feat: found root cause of slow image process is store them in bytes rather than image object

lib/data/services/export_service.dart

@@ -7,6 +7,8 @@ import 'package:pdf/pdf.dart' as pdf;
 import 'package:printing/printing.dart' as printing;
 import 'package:image/image.dart' as img;
 import '../../domain/models/model.dart';
+// math moved to utils in rot
+import '../../utils/rotation_utils.dart' as rot;
 
 // NOTE:
 // - This exporter uses a raster snapshot of the UI (RepaintBoundary) and embeds it into a new PDF.
@@ -15,50 +17,6 @@ import '../../domain/models/model.dart';
 //   cannot import/modify existing PDF pages. If/when a suitable FOSS library exists, wire it here.
 
 class ExportService {
-  /// Compose a new PDF by rasterizing the original PDF pages (via pdfrx engine)
-  /// and optionally stamping a signature image on the specified page.
-  ///
-  /// Inputs:
-  /// - [inputPath]: Path to the original PDF to read
-  /// - [outputPath]: Path to write the composed PDF
-  /// - [uiPageSize]: The logical page size used by the UI layout (SignatureCardStateNotifier.pageSize)
-  /// - [signatureImageBytes]: PNG/JPEG bytes of the signature image to overlay
-  /// - [targetDpi]: Rasterization DPI for background pages
-  Future<bool> exportSignedPdfFromFile({
-    required String inputPath,
-    required String outputPath,
-    required Size uiPageSize,
-    required Uint8List? signatureImageBytes,
-    Map<int, List<SignaturePlacement>>? placementsByPage,
-    Map<String, Uint8List>? libraryBytes,
-    double targetDpi = 144.0,
-  }) async {
-    // Read source bytes and delegate to bytes-based exporter
-    Uint8List? srcBytes;
-    try {
-      srcBytes = await File(inputPath).readAsBytes();
-    } catch (_) {
-      srcBytes = null;
-    }
-    if (srcBytes == null) return false;
-    final bytes = await exportSignedPdfFromBytes(
-      srcBytes: srcBytes,
-      uiPageSize: uiPageSize,
-      signatureImageBytes: signatureImageBytes,
-      placementsByPage: placementsByPage,
-      libraryBytes: libraryBytes,
-      targetDpi: targetDpi,
-    );
-    if (bytes == null) return false;
-    try {
-      final file = File(outputPath);
-      await file.writeAsBytes(bytes, flush: true);
-      return true;
-    } catch (_) {
-      return false;
-    }
-  }
-
   /// Compose a new PDF from source PDF bytes; returns the resulting PDF bytes.
   Future<Uint8List?> exportSignedPdfFromBytes({
     required Uint8List srcBytes,
@@ -68,6 +26,131 @@ class ExportService {
     Map<String, Uint8List>? libraryBytes,
     double targetDpi = 144.0,
   }) async {
+    // Per-call caches to avoid redundant decode/encode and image embedding work
+    final Map<String, Uint8List> _processedBytesCache = <String, Uint8List>{};
+    final Map<String, pw.MemoryImage> _memoryImageCache =
+        <String, pw.MemoryImage>{};
+    final Map<String, double> _aspectRatioCache = <String, double>{};
+
+    // Returns a stable-ish cache key for bytes within this process (not content-hash, but good enough per-call)
+    String _baseKeyForBytes(Uint8List b) =>
+        '${identityHashCode(b)}:${b.length}';
+
+    // Fast PNG signature check (no string allocation)
+    bool _isPng(Uint8List bytes) {
+      if (bytes.length < 8) return false;
+      return bytes[0] == 0x89 &&
+          bytes[1] == 0x50 && // P
+          bytes[2] == 0x4E && // N
+          bytes[3] == 0x47 && // G
+          bytes[4] == 0x0D &&
+          bytes[5] == 0x0A &&
+          bytes[6] == 0x1A &&
+          bytes[7] == 0x0A;
+    }
+
+    // Resolve base (unprocessed) bytes for a placement, considering library override.
+    Uint8List _getBaseBytes(SignaturePlacement placement) {
+      Uint8List baseBytes = placement.asset.bytes;
