcolor = WebPDemuxGetI(dec->demux_, WEBP_FF_BACKGROUND_COLOR); + dec->info_.frame_count = WebPDemuxGetI(dec->demux_, WEBP_FF_FRAME_COUNT); + + // Note: calloc() because we fill frame with zeroes as well. + dec->curr_frame_ = (uint8_t*)WebPSafeCalloc( + dec->info_.canvas_width * NUM_CHANNELS, dec->info_.canvas_height); + if (dec->curr_frame_ == NULL) goto Error; + dec->prev_frame_disposed_ = (uint8_t*)WebPSafeCalloc( + dec->info_.canvas_width * NUM_CHANNELS, dec->info_.canvas_height); + if (dec->prev_frame_disposed_ == NULL) goto Error; + + WebPAnimDecoderReset(dec); + return dec; + + Error: + WebPAnimDecoderDelete(dec); + return NULL; +} + +int WebPAnimDecoderGetInfo(const WebPAnimDecoder* dec, WebPAnimInfo* info) { + if (dec == NULL || info == NULL) return 0; + *info = dec->info_; + return 1; +} + +// Returns true if the frame covers the full canvas. +static int IsFullFrame(int width, int height, int canvas_width, + int canvas_height) { + return (width == canvas_width && height == canvas_height); +} + +// Clear the canvas to transparent. +static int ZeroFillCanvas(uint8_t* buf, uint32_t canvas_width, + uint32_t canvas_height) { + const uint64_t size = + (uint64_t)canvas_width * canvas_height * NUM_CHANNELS * sizeof(*buf); + if (size != (size_t)size) return 0; + memset(buf, 0, (size_t)size); + return 1; +} + +// Clear given frame rectangle to transparent. +static void ZeroFillFrameRect(uint8_t* buf, int buf_stride, int x_offset, + int y_offset, int width, int height) { + int j; + assert(width * NUM_CHANNELS <= buf_stride); + buf += y_offset * buf_stride + x_offset * NUM_CHANNELS; + for (j = 0; j < height; ++j) { + memset(buf, 0, width * NUM_CHANNELS); + buf += buf_stride; + } +} + +// Copy width * height pixels from 'src' to 'dst'. +static int CopyCanvas(const uint8_t* src, uint8_t* dst, + uint32_t width, uint32_t height) { + const uint64_t size = (uint64_t)width * height * NUM_CHANNELS; + if (size != (size_t)size) return 0; + assert(src != NULL && dst != NULL); + memcpy(dst, src, (size_t)size); + return 1; +} + +// Returns true if the current frame is a key-frame. +static int IsKeyFrame(const WebPIterator* const curr, + const WebPIterator* const prev, + int prev_frame_was_key_frame, + int canvas_width, int canvas_height) { + if (curr->frame_num == 1) { + return 1; + } else if ((!curr->has_alpha || curr->blend_method == WEBP_MUX_NO_BLEND) && + IsFullFrame(curr->width, curr->height, + canvas_width, canvas_height)) { + return 1; + } else { + return (prev->dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) && + (IsFullFrame(prev->width, prev->height, canvas_width, + canvas_height) || + prev_frame_was_key_frame); + } +} + + +// Blend a single channel of 'src' over 'dst', given their alpha channel values. +// 'src' and 'dst' are assumed to be NOT pre-multiplied by alpha. +static uint8_t BlendChannelNonPremult(uint32_t src, uint8_t src_a, + uint32_t dst, uint8_t dst_a, + uint32_t scale, int shift) { + const uint8_t src_channel = (src >> shift) & 0xff; + const uint8_t dst_channel = (dst >> shift) & 0xff; + const uint32_t blend_unscaled = src_channel * src_a + dst_channel * dst_a; + assert(blend_unscaled < (1ULL << 32) / scale); + return (blend_unscaled * scale) >> 24; +} + +// Blend 'src' over 'dst' assuming they are NOT pre-multiplied by alpha. +static uint32_t BlendPixelNonPremult(uint32_t src, uint32_t dst) { + const uint8_t src_a = (src >> 24) & 0xff; + + if (src_a == 0) { + return dst; + } else { + const uint8_t dst_a = (dst >> 24) & 0xff; + // This is the approximate integer arithmetic for the actual formula: + // dst_factor_a = (dst_a * (255 - src_a)) / 255. + const uint8_t dst_factor_a = (dst_a * (256 - src_a)) >> 8; + const uint8_t blend_a = src_a + dst_factor_a; + const uint32_t scale = (1UL << 