render()

in libs/game/background.ts [95:140]

• 38 lines of code
• 13 McCabe index (conditional complexity)

        render(offsetX: number, offsetY: number) {
            const w = screen.width;
            const h = screen.height;
            const pw = this.img.width;
            const ph = this.img.height;

            if (!pw || !ph) return; // empty image.

            // left, top aligned
            let rx = -offsetX;
            let ry = -offsetY;

            switch (this.alignX) {
                case BackgroundAlignment.Right: rx -= (w + pw); break;
                case BackgroundAlignment.Center: rx -= (w + pw) >> 1; break;
            }
            switch (this.alignY) {
                case BackgroundAlignment.Bottom: ry -= (h + ph); break;
                case BackgroundAlignment.Center: ry -= (h + ph) >> 1; break;
            }

            rx %= w; if (rx < 0) rx += w;
            ry %= h; if (ry < 0) ry += h;

            // avoid subpixel aliasing
            rx = Math.floor(rx);
            ry = Math.floor(ry);

            let y = 0;
            let py = 0;
            while (y < h) {
                py = y % ph;
                let dh = Math.min(ph - py, h - ry);
                let x = 0;
                let rxl = rx;
                while (x < w) {
                    let px = x % pw;
                    let dw = Math.min(pw - px, w - rxl);
                    screen.drawImage(this.img, rxl, ry);
                    rxl = (rxl + dw) % w;
                    x += this.repeatX ? dw : w;
                }
                ry = (ry + dh) % h;
                y += this.repeatY ? dh : h;
            }
        }