160 lines
4.2 KiB
Rust
160 lines
4.2 KiB
Rust
/*
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* Copyright (C) 2026 Fluxer Contributors
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*
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* This file is part of Fluxer.
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*
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* Fluxer is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Fluxer is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
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*/
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use gif::{ColorOutput, DecodeOptions};
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use std::io::Cursor;
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use wasm_bindgen::prelude::*;
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const PNG_SIGNATURE: [u8; 8] = [137, 80, 78, 71, 13, 10, 26, 10];
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enum ImageFormat {
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Gif,
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Png,
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Webp,
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Avif,
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Unknown,
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}
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fn detect_format(input: &[u8]) -> ImageFormat {
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if input.len() >= 6 && &input[..6] == b"GIF89a" {
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return ImageFormat::Gif;
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}
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if input.len() >= 6 && &input[..6] == b"GIF87a" {
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return ImageFormat::Gif;
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}
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if input.len() >= PNG_SIGNATURE.len() && input[..PNG_SIGNATURE.len()] == PNG_SIGNATURE {
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return ImageFormat::Png;
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}
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if input.len() >= 12 && &input[..4] == b"RIFF" && &input[8..12] == b"WEBP" {
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return ImageFormat::Webp;
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}
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if is_avif_file(input) {
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return ImageFormat::Avif;
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}
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ImageFormat::Unknown
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}
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fn is_animated_gif(input: &[u8]) -> bool {
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let mut options = DecodeOptions::new();
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options.set_color_output(ColorOutput::RGBA);
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let cursor = Cursor::new(input);
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let mut reader = match options.read_info(cursor) {
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Ok(reader) => reader,
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Err(_) => return false,
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};
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let mut frame_count = 0;
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loop {
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match reader.read_next_frame() {
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Ok(Some(_frame)) => {
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frame_count += 1;
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if frame_count > 1 {
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return true;
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}
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}
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Ok(None) => break,
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Err(_) => return false,
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}
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}
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false
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}
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fn has_apng_actl(input: &[u8]) -> bool {
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if input.len() < PNG_SIGNATURE.len() || input[..PNG_SIGNATURE.len()] != PNG_SIGNATURE {
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return false;
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}
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let mut offset = PNG_SIGNATURE.len();
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while offset + 12 <= input.len() {
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let length_bytes = &input[offset..offset + 4];
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let length = u32::from_be_bytes(length_bytes.try_into().unwrap()) as usize;
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let chunk_type = &input[offset + 4..offset + 8];
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if chunk_type == b"acTL" {
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return true;
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}
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offset = offset
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.saturating_add(8)
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.saturating_add(length)
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.saturating_add(4);
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}
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false
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}
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fn has_webp_anim(input: &[u8]) -> bool {
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if input.len() < 12 || &input[..4] != b"RIFF" || &input[8..12] != b"WEBP" {
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return false;
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}
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let mut offset = 12;
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while offset + 8 <= input.len() {
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let chunk_id = &input[offset..offset + 4];
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let size_bytes = &input[offset + 4..offset + 8];
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let size = u32::from_le_bytes(size_bytes.try_into().unwrap()) as usize;
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if chunk_id == b"ANIM" {
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return true;
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}
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let advance = 8 + size + (size % 2);
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offset = offset.saturating_add(advance);
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}
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false
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}
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fn is_avif_file(input: &[u8]) -> bool {
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if input.len() < 12 {
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return false;
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}
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let box_type = &input[4..8];
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if box_type != b"ftyp" {
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return false;
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}
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let brand = &input[8..12];
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brand == b"avif" || brand == b"avis"
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}
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fn has_avif_anim(input: &[u8]) -> bool {
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if !is_avif_file(input) {
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return false;
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}
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if input.len() < 12 {
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return false;
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}
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let brand = &input[8..12];
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brand == b"avis"
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}
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#[wasm_bindgen]
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pub fn is_animated_image(input: &[u8]) -> bool {
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match detect_format(input) {
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ImageFormat::Gif => is_animated_gif(input),
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ImageFormat::Png => has_apng_actl(input),
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ImageFormat::Webp => has_webp_anim(input),
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ImageFormat::Avif => has_avif_anim(input),
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ImageFormat::Unknown => false,
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}
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}
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