ol.control implementation

[achimha]

I started looking into the unfinished control implementations.

There are a few questions. First of all, I don't think you can derive the classes from the OL classes as this breaks the @Input() parameter setting. So I changed it to the instance method used elsewhere. Next, the question is whether to use transclusion with <ng-content>. I couldn't get it to work so I went for this solution which uses the component's DOM element:

@Component({
  selector: 'aol-control-mouseposition',
  template: ``
})
export class ControlMousePositionComponent implements OnInit, OnDestroy {
  instance: control.MousePosition;
  @Input() coordinateFormat: CoordinateFormatType;
  @Input() projection: ProjectionLike;
  target: Element;

  constructor(
    @Host() private map: MapComponent,
    private element: ElementRef
  ) {
  }

  ngOnInit() {
    this.target = this.element.nativeElement;
    // console.log('ol.control.MousePosition init: ', this);
    this.instance = new control.MousePosition(this);
    this.map.instance.addControl(this.instance);
  }

  ngOnDestroy() {
    // console.log('removing aol-control-mouseposition');
    this.map.instance.removeControl(this.instance);
  }
}

In order to style it, you will need the piercing CSS selector ( :host /deep/) which is probably OK. Any thoughts on how to do the controls implementation?

[achimha]

With a wrapper for the <ng-content>, it actually does work. Here's my generic ol.Control implementation that displays the content. Styling with selector piercing.

import { Component, ElementRef, Host, OnDestroy, OnInit, ViewChild } from '@angular/core';
import { control } from 'openlayers';
import { MapComponent } from '../map.component';

@Component({
  selector: 'aol-control',
  template: `<div #wrapper><ng-content></ng-content></div>`
})
export class ControlComponent implements OnInit, OnDestroy {
  public componentType: string = 'control';
  instance: control.Control;
  element: Element;

  @ViewChild('wrapper') wrapper: ElementRef;

  constructor(
    @Host() private map: MapComponent
  ) {
  }

  ngOnInit() {
    this.element = this.wrapper.nativeElement.children[0];
    this.instance = new control.Control(this);
    this.map.instance.addControl(this.instance);
  }

  ngOnDestroy() {
    this.map.instance.removeControl(this.instance);
  }
}

[quentinlampin]

About the subclassing of ol.control classes : you're right. We moved away from this design in every other component but I haven't found the time to change the controls yet.

Regarding the transclusion and the wrapper solution, I'm not sure I understand what you're trying to achieve. Could you provide an example so I understand what's at stake and come back with meaningful ideas ?

[achimha]

My (rather big now) PR has the control reimplementation included.

With the control class copied above, I can do this:

     <aol-control>
            <div id="settingscontrol" class="ol-control ol-unselectable">
                <button (click)="showSettings = true">
                    <i class="fa fa-bars"></i>
                </button>
            </div>
        </aol-control>

The only problem I see is that I get an additional wrapper div. I don't know a way around that as I can't get hold of the <ng-content> without an element to reference. It's probably OK but I don't like the extra div. You can see in my class that I get hold of the #wrapper element and then pass its first child to the OL API.

[quentinlampin]

Hmm, I'm not a fan of the wrapper div solution either.

Have you tried passing the ElementRef to the component constructor and then accessing the transcluded content like this ?

 constructor(
    @Host() private map: MapComponent,
    private element: ElementRef
  ) {
  }
[...]

this.element.nativeElement.childNodes[0]

[achimha]

Actually this works as well. Thanks!

[achimha]

Came up with another issue with this approach (taking the first child). I created a an implementation of ol.Overlay. Among its parameters is the map position for which I used the existing <aol-coordinate>. Now the question is how to differentiate between the content of the overlay (inserted via transclusion) and the coordinate. Example markup:

        <aol-overlay>
            <div><h1>THIS IS AN OVERLAY</h1></div>
            <aol-coordinate [x]="center[0]" [y]="center[1]" [srid]="'EPSG:4326'"></aol-coordinate>
        </aol-overlay>

The approach taken is to get an ElementRef and pass the first child to the OL control. Obviously it works (coordinate is the second) but is this a good approach?

[achimha]

What about enumerating children until we get the first one that does not start with aol-? Uglier? Less ugly? 😄

[quentin-ol]

;)

We could also make use of HTML element IDs (#ugly) or CSS classes but that's .notpretty.

We could also enforce a "unique child" policy but that feels wrong (especially the name :/) Puns aside, I believe we should do multiple-slots content projection and write an "aol-content" directive (not component) to discriminate the content from the rest.

Opinions?

Interesting read on transclusion/projection: https://toddmotto.com/transclusion-in-angular-2-with-ng-content -------- Message d'origine -------- De : Achim Hasenmueller notifications@github.com Date : 13/02/2017 18:48 (GMT+01:00) À : quentin-ol/angular2-openlayers angular2-openlayers@noreply.github.com Cc : Subscribed subscribed@noreply.github.com Objet : Re: [quentin-ol/angular2-openlayers] ol.control implementation (#45)

What about enumerating children until we get the first one that does not start with aol-? Uglier? Less ugly? 😄

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[achimha]

I like the <aol-content> approach. That's at least clean. I'll implement it like this.

[achimha]

Implemented and documented as part of my latest PR.