refactor progress

fluxer_app/crates/libfluxcore/src/animation.rs

@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+use gif::{ColorOutput, DecodeOptions};
+use std::io::Cursor;
+use wasm_bindgen::prelude::*;
+
+const PNG_SIGNATURE: [u8; 8] = [137, 80, 78, 71, 13, 10, 26, 10];
+
+enum ImageFormat {
+    Gif,
+    Png,
+    Webp,
+    Avif,
+    Unknown,
+}
+
+fn detect_format(input: &[u8]) -> ImageFormat {
+    if input.len() >= 6 && &input[..6] == b"GIF89a" {
+        return ImageFormat::Gif;
+    }
+    if input.len() >= 6 && &input[..6] == b"GIF87a" {
+        return ImageFormat::Gif;
+    }
+    if input.len() >= PNG_SIGNATURE.len() && input[..PNG_SIGNATURE.len()] == PNG_SIGNATURE {
+        return ImageFormat::Png;
+    }
+    if input.len() >= 12 && &input[..4] == b"RIFF" && &input[8..12] == b"WEBP" {
+        return ImageFormat::Webp;
+    }
+    if is_avif_file(input) {
+        return ImageFormat::Avif;
+    }
+    ImageFormat::Unknown
+}
+
+fn is_animated_gif(input: &[u8]) -> bool {
+    let mut options = DecodeOptions::new();
+    options.set_color_output(ColorOutput::RGBA);
+    let cursor = Cursor::new(input);
+    let mut reader = match options.read_info(cursor) {
+        Ok(reader) => reader,
+        Err(_) => return false,
+    };
+
+    let mut frame_count = 0;
+    loop {
+        match reader.read_next_frame() {
+            Ok(Some(_frame)) => {
+                frame_count += 1;
+                if frame_count > 1 {
+                    return true;
+                }
+            }
+            Ok(None) => break,
+            Err(_) => return false,
+        }
+    }
+    false
+}
+
+fn has_apng_actl(input: &[u8]) -> bool {
+    if input.len() < PNG_SIGNATURE.len() || input[..PNG_SIGNATURE.len()] != PNG_SIGNATURE {
+        return false;
+    }
+
+    let mut offset = PNG_SIGNATURE.len();
+    while offset + 12 <= input.len() {
+        let length_bytes = &input[offset..offset + 4];
+        let length = u32::from_be_bytes(length_bytes.try_into().unwrap()) as usize;
+        let chunk_type = &input[offset + 4..offset + 8];
+        if chunk_type == b"acTL" {
+            return true;
+        }
+        offset = offset
+            .saturating_add(8)
+            .saturating_add(length)
+            .saturating_add(4);
+    }
+
+    false
+}
+
+fn has_webp_anim(input: &[u8]) -> bool {
+    if input.len() < 12 || &input[..4] != b"RIFF" || &input[8..12] != b"WEBP" {
+        return false;
+    }
+
+    let mut offset = 12;
+    while offset + 8 <= input.len() {
+        let chunk_id = &input[offset..offset + 4];
+        let size_bytes = &input[offset + 4..offset + 8];
+        let size = u32::from_le_bytes(size_bytes.try_into().unwrap()) as usize;
+
+        if chunk_id == b"ANIM" {
+            return true;
+        }
+
+        let advance = 8 + size + (size % 2);
+        offset = offset.saturating_add(advance);
+    }
+
+    false
+}
+
+fn is_avif_file(input: &[u8]) -> bool {
+    if input.len() < 12 {
+        return false;
+    }
+
+    let box_type = &input[4..8];
+
+    if box_type != b"ftyp" {
+        return false;
+    }
+
+    let brand = &input[8..12];
+    brand == b"avif" || brand == b"avis"
+}
+
+fn has_avif_anim(input: &[u8]) -> bool {
+    if !is_avif_file(input) {
+        return false;
+    }
+
+    if input.len() < 12 {
+        return false;
+    }
+
+    let brand = &input[8..12];
+    brand == b"avis"
+}
+
+#[wasm_bindgen]
+pub fn is_animated_image(input: &[u8]) -> bool {
+    match detect_format(input) {
+        ImageFormat::Gif => is_animated_gif(input),
+        ImageFormat::Png => has_apng_actl(input),
+        ImageFormat::Webp => has_webp_anim(input),
+        ImageFormat::Avif => has_avif_anim(input),
+        ImageFormat::Unknown => false,
+    }
+}