discourse/app/assets/javascripts/wizard/lib/preview.js.es6

/*eslint no-bitwise:0 */
import getUrl from 'discourse-common/lib/get-url';

export const LOREM = `
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Nullam eget sem non elit tincidunt rhoncus. Fusce velit nisl,
porttitor sed nisl ac, consectetur interdum metus. Fusce in
consequat augue, vel facilisis felis. Nunc tellus elit, and
semper vitae orci nec, blandit pharetra enim. Aenean a ebus
posuere nunc. Maecenas ultrices viverra enim ac commodo
Vestibulum nec quam sit amet libero ultricies sollicitudin.
Nulla quis scelerisque sem, eget volutpat velit. Fusce eget
accumsan sapien, nec feugiat quam. Quisque non risus.
placerat lacus vitae, lacinia nisi. Sed metus arcu, iaculis
sit amet cursus nec, sodales at eros.`;

const scaled = {};

function canvasFor(image, w, h) {
  w = Math.ceil(w);
  h = Math.ceil(h);

  const can = document.createElement('canvas');
  can.width = w;
  can.height = h;

  const ctx = can.getContext('2d');
  ctx.drawImage(image, 0, 0, w, h);
  return can;
}

export function createPreviewComponent(width, height, obj) {
  return Ember.Component.extend({
    layoutName: 'components/theme-preview',
    width,
    height,
    ctx: null,
    loaded: false,

    didInsertElement() {
      this._super();
      const c = this.$('canvas')[0];
      this.ctx = c.getContext("2d");
      this.reload();
    },

    images() { },

    loadImages() {
      const images = this.images();
      if (images) {
        return Ember.RSVP.Promise.all(Object.keys(images).map(id => {
          return loadImage(images[id]).then(img => this[id] = img);
        }));
      }
      return Ember.RSVP.Promise.resolve();
    },

    reload() {
      this.loadImages().then(() => {
        this.loaded = true;
        this.triggerRepaint();
      });
    },

    triggerRepaint() {
      Ember.run.scheduleOnce('afterRender', this, 'repaint');
    },

    repaint() {
      if (!this.loaded) { return false; }

      const colors = this.get('wizard').getCurrentColors();
      if (!colors) { return; }

      const { ctx } = this;

      ctx.fillStyle = colors.secondary;
      ctx.fillRect(0, 0, width, height);

      this.paint(ctx, colors, this.width, this.height);

      // draw border
      ctx.beginPath();
      ctx.strokeStyle='rgba(0, 0, 0, 0.2)';
      ctx.rect(0, 0, width, height);
      ctx.stroke();
    },

    categories() {
      return [{name: 'consecteteur', color: '#652D90'}, {name: 'ultrices', color: '#3AB54A'}];
    },

    scaleImage(image, x, y, w, h) {
      w = Math.floor(w);
      h = Math.floor(h);

      const { ctx } = this;

      const key = `${image.src}-${w}-${h}`;

      if (!scaled[key]) {

        let copy = image;
        let ratio = copy.width / copy.height;
        let newH = (copy.height * 0.5);
        while (newH > h) {
          copy = canvasFor(copy, ratio * newH, newH);
          newH = newH * 0.5;
        }

        scaled[key] = copy;
      }

      ctx.drawImage(scaled[key], x, y, w, h);
    },

    drawFullHeader(colors) {
      const { ctx } = this;

      const headerHeight = height * 0.15;
      drawHeader(ctx, colors, width, headerHeight);

      const avatarSize = height * 0.1;

      // Logo
      const headerMargin = headerHeight * 0.2;
      const logoHeight = headerHeight - (headerMargin * 2);

      if (this.logo) {
        const logoWidth = (logoHeight / this.logo.height) * this.logo.width;
        this.scaleImage(this.logo, headerMargin, headerMargin, logoWidth, logoHeight);
      }

      // Top right menu
      this.scaleImage(this.avatar, width - avatarSize - headerMargin, headerMargin, avatarSize, avatarSize);
      ctx.fillStyle = darkLightDiff(colors.primary, colors.secondary, 45, 55);

      const headerFontSize = headerHeight / 44;

      ctx.font = `${headerFontSize}em FontAwesome`;
      ctx.fillText("\uf0c9", width - (avatarSize * 2) - (headerMargin * 0.5), avatarSize);
      ctx.fillText("\uf002", width - (avatarSize * 3) - (headerMargin * 0.5), avatarSize);
    },

    drawPills(colors, headerHeight, opts) {
      opts = opts || {};

      const { ctx } = this;

      const categoriesSize = headerHeight * 2;
      const badgeHeight = categoriesSize * 0.25;
      const headerMargin = headerHeight * 0.2;

      ctx.beginPath();
      ctx.fillStyle = darkLightDiff(colors.primary, colors.secondary, 90, -65);
      ctx.rect(headerMargin, headerHeight + headerMargin, categoriesSize, badgeHeight);
      ctx.fill();

      const fontSize = Math.round(badgeHeight * 0.5);
      ctx.font = `${fontSize}px 'Arial'`;
      ctx.fillStyle = colors.primary;
      ctx.fillText("all categories", headerMargin * 1.5, headerHeight + (headerMargin * 1.42) + fontSize);

