GALAXY - RETROSCOPIC CRT SHADER SOURCE CODE
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Retroscope</title>
<style>
* {
box-sizing: border-box;
}
::-webkit-scrollbar {
width: 0.625rem;
height: 0.625rem;
}
::-webkit-scrollbar-thumb {
background: #111;
border-radius: 0.3125rem;
box-shadow: inset 0.125rem 0.125rem 0.125rem rgba(255, 255, 255, 0.25),
inset -0.125rem -0.125rem 0.125rem rgba(0, 0, 0, 0.25);
cursor: default;
}
::-webkit-scrollbar-track {
background: #333;
}
::selection {
background: #0f0;
color: #001100;
}
html {
height: 100vh;
height: 100dvh;
margin: 0;
overflow: hidden;
background: #000;
}
body {
height: 100vh;
height: 100dvh;
margin: 0;
overflow: hidden;
background: transparent;
display: grid;
grid-template-rows: 100%;
grid-template-columns: 100%;
font-family: system-ui, sans-serif;
}
canvas,
.editor,
#crt-overlay {
grid-row: 1;
grid-column: 1;
}
canvas {
--canvas-z-index: 0;
width: 100%;
height: 100%;
display: block;
background: #050805;
touch-action: none;
z-index: var(--canvas-z-index);
}
#crt-overlay {
position: relative;
pointer-events: none;
z-index: 1;
background: repeating-linear-gradient(
to bottom,
rgba(0, 0, 0, 0) 0px,
rgba(0, 0, 0, 0.18) 1px,
rgba(0, 0, 0, 0) 2px
);
mix-blend-mode: multiply;
animation: crtFlicker 6s infinite;
}
#crt-overlay::after {
content: '';
position: absolute;
inset: 0;
background: linear-gradient(
180deg,
rgba(120, 255, 160, 0.05),
rgba(120, 255, 160, 0.015) 40%,
rgba(120, 255, 160, 0.05)
);
mix-blend-mode: overlay;
}
@keyframes crtFlicker {
0%, 96%, 100% { opacity: 1; }
97% { opacity: 0.88; }
98% { opacity: 1; }
99% { opacity: 0.93; }
}
.editor,
.overlay,
#error {
font-family: 'Courier New', Courier, monospace;
background: repeating-linear-gradient(0deg, #000a, #010f0111 .25rem);
padding: 1em;
}
.editor {
color: #7dffa0;
text-shadow: 0 0 4px rgba(125, 255, 160, 0.6);
tab-size: 2;
border: none;
resize: none;
width: 100%;
height: 100%;
box-sizing: border-box;
}
.editor:focus {
outline: none;
}
#error {
position: fixed;
left: 0;
right: 0;
bottom: 0;
z-index: 4;
margin: 0;
padding-block: .5em;
max-height: 8rem;
color: #ff8a4c;
overflow: auto;
text-wrap: pretty;
background: #050805;
}
#indicator {
visibility: hidden;
position: absolute;
top: calc(var(--top, 0px) - var(--scroll-top, 0px));
width: 0;
height: 0;
border-top: 10px solid transparent;
border-bottom: 10px solid transparent;
border-left: 10px solid #ff8a4c;
transform: translateY(-25%);
z-index: 5;
}
.overlay {
position: absolute;
top: 0;
left: 0;
right: 0;
margin: 0;
}
.editor,
.overlay {
font-size: 1rem;
line-height: 1.2;
white-space: pre;
}
.hidden {
display: none !important;
}
.opaque {
opacity: 1 !important;
background: #050805 !important;
}
#webgl-status {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
color: #7dffa0;
font-family: 'Courier New', Courier, monospace;
font-size: 1.2rem;
text-align: center;
pointer-events: none;
z-index: 5;
padding: 1rem 2rem;
background: rgba(0, 8, 0, 0.85);
border-radius: 8px;
border: 1px solid #2f5b34;
transition: opacity 0.5s ease;
}
#webgl-status.error {
color: #ff8a4c;
border-color: #ff8a4c;
}
#webgl-status.ok {
color: #7dffa0;
border-color: #7dffa0;
}
#webgl-status.fade {
opacity: 0;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<div id="crt-overlay"></div>
<div id="webgl-status">⏳ Initializing…</div>
<textarea id="codeEditor" class="editor hidden" spellcheck="false" autocorrect="off" autocapitalize="off" translate="no" oninput="render()"></textarea>
<pre id="error" class="hidden"></pre>
<div id="indicator" class="hidden"></div>
<script type="x-shader/x-fragment" id="mainShader">#version 300 es
precision highp float;
out vec4 O;
uniform float time;
uniform vec2 resolution;
uniform vec2 move;
#define FC gl_FragCoord.xy
#define R resolution
#define T time
#define N normalize
#define S smoothstep
