@lightningtv/renderer/src/core/text-rendering/renderers/SdfTextRenderer/internal/measureText.ts

Lightning 3 Renderer

/*
 * If not stated otherwise in this file or this component's LICENSE file the
 * following copyright and licenses apply:
 *
 * Copyright 2023 Comcast Cable Communications Management, LLC.
 *
 * 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.
 */

import type {
  FontShaper,
  FontShaperProps,
} from '../../../font-face-types/SdfTrFontFace/internal/FontShaper.js';
import { PeekableIterator } from './PeekableGenerator.js';
import { getUnicodeCodepoints } from './getUnicodeCodepoints.js';

/**
 * Measures a single-line of text width ignoring any unmapped glyphs including line breaks
 *
 * @param text
 * @param shaperProps
 * @param shaper
 * @returns
 */
export function measureText(
  text: string,
  shaperProps: FontShaperProps,
  shaper: FontShaper,
): number {
  const glyphs = shaper.shapeText(
    shaperProps,
    new PeekableIterator(getUnicodeCodepoints(text, 0), 0),
  );
  let width = 0;
  for (const glyph of glyphs) {
    if (glyph.mapped && glyph.codepoint !== 8203) {
      // Skip ZWSP (\u200B)
      width += glyph.xAdvance;
    }
  }
  return width;
}