resizeImageForCropper method

@override Future<String?> resizeImageForCropper({ required String path, int maxSize = 1024, })

Implementation

@override
Future<String?> resizeImageForCropper({
  required String path,
  int maxSize = 1024,
}) async {
  try {
    // ── Step 1: load the image from the object URL ─────────────────────
    final img = web.document.createElement('img') as web.HTMLImageElement;
    final loadCompleter = Completer<bool>();

    img.addEventListener(
      'load',
      (web.Event _) {
        loadCompleter.complete(true);
      }.toJS,
    );
    img.addEventListener(
      'error',
      (web.Event _) {
        loadCompleter.complete(false);
      }.toJS,
    );
    img.src = path;
    final loaded = await loadCompleter.future;
    if (!loaded) return path;

    final origW = img.naturalWidth;
    final origH = img.naturalHeight;

    // Already fits — return original path
    if (origW <= maxSize && origH <= maxSize) return path;

    // ── Step 2: compute target dimensions (preserve aspect ratio) ──────
    final larger = origW > origH ? origW : origH;
    final scale = maxSize / larger;
    final newW = (origW * scale).round();
    final newH = (origH * scale).round();

    // ── Step 3: draw at target size on a canvas (native browser path) ──
    final canvas =
        web.document.createElement('canvas') as web.HTMLCanvasElement;
    canvas.width = newW;
    canvas.height = newH;
    final ctx = canvas.getContext('2d') as web.CanvasRenderingContext2D;
    // drawImage with sx/sy/sw/sh/dx/dy/dw/dh triggers the browser's native
    // bilinear/bicubic downscale — no JS pixel loop required.
    ctx.drawImage(
      img,
      0,
      0,
      origW.toDouble(),
      origH.toDouble(),
      0,
      0,
      newW.toDouble(),
      newH.toDouble(),
    );

    // ── Step 4: export as JPEG object URL ──────────────────────────────
    final dataUrl = canvas.toDataURL('image/jpeg', (0.85).toJS);
    final base64 = dataUrl.split(',').last;
    final bytes = _base64ToBytes(base64);
    final blob = web.Blob(
      [bytes.toJS].toJS,
      web.BlobPropertyBag(type: 'image/jpeg'),
    );
    return web.URL.createObjectURL(blob);
  } catch (_) {
    return path;
  }
}