+      final libKey = placement.asset.name;
+      if (libKey != null && libraryBytes != null) {
+        final libBytes = libraryBytes[libKey];
+        if (libBytes != null && libBytes.isNotEmpty) {
+          baseBytes = libBytes;
+        }
+      }
+      return baseBytes;
+    }
+
+    // Get processed bytes for a placement, with caching.
+    Uint8List _getProcessedBytes(SignaturePlacement placement) {
+      final Uint8List baseBytes = _getBaseBytes(placement);
+
+      final adj = placement.graphicAdjust;
+      final cacheKey =
+          '${_baseKeyForBytes(baseBytes)}|c=${adj.contrast}|b=${adj.brightness}|bg=${adj.bgRemoval}';
+      final cached = _processedBytesCache[cacheKey];
+      if (cached != null) return cached;
+
+      // If no graphic changes requested, return bytes as-is (conversion to PNG is deferred to MemoryImage step)
+      final bool needsAdjust =
+          (adj.contrast != 1.0 || adj.brightness != 1.0 || adj.bgRemoval);
+      if (!needsAdjust) {
+        _processedBytesCache[cacheKey] = baseBytes;
+        return baseBytes;
+      }
+
+      try {
+        final decoded = img.decodeImage(baseBytes);
+        if (decoded == null) {
+          _processedBytesCache[cacheKey] = baseBytes;
+          return baseBytes;
+        }
+        img.Image processed = decoded;
+
+        if (adj.contrast != 1.0 || adj.brightness != 1.0) {
+          processed = img.adjustColor(
+            processed,
+            contrast: adj.contrast,
+            brightness: adj.brightness,
+          );
+        }
+
+        if (adj.bgRemoval) {
+          processed = _removeBackground(processed);
+        }
+
+        final outBytes = Uint8List.fromList(img.encodePng(processed));
+        _processedBytesCache[cacheKey] = outBytes;
+        return outBytes;
+      } catch (_) {
+        // If processing fails, fall back to original
+        _processedBytesCache[cacheKey] = baseBytes;
+        return baseBytes;
+      }
+    }
+
+    // Wrap bytes in a pw.MemoryImage with caching, converting to PNG only when necessary.
+    pw.MemoryImage? _getMemoryImage(Uint8List bytes) {
+      final key = _baseKeyForBytes(bytes);
+      final cached = _memoryImageCache[key];
+      if (cached != null) return cached;
+      try {
+        if (_isPng(bytes)) {
+          final imgObj = pw.MemoryImage(bytes);
+          _memoryImageCache[key] = imgObj;
+          return imgObj;
+        }
+        // Convert to PNG to preserve transparency if not already PNG
+        final decoded = img.decodeImage(bytes);
+        if (decoded == null) return null;
+        final png = Uint8List.fromList(img.encodePng(decoded, level: 6));
+        final imgObj = pw.MemoryImage(png);
+        _memoryImageCache[key] = imgObj;
+        return imgObj;
+      } catch (_) {
+        return null;
+      }
+    }
+
+    // Compute and cache aspect ratio (width/height) for given bytes
+    double? _getAspectRatioFromBytes(Uint8List bytes) {
+      final key = _baseKeyForBytes(bytes);
+      final c = _aspectRatioCache[key];
+      if (c != null) return c;
+      try {
+        final decoded = img.decodeImage(bytes);
+        if (decoded == null || decoded.width <= 0 || decoded.height <= 0) {
+          return null;
+        }
+        final ar = decoded.width / decoded.height;
+        _aspectRatioCache[key] = ar;
+        return ar;
+      } catch (_) {
+        return null;
+      }
+    }
+
     final out = pw.Document(version: pdf.PdfVersion.pdf_1_4, compress: false);
     int pageIndex = 0;
     bool anyPage = false;
@@ -123,51 +206,22 @@ class ExportService {
                   final w = r.width * widthPts;
                   final h = r.height * heightPts;
 
