Set component style from variable in Angular 2

Question

My goal is to set a style (height and width in this case) from a component variable using the "styles" attribute. I would think there is a simple data binding method but that may be wishful thinking...

For example if I were using the html mustache binding it might look like this:

@Component({
    selector: '[sidebar]',
    templateUrl: 'app/Nav/sidebar.comp.html',
    styles: [`
        .sidebar-nav {
            overflow: scroll;
            height: {{ height }};
        }
        .sidebar {
            height: {{ 0.9 * height }};
            width: {{ 0.21 * width }};
        }
    `]
})

export class SidebarComp {
    width: number;
    height: number;

    constructor() {
        this.height = window.innerHeight;
        this.width = window.innerWidth;
    }
}

Obviously this is all wrong but I've tried some more likely permutations and had no luck finding solutions on the Angular site, Stack Overflow, or Google. I may be reduced to using ngStyle inline but that's not ideal in this case.

Answer 1

You can style the host element like

@Component({
  selector: '[sidebar]',
  templateUrl: 'app/Nav/sidebar.comp.html',
  host: {
    '[style.height.px]':'0.9 * height',
    '[style.width.px]':'0.21 * width'
  }

})

export class SidebarComp {
    width: number;
    height: number;

    constructor() {
        this.height = window.innerHeight;
        this.width = window.innerWidth;
    }
}

and the content ( app/Nav/sidebar.comp.html ) like

<div class="sidebar-nav" [style.overflow]="'scroll'" [style.height.px]="height">

or

<div class="sidebar-nav" [ngStyle]="{overflow: 'scroll', height: height + 'px'}">

Answer 2

如果您使用百分比 (%) 试试这个：

<div class="sidebar-nav"   [style.height.%]="height">

Answer 3

In my case, I need change image style dynamic switch between px and % unit.

So I use [ngStyle] instead of [style.height.px]

I share for whom concern.

HTML

<img [src]="imageUrl | safe: 'url'" [ngStyle]="{width: imagewidth, height: imageheight}">

TS

    if (this.properties.imageStyle == 'Stretch') {
      this.imagewidth = this.cols * this.unitWidth + 'px';
      this.imageheight = this.rows * this.unitHeight + 'px';
    }

    if (this.properties.imageStyle == 'Clip') {
      this.imagewidth = 100 + '%';
      this.imageheight = 100 + '%';
    }

https://stackblitz.com/edit/angular-image-clip-stretch