discourse/app/assets/javascripts/wizard/components/image-preview-logo-url.js.es6

import { observes } from 'ember-addons/ember-computed-decorators';

import { createPreviewComponent, drawHeader } from 'wizard/lib/preview';

export default createPreviewComponent(400, 100, {
  image: null,

  @observes('field.value')
  imageChanged() {
    this.reload();
  },

  images() {
    return { image: this.get('field.value') };
  },

  paint(ctx, colors, width, height) {
    const headerHeight = height / 2;

    drawHeader(ctx, colors, width, headerHeight);

    const image = this.image;
    const headerMargin = headerHeight * 0.2;

    const imageHeight = headerHeight - (headerMargin * 2);
    const ratio = imageHeight / image.height;
    this.scaleImage(image, headerMargin, headerMargin, image.width * ratio, imageHeight);

    this.drawPills(colors, height / 2);
  }

});