-                  // Process the signature asset with its graphic adjustments
+                  // Get processed bytes (cached) and then embed as MemoryImage (cached)
-                  Uint8List bytes = placement.asset.bytes;
+                  Uint8List bytes = _getProcessedBytes(placement);
-                  if (bytes.isNotEmpty) {
-                    try {
-                      // Decode the image
-                      final decoded = img.decodeImage(bytes);
-                      if (decoded != null) {
-                        img.Image processed = decoded;
-
-                        // Apply contrast and brightness first
-                        if (placement.graphicAdjust.contrast != 1.0 ||
-                            placement.graphicAdjust.brightness != 0.0) {
-                          processed = img.adjustColor(
-                            processed,
-                            contrast: placement.graphicAdjust.contrast,
-                            brightness: placement.graphicAdjust.brightness,
-                          );
-                        }
-
-                        // Apply background removal after color adjustments
-                        if (placement.graphicAdjust.bgRemoval) {
-                          processed = _removeBackground(processed);
-                        }
-
-                        // Encode back to PNG to preserve transparency
-                        bytes = Uint8List.fromList(img.encodePng(processed));
-                      }
-                    } catch (e) {
-                      // If processing fails, use original bytes
-                    }
-                  }
-
-                  // Use fallback if no bytes available
                   if (bytes.isEmpty && signatureImageBytes != null) {
                     bytes = signatureImageBytes;
                   }
 
                   if (bytes.isNotEmpty) {
-                    pw.MemoryImage? imgObj;
+                    final imgObj = _getMemoryImage(bytes);
-                    try {
-                      imgObj = pw.MemoryImage(bytes);
-                    } catch (_) {
-                      imgObj = null;
-                    }
                     if (imgObj != null) {
+                      // Align with RotatedSignatureImage: counterclockwise positive
+                      final angle = rot.radians(placement.rotationDeg);
+                      // Prefer AR from base bytes to avoid extra decode of processed
+                      final baseBytes = _getBaseBytes(placement);
+                      final ar = _getAspectRatioFromBytes(baseBytes);
+                      final scaleToFit = rot.scaleToFitForAngle(angle, ar: ar);
+
                       children.add(
                         pw.Positioned(
                           left: left,
@@ -177,16 +231,16 @@ class ExportService {
                             height: h,
                             child: pw.FittedBox(
                               fit: pw.BoxFit.contain,
+                              child: pw.Transform.scale(
+                                scale: scaleToFit,
                                 child: pw.Transform.rotate(
-                                angle:
+                                  angle: angle,
-                                    placement.rotationDeg *
-                                    3.1415926535 /
-                                    180.0,
                                   child: pw.Image(imgObj),
                                 ),
                               ),
                             ),
                           ),
+                        ),
                       );
                     }
                   }
@@ -227,7 +281,7 @@ class ExportService {
                 color: pdf.PdfColors.white,
               ),
             ];
-            // Multi-placement stamping on fallback page
+
             if (hasMulti && pagePlacements.isNotEmpty) {
               for (var i = 0; i < pagePlacements.length; i++) {
                 final placement = pagePlacements[i];
@@ -238,65 +292,19 @@ class ExportService {
                 final w = r.width * widthPts;
                 final h = r.height * heightPts;
 
