ionic-framework/ionic/components/tabs/tab.ts

import {Component, Inject, forwardRef, ElementRef, NgZone, Renderer, DynamicComponentLoader, ViewContainerRef, ViewChild, Type, ViewEncapsulation, ChangeDetectorRef, EventEmitter, Input, Output} from '@angular/core';

import {IonicApp} from '../app/app';
import {Config} from '../../config/config';
import {isTrueProperty} from '../../util/util';
import {Keyboard} from '../../util/keyboard';
import {NavController, NavOptions} from '../nav/nav-controller';
import {ViewController} from '../nav/view-controller';
import {Tabs} from './tabs';
import {TabButton} from './tab-button';


/**
 * @name Tab
 * @description
 * The Tab component, written `<ion-tab>`, is styled based on the mode and should
 * be used in conjunction with the [Tabs](../Tabs/) component.
 *
 * Each tab has a separate navigation controller. For more information on using
 * navigation controllers take a look at the [NavController API Docs](../../nav/NavController/).
 *
 * See the [Tabs API Docs](../Tabs/) for more details on configuring Tabs.
 *
 * @usage
 *
 * To add a basic tab, you can use the following markup where the `root` property
 * is the page you want to load for that tab, `tabTitle` is the optional text to
 * display on the tab, and `tabIcon` is the optional [icon](../../icon/Icon/).
 *
 * ```html
 * <ion-tabs>
 *  <ion-tab [root]="chatRoot" tabTitle="Chat" tabIcon="chat"><ion-tab>
 * </ion-tabs>
 * ```
 *
 * Then, in your class you can set `chatRoot` to an imported class:
 *
 * ```ts
 * import {ChatPage} from '../chat/chat';
 *
 * export class Tabs {
 *   // here we'll set the property of chatRoot to
 *   // the imported class of ChatPage
 *   chatRoot = ChatPage;
 *
 *   constructor() {
 *
 *   }
 * }
 * ```
 *
 * You can also pass some parameters to the root page of the tab through
 * `rootParams`. Below we pass `chatParams` to the Chat tab:
 *
 * ```html
 * <ion-tabs>
 *  <ion-tab [root]="chatRoot" [rootParams]="chatParams" tabTitle="Chat" tabIcon="chat"><ion-tab>
 * </ion-tabs>
 * ```
 *
 * ```ts
 * export class Tabs {
 *   chatRoot = ChatPage;
 *
 *   // set some user information on chatParams
 *   chatParams = {
 *     user1: "admin",
 *     user2: "ionic"
 *   };
 *
 *   constructor() {
 *
 *   }
 * }
 * ```
 *
 * And in `ChatPage` you can get the data from `NavParams`:
 *
 * ```ts
 * export class ChatPage {
 *   constructor(navParams: NavParams) {
 *     console.log("Passed params", navParams.data);
 *   }
 * }
 * ```
 *
 * Sometimes you may want to call a method instead of navigating to a new
 * page. You can use the `(select)` event to call a method on your class when
 * the tab is selected. Below is an example of presenting a modal from one of
 * the tabs.
 *
 * ```html
 * <ion-tabs preloadTabs="false">
 *   <ion-tab (select)="chat()"></ion-tab>
 * </ion-tabs>
 * ```
 *
 * ```ts
 * export class Tabs {
 *   constructor(nav: NavController) {
 *     this.nav = nav;
 *   }
 *
 *   chat() {
 *     let modal = Modal.create(ChatPage);
 *     this.nav.present(modal);
 *   }
 * }
 * ```
 *
 *
 * @demo /docs/v2/demos/tabs/
 * @see {@link /docs/v2/components#tabs Tabs Component Docs}
 * @see {@link ../../tabs/Tabs Tabs API Docs}
 * @see {@link ../../nav/Nav Nav API Docs}
 * @see {@link ../../nav/NavController NavController API Docs}
 */
@Component({
  selector: 'ion-tab',
  host: {
    '[class.show-tab]': 'isSelected',
    '[attr.id]': '_panelId',
    '[attr.aria-labelledby]': '_btnId',
    'role': 'tabpanel'
  },
  template: '<div #viewport></div>',
  encapsulation: ViewEncapsulation.None,
})
export class Tab extends NavController {
  private _isInitial: boolean;
  private _isEnabled: boolean = true;
  private _isShown: boolean = true;
  private _panelId: string;
  private _btnId: string;
  private _loaded: boolean;
  private _loadTmr: any;

  /**
   * @private
   */
  isSelected: boolean;

  /**
   * @private
   */
  btn: TabButton;

