ngrx-forms uses a mechanism called FormViewAdapter to connect form elements in the DOM to the state. These adapters are basically the same as the ControlValueAccessor concept of @angular/forms, however, they are optimized for ngrx-forms and allow for having fewer touching points in the library with @angular/forms.
However, since many third party libraries are using the ControlValueAccessor already, ngrx-forms integrates with these libraries by converting the value accessor internally into a view adapter. Therefore, all third party form components should work with ngrx-forms out of the box as long as they properly export the value accessor.
However, in case a library does not do this you can write a custom view adapter (if you want to integrate more directly with ngrx-forms) or a value accessor. Use the injection token NGRX_FORM_VIEW_ADAPTER to register a custom adapter. See the example app for such a custom view adapter (in this case for the mat-select from @angular/material which in version 5.0.0-rc0 does not export the mat-select's value accessor).
A FormViewAdapter is defined as follows:
export interface FormViewAdapter {
/**
* Sets a new value for the form element.
*/
setViewValue(value: any): void;
/**
* Set the function to be called when the form element receives a change event.
*/
setOnChangeCallback(fn: (value: any) => void): void;
/**
* Set the function to be called when the form element receives a touch event.
*/
setOnTouchedCallback(fn: () => void): void;
/**
* Enable or disable the form element.
*/
setIsDisabled?(isDisabled: boolean): void;
}