-                // Process the signature asset with its graphic adjustments
+                Uint8List bytes = _getProcessedBytes(placement);
-                Uint8List bytes = placement.asset.bytes;
-                if (bytes.isNotEmpty) {
-                  try {
-                    // Decode the image
-                    final decoded = img.decodeImage(bytes);
-                    if (decoded != null) {
-                      img.Image processed = decoded;
-
-                      // Apply contrast and brightness first
-                      if (placement.graphicAdjust.contrast != 1.0 ||
-                          placement.graphicAdjust.brightness != 0.0) {
-                        processed = img.adjustColor(
-                          processed,
-                          contrast: placement.graphicAdjust.contrast,
-                          brightness: placement.graphicAdjust.brightness,
-                        );
-                      }
-
-                      // Apply background removal after color adjustments
-                      if (placement.graphicAdjust.bgRemoval) {
-                        processed = _removeBackground(processed);
-                      }
-
-                      // Encode back to PNG to preserve transparency
-                      bytes = Uint8List.fromList(img.encodePng(processed));
-                    }
-                  } catch (e) {
-                    // If processing fails, use original bytes
-                  }
-                }
-
-                // Use fallback if no bytes available
                 if (bytes.isEmpty && signatureImageBytes != null) {
                   bytes = signatureImageBytes;
                 }
 
                 if (bytes.isNotEmpty) {
-                  pw.MemoryImage? imgObj;
+                  final imgObj = _getMemoryImage(bytes);
-                  try {
-                    // Ensure PNG for transparency if not already
-                    final asStr = String.fromCharCodes(bytes.take(8));
-                    final isPng =
-                        bytes.length > 8 &&
-                        bytes[0] == 0x89 &&
-                        asStr.startsWith('\u0089PNG');
-                    if (isPng) {
-                      imgObj = pw.MemoryImage(bytes);
-                    } else {
-                      final decoded = img.decodeImage(bytes);
-                      if (decoded != null) {
-                        final png = img.encodePng(decoded, level: 6);
-                        imgObj = pw.MemoryImage(Uint8List.fromList(png));
-                      }
-                    }
-                  } catch (_) {
-                    imgObj = null;
-                  }
                   if (imgObj != null) {
+                    final angle = rot.radians(placement.rotationDeg);
+                    final baseBytes = _getBaseBytes(placement);
+                    final ar = _getAspectRatioFromBytes(baseBytes);
+                    final scaleToFit = rot.scaleToFitForAngle(angle, ar: ar);
+
                     children.add(
                       pw.Positioned(
                         left: left,
@@ -306,14 +314,16 @@ class ExportService {
                           height: h,
                           child: pw.FittedBox(
                             fit: pw.BoxFit.contain,
+                            child: pw.Transform.scale(
+                              scale: scaleToFit,
                               child: pw.Transform.rotate(
-                              angle:
+                                angle: angle,
-                                  placement.rotationDeg * 3.1415926535 / 180.0,
                                 child: pw.Image(imgObj),
                               ),
                             ),
                           ),
                         ),
+                      ),
                     );
                   }
                 }

lib/domain/models/signature_card.dart

@@ -18,7 +18,7 @@ class SignatureCard {
   });
 
   SignatureCard copyWith({
-    double? rotationDeg,
+    double? rotationDeg, //z axis is out of the screen, positive is CCW
     SignatureAsset? asset,
     GraphicAdjust? graphicAdjust,
   }) => SignatureCard(

lib/ui/features/pdf/widgets/draw_canvas.dart

@@ -54,8 +54,8 @@ class _DrawCanvasState extends State<DrawCanvas> {
                   onPressed: () async {
                     // Export signature to PNG bytes first
                     final byteData = await _control.toImage(
-                      width: 1024,
+                      width: 512,
-                      height: 512,
+                      height: 256,
                       fit: true,
                       color: Colors.black,
                       background: Colors.transparent,

lib/ui/features/pdf/widgets/pdf_page_area.dart

@@ -11,21 +11,10 @@ class PdfPageArea extends ConsumerStatefulWidget {
   const PdfPageArea({
     super.key,
     required this.pageSize,
-    required this.onDragSignature,
-    required this.onResizeSignature,
-    required this.onConfirmSignature,
-    required this.onClearActiveOverlay,
-    required this.onSelectPlaced,
     required this.controller,
   });
 
