protected interpolate()

in share/src/sprite-editor/tools.ts [138:168]

• 29 lines of code
• 12 McCabe index (conditional complexity)

    protected interpolate(x0: number, y0: number, x1: number, y1: number) {
        const dx = x1 - x0;
        const dy = y1 - y0;
        const draw = (c: number, r: number) => this.mask.set(c, r);
        if (dx === 0) {
            const startY = dy >= 0 ? y0 : y1;
            const endY = dy >= 0 ? y1 : y0;
            for (let y = startY; y <= endY; y++) {
                this.drawCore(x0, y, draw);
            }
            return;
        }

        const xStep = dx > 0 ? 1 : -1;
        const yStep = dy > 0 ? 1 : -1;
        const dErr = Math.abs(dy / dx);

        let err = 0;
        let y = y0;
        for (let x = x0; xStep > 0 ? x <= x1 : x >= x1; x += xStep) {
            this.drawCore(x, y, draw);
            err += dErr;
            while (err >= 0.5) {
                if (yStep > 0 ? y <= y1 : y >= y1) {
                    this.drawCore(x, y, draw);
                }
                y += yStep;
                err -= 1;
            }
        }
    }