<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
<title>HarfBuzz GPU Demo</title>
<script>
if (location.pathname.indexOf('webgpu') !== -1)
  document.title = 'HarfBuzz WebGPU Demo';
else
  document.title = 'HarfBuzz WebGL Demo';
</script>
<style>
  body { margin: 0; background: #fff; overflow: hidden; touch-action: none; }
  #loading { position: fixed; inset: 0; z-index: 100;
             display: flex; justify-content: center; align-items: center;
             background: #fff; color: #999; font: 32px monospace; }
  canvas { display: block; width: 100vw; height: 100vh; }
  #fps { position: fixed; top: 8px; right: 12px; color: #999;
         font: 14px monospace; pointer-events: none; z-index: 1; }
  #help { position: fixed; bottom: 12px; left: 12px; color: #999;
          font: 12px monospace; pointer-events: none; z-index: 1;
          line-height: 1.6; }
  #controls { position: fixed; top: 8px; left: 12px; z-index: 1;
              display: flex; gap: 6px; }
  @media (hover: none) { #controls { display: none; }
                         #help-desktop { display: none; } }
  @media (hover: hover)  { #help-mobile { display: none; } }
  #controls label { color: #fff; font: 12px monospace; cursor: pointer;
                    padding: 4px 8px; border: 1px solid #888; border-radius: 4px;
                    background: rgba(128,128,128,0.5);
                    text-shadow: 0 1px 2px rgba(0,0,0,0.8); }
  #controls label:hover { border-color: #ccc; background: rgba(128,128,128,0.7); }
  #controls input[type=file] { display: none; }
  #controls button { color: #fff; font: 12px monospace; cursor: pointer;
                     padding: 4px 8px; border: 1px solid #888; border-radius: 4px;
                     background: rgba(128,128,128,0.5);
                     text-shadow: 0 1px 2px rgba(0,0,0,0.8); }
  #controls button:hover { border-color: #ccc; background: rgba(128,128,128,0.7); }
  #controls select { color: #fff; font: 12px monospace; cursor: pointer;
                     padding: 3px 4px; border: 1px solid #888; border-radius: 4px;
                     background: rgba(128,128,128,0.5);
                     text-shadow: 0 1px 2px rgba(0,0,0,0.8); }
  #drop-overlay { display: none; position: fixed; inset: 0; z-index: 10;
                  background: rgba(0,0,0,0.6); color: #fff;
                  font: 24px monospace; justify-content: center;
                  align-items: center; }
  #text-modal { display: none; position: fixed; inset: 0; z-index: 20;
                background: rgba(0,0,0,0.7); justify-content: center;
                align-items: center; }
  #text-modal-inner { background: #333; border: 1px solid #666; border-radius: 8px;
                      padding: 16px; width: 90vw; max-width: 1600px; }
  #text-modal textarea { width: 100%; height: 70vh; background: #222; color: #ccc;
                         border: 1px solid #555; border-radius: 4px;
                         font: 14px monospace; padding: 8px; resize: vertical;
                         outline: none; box-sizing: border-box; }
  #text-modal textarea:focus { border-color: #999; }
  #text-modal-buttons { margin-top: 10px; text-align: right; }
  #text-modal-buttons button { color: #fff; font: 13px monospace; cursor: pointer;
                               padding: 6px 16px; border: 1px solid #888;
                               border-radius: 4px; background: rgba(128,128,128,0.5);
                               margin-left: 8px; }
  #text-modal-buttons button:hover { border-color: #ccc; background: rgba(128,128,128,0.7); }
  #help-modal { display: none; position: fixed; inset: 0; z-index: 20;
                background: rgba(0,0,0,0.7); justify-content: center;
                align-items: center; }
  #help-modal pre { background: #333; color: #ccc; font: 14px monospace;
                    padding: 24px 32px; border-radius: 8px; border: 1px solid #666;
                    line-height: 1.8; }
  /* Embed mode (?embed=1): hide UI chrome; host page drives
   * the demo via postMessage. */
  html.embed #controls,
  html.embed #fps,
  html.embed #help,
  html.embed #help-mobile,
  html.embed #text-btn { display: none !important; }
</style>
</head>
<body>
<div id="loading">loading</div>
<div id="fps"></div>
<div id="controls">
  <label>font <input type="file" id="font-input" accept=".ttf,.otf"></label>
  <button id="text-btn">text</button>
  <select id="backend-sel">
    <option value="index.html">WebGL</option>
    <option value="webgpu.html">WebGPU</option>
  </select>
</div>
<div id="drop-overlay">drop font file</div>
<div id="text-modal">
  <div id="text-modal-inner">
    <textarea id="text-area"></textarea>
    <div id="text-modal-buttons">
      <button id="text-cancel">cancel</button>
      <button id="text-apply">apply</button>
    </div>
  </div>
</div>
<div id="help-modal"><pre>
Keyboard:                        Mouse:
  space     toggle animation       drag          pan
  b         dark mode              scroll        zoom
                                   right-drag    rotate
  s         stem darkening         click         toggle animation
  d         debug heatmap          dblclick      reset view
  r         reset view             middle-drag   zoom
  =/-       zoom in/out
  [ ] { }   stretch              Touch:
  arrows    pan                    drag          pan
  h j k l   pan (vim)             pinch         zoom
  /         clean screen           3-finger      rotate
  ?         this help              tap           animate

