nehan/dist/text-measure.js

Html layout engine for paged-media written in Typescript

import { LogicalSize, } from './public-api';
function createOffscreenCanvasContext2d() {
    if (typeof OffscreenCanvas === "undefined") {
        return null;
    }
    return new OffscreenCanvas(0, 0).getContext("2d");
}
function createCanvasContext2d() {
    const canvas = document.createElement("canvas");
    canvas.style.display = "hidden";
    canvas.style.width = canvas.style.height = "0";
    if (document.body) {
        document.body.appendChild(canvas);
    }
    return canvas.getContext("2d");
}
function createDomContextElement() {
    const dom = document.createElement("span");
    const style = dom.style;
    style.display = "inline";
    style.margin = "0";
    style.padding = "0";
    style.borderWidth = "0";
    style.lineHeight = "1";
    style.width = "auto";
    style.height = "auto";
    style.visibility = "hidden";
    return dom;
}
;
class OffCanvasTextMetricsMeasure {
    static isEnabled() {
        return this.offCanvasCtx !== null;
    }
    getMeasure(text, font) {
        const ctx = OffCanvasTextMetricsMeasure.offCanvasCtx;
        if (!ctx) {
            return 0;
        }
        ctx.font = font.css;
        return ctx.measureText(text).width;
    }
}
OffCanvasTextMetricsMeasure.offCanvasCtx = createOffscreenCanvasContext2d();
class CanvasTextMetricsMeasure {
    static isEnabled() {
        return this.canvasCtx !== null;
    }
    getMeasure(text, font) {
        const ctx = CanvasTextMetricsMeasure.canvasCtx;
        if (!ctx) {
            return 0;
        }
        ctx.font = font.css;
        return ctx.measureText(text).width;
    }
}
CanvasTextMetricsMeasure.canvasCtx = createCanvasContext2d();
class DomNodeTextMetricsMeasure {
    getMeasure(text, font) {
        const node = DomNodeTextMetricsMeasure.node;
        if (!node) {
            return 0;
        }
        node.style.font = font.css;
        node.innerHTML = text;
        document.body.appendChild(node);
        const rect = node.getBoundingClientRect();
        document.body.removeChild(node);
        return rect.width;
    }
}
DomNodeTextMetricsMeasure.node = createDomContextElement();
const textMetricsMeasure = OffCanvasTextMetricsMeasure.isEnabled() ? new OffCanvasTextMetricsMeasure() :
    CanvasTextMetricsMeasure.isEnabled() ? new CanvasTextMetricsMeasure() : new DomNodeTextMetricsMeasure();
export class TextMeasure {
    static getWordSize(font, word) {
        const measure = textMetricsMeasure.getMeasure(word, font);
        const extent = font.size;
        return new LogicalSize({ measure, extent });
    }
}
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