canvas-trading/dist/src/scrollZoom.js

Interactive HTML5 Canvas Trading Chart

import { canvasSettings } from './config';
function scrollZoom(movement, shift, candlesShown, maxCandles, setShift, setCandlesShown) {
    maxCandles -= 3;
    var newCandlesShown = yMovement(movement, candlesShown, maxCandles, shift, setCandlesShown);
    xMovement(movement, shift, newCandlesShown, maxCandles, setShift);
}
function yMovement(movement, candlesShown, maxCandles, shift, setCandlesShown) {
    if (movement.y !== 0) {
        if ((candlesShown > canvasSettings.minCandlesShown - 1 ||
            (candlesShown === canvasSettings.minCandlesShown && movement.y > 0)) &&
            (candlesShown < maxCandles - shift + 1 ||
                (candlesShown === maxCandles - shift && movement.y < 0))) {
            var exponentialMultiplier = Math.max(0.3, candlesShown / maxCandles * 3);
            var newCandlesShown = Math.max(Math.min(candlesShown + Math.round(movement.y * exponentialMultiplier * canvasSettings.zoomStrength), maxCandles - shift), canvasSettings.minCandlesShown);
            setCandlesShown(newCandlesShown);
            return newCandlesShown;
        }
    }
    return candlesShown;
}
function xMovement(movement, shift, candlesShown, maxCandles, setShift) {
    if (movement.x !== 0) {
        if ((shift > 0 || (shift === 0 && movement.x < 0)) &&
            (shift < maxCandles - candlesShown + 1 ||
                (shift === maxCandles - candlesShown && movement.x > 0))) {
            var exponentialMultiplier = Math.max(0.6, candlesShown / maxCandles * 3);
            var newShift = Math.max(Math.min(shift - Math.round(movement.x * exponentialMultiplier * canvasSettings.shiftStrength), maxCandles - candlesShown), 0);
            setShift(newShift);
            return newShift;
        }
    }
    return shift;
}
export default scrollZoom;