custom_modal.ts

/* Copyright 2024 The TensorFlow Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/
import {Injectable, TemplateRef, ViewContainerRef} from '@angular/core';
import {ConnectedPosition, Overlay, OverlayRef} from '@angular/cdk/overlay';
import {TemplatePortal} from '@angular/cdk/portal';
import {Subject, Subscription} from 'rxjs';
import {isMouseEventInElement} from '../../util/dom';

/**
 * Enables dynamic creation of modal components.
 *
 * # Usage
 * Define a modal using an ng-template:
 * ```
 * <ng-template #myModalTemplate>
 *    <my-awesome-modal-content
 *      [input1]="input1"
 *      (output1)="output1"
 *    >
 *    </my-awesome-modal-content>
 * </ng-template>
 * ```
 *
 * Define a ViewChild to reference the template in the component file:
 * ```
 * // my_component.ts
 * ...
 * @ViewChild('myModalTemplate', {read: TemplateRef})
 * myModalTemplate!: TemplateRef<unknown>;
 * ...
 * ```
 *
 * Inject CustomModal and ViewContainerRef into the component
 * ```
 * // my_component.ts
 * ...
 * constructor(
 *  private readonly customModal: CustomModal,
 *  private readonly viewContainerRef: ViewContainerRef,
 * ) {}
 * ...
 * ```
 *
 * To create a modal, call createNextToElement():
 * ```
 * // my_component.ts
 * ...
 * onSomeButtonClick(mouseEvent: MouseEventj) {
 *   this.customModal.createNextToElement(
 *     this.myModalTemplate,
 *     mouseEvent.target as HTMLElement,
 *     this.viewContainerRef
 *   );
 * }
 * ...
 * ```
 */

export class CustomModalRef {
  overlayRef: OverlayRef;
  subscriptions: Subscription[] = [];
  onClose = new Subject<void>();

  constructor(overlayRef: OverlayRef) {
    this.overlayRef = overlayRef;
  }
}

@Injectable({providedIn: 'root'})
export class CustomModal {
  private customModalRefs: CustomModalRef[] = [];

  constructor(private readonly overlay: Overlay) {}

  /** Creates a modal from a template next to an element. */
  createNextToElement(
    templateRef: TemplateRef<unknown>,
    element: Element,
    viewContainerRef: ViewContainerRef,
    connectedPosition: ConnectedPosition = {
      originX: 'end',
      originY: 'top',
      overlayX: 'start',
      overlayY: 'top',
    }
  ): CustomModalRef | undefined {
    let positionStrategy = this.overlay.position().flexibleConnectedTo(element);
    if (connectedPosition) {
      positionStrategy = positionStrategy.withPositions([connectedPosition]);
    }

    const overlayRef = this.overlay.create({
      positionStrategy,
      hasBackdrop: false,
    });
    overlayRef.attach(new TemplatePortal(templateRef, viewContainerRef));
    const customModalRef = new CustomModalRef(overlayRef);
    this.customModalRefs.push(customModalRef);

    // setTimeout to prevent closing immediately after modal open.
    setTimeout(() => {
      const outsidePointerEventsSubscription = overlayRef
        .outsidePointerEvents()
        .subscribe((event) => {
          // Only close when click is outside of every modal
          if (
            this.customModalRefs.every(
              (ref) =>
                !isMouseEventInElement(event, ref.overlayRef.overlayElement)
            )
          ) {
            this.closeAll();
          }
        });
      customModalRef.subscriptions.push(outsidePointerEventsSubscription);
    });

    const keydownEventsSubscription = overlayRef
      .keydownEvents()
      .subscribe((event) => {
        if (event.key === 'Escape') {
          this.closeAll();
        }
      });
    customModalRef.subscriptions.push(keydownEventsSubscription);

    return customModalRef;
  }

  /** Destroys given custom modal and related resources. */
  close(customModalRef: CustomModalRef) {
    const index = this.customModalRefs.findIndex(
      (ref) => ref === customModalRef
    );
    if (index === -1) {
      console.warn('Could not find customModalRef', customModalRef);
      return;
    }

    customModalRef.subscriptions.forEach((subscription) => {
      subscription.unsubscribe();
    });
    customModalRef.subscriptions = [];
    customModalRef.overlayRef?.dispose();

    this.customModalRefs.splice(index, 1);

    customModalRef.onClose.next();
    customModalRef.onClose.complete();
  }

  /** Destroys all created modals. */
  closeAll() {
    while (this.customModalRefs.length) {
      this.close(this.customModalRefs[0]);
    }
  }
}