Shortcuts:                       Text editor:
  t         edit text              Ctrl+Enter    apply
  f         load font              Esc           cancel
  w         switch backend
  R         reload page                  <a href="https://github.com/harfbuzz/harfbuzz" style="color:#88f">HarfBuzz</a>
</pre></div>
<div id="help">
<span id="help-desktop">drag: pan · scroll: zoom · click: animate · dblclick: reset · right-drag: rotate<br>
space: animate · b: dark mode · s: stem · d: debug · r: reset · ?: help</span>
<span id="help-mobile">drag: pan · pinch: zoom/rotate · 3-finger: 3D rotate<br>
tap: animate · dbl-tap+drag: zoom · long-press: reset</span>
</div>
<canvas id="canvas" oncontextmenu="event.preventDefault()" tabindex="-1"></canvas>
<script>
  var canvas = document.getElementById('canvas');
  function resizeCanvas () {
    var dpr = window.devicePixelRatio || 1;
    var width = Math.round(canvas.clientWidth * dpr);
    var height = Math.round(canvas.clientHeight * dpr);
    /* Skip zero-sized updates -- iframe-hosted case runs
     * this at parse time before layout, and installing a
     * 0x0 drawing buffer then leaves GL stuck at 0x0 even
     * after the canvas later gets a real size.  Leaving
     * canvas.width / .height alone keeps the default 300x150
     * buffer until ResizeObserver fires with real dims. */
    if (!width || !height) return;
    if (canvas.width !== width)
      canvas.width = width;
    if (canvas.height !== height)
      canvas.height = height;
  }
  function requestRedraw () {
    if (typeof _web_request_redraw === 'function')
      _web_request_redraw();
  }
  function handleResume () {
    resizeCanvas();
    requestRedraw();
  }
  resizeCanvas();
  window.addEventListener('resize', resizeCanvas);
  /* When embedded in an iframe, script executes before the
   * iframe has done layout, so clientWidth/clientHeight
   * are 0 and resizeCanvas() above installs a 0x0 GL
   * backbuffer.  A plain 'resize' window event never fires
   * just because the iframe sized itself, so watch the
   * canvas with ResizeObserver and pick up its first real
   * size whenever it appears. */
  if (typeof ResizeObserver !== 'undefined') {
    new ResizeObserver(function () {
      resizeCanvas();
      /* Also dispatch a window resize: emscripten's GLFW
       * port listens for that to re-fire its framebuffer
       * size callback into wasm, which re-sets glViewport
       * and forces a redraw at the correct size. */
      window.dispatchEvent(new Event('resize'));
      requestRedraw();
    }).observe(canvas);
  }
  window.addEventListener('focus', handleResume);
  window.addEventListener('pageshow', handleResume);
  document.addEventListener('visibilitychange', function () {
    if (!document.hidden)
      handleResume();
  });
  canvas.addEventListener('webglcontextrestored', handleResume);

  /* Backend selector */
  var isWebGPU = location.pathname.indexOf('webgpu') !== -1;
  var backendSel = document.getElementById('backend-sel');
  if (isWebGPU)
    backendSel.value = 'webgpu.html';
  backendSel.addEventListener('change', function () {
    backendSel.blur();
    location.href = backendSel.value + location.search;
  });

