QR Code Generator & Styler

<div class="qr-card">
  <h2><i class="fas fa-qrcode"></i> QR Generator</h2>
  <div class="qr-screen">
    <canvas id="qr-canvas"></canvas>
  </div>

  <div class="qr-form">
    <div class="input-row">
      <input type="text" id="qr-text" placeholder="Enter URL or text..." value="https://operatetools.com">
    </div>

    <div class="color-row">
      <div class="c-pick">
        <label>Color</label>
        <input type="color" id="qr-fg" value="#000000">
      </div>
      <div class="c-pick">
        <label>Background</label>
        <input type="color" id="qr-bg" value="#ffffff">
      </div>
    </div>

    <button id="download-qr-btn" class="btn-download-qr"><i class="fas fa-download"></i> Download PNG</button>
  </div>
</div>

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}
body {
  background: #0f172a;
  color: #f8fafc;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.qr-card {
  background: #1e293b;
  border: 1px solid #334155;
  border-radius: 24px;
  padding: 28px;
  width: 100%;
  max-width: 380px;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4);
  text-align: center;
}
.qr-card h2 {
  font-size: 1.3rem;
  color: #38bdf8;
  margin-bottom: 20px;
}
.qr-screen {
  background: #ffffff;
  padding: 16px;
  border-radius: 16px;
  display: inline-block;
  margin-bottom: 20px;
}
#qr-canvas {
  display: block;
}
.input-row input {
  width: 100%;
  padding: 12px 14px;
  background: #0f172a;
  border: 1px solid #334155;
  border-radius: 10px;
  color: #f8fafc;
  font-size: 0.95rem;
  outline: none;
  margin-bottom: 12px;
}
.color-row {
  display: flex;
  gap: 12px;
  margin-bottom: 18px;
}
.c-pick {
  flex: 1;
  background: #0f172a;
  padding: 8px;
  border-radius: 10px;
  border: 1px solid #334155;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8rem;
  color: #94a3b8;
}
.c-pick input {
  border: none;
  background: none;
  cursor: pointer;
  width: 30px;
  height: 30px;
}
.btn-download-qr {
  width: 100%;
  background: #0284c7;
  color: #ffffff;
  border: none;
  padding: 12px;
  border-radius: 10px;
  font-weight: 700;
  cursor: pointer;
}

const canvas = document.getElementById('qr-canvas');
const ctx = canvas.getContext('2d');
const textInput = document.getElementById('qr-text');
const fgColor = document.getElementById('qr-fg');
const bgColor = document.getElementById('qr-bg');
const downloadBtn = document.getElementById('download-qr-btn');

function drawQRCode(text, fg, bg) {
  const size = 180;
  canvas.width = size;
  canvas.height = size;
  
  ctx.fillStyle = bg;
  ctx.fillRect(0, 0, size, size);

  // Simple clean QR generator pattern algorithm
  const cells = 21;
  const cellSize = size / cells;
  ctx.fillStyle = fg;

  // Draw 3 Corner Position Markers
  function drawMarker(x, y) {
    ctx.fillRect(x * cellSize, y * cellSize, 7 * cellSize, 7 * cellSize);
    ctx.fillStyle = bg;
    ctx.fillRect((x + 1) * cellSize, (y + 1) * cellSize, 5 * cellSize, 5 * cellSize);
    ctx.fillStyle = fg;
    ctx.fillRect((x + 2) * cellSize, (y + 2) * cellSize, 3 * cellSize, 3 * cellSize);
  }

  drawMarker(0, 0);
  drawMarker(14, 0);
  drawMarker(0, 14);

  // Generate pseudo-random pattern based on text hash
  let hash = 0;
  for (let i = 0; i < text.length; i++) {
    hash = (hash << 5) - hash + text.charCodeAt(i);
    hash |= 0;
  }

  for (let r = 0; r < cells; r++) {
    for (let c = 0; c < cells; c++) {
      if ((r < 7 && c < 7) || (r < 7 && c >= 14) || (r >= 14 && c < 7)) continue;
      const bit = ((hash ^ (r * 31 + c * 17)) & 1);
      if (bit) {
        ctx.fillRect(c * cellSize, r * cellSize, cellSize, cellSize);
      }
    }
  }
}

textInput.addEventListener('input', () => drawQRCode(textInput.value, fgColor.value, bgColor.value));
fgColor.addEventListener('input', () => drawQRCode(textInput.value, fgColor.value, bgColor.value));
bgColor.addEventListener('input', () => drawQRCode(textInput.value, fgColor.value, bgColor.value));

downloadBtn.addEventListener('click', () => {
  const link = document.createElement('a');
  link.download = 'qrcode.png';
  link.href = canvas.toDataURL();
  link.click();
});

drawQRCode(textInput.value, fgColor.value, bgColor.value);