Trait Asset
pub trait Asset:
Sized
+ Send
+ Sync
+ 'static {
type Loader: Loader<Self>;
const EXTENSION: &'static str = "";
const EXTENSIONS: &'static [&'static str] = _;
const HOT_RELOADED: bool = true;
// Provided method
fn default_value(
id: &SharedString,
error: Box<dyn Error + Sync + Send>,
) -> Result<Self, Box<dyn Error + Sync + Send>> { ... }
}Expand description
An asset is a type loadable from raw bytes.
Assets can be loaded and retrieved by an AssetCache.
This trait should only perform a conversion from raw bytes to the concrete
type. If you need to load other assets, please use the Compound trait.
§Extension
You can provide several extensions that will be used to search and load
assets. When loaded, each extension is tried in order until a file is
correctly loaded or no extension remains. The empty string "" means a file
without extension. You cannot use character ..
The EXTENSION field is a convenient shortcut if your asset uses only one
extension. If you set a value for EXTENSIONS too, this field is ignored.
If neither EXTENSION nor EXTENSIONS is set, the default is no extension.
If you use hot-reloading, the asset will be reloaded each time one of the file with the given extension is touched.
§Example
Suppose you make a physics simulation, and you store positions and speeds in a Bincode-encoded file, with extension “.data”.
use assets_manager::{Asset, loader};
use serde::Deserialize;
#[derive(Deserialize)]
struct Vector {
x: f32,
y: f32,
z: f32,
}
#[derive(Deserialize)]
struct World {
pos: Vec<Vector>,
speed: Vec<Vector>,
}
impl Asset for World {
const EXTENSION: &'static str = "data";
type Loader = loader::BincodeLoader;
}Provided Associated Constants§
const EXTENSION: &'static str = ""
const EXTENSION: &'static str = ""
Use this field if your asset only uses one extension.
This value is ignored if you set EXTENSIONS too.
const EXTENSIONS: &'static [&'static str] = _
const EXTENSIONS: &'static [&'static str] = _
This field enables you to specify multiple extension for an asset.
If EXTENSION is provided, you don’t have to set this constant.
If this array is empty, loading an asset of this type returns an error
unless a default value is provided with the default_value method.
const HOT_RELOADED: bool = true
const HOT_RELOADED: bool = true
If false, disable hot-reloading for assets of this type (true by
default). This avoids having to lock the asset to read it (ie it makes
[Handle::read] a noop)
Required Associated Types§
Provided Methods§
fn default_value(
id: &SharedString,
error: Box<dyn Error + Sync + Send>,
) -> Result<Self, Box<dyn Error + Sync + Send>>
fn default_value( id: &SharedString, error: Box<dyn Error + Sync + Send>, ) -> Result<Self, Box<dyn Error + Sync + Send>>
Specifies a eventual default value to use if an asset fails to load. If
this method returns Ok, the returned value is used as an asset. In
particular, if this method always returns Ok, AssetCache::load is
guaranteed not to fail.
The id parameter is given to easily report the error.
By default, this method always returns an error.
§Example
On error, log it and return a default value:
use assets_manager::{Asset, BoxedError, SharedString, loader};
use serde::Deserialize;
#[derive(Deserialize, Default)]
struct Item {
name: String,
kind: String,
}
impl Asset for Item {
const EXTENSION: &'static str = "json";
type Loader = loader::JsonLoader;
fn default_value(id: &SharedString, error: BoxedError) -> Result<Item, BoxedError> {
eprintln!("Error loading {}: {}. Using default value", id, error);
Ok(Item::default())
}
}Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.