  /* Early WebGL2 availability check */
  if (!isWebGPU && !canvas.getContext('webgl2')) {
    var el = document.getElementById('loading');
    el.innerHTML = 'WebGL2 not available.<br>' +
                   'Check that hardware acceleration is enabled in your browser settings.<br>' +
                   '<a href="https://webglreport.com/?v=2" style="color:#88f">WebGL2 support status</a>';
    el.style.font = '18px sans-serif';
    el.style.color = '#666';
    el.style.textAlign = 'center';
    el.style.flexDirection = 'column';
    window._webglError = true;
  }

  /* Early WebGPU availability check */
  if (isWebGPU && !navigator.gpu) {
    var el = document.getElementById('loading');
    var html = 'WebGPU not available in this browser.<br>' +
               '<a href="https://github.com/gpuweb/gpuweb/wiki/Implementation-Status" ' +
               'style="color:#88f">Browser support status</a>';
    if (navigator.userAgent.indexOf('Linux') !== -1 &&
        navigator.userAgent.indexOf('Chrome') !== -1)
      html += '<br><br>On Linux Chrome, try restarting with:<br>' +
              '<code style="font-size:13px">google-chrome --enable-unsafe-webgpu --ozone-platform=x11 ' +
              '--use-angle=vulkan --enable-features=Vulkan,VulkanFromANGLE</code>';
    el.innerHTML = html;
    el.style.font = '18px sans-serif';
    el.style.color = '#666';
    el.style.textAlign = 'center';
    el.style.flexDirection = 'column';
    window._webgpuError = true;
  }

  var fpsEl = document.getElementById('fps');
  var frames = 0, lastTime = performance.now();
  (function fpsLoop () {
    requestAnimationFrame(fpsLoop);
    frames++;
    var now = performance.now();
    if (now - lastTime >= 1000) {
      fpsEl.textContent = Math.round(frames * 1000 / (now - lastTime)) + ' fps';
      frames = 0;
      lastTime = now;
    }
  })();