#define MN min(R.x,R.y)
#define rot(a) mat2(cos((a)-vec4(0,11,33,0)))
#define csqr(a) vec2(a.x*a.x-a.y*a.y,2.*a.x*a.y)
float rnd(vec3 p) {
p=fract(p*vec3(12.9898,78.233,156.34));
p+=dot(p,p+34.56);
return fract(p.x*p.y*p.z);
}
float swirls(in vec3 p) {
float d=.0;
vec3 c=p;
for(float i=min(.0,time); i<9.; i++) {
p=.7*abs(p)/dot(p,p)-.7;
p.yz=csqr(p.yz);
p=p.zxy;
d+=exp(-19.*abs(dot(p,c)));
}
return d;
}
vec3 march(in vec3 p, vec3 rd) {
float d=.2, t=.0, c=.0, k=mix(.9,1.,rnd(rd)),
maxd=length(p)-1.;
vec3 col=vec3(0);
for(float i=min(.0,time); i<120.; i++) {
t+=d*exp(-2.*c)*k;
c=swirls(p+rd*t);
if (t<5e-2 || t>maxd) break;
col+=vec3(c*c,c/1.05,c)*8e-3;
}
return col;
}
float rnd(vec2 p) {
p=fract(p*vec2(12.9898,78.233));
p+=dot(p,p+34.56);
return fract(p.x*p.y);
}
vec3 sky(vec2 p, bool anim) {
p.x-=.17-(anim?2e-4*T:.0);
p*=500.;
vec2 id=floor(p), gv=fract(p)-.5;
float n=rnd(id), d=length(gv);
if (n<.975) return vec3(0);
return vec3(S(3e-2*n,1e-3*n,d*d));
}
void cam(inout vec3 p) {
p.yz*=rot(move.y*6.3/MN-T*.05);
p.xz*=rot(-move.x*6.3/MN+T*.025);
}
float grain(vec2 p, float t) {
return fract(sin(dot(p, vec2(41.3, 289.1)) + t * 13.7) * 43758.5453);
}
void main() {
vec2 uv=(FC-.5*R)/MN;
vec3 col=vec3(0),
p=vec3(0,0,-16),
rd=N(vec3(uv,1)), rdd=rd;
cam(p); cam(rd);
col=march(p,rd);
col=S(-.2,.9,col);
vec2 sn=.5+vec2(atan(rdd.x,rdd.z),atan(length(rdd.xz),rdd.y))/6.28318;
col=max(col,vec3(sky(sn,true)+sky(2.+sn*2.,true)));
float t=min((time-.5)*.3,1.);
col=mix(vec3(0),col,t);
col=max(col,.08);
float lum = dot(col, vec3(0.299, 0.587, 0.114));
vec3 phosphor = vec3(0.12, 1.0, 0.35);
vec3 amber = vec3(1.0, 0.55, 0.08);
vec3 tinted = mix(lum * phosphor, lum * amber, S(0.55, 1.0, lum) * 0.35);
col = mix(col, tinted, 0.88);
col = floor(col * 14.0 + 0.5) / 14.0;
float scan = sin(FC.y * 1.02) * 0.5 + 0.5;
col *= mix(0.82, 1.0, scan);
float sweep = smoothstep(0.0, 0.02, abs(fract(uv.y * 0.5 + T * 0.06) - 0.5));
col += (1.0 - sweep) * 0.03 * phosphor;
col += (grain(FC, T) - 0.5) * 0.035;
col *= 0.94 + 0.06 * sin(T * 47.0);
O=vec4(col,1);
}</script>
<script type="x-shader/x-fragment" id="fallbackShader">#version 300 es
precision highp float;
out vec4 O;
uniform float time;
uniform vec2 resolution;
void main() {
vec2 uv = gl_FragCoord.xy / resolution;
float scan = sin(gl_FragCoord.y * 1.02) * 0.5 + 0.5;
float g = (sin(uv.x * 8.0 - time) * 0.25 + 0.75) * mix(0.8, 1.0, scan);
O = vec4(0.1 * g, g, 0.3 * g, 1.0);
}</script>
<script>
let editMode = false;
let resolution = 0.5;
let renderDelay = 1000;
let dpr = Math.max(1, resolution * window.devicePixelRatio);
let frm, source, editor, store, renderer, pointers, statusEl;
const shaderId = 'oggKrGW-retroscope';
const canvas = document.getElementById('canvas');
const codeEditor = document.getElementById('codeEditor');
const errorEl = document.getElementById('error');
const indicator = document.getElementById('indicator');
statusEl = document.getElementById('webgl-status');
function setStatus(msg, type) {
if (!statusEl) return;
statusEl.textContent = msg;
statusEl.className = type || '';
if (type === 'ok') {
setTimeout(() => {
statusEl.classList.add('fade');
setTimeout(() => { statusEl.style.display = 'none'; }, 500);
}, 1500);
}
}
function resize() {
const w = window.innerWidth;
const h = window.innerHeight;
canvas.width = w * dpr;
canvas.height = h * dpr;
if (renderer) renderer.updateScale(dpr);
}
function toggleView(show) {
editMode = (typeof show === 'boolean') ? show : !editMode;
editor.hidden = !editMode;
if (editMode) editor.focus();
}
function reset() {
const src = source ? source.textContent : renderer.defaultSource;
editor.text = src;
if (store) store.putShaderSource(shaderId, src);
renderThis();
}
function setResolution(scale) {
resolution = scale;
dpr = Math.max(1, resolution * window.devicePixelRatio);