   final Size pageSize;
-  // viewerController removed in migration
-  final ValueChanged<Offset> onDragSignature;
-  final ValueChanged<Offset> onResizeSignature;
-  final VoidCallback onConfirmSignature;
-  final VoidCallback onClearActiveOverlay;
-  final ValueChanged<int?> onSelectPlaced;
   final PdfViewerController controller;
   @override
   ConsumerState<PdfPageArea> createState() => _PdfPageAreaState();
@@ -156,11 +145,6 @@ class _PdfPageAreaState extends ConsumerState<PdfPageArea> {
     if (isContinuous) {
       return PdfViewerWidget(
         pageSize: widget.pageSize,
-        onDragSignature: widget.onDragSignature,
-        onResizeSignature: widget.onResizeSignature,
-        onConfirmSignature: widget.onConfirmSignature,
-        onClearActiveOverlay: widget.onClearActiveOverlay,
-        onSelectPlaced: widget.onSelectPlaced,
         pageKeyBuilder: _pageKey,
         scrollToPage: _scrollToPage,
         controller: widget.controller,

lib/ui/features/pdf/widgets/pdf_screen.dart

@@ -109,22 +109,6 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
     return bytes;
   }
 
-  void _confirmSignature() {
-    // In simplified UI, confirmation is a no-op
-  }
-
-  void _onDragSignature(Offset delta) {
-    // In simplified UI, interactive overlay disabled
-  }
-
-  void _onResizeSignature(Offset delta) {
-    // In simplified UI, interactive overlay disabled
-  }
-
-  void _onSelectPlaced(int? index) {
-    // In simplified UI, selection is a no-op for tests
-  }
-
   Future<Uint8List?> _openDrawCanvas() async {
     final result = await showModalBottomSheet<Uint8List>(
       context: context,
@@ -323,11 +307,6 @@ class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
                 controller: _viewModel.controller,
                 key: const ValueKey('pdf_page_area'),
                 pageSize: _pageSize,
-                onDragSignature: _onDragSignature,
-                onResizeSignature: _onResizeSignature,
-                onConfirmSignature: _confirmSignature,
-                onClearActiveOverlay: () {},
-                onSelectPlaced: _onSelectPlaced,
               ),
             ),
       ),

lib/ui/features/pdf/widgets/pdf_viewer_widget.dart

@@ -10,22 +10,12 @@ class PdfViewerWidget extends ConsumerStatefulWidget {
   const PdfViewerWidget({
     super.key,
     required this.pageSize,
-    required this.onDragSignature,
-    required this.onResizeSignature,
-    required this.onConfirmSignature,
-    required this.onClearActiveOverlay,
-    required this.onSelectPlaced,
     this.pageKeyBuilder,
     this.scrollToPage,
     required this.controller,
   });
 
   final Size pageSize;
-  final ValueChanged<Offset> onDragSignature;
-  final ValueChanged<Offset> onResizeSignature;
-  final VoidCallback onConfirmSignature;
-  final VoidCallback onClearActiveOverlay;
-  final ValueChanged<int?> onSelectPlaced;
   final GlobalKey Function(int page)? pageKeyBuilder;
   final void Function(int page)? scrollToPage;
   final PdfViewerController controller;
@@ -88,11 +78,6 @@ class _PdfViewerWidgetState extends ConsumerState<PdfViewerWidget> {
             widget.pageKeyBuilder ??
             (page) => GlobalKey(debugLabel: 'page_$page'),
         scrollToPage: widget.scrollToPage ?? (page) {},
-        onDragSignature: widget.onDragSignature,
-        onResizeSignature: widget.onResizeSignature,
-        onConfirmSignature: widget.onConfirmSignature,
-        onClearActiveOverlay: widget.onClearActiveOverlay,
-        onSelectPlaced: widget.onSelectPlaced,
       );
     }
 