  /* Multi-touch: 2-finger pinch → zoom, 3-finger drag → 3D rotate. */
  var pinchDist = 0;
  var pinchAngle = 0;
  var pinchCX = 0, pinchCY = 0;
  var gestureX = 0, gestureY = 0;
  var pinchActive = false;
  var singlePanActive = false;
  var threeFingerActive = false;
  var skipNextPinchMove = false;
  var longPressTimer = null;
  var longPressFired = false;
  var lastTapTime = 0;
  var doubleTapZoom = false;
  var doubleTapY = 0;
  function swallowTouch (e) {
    e.preventDefault();
    e.stopImmediatePropagation();
  }
  if (!isWebGPU) canvas.addEventListener('touchstart', function (e) {
    if (e.touches.length === 1) {
      var now = performance.now();
      if (now - lastTapTime < 300) {
        /* Double-tap: start zoom drag.
         * Undo animation toggle from first tap. */
        e.preventDefault();
        if (typeof _web_toggle_animation === 'function')
          _web_toggle_animation();
        doubleTapZoom = true;
        doubleTapY = e.touches[0].clientY;
        lastTapTime = 0;
        if (longPressTimer) { clearTimeout(longPressTimer); longPressTimer = null; }
      } else {
        lastTapTime = now;
        longPressX = e.touches[0].clientX;
        longPressY = e.touches[0].clientY;
        longPressTimer = setTimeout(function () {
          longPressTimer = null;
          longPressFired = true;
          if (typeof _web_reset === 'function') _web_reset();
        }, 500);
      }
    } else if (longPressTimer) {
      clearTimeout(longPressTimer);
      longPressTimer = null;
    }
    if (e.touches.length === 2) {
      swallowTouch(e);
      pinchActive = true;
      singlePanActive = false;
      var t = e.touches;
      pinchDist = Math.hypot(t[1].clientX - t[0].clientX,
                             t[1].clientY - t[0].clientY);
      pinchAngle = Math.atan2(t[1].clientY - t[0].clientY,
                              t[1].clientX - t[0].clientX);
      pinchCX = (t[0].clientX + t[1].clientX) / 2;
      pinchCY = (t[0].clientY + t[1].clientY) / 2;
      gestureX = pinchCX;
      gestureY = pinchCY;
      if (typeof _web_cancel_gesture === 'function')
        _web_cancel_gesture();
      canvas.dispatchEvent(new MouseEvent('mouseup', {
        button: 0, clientX: pinchCX, clientY: pinchCY
      }));
      skipNextPinchMove = false;
    } else if (e.touches.length >= 3) {
      swallowTouch(e);
      pinchActive = false;
      singlePanActive = false;
      threeFingerActive = true;
      skipNextPinchMove = false;
      var t = e.touches;
      var cx = (t[0].clientX + t[1].clientX + t[2].clientX) / 3;
      var cy = (t[0].clientY + t[1].clientY + t[2].clientY) / 3;
      gestureX = cx;
      gestureY = cy;
      if (typeof _web_cancel_gesture === 'function')
        _web_cancel_gesture();
      canvas.dispatchEvent(new MouseEvent('mouseup', {
        button: 0, clientX: cx, clientY: cy
      }));
      /* Synthesize right-button press at centroid */
      canvas.dispatchEvent(new MouseEvent('mousedown', {
        button: 2, clientX: cx, clientY: cy
      }));
    }
  }, {passive: false, capture: true});
  var longPressX = 0, longPressY = 0;
  if (!isWebGPU) canvas.addEventListener('touchmove', function (e) {
    if (singlePanActive && e.touches.length === 1) {
      swallowTouch(e);
      gestureX = e.touches[0].clientX;
      gestureY = e.touches[0].clientY;
      canvas.dispatchEvent(new MouseEvent('mousemove', {
        clientX: gestureX, clientY: gestureY
      }));
      return;
    }
    if (longPressTimer && e.touches.length === 1) {
      var dx = e.touches[0].clientX - longPressX;
      var dy = e.touches[0].clientY - longPressY;
      if (dx*dx + dy*dy > 100) { clearTimeout(longPressTimer); longPressTimer = null; }
    }
    if (doubleTapZoom && e.touches.length === 1) {
      swallowTouch(e);
      var dy = e.touches[0].clientY - doubleTapY;
      doubleTapY = e.touches[0].clientY;
      canvas.dispatchEvent(new WheelEvent('wheel', {
        deltaY: dy * 5,
        clientX: e.touches[0].clientX,
        clientY: e.touches[0].clientY
      }));
      return;
    }
    if (e.touches.length >= 3 && threeFingerActive) {
      swallowTouch(e);
      pinchActive = false;
      var t = e.touches;
      var cx = (t[0].clientX + t[1].clientX + t[2].clientX) / 3;
      var cy = (t[0].clientY + t[1].clientY + t[2].clientY) / 3;
      gestureX = cx;
      gestureY = cy;
      canvas.dispatchEvent(new MouseEvent('mousemove', {
        clientX: cx, clientY: cy
      }));
      return;
    }
    if (e.touches.length === 2) {
      swallowTouch(e);
      pinchActive = true;
      var t = e.touches;
      var cx = (t[0].clientX + t[1].clientX) / 2;
      var cy = (t[0].clientY + t[1].clientY) / 2;
      var dist = Math.hypot(t[1].clientX - t[0].clientX,
                            t[1].clientY - t[0].clientY);
      var angle = Math.atan2(t[1].clientY - t[0].clientY,
                             t[1].clientX - t[0].clientX);
      if (skipNextPinchMove) {
        pinchDist = dist;
        pinchAngle = angle;
        pinchCX = cx;
        pinchCY = cy;
        gestureX = cx;
        gestureY = cy;
        skipNextPinchMove = false;
        return;
      }
      var dAngle = angle - pinchAngle;
      if (dAngle > Math.PI) dAngle -= 2 * Math.PI;
      if (dAngle < -Math.PI) dAngle += 2 * Math.PI;
      var factor = pinchDist > 0 ? dist / pinchDist : 1;
      if (typeof _web_pinch === 'function')
        _web_pinch(cx - pinchCX, cy - pinchCY,
                   factor, dAngle,
                   cx, cy, canvas.clientWidth, canvas.clientHeight);
      else {
        /* Fallback: zoom only via wheel */
        var delta = (factor - 1) * 5;
        canvas.dispatchEvent(new WheelEvent('wheel', { deltaY: -delta * 120 }));
      }
      pinchDist = dist;
      pinchAngle = angle;
      pinchCX = cx; pinchCY = cy;
      gestureX = cx;
      gestureY = cy;
    }
  }, {passive: false, capture: true});
  if (!isWebGPU) canvas.addEventListener('touchend', function (e) {
    var pinchEnding = pinchActive && e.touches.length < 2;
    var singlePanEnding = singlePanActive && e.touches.length === 0;
    if (threeFingerActive || pinchEnding || singlePanEnding ||
        skipNextPinchMove ||
        e.touches.length >= 2 || doubleTapZoom)
      swallowTouch(e);
    if (longPressTimer) { clearTimeout(longPressTimer); longPressTimer = null; }
    if (longPressFired) {
      longPressFired = false;
      e.preventDefault(); /* Don't let GLFW see this as a click */
    }
    doubleTapZoom = false;
    if (threeFingerActive && e.touches.length < 3) {
      threeFingerActive = false;
      var releaseX = gestureX, releaseY = gestureY;
      if (e.touches.length === 2) {
        var t = e.touches;
        releaseX = (t[0].clientX + t[1].clientX) / 2;
        releaseY = (t[0].clientY + t[1].clientY) / 2;
        pinchDist = Math.hypot(t[1].clientX - t[0].clientX,
                               t[1].clientY - t[0].clientY);
        pinchAngle = Math.atan2(t[1].clientY - t[0].clientY,
                                t[1].clientX - t[0].clientX);
        pinchCX = releaseX;
        pinchCY = releaseY;
        gestureX = releaseX;
        gestureY = releaseY;
        pinchActive = true;
        skipNextPinchMove = true;
      } else {
        pinchActive = false;
        skipNextPinchMove = false;
      }
      if (typeof _web_cancel_gesture === 'function')
        _web_cancel_gesture();
      canvas.dispatchEvent(new MouseEvent('mouseup', {
        button: 2, clientX: releaseX, clientY: releaseY
      }));
    } else if (pinchEnding) {
      pinchActive = false;
      skipNextPinchMove = false;
      if (e.touches.length === 1) {
        /* Hand single-finger pan off from the remaining touch point. */
        singlePanActive = true;
        gestureX = e.touches[0].clientX;
        gestureY = e.touches[0].clientY;
        canvas.dispatchEvent(new MouseEvent('mousemove', {
          clientX: gestureX,
          clientY: gestureY
        }));
        canvas.dispatchEvent(new MouseEvent('mousedown', {
          button: 0,
          clientX: gestureX,
          clientY: gestureY
        }));
      }
    } else if (singlePanEnding) {
      singlePanActive = false;
      if (typeof _web_cancel_gesture === 'function')
        _web_cancel_gesture();
      canvas.dispatchEvent(new MouseEvent('mouseup', {
        button: 0, clientX: gestureX, clientY: gestureY
      }));
    } else if (e.touches.length < 2) {
      skipNextPinchMove = false;
    }
  }, {passive: false, capture: true});
  if (!isWebGPU) canvas.addEventListener('touchcancel', function (e) {
    var handledGesture = threeFingerActive || pinchActive ||
                         singlePanActive ||
                         skipNextPinchMove ||
                         e.touches.length >= 2 || doubleTapZoom;
    if (handledGesture)
      swallowTouch(e);
    if (longPressTimer) { clearTimeout(longPressTimer); longPressTimer = null; }
    longPressFired = false;
    doubleTapZoom = false;
    pinchActive = false;
    if (singlePanActive) {
      singlePanActive = false;
      if (typeof _web_cancel_gesture === 'function')
        _web_cancel_gesture();
      canvas.dispatchEvent(new MouseEvent('mouseup', {
        button: 0, clientX: gestureX, clientY: gestureY
      }));
    }
    skipNextPinchMove = false;
    if (threeFingerActive) {
      threeFingerActive = false;
      if (typeof _web_cancel_gesture === 'function')
        _web_cancel_gesture();
      canvas.dispatchEvent(new MouseEvent('mouseup', {
        button: 2, clientX: gestureX, clientY: gestureY
      }));
    }
  }, {passive: false, capture: true});