if (pointers) pointers.updateScale(dpr);
resize();
}
function loop(now) {
if (renderer && renderer.isReady()) {
renderer.updateMouse(pointers.first);
renderer.updatePointerCount(pointers.count);
renderer.updatePointerCoords(pointers.coords);
renderer.updateMove(pointers.move);
renderer.render(now);
}
frm = requestAnimationFrame(loop);
}
function renderThis() {
editor.clearError();
if (store) store.putShaderSource(shaderId, editor.text);
const result = renderer.test(editor.text);
if (result) {
editor.setError('Shader error – using fallback.\n' + result);
renderer.useFallback();
} else {
renderer.updateShader(editor.text);
editor.clearError();
}
cancelAnimationFrame(frm);
loop(0);
}
const debounce = (fn, delay) => {
let timer;
return (...args) => {
clearTimeout(timer);
timer = setTimeout(() => fn.apply(this, args), delay);
};
};
const render = debounce(renderThis, renderDelay);
function init() {
source = document.getElementById('mainShader');
const fallbackSrc = document.getElementById('fallbackShader').textContent;
document.title = 'Retroscope';
resize();
renderer = new Renderer(canvas, dpr, fallbackSrc);
if (!renderer.gl) {
setStatus('❌ WebGL2 not supported', 'error');
return;
}
pointers = new PointerHandler(canvas, dpr);
try {
store = new Store(window.location);
} catch (e) {
console.warn('localStorage not available, using in‑memory store');
store = new MemoryStore();
}
editor = new Editor(codeEditor, errorEl, indicator);
const mainSrc = source.textContent;
editor.text = mainSrc;
renderer.setup();
renderer.init();
const testResult = renderer.test(mainSrc);
if (testResult) {
console.warn('Main shader failed, using fallback:', testResult);
editor.setError('⚠️ Main shader failed – using fallback gradient.\n' + testResult);
renderer.updateShader(fallbackSrc);
setStatus('⚠️ Using fallback shader', 'error');
} else {
renderer.updateShader(mainSrc);
statusEl.style.display = 'none';
}
toggleView(editMode);
setResolution(resolution);
canvas.addEventListener('shader-error', (e) => {
editor.setError(e.detail);
});
loop(0);
window.onresize = resize;
window.addEventListener('keydown', (e) => {
if (e.key === 'l' && (e.ctrlKey || e.metaKey)) {
e.preventDefault();
toggleView();
}
});
}
class Renderer {
#vertexSrc = `#version 300 es
precision highp float;
in vec4 position;
void main() { gl_Position = position; }`;
#vertices = [-1, 1, -1, -1, 1, 1, 1, -1];
constructor(canvas, scale, fallbackSrc) {
this.canvas = canvas;
this.scale = scale;
this.fallbackSource = fallbackSrc;
this.shaderSource = fallbackSrc;
this.mouseMove = [0, 0];
this.mouseCoords = [0, 0];
this.pointerCoords = [0, 0];
this.nbrOfPointers = 0;
this.program = null;
this.buffer = null;
this.vs = null;
this.fs = null;
this._ready = false;
try {
this.gl = canvas.getContext('webgl2', {
alpha: false,
antialias: true,
depth: false,
stencil: false,
premultipliedAlpha: false,
powerPreference: 'high-performance'
});
} catch (e) {
this.gl = null;
console.error('WebGL2 init error:', e);
}
if (this.gl) {
this.gl.viewport(0, 0, canvas.width * scale, canvas.height * scale);
this.gl.clearColor(0.02, 0.03, 0.02, 1);
}
}
get defaultSource() { return this.fallbackSource; }
isReady() { return this._ready && this.program !== null; }
useFallback() {
this.updateShader(this.fallbackSource);
}
updateShader(source) {
this.reset();
this.shaderSource = source;
this.setup();
this.init();
}
updateMove(d) { this.mouseMove = d; }
updateMouse(c) { this.mouseCoords = c; }
updatePointerCoords(c) { this.pointerCoords = c; }
updatePointerCount(n) { this.nbrOfPointers = n; }
updateScale(scale) {
this.scale = scale;
if (this.gl) {
this.gl.viewport(0, 0, this.canvas.width * scale, this.canvas.height * scale);
}
}
compile(shader, source) {
const gl = this.gl;
if (!gl) return false;
gl.shaderSource(shader, source);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