  /**
   * @input {Page} Set the root page for this tab.
   */
  @Input() root: Type;

  /**
   * @input {object} Any nav-params to pass to the root page of this tab.
   */
  @Input() rootParams: any;

  /**
   * @input {string} The title of the tab button.
   */
  @Input() tabTitle: string;

  /**
   * @input {string} The icon for the tab button.
   */
  @Input() tabIcon: string;

  /**
   * @input {string} The badge for the tab button.
   */
  @Input() tabBadge: string;

  /**
   * @input {string} The badge color for the tab button.
   */
  @Input() tabBadgeStyle: string;

  /**
   * @input {boolean} If the tab is enabled or not. If the tab
   * is not enabled then the tab button will still show, however,
   * the button will appear grayed out and will not be clickable.
   * Defaults to `true`.
   */
  @Input()
  get enabled(): boolean {
    return this._isEnabled;
  }
  set enabled(val: boolean) {
    this._isEnabled = isTrueProperty(val);
  }

  /**
   * @input {boolean} If the tab button is visible within the
   * tabbar or not. Defaults to `true`.
   */
  @Input()
  get show(): boolean {
    return this._isShown;
  }
  set show(val: boolean) {
    this._isShown = isTrueProperty(val);
  }

  /**
   * @output {Tab} Method to call when the current tab is selected
   */
  @Output() select: EventEmitter<Tab> = new EventEmitter();

  constructor(
    @Inject(forwardRef(() => Tabs)) parentTabs: Tabs,
    app: IonicApp,
    config: Config,
    keyboard: Keyboard,
    elementRef: ElementRef,
    zone: NgZone,
    renderer: Renderer,
    loader: DynamicComponentLoader,
    private _cd: ChangeDetectorRef
  ) {
    // A Tab is a NavController for its child pages
    super(parentTabs, app, config, keyboard, elementRef, zone, renderer, loader);

    parentTabs.add(this);

    this._panelId = 'tabpanel-' + this.id;
    this._btnId = 'tab-' + this.id;
  }

  /**
   * @private
   */
  @ViewChild('viewport', {read: ViewContainerRef})
  set _vp(val: ViewContainerRef) {
    this.setViewport(val);
  }

  /**
   * @private
   */
  ngOnInit() {
    this.tabBadgeStyle = this.tabBadgeStyle ? this.tabBadgeStyle : 'default';
  }

  /**
   * @private
   */
  load(opts: NavOptions, done?: Function) {
    if (!this._loaded && this.root) {
      this.push(this.root, this.rootParams, opts).then(() => {
        done();
      });
      this._loaded = true;

    } else {
      done();
    }
  }


  /**
   * @private
   */
  preload(wait: number) {
    this._loadTmr = setTimeout(() => {
      if (!this._loaded) {
        console.debug('Tabs, preload', this.id);
        this.load({
          animate: false,
          preload: true,
          postLoad: (viewCtrl) => {
            let navbar = viewCtrl.getNavbar();
            navbar && navbar.setHidden(true);
          }
        }, function(){});
      }
    }, wait);
  }

  /**
   * @private
   */
  loadPage(viewCtrl: ViewController, navbarContainerRef: any, opts: NavOptions, done: Function) {
    // by default a page's navbar goes into the shared tab's navbar section
    navbarContainerRef = this.parent.navbarContainerRef;

    let isTabSubPage = (this.parent.subPages && viewCtrl.index > 0);
    if (isTabSubPage) {
      // a subpage, that's not the first index
      // should not use the shared tabs navbar section, but use it's own
      navbarContainerRef = null;
    }

    super.loadPage(viewCtrl, navbarContainerRef, opts, () => {
      if (viewCtrl.instance) {
        viewCtrl.instance._tabSubPage = isTabSubPage;
      }
      done();
    });
  }

  /**
   * @private
   */
  setSelected(isSelected: boolean) {
    this.isSelected = isSelected;

    if (isSelected) {
      // this is the selected tab, detect changes
      this._cd.reattach();

    } else {
      // this tab is not selected, do not detect changes
      this._cd.detach();
    }

    this.hideNavbars(!isSelected);
  }

  /**
   * @private
   */
  hideNavbars(shouldHideNavbars: boolean) {
    this._views.forEach(viewCtrl => {
      let navbar = viewCtrl.getNavbar();
      navbar && navbar.setHidden(shouldHideNavbars);
    });
  }

  /**
   * @private
   */
  get index(): number {
    return this.parent.getIndex(this);
  }

  /**
   * @private
   */
  ngOnDestroy() {
    clearTimeout(this._loadTmr);
    super.ngOnDestroy();
  }

}