ionic-framework/ionic/components/toolbar/toolbar.ts

import {Component, Directive, View, ElementRef} from 'angular2/angular2';
import {ProtoViewRef} from 'angular2/src/core/compiler/view_ref';

import * as dom from '../../util/dom';


@Component({
  selector: 'ion-toolbar'
})
@View({
  template: `<div class="toolbar-inner"><content></content></div>`
})
export class Toolbar {
  constructor(elementRef:ElementRef) {
    this.ele = elementRef.nativeElement;
  }

  alignTitle() {
    const toolbarEle = this.ele;
    const innerTitleEle = this._innerTitleEle || (this._innerTitleEle = toolbarEle.querySelector('.toolbar-inner-title'));
    const titleEle = this._titleEle || (this._titleEle = innerTitleEle.querySelector('ion-title'));
    const style = this._style || (this._style = window.getComputedStyle(titleEle));

    const titleOffsetWidth = titleEle.offsetWidth;
    const titleOffsetLeft = titleEle.offsetLeft;
    const titleScrollWidth = titleEle.scrollWidth;
    const toolbarOffsetWidth = toolbarEle.offsetWidth;

    // TODO!!! When an element is being reused by angular2, it'll sometimes keep the
    // styles from the original element's use, causing these calculations to be wrong
    if (window.getComputedStyle(innerTitleEle).margin !== '0px') {
      this._showTitle();
      return;
    }

    // only align if the title is center and if it isn't already overflowing
    if (style.textAlign !== 'center' || titleOffsetWidth < titleScrollWidth) {
      this._showTitle();

    } else {
      let rightMargin = toolbarOffsetWidth - (titleOffsetLeft + titleOffsetWidth);
      let centerMargin = titleOffsetLeft - rightMargin;

      innerTitleEle.style.margin = `0 ${centerMargin}px 0 0`;

      dom.raf(() => {
        if (titleEle.offsetWidth < titleEle.scrollWidth) {
          // not enough room yet, just left align title
          innerTitleEle.style.margin = '';
          innerTitleEle.style.textAlign = 'left';
        }
        this._showTitle();
      })
    }
  }

  _showTitle() {
    if (!this._shown) {
      this._shown = true;
      this._innerTitleEle.classList.remove('toolbar-title-hide');
    }
  }

}


/*
  Used to find and register headers in a view, and this directive's
  content will be moved up to the common toolbar location, and created
  using the same context as the view's content area.
*/
@Directive({
  selector: 'template[toolbar]'
})
export class ToolbarTemplate {
  constructor(item: ViewItem, protoViewRef: ProtoViewRef) {
    item.addProtoViewRef('toolbar', protoViewRef);
  }
}