  /* Block Emscripten/GLFW from eating key events while the text modal is open.
   * Registered before Module so it runs before Emscripten's capture-phase handlers. */
  var textModalEl = document.getElementById('text-modal');
  function blockKeysIfModal(e) {
    if (textModalEl.style.display !== 'flex') {
      if (e.key === '?') {
        if (e.type === 'keydown') {
          var hm = document.getElementById('help-modal');
          hm.style.display = hm.style.display === 'flex' ? 'none' : 'flex';
        }
        e.preventDefault();
        e.stopImmediatePropagation();
        return;
      }
      if (e.key === '/') {
        if (e.type === 'keydown') {
          var h = document.getElementById('help');
          var fp = document.getElementById('fps');
          var c = document.getElementById('controls');
          var hidden = h.style.display === 'none';
          h.style.display = hidden ? '' : 'none';
          fp.style.display = hidden ? '' : 'none';
          if (c) c.style.display = hidden ? '' : 'none';
        }
        e.preventDefault();
        e.stopImmediatePropagation();
        return;
      }
      if (e.key === 'Escape') {
        var hm = document.getElementById('help-modal');
        if (hm.style.display === 'flex') {
          hm.style.display = 'none';
          e.stopImmediatePropagation();
          return;
        }
      }
      if (e.key === 'R') {
        location.reload();
        return;
      }
      if (e.key === 't') {
        e.preventDefault();
        if (e.type === 'keydown')
          document.getElementById('text-btn').click();
        e.stopImmediatePropagation();
        return;
      }
      if (e.type === 'keydown' && e.key === 'f') {
        document.getElementById('font-input').click();
        e.stopImmediatePropagation();
      }
      if (e.type === 'keydown' && e.key === 'w') {
        var sel = document.getElementById('backend-sel');
        sel.value = sel.value === 'webgpu.html' ? 'index.html' : 'webgpu.html';
        location.href = sel.value;
        e.stopImmediatePropagation();
      }
      return;
    }
    if (e.key === 'Escape') { textModalEl.style.display = 'none'; e.stopImmediatePropagation(); return; }
    if (e.key === 'Enter' && (e.shiftKey || e.ctrlKey || e.metaKey)) {
      document.getElementById('text-apply').click();
      e.stopImmediatePropagation(); return;
    }
    e.stopImmediatePropagation();
  }
  window.addEventListener('keydown', blockKeysIfModal, true);
  window.addEventListener('keyup', blockKeysIfModal, true);
  window.addEventListener('keypress', blockKeysIfModal, true);

