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draw-context.ts
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draw-context.ts
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import {Point} from '../core/point';
export class DrawContext {
ctx: OffscreenCanvasRenderingContext2D;
constructor(private canvas: OffscreenCanvas) {
this.ctx = canvas.getContext('2d', {
alpha: true,
desynchronized: true,
willReadFrequently: true
});
}
clear(): DrawContext {
this.ctx.clearRect(-1, -1, this.canvas.width + 1, this.canvas.height + 1);
return this;
}
drawImage(image: OffscreenCanvas | ImageData, position: Point) {
if (image instanceof ImageData) {
this.ctx.putImageData(image, position.x, position.y);
} else {
this.ctx.drawImage(image, position.x, position.y);
}
}
line(from: Point, to: Point): DrawContext {
this.ctx.beginPath();
this.ctx.moveTo(from.x, from.y);
this.ctx.lineTo(to.x, to.y);
this.ctx.stroke();
this.ctx.closePath();
return this;
}
rect(position: Point, size: Point, fill: boolean): DrawContext {
this.ctx.beginPath();
if (fill) {
this.ctx.rect(position.x, position.y, size.x, size.y);
} else {
this.ctx.rect(position.x, position.y, size.x, 1);
this.ctx.rect(position.x, position.y + size.y - 1, size.x, 1);
this.ctx.rect(position.x, position.y, 1, size.y);
this.ctx.rect(position.x + size.x - 1, position.y, 1, size.y);
}
this.ctx.fill();
if (!fill) {
this.ctx.save();
this.ctx.fillStyle = 'rgba(0,0,0,0)';
this.ctx.beginPath();
this.ctx.rect(position.x, position.y, size.x, size.y);
this.ctx.fill();
this.ctx.restore();
}
this.ctx.closePath();
return this;
}
circle(position: Point, radius: number, fill: boolean): DrawContext {
radius = Math.max(1, radius);
this.ctx.beginPath();
this.ctx.arc(position.x, position.y, radius - 1, 0, 2 * Math.PI);
if (fill) {
this.ctx.fill();
}
this.ctx.stroke();
this.ctx.closePath();
return this;
}
text(position: Point, text: string, font: string): DrawContext {
this.ctx.font = font;
this.ctx.textBaseline = 'top';
this.ctx.fillText(text, position.x, position.y);
return this;
}
pixelateLine(from: Point, to: Point, size: number): DrawContext {
const a = from.clone().round();
const b = to.clone().round();
const dx = Math.abs(a.x - b.x);
const dy = Math.abs(a.y - b.y);
const sx = a.x < b.x ? 1 : -1;
const sy = a.y < b.y ? 1 : -1;
let err = dx - dy;
this.ctx.beginPath();
while (true) {
this.ctx.rect(a.x, a.y, size, size);
if (a.x === b.x && a.y === b.y) break;
const e2 = 2 * err;
if (e2 > -dy) {
err -= dy;
a.x += sx;
}
if (e2 < dx) {
err += dx;
a.y += sy;
}
}
this.ctx.fill();
this.ctx.closePath();
return this;
}
pixelateCircle(center: Point, radius: number, fill: boolean): DrawContext {
this.ctx.beginPath();
for (let n = 0; n < radius; n++) {
const x = n;
const y = Math.round(Math.sqrt(radius * radius - x * x));
this.ctx.rect(center.x - x, center.y - y, 1, 1);
this.ctx.rect(center.x - x, center.y + y, 1, 1);
this.ctx.rect(center.x + x, center.y - y, 1, 1);
this.ctx.rect(center.x + x, center.y + y, 1, 1);
this.ctx.rect(center.x - y, center.y - x, 1, 1);
this.ctx.rect(center.x - y, center.y + x, 1, 1);
this.ctx.rect(center.x + y, center.y - x, 1, 1);
this.ctx.rect(center.x + y, center.y + x, 1, 1);
if (fill) {
this.ctx.rect(center.x - x, center.y - y, 1, y * 2);
this.ctx.rect(center.x + x, center.y - y, 1, y * 2);
this.ctx.rect(center.x - y, center.y - x, 1, x * 2);
this.ctx.rect(center.x + y, center.y - x, 1, x * 2);
}
}
this.ctx.fill();
this.ctx.closePath();
return this;