      ctx.font = "0.9em 'FontAwesome'";
      ctx.fillStyle = colors.primary;
      ctx.fillText("\uf0da", categoriesSize - (headerMargin / 4), headerHeight + (headerMargin * 1.6) + fontSize);

      const text = opts.categories ? "Categories" : "Latest";

      const activeWidth = categoriesSize * (opts.categories ? 0.80 : 0.55);
      ctx.beginPath();
      ctx.fillStyle = colors.quaternary;
      ctx.rect((headerMargin * 2)+ categoriesSize, headerHeight + headerMargin, activeWidth, badgeHeight);
      ctx.fill();

      ctx.font = `${fontSize}px 'Arial'`;
      ctx.fillStyle = colors.secondary;
      let x = (headerMargin * 3.0) + categoriesSize;
      ctx.fillText(text, x - (headerMargin * 0.1), headerHeight + (headerMargin * 1.5) + fontSize);

      ctx.fillStyle = colors.primary;
      x += categoriesSize * (opts.categories ? 0.8 : 0.6);
      ctx.fillText("New", x, headerHeight + (headerMargin * 1.5) + fontSize);

      x += categoriesSize * 0.4;
      ctx.fillText("Unread", x, headerHeight + (headerMargin * 1.5) + fontSize);

      x += categoriesSize * 0.6;
      ctx.fillText("Top", x, headerHeight + (headerMargin * 1.5) + fontSize);
    }

  }, obj);
}

function loadImage(src) {
  if (!src) { return Ember.RSVP.Promise.resolve(); }

  const img = new Image();
  img.src = getUrl(src);
  return new Ember.RSVP.Promise(resolve => img.onload = () => resolve(img));
};

export function parseColor(color) {
  const m = color.match(/^#([0-9a-f]{6})$/i);
  if (m) {
    const c = m[1];
    return [ parseInt(c.substr(0,2),16), parseInt(c.substr(2,2),16), parseInt(c.substr(4,2),16) ];
  }

  return [0, 0, 0];
}

export function brightness(color) {
  return (color[0] * 0.299) + (color[1] * 0.587) + (color[2] * 0.114);
}

function rgbToHsl(r, g, b) {
  r /= 255;
  g /= 255;
  b /= 255;
  let max = Math.max(r, g, b), min = Math.min(r, g, b);
  let h, s, l = (max + min) / 2;

  if (max === min) {
    h = s = 0;
  } else {
    const d = max - min;
    s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
    switch(max){
      case r: h = (g - b) / d + (g < b ? 6 : 0); break;
      case g: h = (b - r) / d + 2; break;
      case b: h = (r - g) / d + 4; break;
    }
    h /= 6;
  }

  return [h, s, l];
}

function hue2rgb(p, q, t) {
  if (t < 0) { t += 1; }
  if (t > 1) { t -= 1; }
  if (t < 1/6) { return p + (q - p) * 6 * t; }
  if (t < 1/2) { return q; }
  if (t < 2/3) { return p + (q - p) * (2/3 - t) * 6; }
  return p;
}

function hslToRgb(h, s, l) {
  let r, g, b;

  if (s === 0) {
    r = g = b = l; // achromatic
  } else {
    const q = l < 0.5 ? l * (1 + s) : l + s - l * s;
    const p = 2 * l - q;
    r = hue2rgb(p, q, h + 1/3);
    g = hue2rgb(p, q, h);
    b = hue2rgb(p, q, h - 1/3);
  }

  return [r * 255, g * 255, b * 255];
}

export function lighten(color, percent) {
  const hsl = rgbToHsl(color[0], color[1], color[2]);
  const scale = percent / 100.0;
  const diff = scale > 0 ? 1.0 - hsl[2] : hsl[2];

  hsl[2] = hsl[2] + diff * scale;
  color = hslToRgb(hsl[0], hsl[1], hsl[2]);

  return '#' +
    ((0|(1<<8) + color[0]).toString(16)).substr(1) +
    ((0|(1<<8) + color[1]).toString(16)).substr(1) +
    ((0|(1<<8) + color[2]).toString(16)).substr(1);
}

export function chooseBrighter(primary, secondary) {
  const primaryCol = parseColor(primary);
  const secondaryCol = parseColor(secondary);
  return brightness(primaryCol) < brightness(secondaryCol) ? secondary : primary;
}

export function darkLightDiff(adjusted, comparison, lightness, darkness) {
  const adjustedCol = parseColor(adjusted);
  const comparisonCol = parseColor(comparison);
  return lighten(adjustedCol, (brightness(adjustedCol) < brightness(comparisonCol)) ?
                               lightness : darkness);
}


export function drawHeader(ctx, colors, width, headerHeight) {
  ctx.save();
  ctx.beginPath();
  ctx.rect(0, 0, width, headerHeight);
  ctx.fillStyle = colors.header_background;
  ctx.shadowColor = "rgba(0, 0, 0, 0.25)";
  ctx.shadowBlur = 2;
  ctx.shadowOffsetX = 0;
  ctx.shadowOffsetY = 2;
  ctx.fill();
  ctx.restore();
}