@@ -163,11 +148,6 @@ class _PdfViewerWidgetState extends ConsumerState<PdfViewerWidget> {
             PdfPageOverlays(
               pageSize: Size(pageRect.width, pageRect.height),
               pageNumber: page.pageNumber,
-              onDragSignature: widget.onDragSignature,
-              onResizeSignature: widget.onResizeSignature,
-              onConfirmSignature: widget.onConfirmSignature,
-              onClearActiveOverlay: widget.onClearActiveOverlay,
-              onSelectPlaced: widget.onSelectPlaced,
             ),
           ];
         },

lib/ui/features/signature/widgets/image_editor_dialog.dart

@@ -41,7 +41,7 @@ class _ImageEditorDialogState extends State<ImageEditorDialog> {
   late bool _bgRemoval;
   late double _contrast;
   late double _brightness;
-  late double _rotation;
+  late final ValueNotifier<double> _rotation;
 
   // Cached image data
   late Uint8List _originalBytes; // Original asset bytes (never mutated)
@@ -59,7 +59,7 @@ class _ImageEditorDialogState extends State<ImageEditorDialog> {
     _bgRemoval = widget.initialGraphicAdjust.bgRemoval;
     _contrast = widget.initialGraphicAdjust.contrast;
     _brightness = widget.initialGraphicAdjust.brightness;
-    _rotation = widget.initialRotation;
+    _rotation = ValueNotifier<double>(widget.initialRotation);
     _originalBytes = widget.asset.bytes;
     // Decode lazily only if/when background removal is needed
     if (_bgRemoval) {
@@ -172,6 +172,7 @@ class _ImageEditorDialogState extends State<ImageEditorDialog> {
 
   @override
   void dispose() {
+    _rotation.dispose();
     _bgRemovalDebounce?.cancel();
     super.dispose();
   }
@@ -206,18 +207,19 @@ class _ImageEditorDialogState extends State<ImageEditorDialog> {
                     ),
                     child: ClipRRect(
                       borderRadius: BorderRadius.circular(8),
-                      child:
+                      child: ValueListenableBuilder<double>(
-                          _bgRemoval
+                        valueListenable: _rotation,
-                              ? RotatedSignatureImage(
+                        builder: (context, rot, child) {
+                          final image = RotatedSignatureImage(
                             bytes: _displayBytes,
-                                rotationDeg: _rotation,
+                            rotationDeg: rot,
-                              )
+                          );
-                              : ColorFiltered(
+                          if (_bgRemoval) return image;
+                          return ColorFiltered(
                             colorFilter: _currentColorFilter(),
-                                child: RotatedSignatureImage(
+                            child: image,
-                                  bytes: _displayBytes,
+                          );
-                                  rotationDeg: _rotation,
+                        },
-                                ),
                       ),
                     ),
                   ),
@@ -248,16 +250,26 @@ class _ImageEditorDialogState extends State<ImageEditorDialog> {
                   children: [
                     Text(l10n.rotate),
                     Expanded(
-                      child: Slider(
+                      child: ValueListenableBuilder<double>(
+                        valueListenable: _rotation,
+                        builder: (context, rot, _) {
+                          return Slider(
                             key: const Key('sld_rotation'),
                             min: -180,
                             max: 180,
                             divisions: 72,
-                        value: _rotation,
+                            value: rot,
-                        onChanged: (v) => setState(() => _rotation = v),
+                            onChanged: (v) => _rotation.value = v,
+                          );
+                        },
                       ),
                     ),
-                    Text('${_rotation.toStringAsFixed(0)}°'),
+                    ValueListenableBuilder<double>(
+                      valueListenable: _rotation,
+                      builder:
+                          (context, rot, _) =>
+                              Text('${rot.toStringAsFixed(0)}°'),
+                    ),
                   ],
                 ),
                 const SizedBox(height: 12),
@@ -269,7 +281,7 @@ class _ImageEditorDialogState extends State<ImageEditorDialog> {
                       onPressed:
                           () => Navigator.of(context).pop(
                             ImageEditorResult(
-                              rotation: _rotation,
+                              rotation: _rotation.value,
                               graphicAdjust: domain.GraphicAdjust(
                                 contrast: _contrast,
                                 brightness: _brightness,

