feat: composition parsing errors are now public (#19)

Makes potential errors public so developers can use it.

CHANGELOG.md

@@ -17,6 +17,7 @@ Subheadings to categorize changes are `added, changed, deprecated, removed, fixe
 ### Fixed
 
 - ViewBox clipping is now applied to the animation
+- Errors that may occur on parsing a lottie composition are now public as `VelatoError`. ([#19](https://github.com/linebender/velato/pull/19))
 
 ## 0.1.0 (2024-03-26)
 

Cargo.toml

@@ -25,6 +25,7 @@ vello = { version = "0.1.0", default-features = false }
 vello = { workspace = true }
 keyframe = "1.1.1"
 once_cell = "1.19.0"
+thiserror = "1.0.61"
 
 # For the parser
 serde = { version = "1.0.197", features = ["derive"] }

src/lib.rs

@@ -50,4 +50,4 @@ pub(crate) mod schema;
 // Re-export vello
 pub use vello;
 
-pub use runtime::{model, Composition, Renderer};
+pub use runtime::{model, Composition, Renderer, VelatoError};

src/runtime/mod.rs

@@ -3,16 +3,16 @@
 
 mod render;
 
+use crate::import;
+use crate::schema::Animation;
 use std::collections::HashMap;
 use std::ops::Range;
+use thiserror::Error;
 
 pub mod model;
 
 pub use render::Renderer;
 
-use crate::import;
-use crate::schema::Animation;
-
 /// Model of a Lottie file.
 #[derive(Clone, Default, Debug)]
 pub struct Composition {
@@ -30,24 +30,32 @@ pub struct Composition {
     pub layers: Vec<model::Layer>,
 }
 
+/// Triggered when is an issue parsing a lottie file.
+#[derive(Error, Debug)]
+#[non_exhaustive]
+pub enum VelatoError {
+    #[error("Error parsing lottie: {0}")]
+    Json(#[from] serde_json::Error),
+}
+
 impl Composition {
     /// Creates a new runtime composition from a buffer of Lottie file contents.
-    pub fn from_slice(source: impl AsRef<[u8]>) -> Result<Composition, serde_json::Error> {
+    pub fn from_slice(source: impl AsRef<[u8]>) -> Result<Composition, VelatoError> {
         let source = Animation::from_slice(source.as_ref())?;
         let composition = import::conv_animation(source);
         Ok(composition)
     }
 
     /// Creates a new runtime composition from a json object of Lottie file contents.
-    pub fn from_json(v: serde_json::Value) -> Result<Composition, serde_json::Error> {
+    pub fn from_json(v: serde_json::Value) -> Result<Composition, VelatoError> {
         let source = Animation::from_json(v)?;
         let composition = import::conv_animation(source);
         Ok(composition)
     }
 }
 
 impl std::str::FromStr for Composition {
-    type Err = serde_json::Error;
+    type Err = VelatoError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let source = Animation::from_str(s)?;