24) / blend_a; + + const uint8_t blend_r = + BlendChannelNonPremult(src, src_a, dst, dst_factor_a, scale, 0); + const uint8_t blend_g = + BlendChannelNonPremult(src, src_a, dst, dst_factor_a, scale, 8); + const uint8_t blend_b = + BlendChannelNonPremult(src, src_a, dst, dst_factor_a, scale, 16); + assert(src_a + dst_factor_a < 256); + + return (blend_r << 0) | + (blend_g << 8) | + (blend_b << 16) | + ((uint32_t)blend_a << 24); + } +} + +// Blend 'num_pixels' in 'src' over 'dst' assuming they are NOT pre-multiplied +// by alpha. +static void BlendPixelRowNonPremult(uint32_t* const src, + const uint32_t* const dst, int num_pixels) { + int i; + for (i = 0; i < num_pixels; ++i) { + const uint8_t src_alpha = (src[i] >> 24) & 0xff; + if (src_alpha != 0xff) { + src[i] = BlendPixelNonPremult(src[i], dst[i]); + } + } +} + +// Individually multiply each channel in 'pix' by 'scale'. +static WEBP_INLINE uint32_t ChannelwiseMultiply(uint32_t pix, uint32_t scale) { + uint32_t mask = 0x00FF00FF; + uint32_t rb = ((pix & mask) * scale) >> 8; + uint32_t ag = ((pix >> 8) & mask) * scale; + return (rb & mask) | (ag & ~mask); +} + +// Blend 'src' over 'dst' assuming they are pre-multiplied by alpha. +static uint32_t BlendPixelPremult(uint32_t src, uint32_t dst) { + const uint8_t src_a = (src >> 24) & 0xff; + return src + ChannelwiseMultiply(dst, 256 - src_a); +} + +// Blend 'num_pixels' in 'src' over 'dst' assuming they are pre-multiplied by +// alpha. +static void BlendPixelRowPremult(uint32_t* const src, const uint32_t* const dst, + int num_pixels) { + int i; + for (i = 0; i < num_pixels; ++i) { + const uint8_t src_alpha = (src[i] >> 24) & 0xff; + if (src_alpha != 0xff) { + src[i] = BlendPixelPremult(src[i], dst[i]); + } + } +} + +// Returns two ranges (<left, width> pairs) at row 'canvas_y', that belong to +// 'src' but not 'dst'. A point range is empty if the corresponding width is 0. +static void FindBlendRangeAtRow(const WebPIterator* const src, + const WebPIterator* const dst, int canvas_y, + int* const left1, int* const width1, + int* const left2, int* const width2) { + const int src_max_x = src->x_offset + src->width; + const int dst_max_x = dst->x_offset + dst->width; + const int dst_max_y = dst->y_offset + dst->height; + assert(canvas_y >= src->y_offset && canvas_y < (src->y_offset + src->height)); + *left1 = -1; + *width1 = 0; + *left2 = -1; + *width2 = 0; + + if (canvas_y < dst->y_offset || canvas_y >= dst_max_y || + src->x_offset >= dst_max_x || src_max_x <= dst->x_offset) { + *left1 = src->x_offset; + *width1 = src->width; + return; + } + + if (src->x_offset < dst->x_offset) { + *left1 = src->x_offset; + *width1 = dst->x_offset - src->x_offset; + } + + if (src_max_x > dst_max_x) { + *left2 = dst_max_x; + *width2 = src_max_x - dst_max_x; + } +} + +int WebPAnimDecoderGetNext(WebPAnimDecoder* dec, + uint8_t** buf_ptr, int* timestamp_ptr) { + WebPIterator iter; + uint32_t width; + uint32_t height; + int is_key_frame; + int timestamp; + BlendRowFunc blend_row; + + if (dec == NULL || buf_ptr == NULL || timestamp_ptr == NULL) return 0; + if (!WebPAnimDecoderHasMoreFrames(dec)) return 0; + + width = dec->info_.canvas_width; + height = dec->info_.canvas_height; + blend_row = dec->blend_func_; + + // Get compressed frame. + if (!WebPDemuxGetFrame(dec->demux_, dec->next_frame_, &iter)) { + return 0; + } + timestamp = dec->prev_frame_timestamp_ + iter.duration; + + // Initialize. + is_key_frame = IsKeyFrame(&iter, &dec->prev_iter_, + dec->prev_frame_was_keyframe_, width, height); + if (is_key_frame) { + if (!ZeroFillCanvas(dec->curr_frame_, width, height)) { + goto Error; + } + } else { + if (!CopyCanvas(dec->prev_frame_disposed_, dec->curr_frame_, + width, height)) { + goto Error; + } + } + + // Decode. + { + const