  /* URL parameters: forwarded to C main() as argv so main can
   * apply them before first frame (no default-demo flash). */
  var urlParams = new URLSearchParams(location.search);
  var moduleArgs = [];
  var urlText = urlParams.get('text');
  var urlFont = urlParams.get('font');
  if (urlText) moduleArgs.push('--text=' + urlText);
  if (urlFont) moduleArgs.push('--font=' + urlFont);

  /* Embed mode: hide the demo's own chrome (font picker,
   * text button, backend selector, help overlays) so a host
   * page embedding this in an iframe can drive it purely
   * through postMessage.  The canvas-only view keeps the
   * FPS counter and the loading overlay. */
  /* Any presence of ?embed (with or without a value, except
   * explicit =0 / =false) turns on embed mode. */
  var embedMode = urlParams.has('embed') &&
                  urlParams.get('embed') !== '0' &&
                  urlParams.get('embed') !== 'false';
  if (embedMode) {
    document.documentElement.classList.add('embed');
  }

  var Module = {
    canvas: canvas,
    arguments: moduleArgs,
    onRuntimeInitialized: function () {
      if (!window._webgpuError && !window._webglError) {
        document.getElementById('loading').style.display = 'none';
        document.body.style.background = '#222';
      }
      console.log('HarfBuzz GPU Demo loaded');

      /* Font file input */
      var fontInput = document.getElementById('font-input');
      fontInput.addEventListener('change', function () {
        if (fontInput.files.length)
          loadFontFile(fontInput.files[0]);
      });

      /* Drag and drop */
      var overlay = document.getElementById('drop-overlay');
      document.addEventListener('dragover', function (e) {
        e.preventDefault();
        overlay.style.display = 'flex';
      });
      document.addEventListener('dragleave', function (e) {
        if (e.relatedTarget === null)
          overlay.style.display = 'none';
      });
      document.addEventListener('drop', function (e) {
        e.preventDefault();
        overlay.style.display = 'none';
        if (e.dataTransfer.files.length)
          loadFontFile(e.dataTransfer.files[0]);
      });

      /* Text editor modal */
      var textModal = document.getElementById('text-modal');
      var textArea = document.getElementById('text-area');
      var textBtn = document.getElementById('text-btn');

      var textOnOpen = '';
      textBtn.addEventListener('click', function () {
        var ptr = _web_get_text();
        textOnOpen = UTF8ToString(ptr);
        textArea.value = textOnOpen;
        textModal.style.display = 'flex';
        textArea.focus();
      });

      document.getElementById('text-cancel').addEventListener('click', function () {
        textModal.style.display = 'none';
      });

      document.getElementById('text-apply').addEventListener('click', function () {
        var text = textArea.value.trim();
        if (!text) { textModal.style.display = 'none'; return; }
        if (text !== textOnOpen) {
          applyText(text);
          /* Reflect custom text in the URL so it's copy/pasteable. */
          var url = new URL(location.href);
          url.searchParams.set('text', text);
          history.replaceState(null, '', url.toString());
        }
        textModal.style.display = 'none';
      });


