# Custom field renderers

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Custom renderers change native presentation without moving calculations, visibility,
requirements, or validation out of `form0-core`.

## Per-form overrides

Pass a renderer map directly to `FormRenderer` for an isolated form:

```jsx
import { FormRenderer } from "form0-react-native"
import { PhotoField } from "./photo-field.jsx"

;<FormRenderer schema={schema} renderers={{ PhotoField }} />
```

A renderer receives the field and its evaluated interaction state:

```jsx
function PhotoField({ field, value, onChange, readOnly, required, error, inputProps }) {
  // Render application-owned capture, preview, and removal controls.
}
```

Preserve applicable properties from `inputProps`, and call `onChange` with the value shape expected
by the schema and submission boundary.

## Providers, registries, and global overrides

Use `FieldRegistryProvider` for a subtree override or
`createFieldRegistry({ includeDefaults, renderers })` for an explicit registry instance. The
module-level `registerFieldComponent`, `unregisterFieldComponent`, and `resetFieldComponents`
helpers mutate the shared default registry and are best reserved for bootstrap code or tests.

Only field types declared by `form0-core` can be registered. A new schema field type must first be
defined in Core; a native renderer alone cannot extend the schema contract.