const err = gl.getShaderInfoLog(shader);
console.error('Shader compile error:', err);
this.canvas.dispatchEvent(new CustomEvent('shader-error', { detail: err }));
return false;
}
return true;
}
test(source) {
const gl = this.gl;
if (!gl) return 'No WebGL context';
const shader = gl.createShader(gl.FRAGMENT_SHADER);
if (!shader) return 'Failed to create shader';
gl.shaderSource(shader, source);
gl.compileShader(shader);
let result = null;
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
result = gl.getShaderInfoLog(shader);
}
gl.deleteShader(shader);
return result;
}
reset() {
const gl = this.gl;
if (!gl) return;
const { program, vs, fs } = this;
if (program) {
try {
if (vs) { gl.detachShader(program, vs);
gl.deleteShader(vs); }
if (fs) { gl.detachShader(program, fs);
gl.deleteShader(fs); }
gl.deleteProgram(program);
} catch (e) {}
}
this.program = null;
this.vs = null;
this.fs = null;
this.buffer = null;
this._ready = false;
}
setup() {
const gl = this.gl;
if (!gl) return;
this.vs = gl.createShader(gl.VERTEX_SHADER);
this.fs = gl.createShader(gl.FRAGMENT_SHADER);
if (!this.compile(this.vs, this.#vertexSrc)) return;
if (!this.compile(this.fs, this.shaderSource)) return;
this.program = gl.createProgram();
if (!this.program) return;
gl.attachShader(this.program, this.vs);
gl.attachShader(this.program, this.fs);
gl.linkProgram(this.program);
if (!gl.getProgramParameter(this.program, gl.LINK_STATUS)) {
const err = gl.getProgramInfoLog(this.program);
console.error('Program link error:', err);
this.canvas.dispatchEvent(new CustomEvent('shader-error', { detail: err }));
this.program = null;
return;
}
this._ready = true;
}
init() {
const gl = this.gl;
const prog = this.program;
if (!prog || !gl) return;
this.buffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, this.buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(this.#vertices), gl.STATIC_DRAW);
const pos = gl.getAttribLocation(prog, 'position');
gl.enableVertexAttribArray(pos);
gl.vertexAttribPointer(pos, 2, gl.FLOAT, false, 0, 0);
prog.resolution = gl.getUniformLocation(prog, 'resolution');
prog.time = gl.getUniformLocation(prog, 'time');
prog.move = gl.getUniformLocation(prog, 'move');
prog.touch = gl.getUniformLocation(prog, 'touch');
prog.pointerCount = gl.getUniformLocation(prog, 'pointerCount');
prog.pointers = gl.getUniformLocation(prog, 'pointers');
}
render(now = 0) {
const gl = this.gl;
const prog = this.program;
if (!gl || !prog || !this._ready) return;
try {
if (gl.getProgramParameter(prog, gl.DELETE_STATUS)) return;
} catch (e) { return; }
gl.clearColor(0.02, 0.03, 0.02, 1);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.useProgram(prog);
gl.bindBuffer(gl.ARRAY_BUFFER, this.buffer);
gl.uniform2f(prog.resolution, this.canvas.width, this.canvas.height);
gl.uniform1f(prog.time, now * 1e-3);
gl.uniform2f(prog.move, ...this.mouseMove);
gl.uniform2f(prog.touch, ...this.mouseCoords);
gl.uniform1i(prog.pointerCount, this.nbrOfPointers);
gl.uniform2fv(prog.pointers, this.pointerCoords);
gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
}
}
class Store {
constructor(key) {
this.key = key;
this.store = window.localStorage;
}
#ownShadersKey = 'ownShaders';
#StorageType = Object.freeze({ shader: 'fragmentSource', config: 'config' });
#getKeyPrefix(type) { return `${type}${btoa(this.key)}`; }
#getKey(type, name) { return `${this.#getKeyPrefix(type)}${btoa(name)}`; }
putShaderSource(name, src) { this.store.setItem(this.#getKey(this.#StorageType.shader, name), src); }
getShaderSource(name) { return this.store.getItem(this.#getKey(this.#StorageType.shader, name)); }
deleteShaderSource(name) { this.store.removeItem(this.#getKey(this.#StorageType.shader, name)); }
getOwnShaders() { const r = this.store.getItem(this.#getKey(this.#StorageType.config, this.#ownShadersKey)); return r ?
