showRainbow()

in neopixel.ts [80:135]

• 47 lines of code
• 7 McCabe index (conditional complexity)

        showRainbow(startHue: number = 1, endHue: number = 360) {
            if (this._length <= 0) return;

            startHue = startHue >> 0;
            endHue = endHue >> 0;
            const saturation = 100;
            const luminance = 50;
            const steps = this._length;
            const direction = HueInterpolationDirection.Clockwise;

            //hue
            const h1 = startHue;
            const h2 = endHue;
            const hDistCW = ((h2 + 360) - h1) % 360;
            const hStepCW = Math.idiv((hDistCW * 100), steps);
            const hDistCCW = ((h1 + 360) - h2) % 360;
            const hStepCCW = Math.idiv(-(hDistCCW * 100), steps);
            let hStep: number;
            if (direction === HueInterpolationDirection.Clockwise) {
                hStep = hStepCW;
            } else if (direction === HueInterpolationDirection.CounterClockwise) {
                hStep = hStepCCW;
            } else {
                hStep = hDistCW < hDistCCW ? hStepCW : hStepCCW;
            }
            const h1_100 = h1 * 100; //we multiply by 100 so we keep more accurate results while doing interpolation

            //sat
            const s1 = saturation;
            const s2 = saturation;
            const sDist = s2 - s1;
            const sStep = Math.idiv(sDist, steps);
            const s1_100 = s1 * 100;

            //lum
            const l1 = luminance;
            const l2 = luminance;
            const lDist = l2 - l1;
            const lStep = Math.idiv(lDist, steps);
            const l1_100 = l1 * 100

            //interpolate
            if (steps === 1) {
                this.setPixelColor(0, hsl(h1 + hStep, s1 + sStep, l1 + lStep))
            } else {
                this.setPixelColor(0, hsl(startHue, saturation, luminance));
                for (let i = 1; i < steps - 1; i++) {
                    const h = Math.idiv((h1_100 + i * hStep), 100) + 360;
                    const s = Math.idiv((s1_100 + i * sStep), 100);
                    const l = Math.idiv((l1_100 + i * lStep), 100);
                    this.setPixelColor(i, hsl(h, s, l));
                }
                this.setPixelColor(steps - 1, hsl(endHue, saturation, luminance));
            }
            this.show();
        }