136 lines
3.8 KiB
JavaScript
136 lines
3.8 KiB
JavaScript
import {splitWords} from './utils.js';
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import {parable} from './math.js';
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import {FONT_HEIGHT, FONT_WIDTH} from './constants.js';
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export function createCanvas(width, height) {
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const canvas = document.createElement('canvas');
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const ctx = canvas.getContext('2d');
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canvas.width = width; canvas.height = height
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return ctx;
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}
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export function loadImage(src) {
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return new Promise((resolve, reject) => {
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const img = document.createElement('img');
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img.onload = (e) => resolve(img);
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// @ts-ignore
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img.onerror = (e) => reject(e.error);
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img.src = src;
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});
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}
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export function clipCanvas(ctx, fn) {
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ctx.globalCompositeOperation = 'destination-out';
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fn(ctx);
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ctx.globalCompositeOperation = 'source-over';
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}
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export function plot(ctx, x, y, color) {
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x = Math.round(x); y = Math.round(y);
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ctx.fillStyle = color;
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ctx.fillRect(x, y, 1, 1);
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}
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export function drawLine(ctx, x1, y1, x2, y2, color, plotFn=plot) {
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x1 = Math.round(x1); y1 = Math.round(y1);
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x2 = Math.round(x2); y2 = Math.round(y2);
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const steep = Math.abs(y2 - y1) > Math.abs(x2 - x1);
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if (steep) [x1, y1, x2, y2] = [y1, x1, y2, x2];
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if (x1 > x2) [x1, y1, x2, y2] = [x2, y2, x1, y1];
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const dX = (x2 - x1);
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const dY = Math.abs(y2 - y1);
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const ystep = (y1 < y2 ? 1 : -1);
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let err = (dX / 2);
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let y = y1;
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for (let x = x1; x <= x2; ++x) {
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if (steep) plotFn(ctx, y, x, color); else plotFn(ctx, x, y, color);
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err = err - dY; if (err < 0) { y += ystep; err += dX }
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}
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}
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export function drawLineVirtual(x1, y1, x2, y2, color) {
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const points = [];
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drawLine(null, x1, y1, x2, y2, color, (ctx, x, y, c) => points.push({x, y, c}));
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return points;
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}
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export function drawRect(ctx, x, y, w, h, color) {
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x = Math.round(x); y = Math.round(y);
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w = Math.round(w); h = Math.round(h);
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ctx.fillStyle = color;
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ctx.fillRect(x, y, w, h);
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}
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export function strokeRect(ctx, x, y, w, h, color) {
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if (w === 1 || h === 1) return drawRect(x, y, w, h, color);
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x = Math.round(x); y = Math.round(y);
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w = Math.round(w); h = Math.round(h);
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ctx.lineWidth = 1;
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ctx.strokeStyle = color;
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ctx.strokeRect(x+0.5, y+0.5, w-1, h-1);
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}
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export function drawCircle(ctx, x, y, r, color) {
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x = Math.round(x);
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y = Math.round(y);
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r = Math.round(r);
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for (let cy = -r; cy <= r; cy++) {
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const w = Math.round(Math.sqrt(r*r - cy*cy));
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drawRect(ctx, x-w, y+cy, w*2, 1, color);
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}
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}
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/** @param align {CanvasTextAlign} */
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/** @param baseline {CanvasTextBaseline} */
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export function drawText(ctx, text, x, y, color, align='left', baseline='top') {
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x = Math.round(x); y = Math.round(y);
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ctx.font = '5px text';
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ctx.textBaseline = 'top';
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ctx.textAlign = 'left';
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ctx.fillStyle = color;
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ctx.strokeStyle = 'black';
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const length = (text.length * FONT_WIDTH) + (text.length -1);
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const left = (
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align === 'right' ? x - length :
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align === 'center' ? x - Math.round(length /2) :
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x
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);
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const top = (
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baseline === 'bottom' ? y - FONT_HEIGHT :
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baseline === 'middle' ? y - Math.round(FONT_HEIGHT /2) :
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y
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);
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for (let i=0; i<text.length; i++) {
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ctx.strokeText(text[i], left + i*FONT_WIDTH + i, top);
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ctx.fillText(text[i], left + i*FONT_WIDTH + i, top);
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}
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}
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export function drawParagraph(ctx, text, x, y, w, h, color) {
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x = Math.round(x); y = Math.round(y);
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w = Math.round(w); h = Math.round(h);
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let tx = 0; let ty = 0;
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// FIXME: Handle unbreakable words longer than width
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const words = splitWords(text);
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for (let word of words) {
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const wordLength = word.length * 4;
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if (word === '\n') { tx = 0; ty += 6; continue }
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else if (tx + wordLength > w) { tx = 0; ty += 6 }
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if (ty+6 > h) return;
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for (let char of word) {
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drawText(ctx, char, x+tx, y+ty, color);
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tx += 4;
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}
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}
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}
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export function loop(fn) {
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(function looped() {
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fn();
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requestAnimationFrame(looped);
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})();
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}
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