lib/ui/features/signature/widgets/rotated_signature_image.dart

@@ -1,17 +1,19 @@
-import 'dart:math' as math;
 import 'dart:typed_data';
 import 'package:flutter/material.dart';
-import 'package:image/image.dart' as img;
+import '../../../../utils/rotation_utils.dart' as rot;
 
 /// A lightweight widget to render signature bytes with rotation and an
 /// angle-aware scale-to-fit so the rotated image stays within its bounds.
+/// Aware that `decodeImage` large images can be crazily slow, especially on web.
 class RotatedSignatureImage extends StatefulWidget {
   const RotatedSignatureImage({
     super.key,
     required this.bytes,
-    this.rotationDeg = 0.0,
+    this.rotationDeg = 0.0, // counterclockwise as positive
     this.filterQuality = FilterQuality.low,
     this.semanticLabel,
+    this.cacheWidth,
+    this.cacheHeight,
   });
 
   final Uint8List bytes;
@@ -22,6 +24,10 @@ class RotatedSignatureImage extends StatefulWidget {
   final Alignment alignment = Alignment.center;
   final bool wrapInRepaintBoundary = true;
   final String? semanticLabel;
+  // Hint the decoder to decode at a smaller size to reduce memory/latency.
+  // On some platforms these may be ignored, but they are safe no-ops.
+  final int? cacheWidth;
+  final int? cacheHeight;
 
   @override
   State<RotatedSignatureImage> createState() => _RotatedSignatureImageState();
@@ -45,8 +51,9 @@ class _RotatedSignatureImageState extends State<RotatedSignatureImage> {
   @override
   void didUpdateWidget(covariant RotatedSignatureImage oldWidget) {
     super.didUpdateWidget(oldWidget);
-    if (!identical(oldWidget.bytes, widget.bytes) ||
+    // Only re-resolve when the bytes change. Rotation does not affect
-        oldWidget.rotationDeg != widget.rotationDeg) {
+    // intrinsic aspect ratio, so avoid expensive decode/resolve on slider drags.
+    if (!identical(oldWidget.bytes, widget.bytes)) {
       _derivedAspectRatio = null;
       _resolveImage();
     }
@@ -60,25 +67,12 @@ class _RotatedSignatureImageState extends State<RotatedSignatureImage> {
 
   void _resolveImage() {
     _unlisten();
-    // Decode synchronously to get aspect ratio
+    // Resolve via ImageProvider; when first frame arrives, capture intrinsic size.
-    // Guard against empty / invalid bytes that some simplified tests may inject.
+    // Avoid synchronous decode on UI thread to keep rotation smooth.
     if (widget.bytes.isEmpty) {
-      _setAspectRatio(1.0); // assume square to avoid layout exceptions
+      _setAspectRatio(1.0); // safe fallback
       return;
     }
-    try {
-      final decoded = img.decodePng(widget.bytes);
-      if (decoded != null) {
-        final w = decoded.width;
-        final h = decoded.height;
-        if (w > 0 && h > 0) {
-          _setAspectRatio(w / h);
-        }
-      }
-    } catch (_) {
-      // Swallow decode errors for test-provided dummy data; assume square.
-      _setAspectRatio(1.0);
-    }
     final stream = _provider.resolve(createLocalImageConfiguration(context));
     _stream = stream;
     _listener = ImageStreamListener((ImageInfo info, bool sync) {
@@ -107,7 +101,7 @@ class _RotatedSignatureImageState extends State<RotatedSignatureImage> {
 