      /* Prevent mouse events on the modal from reaching the canvas/GLFW. */
      textModal.addEventListener('mousedown', function (e) { e.stopPropagation(); });
      textModal.addEventListener('mouseup', function (e) { e.stopPropagation(); });
      textModal.addEventListener('click', function (e) { e.stopPropagation(); });

      function loadFontFile(file) {
        var reader = new FileReader();
        reader.onload = function () {
          var data = new Uint8Array(reader.result);
          var buf = _malloc(data.length);
          HEAPU8.set(data, buf);
          _web_load_font(buf, data.length);
          _free(buf);
        };
        reader.readAsArrayBuffer(file);
      }

      function applyText(text) {
        var len = lengthBytesUTF8(text) + 1;
        var buf = _malloc(len);
        stringToUTF8(text, buf, len);
        _web_set_text(buf);
        _free(buf);
        requestRedraw();
      }

      function applyFontBytes(bytes) {
        var data = new Uint8Array(bytes);
        var buf = _malloc(data.length);
        HEAPU8.set(data, buf);
        _web_load_font(buf, data.length);
        _free(buf);
      }

      function applyVariations(settings) {
        var len = lengthBytesUTF8(settings) + 1;
        var buf = _malloc(len);
        stringToUTF8(settings, buf, len);
        _web_set_variations(buf);
        _free(buf);
        requestRedraw();
      }

      function applyFeatures(settings) {
        var len = lengthBytesUTF8(settings) + 1;
        var buf = _malloc(len);
        stringToUTF8(settings, buf, len);
        _web_set_features(buf);
        _free(buf);
        requestRedraw();
      }

      function applyPalette(idx) {
        _web_set_palette(idx >>> 0);
        requestRedraw();
      }

      /* Embed-mode message protocol: host page drives the
       * demo with { kind: 'text', value }  and
       * { kind: 'font', bytes: ArrayBuffer }.  No origin
       * check -- hb-gpu-demo is read-only w.r.t. the host. */
      window.addEventListener('message', function (e) {
        var d = e.data;
        if (!d || typeof d !== 'object') return;
        if (d.kind === 'text' && typeof d.value === 'string')
          applyText(d.value);
        else if (d.kind === 'font' && d.bytes)
          applyFontBytes(d.bytes);
        else if (d.kind === 'variations' && typeof d.value === 'string')
          applyVariations(d.value);
        else if (d.kind === 'palette' && typeof d.value === 'number')
          applyPalette(d.value);
        else if (d.kind === 'features' && typeof d.value === 'string')
          applyFeatures(d.value);
        else if (d.kind === 'dark' && typeof d.value === 'boolean')
          _web_set_dark(d.value ? 1 : 0);
      });

      /* Tell any parent frame we're ready to receive
       * messages.  Host may have queued them during load. */
      if (window.parent && window.parent !== window)
        window.parent.postMessage({ kind: 'ready' }, '*');

      /* ?text= is applied pre-main via Module.arguments; here we
       * handle the async ?font= fetch.  Text (if any) is re-applied
       * after the font loads.
       *
       * For WebGPU, init_demo is async -- wait for the C side to
       * signal readiness before calling exported functions. */
      function startFontFetch () {
        if (!urlFont) return;
        fetch(urlFont)
          .then(function (r) {
            if (!r.ok) throw new Error('HTTP ' + r.status);
            return r.arrayBuffer();
          })
          .then(function (ab) {
            var data = new Uint8Array(ab);
            var buf = _malloc(data.length);
            HEAPU8.set(data, buf);
            _web_load_font(buf, data.length);
            _free(buf);
            if (urlText) applyText(urlText);
          })
          .catch(function (err) {
            console.warn('?font= fetch failed: ' + err.message);
          });
      }
      if (isWebGPU) {
        window._webDemoReady = startFontFetch;
      } else {
        startFontFetch ();
      }
    }
  };
</script>
{{{ SCRIPT }}}
</body>
</html>