uint8_t* in = iter.fragment.bytes; + const size_t in_size = iter.fragment.size; + const size_t out_offset = + (iter.y_offset * width + iter.x_offset) * NUM_CHANNELS; + WebPDecoderConfig* const config = &dec->config_; + WebPRGBABuffer* const buf = &config->output.u.RGBA; + buf->stride = NUM_CHANNELS * width; + buf->size = buf->stride * iter.height; + buf->rgba = dec->curr_frame_ + out_offset; + + if (WebPDecode(in, in_size, config) != VP8_STATUS_OK) { + goto Error; + } + } + + // During the decoding of current frame, we may have set some pixels to be + // transparent (i.e. alpha < 255). However, the value of each of these + // pixels should have been determined by blending it against the value of + // that pixel in the previous frame if blending method of is WEBP_MUX_BLEND. + if (iter.frame_num > 1 && iter.blend_method == WEBP_MUX_BLEND && + !is_key_frame) { + if (dec->prev_iter_.dispose_method == WEBP_MUX_DISPOSE_NONE) { + int y; + // Blend transparent pixels with pixels in previous canvas. + for (y = 0; y < iter.height; ++y) { + const size_t offset = + (iter.y_offset + y) * width + iter.x_offset; + blend_row((uint32_t*)dec->curr_frame_ + offset, + (uint32_t*)dec->prev_frame_disposed_ + offset, iter.width); + } + } else { + int y; + assert(dec->prev_iter_.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND); + // We need to blend a transparent pixel with its value just after + // initialization. That is, blend it with: + // * Fully transparent pixel if it belongs to prevRect <-- No-op. + // * The pixel in the previous canvas otherwise <-- Need alpha-blending. + for (y = 0; y < iter.height; ++y) { + const int canvas_y = iter.y_offset + y; + int left1, width1, left2, width2; + FindBlendRangeAtRow(&iter, &dec->prev_iter_, canvas_y, &left1, &width1, + &left2, &width2); + if (width1 > 0) { + const size_t offset1 = canvas_y * width + left1; + blend_row((uint32_t*)dec->curr_frame_ + offset1, + (uint32_t*)dec->prev_frame_disposed_ + offset1, width1); + } + if (width2 > 0) { + const size_t offset2 = canvas_y * width + left2; + blend_row((uint32_t*)dec->curr_frame_ + offset2, + (uint32_t*)dec->prev_frame_disposed_ + offset2, width2); + } + } + } + } + + // Update info of the previous frame and dispose it for the next iteration. + dec->prev_frame_timestamp_ = timestamp; + WebPDemuxReleaseIterator(&dec->prev_iter_); + dec->prev_iter_ = iter; + dec->prev_frame_was_keyframe_ = is_key_frame; + CopyCanvas(dec->curr_frame_, dec->prev_frame_disposed_, width, height); + if (dec->prev_iter_.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) { + ZeroFillFrameRect(dec->prev_frame_disposed_, width * NUM_CHANNELS, + dec->prev_iter_.x_offset, dec->prev_iter_.y_offset, + dec->prev_iter_.width, dec->prev_iter_.height); + } + ++dec->next_frame_; + + // All OK, fill in the values. + *buf_ptr = dec->curr_frame_; + *timestamp_ptr = timestamp; + return 1; + + Error: + WebPDemuxReleaseIterator(&iter); + return 0; +} + +int WebPAnimDecoderHasMoreFrames(const WebPAnimDecoder* dec) { + if (dec == NULL) return 0; + return (dec->next_frame_ <= (int)dec->info_.frame_count); +} + +void WebPAnimDecoderReset(WebPAnimDecoder* dec) { + if (dec != NULL) { + dec->prev_frame_timestamp_ = 0; + WebPDemuxReleaseIterator(&dec->prev_iter_); + memset(&dec->prev_iter_, 0, sizeof(dec->prev_iter_)); + dec->prev_frame_was_keyframe_ = 0; + dec->next_frame_ = 1; + } +} + +const WebPDemuxer* WebPAnimDecoderGetDemuxer(const WebPAnimDecoder* dec) { + if (dec == NULL) return NULL; + return dec->demux_; +} + +void WebPAnimDecoderDelete(WebPAnimDecoder* dec) { + if (dec != NULL) { + WebPDemuxReleaseIterator(&dec->prev_iter_); + WebPDemuxDelete(dec->demux_); + WebPSafeFree(dec->curr_frame_); + WebPSafeFree(dec->prev_frame_disposed_); + WebPSafeFree(dec); + } +} |