import { ProgressTracker } from '../../utils/progressTracker';
import { ImageQuantizerYieldValue } from '../imageQuantizerYieldValue';
enum Direction {
NONE = 0,
UP,
LEFT,
RIGHT,
DOWN,
}
interface Data {
x: number;
y: number;
width: number;
height: number;
level: number;
index: number;
tracker: ProgressTracker;
callback(x: number, y: number): void;
}
export function* hilbertCurve(
width: number,
height: number,
callback: (x: number, y: number) => void,
) {
const maxBound = Math.max(width, height);
const level = Math.floor(Math.log(maxBound) / Math.log(2) + 1);
const tracker = new ProgressTracker(width * height, 99);
const data = {
width,
height,
level,
callback,
tracker,
index: 0,
x: 0,
y: 0,
};
yield* walkHilbert(data, Direction.UP);
visit(data, Direction.NONE);
}
function* walkHilbert(
data: Data,
direction: Direction,
): IterableIterator<ImageQuantizerYieldValue> {
if (data.level < 1) return;
if (data.tracker.shouldNotify(data.index)) {
yield { progress: data.tracker.progress };
}
data.level--;
switch (direction) {
case Direction.LEFT:
yield* walkHilbert(data, Direction.UP);
visit(data, Direction.RIGHT);
yield* walkHilbert(data, Direction.LEFT);
visit(data, Direction.DOWN);
yield* walkHilbert(data, Direction.LEFT);
visit(data, Direction.LEFT);
yield* walkHilbert(data, Direction.DOWN);
break;
case Direction.RIGHT:
yield* walkHilbert(data, Direction.DOWN);
visit(data, Direction.LEFT);
yield* walkHilbert(data, Direction.RIGHT);
visit(data, Direction.UP);
yield* walkHilbert(data, Direction.RIGHT);
visit(data, Direction.RIGHT);
yield* walkHilbert(data, Direction.UP);
break;
case Direction.UP:
yield* walkHilbert(data, Direction.LEFT);
visit(data, Direction.DOWN);
yield* walkHilbert(data, Direction.UP);
visit(data, Direction.RIGHT);
yield* walkHilbert(data, Direction.UP);
visit(data, Direction.UP);
yield* walkHilbert(data, Direction.RIGHT);
break;
case Direction.DOWN:
yield* walkHilbert(data, Direction.RIGHT);
visit(data, Direction.UP);
yield* walkHilbert(data, Direction.DOWN);
visit(data, Direction.LEFT);
yield* walkHilbert(data, Direction.DOWN);
visit(data, Direction.DOWN);
yield* walkHilbert(data, Direction.LEFT);
break;
default:
break;
}
data.level++;
}
function visit(data: Data, direction: Direction) {
if (
data.x >= 0 &&
data.x < data.width &&
data.y >= 0 &&
data.y < data.height
) {
data.callback(data.x, data.y);
data.index++;
}
switch (direction) {
case Direction.LEFT:
data.x--;
break;
case Direction.RIGHT:
data.x++;
break;
case Direction.UP:
data.y--;
break;
case Direction.DOWN:
data.y++;
break;
}
}
