@lightningtv/renderer
Version:
Lightning 3 Renderer
131 lines • 4.85 kB
JavaScript
/*
* 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.
*/
const weightConversions = {
normal: 400,
bold: 700,
bolder: 900,
lighter: 100,
};
const fontWeightToNumber = (weight) => {
if (typeof weight === 'number') {
return weight;
}
return weightConversions[weight] || 400;
};
function resolveFontToUse(familyMapsByPriority, family, weightIn, style, stretch) {
let weight = fontWeightToNumber(weightIn);
for (const fontFamiles of familyMapsByPriority) {
const fontFaces = fontFamiles[family];
if (!fontFaces) {
continue;
}
if (fontFaces.size === 1) {
// No Exact match found, find nearest weight match
console.warn(`TrFontManager: Only one font face found for family: '${family}' - will be used for all weights and styles`);
return fontFaces.values().next().value;
}
const weightMap = new Map();
for (const fontFace of fontFaces) {
const fontFamilyWeight = fontWeightToNumber(fontFace.descriptors.weight);
if (fontFamilyWeight === weight &&
fontFace.descriptors.style === style &&
fontFace.descriptors.stretch === stretch) {
return fontFace;
}
weightMap.set(fontFamilyWeight, fontFace);
}
// No Exact match found, find nearest weight match
const msg = `TrFontManager: No exact match: '${family} Weight: ${weight} Style: ${style} Stretch: ${stretch}'`;
console.error(msg);
// Follow the CSS font-weight algorithm to find the nearest weight match
// https://www.w3.org/TR/2018/REC-css-fonts-3-20180920/#font-matching-algorithm
if (weight === 400 && weightMap.has(500)) {
return weightMap.get(500);
}
if (weight === 500 && weightMap.has(400)) {
return weightMap.get(400);
}
if (weight < 400) {
while (weight > 0) {
if (weightMap.has(weight)) {
return weightMap.get(weight);
}
weight -= 100;
}
// reset back for the next loop
weight = 600;
}
while (weight < 1000) {
if (weightMap.has(weight)) {
return weightMap.get(weight);
}
weight += 100;
}
// finally check lower again
weight = 500;
while (weight > 0) {
if (weightMap.has(weight)) {
return weightMap.get(weight);
}
weight -= 100;
}
}
return;
}
export class TrFontManager {
textRenderers;
fontCache = new Map();
constructor(textRenderers) {
this.textRenderers = textRenderers;
// Intentionally left blank
}
addFontFace(font) {
// All the font face to all of the text renderers that support it
for (const trId in this.textRenderers) {
const tr = this.textRenderers[trId];
if (tr && tr.isFontFaceSupported(font)) {
tr.addFontFace(font);
}
}
}
/**
* Utility method to resolve a single font face from a list of prioritized family maps based on
* a set of font properties.
*
* @remarks
* These are to be used by a text renderer to resolve a font face if needed.
*
* @param familyMapsByPriority
* @param props
* @returns
*/
resolveFontFace(familyMapsByPriority, props, rendererType) {
const { fontFamily, fontWeight, fontStyle, fontStretch } = props;
const fontCacheString = `${rendererType}_${fontFamily}_${fontStyle}_${fontWeight}_${fontStretch}`;
if (this.fontCache.has(fontCacheString) === true) {
return this.fontCache.get(fontCacheString);
}
const resolvedFont = resolveFontToUse(familyMapsByPriority, fontFamily, fontWeight, fontStyle, fontStretch);
if (resolvedFont !== undefined) {
this.fontCache.set(fontCacheString, resolvedFont);
}
return resolvedFont;
}
}
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