feat: dotLottie optimized ZIP reader

dotlottie-rs/Cargo.toml

@@ -29,7 +29,7 @@ tvg-webp = []
 tvg-ttf = []
 tvg-threads = []
 tvg-simd = []
-dotlottie = ["dep:zip"]
+dotlottie = []
 state-machines = ["dotlottie"]
 theming = ["dotlottie"]
 wasm = []                                       # base: enables libc/C++ stubs for wasm32-unknown-unknown
@@ -41,7 +41,6 @@ webgpu = ["wasm-bindgen-api", "web-sys/Gpu", "web-sys/GpuAdapter", "web-sys/GpuA
 [dependencies]
 serde_json = { version = "1.0", default-features = false, features = ["preserve_order"] }
 serde = { version = "1.0", features = ["derive"] }
-zip = { version = "2.4.2", default-features = false, features = ["deflate"], optional = true }
 bitflags = { version = "2.6", optional = true }
 
 [target.wasm32-unknown-unknown.dependencies]

dotlottie-rs/src/io/dotlottie/base64.rs

@@ -0,0 +1,52 @@
+const BASE64_CHARS: &[u8; 64] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+pub(super) fn encode_into(input: &[u8], out: &mut String) {
+    let output_len = input.len().div_ceil(3) * 4;
+    out.reserve(output_len);
+
+    let mut i = 0;
+    while i + 2 < input.len() {
+        let b0 = input[i] as u32;
+        let b1 = input[i + 1] as u32;
+        let b2 = input[i + 2] as u32;
+        let n = (b0 << 16) | (b1 << 8) | b2;
+
+        out.push(BASE64_CHARS[((n >> 18) & 63) as usize] as char);
+        out.push(BASE64_CHARS[((n >> 12) & 63) as usize] as char);
+        out.push(BASE64_CHARS[((n >> 6) & 63) as usize] as char);
+        out.push(BASE64_CHARS[(n & 63) as usize] as char);
+        i += 3;
+    }
+
+    if i < input.len() {
+        let b0 = input[i] as u32;
+        let b1 = input.get(i + 1).copied().unwrap_or(0) as u32;
+        let n = (b0 << 16) | (b1 << 8);
+
+        out.push(BASE64_CHARS[((n >> 18) & 63) as usize] as char);
+        out.push(BASE64_CHARS[((n >> 12) & 63) as usize] as char);
+        out.push(if i + 1 < input.len() {
+            BASE64_CHARS[((n >> 6) & 63) as usize] as char
+        } else {
+            '='
+        });
+        out.push('=');
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn encode(input: &[u8]) -> String {
+        let mut out = String::new();
+        encode_into(input, &mut out);
+        out
+    }
+
+    #[test]
+    fn test_base64_encoding() {
+        assert_eq!(encode(b"Hello, World!"), "SGVsbG8sIFdvcmxkIQ==");
+        assert_eq!(encode(b""), "");
+    }
+}