JSON.parse(r) : []; }
putOwnShader(s) { const own = this.getOwnShaders();
const i = own.findIndex(x => x.uuid === s.uuid); if (i === -1) own.push(s);
else own[i] = s; this.store.setItem(this.#getKey(this.#StorageType.config, this.#ownShadersKey), JSON.stringify(
own)); }
deleteOwnShader(uuid) { const own = this.getOwnShaders(); this.store.setItem(this.#getKey(this.#StorageType
.config, this.#ownShadersKey), JSON.stringify(own.filter(s => s.uuid !== uuid))); this
.deleteShaderSource(uuid); }
cleanup(keep = []) { const st = this.#StorageType.shader; const own = this.getOwnShaders().map(s => this.#getKey(st,
s.uuid)); const premade = keep.map(n => this.#getKey(st, n)); const toKeep = [...own, ...premade];
const result = []; for (let i = 0; i < this.store.length; i++) { const key = this.store.key(i); if (key
.startsWith(this.#getKeyPrefix(st)) && !toKeep.includes(key)) result.push(key); } result.forEach(
k => this.store.removeItem(k)); }
}
class MemoryStore {
constructor() {
this.data = new Map();
}
putShaderSource(name, src) { this.data.set(name, src); }
getShaderSource(name) { return this.data.get(name) || null; }
deleteShaderSource(name) { this.data.delete(name); }
getOwnShaders() { return []; }
putOwnShader() {}
deleteOwnShader() {}
cleanup() {}
}
class PointerHandler {
constructor(element, scale) {
this.scale = scale;
this.active = false;
this.pointers = new Map();
this.lastCoords = [0, 0];
this.moves = [0, 0];
const map = (el, sc, x, y) => [x * sc, el.height - y * sc];
element.addEventListener('pointerdown', (e) => {
this.active = true;
this.pointers.set(e.pointerId, map(element, this.getScale(), e.clientX, e.clientY));
});
element.addEventListener('pointerup', (e) => {
if (this.count === 1) this.lastCoords = this.first;
this.pointers.delete(e.pointerId);
this.active = this.pointers.size > 0;
});
element.addEventListener('pointerleave', (e) => {
if (this.count === 1) this.lastCoords = this.first;
this.pointers.delete(e.pointerId);
this.active = this.pointers.size > 0;
});
element.addEventListener('pointermove', (e) => {
if (!this.active) return;
this.lastCoords = [e.clientX, e.clientY];
this.pointers.set(e.pointerId, map(element, this.getScale(), e.clientX, e.clientY));
this.moves = [this.moves[0] + e.movementX, this.moves[1] + e.movementY];
});
}
getScale() { return this.scale; }
updateScale(s) { this.scale = s; }
reset() { this.pointers.clear();
this.active = false;
this.moves = [0, 0]; }
get count() { return this.pointers.size; }
get move() { return this.moves; }
get coords() { return this.pointers.size > 0 ? Array.from(this.pointers.values()).map(p => [...p]).flat() : [0,
0]; }
get first() { return this.pointers.values().next().value || this.lastCoords; }
}
class Editor {
constructor(textarea, errorfield, errorindicator) {
this.textarea = textarea;
this.errorfield = errorfield;
this.errorindicator = errorindicator;
textarea.addEventListener('keydown', this.handleKeydown.bind(this));
textarea.addEventListener('scroll', this.handleScroll.bind(this));
}
get hidden() { return this.textarea.classList.contains('hidden'); }
set hidden(v) { v ? this.#hide() : this.#show(); }
get text() { return this.textarea.value; }
set text(v) { this.textarea.value = v; }
get scrollTop() { return this.textarea.scrollTop; }
set scrollTop(v) { this.textarea.scrollTop = v; }
setError(msg) {
this.errorfield.innerHTML = msg;
