ag-charts-community/dist/cjs/es6/canvas/canvas.js

Advanced Charting / Charts supporting Javascript / Typescript / React / Angular / Vue

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
// This is the property we set on an HTMLCanvasElement to let us know we've applied
// the resolution independent overrides to it, and what its current DPR is.
const DevicePixelRatioKey = '__DevicePixelRatio';
// TODO: use Symbol() here in the future to truly hide this property.
function makeHdpiOverrides(dpr) {
    let depth = 0;
    return {
        save() {
            this.$save();
            depth++;
        },
        restore() {
            if (depth > 0) {
                this.$restore();
                depth--;
            }
        },
        resetTransform() {
            this.$resetTransform();
            this.scale(dpr, dpr);
            this.save();
            depth = 0;
            // The scale above will be impossible to restore,
            // because we override the `ctx.restore` above and
            // check `depth` there.
        }
    };
}
/**
 * Creates an HTMLCanvasElement element with HDPI overrides applied.
 * The `width` and `height` parameters are optional and default to
 * the values defined in the W3C Recommendation:
 * https://www.w3.org/TR/html52/semantics-scripting.html#the-canvas-element
 * @param width
 * @param height
 */
function createHdpiCanvas(width = 300, height = 150) {
    const canvas = document.createElement('canvas');
    canvas.width = width;
    canvas.height = height;
    applyHdpiOverrides(canvas);
    return canvas;
}
exports.createHdpiCanvas = createHdpiCanvas;
function applyHdpiOverrides(canvas) {
    const canvasDpr = canvas[DevicePixelRatioKey];
    const dpr = window.devicePixelRatio;
    // if overrides haven't been applied and actually needed
    if (!canvasDpr && dpr !== 1) {
        const overrides = makeHdpiOverrides(dpr);
        const ctx = canvas.getContext('2d');
        const ctxObj = ctx;
        for (const name in overrides) {
            // Save native methods under prefixed names.
            ctxObj['$' + name] = ctxObj[name];
            // Pretend our overrides are native methods.
            ctxObj[name] = overrides[name];
        }
        canvas[DevicePixelRatioKey] = dpr;
        const logicalWidth = canvas.width;
        const logicalHeight = canvas.height;
        canvas.width = Math.round(logicalWidth * dpr);
        canvas.height = Math.round(logicalHeight * dpr);
        canvas.style.width = Math.round(logicalWidth) + 'px';
        canvas.style.height = Math.round(logicalHeight) + 'px';
        ctx.resetTransform(); // should be called every time the size changes
        return dpr;
    }
    return 0;
}
exports.applyHdpiOverrides = applyHdpiOverrides;
/**
 * Resizes the given Canvas element, taking HDPI overrides (if any) into account.
 * @param canvas
 * @param width
 * @param height
 */
function resizeCanvas(canvas, width, height) {
    const canvasDpr = canvas[DevicePixelRatioKey] || 1;
    canvas.width = Math.round(width * canvasDpr);
    canvas.height = Math.round(height * canvasDpr);
    canvas.style.width = Math.round(width) + 'px';
    canvas.style.height = Math.round(height) + 'px';
    canvas.getContext('2d').resetTransform();
}
exports.resizeCanvas = resizeCanvas;
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