form-field-control.ts

/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.dev/license
 */

import {Observable} from 'rxjs';
import {AbstractControlDirective, NgControl} from '@angular/forms';
import {Directive} from '@angular/core';

/** An interface which allows a control to work inside of a `MatFormField`. */
@Directive()
export abstract class MatFormFieldControl<T> {
  /** The value of the control. */
  value: T | null;

  /**
   * Stream that emits whenever the state of the control changes such that the parent `MatFormField`
   * needs to run change detection.
   */
  readonly stateChanges: Observable<void>;

  /** The element ID for this control. */
  readonly id: string;

  /** The placeholder for this control. */
  readonly placeholder: string;

  /** Gets the AbstractControlDirective for this control. */
  readonly ngControl: NgControl | AbstractControlDirective | null;

  /** Whether the control is focused. */
  readonly focused: boolean;

  /** Whether the control is empty. */
  readonly empty: boolean;

  /** Whether the `MatFormField` label should try to float. */
  readonly shouldLabelFloat: boolean;

  /** Whether the control is required. */
  readonly required: boolean;

  /** Whether the control is disabled. */
  readonly disabled: boolean;

  /** Whether the control is in an error state. */
  readonly errorState: boolean;

  /**
   * An optional name for the control type that can be used to distinguish `mat-form-field` elements
   * based on their control type. The form field will add a class,
   * `mat-form-field-type-{{controlType}}` to its root element.
   */
  readonly controlType?: string;

  /**
   * Whether the input is currently in an autofilled state. If property is not present on the
   * control it is assumed to be false.
   */
  readonly autofilled?: boolean;

  /**
   * Value of `aria-describedby` that should be merged with the described-by ids
   * which are set by the form-field.
   */
  readonly userAriaDescribedBy?: string;

  /**
   * Value of `aria-labelledby` that should be merged with the labelled-by ids
   * which are set by the form-field.
   */
  readonly userAriaLabelledBy?: string;

  /**
   * Whether to automatically assign the ID of the form field as the `for` attribute
   * on the `<label>` inside the form field. Set this to true to prevent the form
   * field from associating the label with non-native elements.
   */
  readonly disableAutomaticLabeling?: boolean;

  /** Sets the list of element IDs that currently describe this control. */
  abstract setDescribedByIds(ids: string[]): void;

  /** Sets the list of element IDs that currently label this control. */
  abstract setLabelledByIds(ids: string[]): void;

  /** Handles a click on the control's container. */
  abstract onContainerClick(event: MouseEvent): void;
}