# irondash_texture
Platform agnostic (as much as possible) interface to Flutter external textures.
Core idea is to implement `PayloadProvider` trait for your object that
provides texture data and then create `Texture` for the provider:
```rust
struct MyPayloadProvider {
// ...
}
impl PayloadProvider<PixelBuffer> for MyPayloadProvider {
// This method will be called by Flutter during rasterization
// to get new texture data.
fn get_payload(&self) -> BoxedPayload<PixelBuffer> {
let buffer = PixelBuffer {
width,
height,
data,
};
buffer.into_boxed_payload();
}
}
```
After you have `PayloadProvider` you can create `Texture`:
```rust
let provider = Arc::new(MyPayloadProvider::new());
let texture = Texture::new_with_provider(engine_handle, provider)?;
let id = texture.id(); // pass this ID back to Flutter to create Texture widget.
/// This tells Flutter that it should refresh the texture and redraw frame.
texture.mark_frame_available();
```
To create texture, you need to have handle for current Flutter engine, which you can obtain through [irondash_engine_context](https://github.com/irondash/irondash/tree/main/engine_context).
`PixelBuffer` payload type is supported on all platforms, though pixel order may change depending on platform. To find out pixel order for current platform use `PixelBuffer::FORMAT`.
Other than `PixelBuffer`, there are platform specific payload types that can be used to display GPU texture.
- `IOSurface` on macOS and iOS
- `GLTexture` on Linux
- `TextureDescriptor<ID3D11Texture2D>` and `TextureDescriptor<DxgiSharedHandle>` on Windows
To use GPU texture on Android, instead of setting payload, you can request JNI `Surface` or NDK `ANativeWindow` from the texture:
```rust
let texture = Texture::<NativeWindow>::new(engine_handle)?;
let native_window = texture.get()?;
```
## Threading
`PayloadProvider` must be `Send` and `Sync`, the texture payload will be requested on platform thread.
`Texture` itself must be created on platform thread. However once the texture is
created, you can convert it to `SendableTexture`, which can be moved between threads:
```rust
let texture = Texture::new_with_provider(engine_handle, provider)?;
let texture = texture.into_sendable_texture();
texture.mark_frame_available();
});
```