}
pixelateRectCorner(point: Point, radius: number, quadrant: number, fill: boolean): DrawContext {
const signs = new Point(quadrant == 0 || quadrant == 3 ? 1 : -1, quadrant == 0 || quadrant == 1 ? 1 : -1);
const center = point.clone().add(new Point(radius).multiply(signs));
for (let x = 0; x < radius; x++) {
let y = Math.sqrt(radius * radius - x * x);
let p = center.clone().subtract(new Point(x, y).multiply(signs)).round();
this.ctx.rect(p.x, p.y, 1, 1);
fill && this.ctx.fillRect(p.x, p.y, 1, signs.y * (radius - Math.abs(p.y - point.y)));
p = center.clone().subtract(new Point(y, x).multiply(signs)).round();
this.ctx.rect(p.x, p.y, 1, 1);
}
return this;
}
pixelateRoundedRect(position: Point, size: Point, radius: number, fill: boolean): DrawContext {
this.ctx.beginPath();
this.ctx.rect(position.x + radius, position.y, size.x - 2 * radius, 1);
this.ctx.rect(position.x + radius, position.y + size.y - 1, size.x - 2 * radius, 1);
this.ctx.rect(position.x, position.y + radius, 1, size.y - 2 * radius);
this.ctx.rect(position.x + size.x - 1, position.y + radius, 1, size.y - 2 * radius);
if (fill) {
this.ctx.fillRect(position.x + radius, position.y, size.x - 2 * radius, size.y);
this.ctx.fillRect(position.x, position.y + radius, size.x, size.y - 2 * radius);
}
this.pixelateRectCorner(position, radius + 1, 0, fill);
this.pixelateRectCorner(new Point(position.x + size.x - 1, position.y), radius + 1, 1, fill);
this.pixelateRectCorner(new Point(position.x + size.x - 1, position.y + size.y - 1), radius + 1, 2, fill);
this.pixelateRectCorner(new Point(position.x, position.y + size.y - 1), radius + 1, 3, fill);
this.ctx.fill();
if (fill) {
this.ctx.save();
this.ctx.fillStyle = 'rgba(0,0,0,0)';
this.ctx.beginPath();
this.ctx.arc(position.x + radius, position.y + radius, radius, Math.PI, 1.5 * Math.PI);
this.ctx.arc(position.x + size.x - radius, position.y + radius, radius, 1.5 * Math.PI, 2 * Math.PI);
this.ctx.arc(position.x + size.x - radius, position.y + size.y - radius, radius, 0, 0.5 * Math.PI);
this.ctx.arc(position.x + radius, position.y + size.y - radius, radius, 0.5 * Math.PI, Math.PI);
this.ctx.fill();
}
return this;
}
pixelateEllipse(center: Point, radiusX: number, radiusY: number, fill: boolean): DrawContext {
this.ctx.beginPath();
for (let n = 0; n < radiusX; n++) {
const x = n;
const y = Math.round(Math.sqrt(radiusY * radiusY * (1 - (x * x) / radiusX / radiusX)));
this.ctx.rect(center.x - x, center.y - y, 1, 1);
this.ctx.rect(center.x - x, center.y + y, 1, 1);
this.ctx.rect(center.x + x, center.y - y, 1, 1);
this.ctx.rect(center.x + x, center.y + y, 1, 1);
if (fill) {
this.ctx.rect(center.x - x, center.y - y, 1, y * 2);
this.ctx.rect(center.x + x, center.y - y, 1, y * 2);
}
}
for (let n = 0; n < radiusY; n++) {
const y = n;
const x = Math.round(Math.sqrt(radiusX * radiusX * (1 - (y * y) / radiusY / radiusY)));
this.ctx.rect(center.x - x, center.y - y, 1, 1);
this.ctx.rect(center.x - x, center.y + y, 1, 1);
this.ctx.rect(center.x + x, center.y - y, 1, 1);
this.ctx.rect(center.x + x, center.y + y, 1, 1);
if (fill) {
this.ctx.rect(center.x - x, center.y - y, 1, y * 2);
this.ctx.rect(center.x + x, center.y - y, 1, y * 2);
}
}
this.ctx.fill();
if (!fill) {
this.ctx.save();
this.ctx.fillStyle = 'rgba(0,0,0,0)';
this.ctx.beginPath();
this.ctx.ellipse(center.x + 0.5, center.y + 0.5, radiusX + 0.5, radiusY + 0.5, 0, 0, 2 * Math.PI);
this.ctx.fill();
this.ctx.restore();
}
this.ctx.closePath();
return this;
}
}