this.errorfield.classList.add('opaque');
this.errorfield.classList.remove('hidden');
const match = msg.match(/ERROR: \d+:(\d+):/);
const line = match ? parseInt(match[1]) : 0;
const overlay = document.createElement('pre');
overlay.classList.add('overlay');
overlay.textContent = '\n'.repeat(line);
document.body.appendChild(overlay);
const off = parseInt(getComputedStyle(overlay).height);
this.errorindicator.style.setProperty('--top', off + 'px');
this.errorindicator.style.visibility = 'visible';
this.errorindicator.classList.remove('hidden');
document.body.removeChild(overlay);
}
clearError() {
this.errorfield.textContent = '';
this.errorfield.classList.remove('opaque');
this.errorfield.classList.add('hidden');
this.errorfield.blur();
this.errorindicator.style.visibility = 'hidden';
this.errorindicator.classList.add('hidden');
}
focus() { this.textarea.focus(); }
#hide() { for (const el of [this.errorindicator, this.errorfield, this.textarea]) el.classList.add('hidden'); }
#show() { for (const el of [this.errorindicator, this.errorfield, this.textarea]) el.classList.remove('hidden');
this.focus(); }
handleScroll() { this.errorindicator.style.setProperty('--scroll-top', `${this.textarea.scrollTop}px`); }
handleKeydown(e) {
if (e.key === 'Tab') { e.preventDefault();
this.handleTabKey(e.shiftKey); } else if (e.key === 'Enter') { e.preventDefault();
this.handleEnterKey(); }
}
handleTabKey(shift) {
if (this.#getSelectedText() !== '') {
if (shift) { this.#unindentSelectedText(); return; }
this.#indentSelectedText();
} else { this.#indentAtCursor(); }
}
#getSelectedText() { const ed = this.textarea; return ed.value.substring(ed.selectionStart, ed.selectionEnd); }
#indentAtCursor() { const ed = this.textarea; const pos = ed.selectionStart; document.execCommand('insertText',
false, '\t');
ed.selectionStart = ed.selectionEnd = pos + 1; }
#indentSelectedText() { const ed = this.textarea; const pos = ed.selectionStart; const sel = this
.#getSelectedText(); const lines = sel.split('\n'); const indented = lines.map(l => '\t' + l).join(
'\n'); document.execCommand('insertText', false, indented);
ed.selectionStart = pos; }
#unindentSelectedText() { const ed = this.textarea; const pos = ed.selectionStart; const sel = this
.#getSelectedText(); const lines = sel.split('\n'); const indented = lines.map(l => l.replace(/^\t/,
'').replace(/^ /, '')).join('\n'); document.execCommand('insertText', false, indented);
ed.selectionStart = pos; }
handleEnterKey() {
const ed = this.textarea;
const visTop = ed.scrollTop;
const pos = ed.selectionStart;
let start = pos - 1;
while (start >= 0 && ed.value[start] !== '\n') start--;
let newLine = '';
while (start < pos - 1 && (ed.value[start + 1] === ' ' || ed.value[start + 1] === '\t')) {
newLine += ed.value[start + 1];
start++;
}
document.execCommand('insertText', false, '\n' + newLine);
ed.selectionStart = ed.selectionEnd = pos + 1 + newLine.length;
ed.scrollTop = visTop;
const lineH = ed.scrollHeight / ed.value.split('\n').length;
const line = ed.value.substring(0, pos).split('\n').length;
const visBot = ed.scrollTop + ed.clientHeight;
const lineTop = lineH * (line - 1);
const lineBot = lineH * (line + 2);
if (lineTop < visTop) ed.scrollTop = lineTop;
if (lineBot > visBot) ed.scrollTop = lineBot - ed.clientHeight;
}
}
window.onload = init;
</script>
</body>
</html>