ui/src/frontend/css_constants.ts

// Copyright (C) 2019 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// This code can be used in unittests where we can't read CSS variables.
// Also we cannot have global constructors beacause when the javascript is
// loaded, the CSS might not be ready yet.
export let TRACK_SHELL_WIDTH = 100;
export let SIDEBAR_WIDTH = 100;
export let TRACK_BORDER_COLOR = '#ffc0cb';
export let TOPBAR_HEIGHT = 48;
export let SELECTION_STROKE_COLOR = '#00344596';
export let SELECTION_FILL_COLOR = '#8398e64d';
export let OVERVIEW_TIMELINE_NON_VISIBLE_COLOR = '#c8c8c8cc';
export let DEFAULT_DETAILS_CONTENT_HEIGHT = 280;
export let BACKGROUND_COLOR = '#ffffff';
export let FOREGROUND_COLOR = '#222';
export let COLLAPSED_BACKGROUND = '#ffffff';
export let EXPANDED_BACKGROUND = '#ffffff';

export function initCssConstants() {
  TRACK_SHELL_WIDTH = getCssNum('--track-shell-width') ?? TRACK_SHELL_WIDTH;
  SIDEBAR_WIDTH = getCssNum('--sidebar-width') ?? SIDEBAR_WIDTH;
  TRACK_BORDER_COLOR = getCssStr('--track-border-color') ?? TRACK_BORDER_COLOR;
  TOPBAR_HEIGHT = getCssNum('--topbar-height') ?? TOPBAR_HEIGHT;
  SELECTION_STROKE_COLOR =
    getCssStr('--selection-stroke-color') ?? SELECTION_STROKE_COLOR;
  SELECTION_FILL_COLOR =
    getCssStr('--selection-fill-color') ?? SELECTION_FILL_COLOR;
  OVERVIEW_TIMELINE_NON_VISIBLE_COLOR =
    getCssStr('--overview-timeline-non-visible-color') ??
    OVERVIEW_TIMELINE_NON_VISIBLE_COLOR;
  DEFAULT_DETAILS_CONTENT_HEIGHT =
    getCssNum('--details-content-height') ?? DEFAULT_DETAILS_CONTENT_HEIGHT;
  BACKGROUND_COLOR = getCssStr('--main-background-color') ?? BACKGROUND_COLOR;
  FOREGROUND_COLOR = getCssStr('--main-foreground-color') ?? FOREGROUND_COLOR;
  COLLAPSED_BACKGROUND =
    getCssStr('--collapsed-background') ?? COLLAPSED_BACKGROUND;
  EXPANDED_BACKGROUND =
    getCssStr('--expanded-background') ?? EXPANDED_BACKGROUND;
}

function getCssStr(prop: string): string | undefined {
  if (typeof window === 'undefined') return undefined;
  const body = window.document.body;
  const value = window.getComputedStyle(body).getPropertyValue(prop);
  // Note: getPropertyValue() returns an empty string if not set
  // https://developer.mozilla.org/en-US/docs/Web/API/CSSStyleDeclaration/getPropertyValue#return_value
  return value === '' ? undefined : value;
}

function getCssNum(prop: string): number | undefined {
  const str = getCssStr(prop);
  if (str === undefined) return undefined;
  const match = str.match(/^\W*(\d+)px(|\!important')$/);
  if (!match) throw Error(`Could not parse CSS property "${str}" as a number`);
  return Number(match[1]);
}