   @override
   Widget build(BuildContext context) {
-    final angle = widget.rotationDeg * math.pi / 180.0;
+    final angle = rot.ccwRadians(widget.rotationDeg);
     Widget img = Image.memory(
       widget.bytes,
       fit: widget.fit,
@@ -115,6 +109,10 @@ class _RotatedSignatureImageState extends State<RotatedSignatureImage> {
       filterQuality: widget.filterQuality,
       alignment: widget.alignment,
       semanticLabel: widget.semanticLabel,
+      // Provide at most one dimension to preserve aspect ratio if only one is set
+      cacheWidth: widget.cacheWidth,
+      cacheHeight: widget.cacheHeight,
+      isAntiAlias: false,
       errorBuilder: (context, error, stackTrace) {
         // Return a placeholder for invalid images
         return Container(
@@ -125,16 +123,7 @@ class _RotatedSignatureImageState extends State<RotatedSignatureImage> {
     );
 
     if (angle != 0.0) {
-      final double c = math.cos(angle).abs();
+      final scaleToFit = rot.scaleToFitForAngle(angle, ar: _derivedAspectRatio);
-      final double s = math.sin(angle).abs();
-      final ar = _derivedAspectRatio;
-      double scaleToFit;
-      if (ar != null && ar > 0) {
-        scaleToFit = math.min(ar / (ar * c + s), 1.0 / (ar * s + c));
-      } else {
-        // Fallback: square approximation
-        scaleToFit = 1.0 / (c + s).clamp(1.0, double.infinity);
-      }
       img = Transform.scale(
         scale: scaleToFit,
         child: Transform.rotate(angle: angle, child: img),

lib/ui/features/signature/widgets/signature_card_view.dart

@@ -1,3 +1,4 @@
+import 'dart:typed_data';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:pdf_signature/domain/models/model.dart' as domain;
@@ -7,15 +8,14 @@ import 'package:pdf_signature/l10n/app_localizations.dart';
 import '../view_model/signature_view_model.dart';
 import '../view_model/dragging_signature_view_model.dart';
 
-class SignatureCard extends ConsumerWidget {
+class SignatureCardView extends ConsumerStatefulWidget {
-  const SignatureCard({
+  const SignatureCardView({
     super.key,
     required this.asset,
     required this.disabled,
     required this.onDelete,
     this.onTap,
     this.onAdjust,
-    this.useCurrentBytesForDrag = false,
     this.rotationDeg = 0.0,
     this.graphicAdjust = const domain.GraphicAdjust(),
   });
@@ -24,9 +24,14 @@ class SignatureCard extends ConsumerWidget {
   final VoidCallback onDelete;
   final VoidCallback? onTap;
   final VoidCallback? onAdjust;
-  final bool useCurrentBytesForDrag;
   final double rotationDeg;
   final domain.GraphicAdjust graphicAdjust;
+  @override
+  ConsumerState<SignatureCardView> createState() => _SignatureCardViewState();
+}
+
+class _SignatureCardViewState extends ConsumerState<SignatureCardView> {
+  Uint8List? _lastBytesRef;
   Future<void> _showContextMenu(BuildContext context, Offset position) async {
     final selected = await showMenu<String>(
       context: context,
@@ -50,22 +55,40 @@ class SignatureCard extends ConsumerWidget {
       ],
     );
     if (selected == 'adjust') {
-      onAdjust?.call();
+      widget.onAdjust?.call();
     } else if (selected == 'delete') {
-      onDelete();
+      widget.onDelete();
     }
   }
 
+  void _maybePrecache(Uint8List bytes) {
+    if (identical(_lastBytesRef, bytes)) return;
+    _lastBytesRef = bytes;
+    // Schedule after frame to avoid doing work during build.
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      // Use single-dimension hints to preserve aspect ratio.
+      final img128 = ResizeImage(MemoryImage(bytes), height: 128);
+      final img256 = ResizeImage(MemoryImage(bytes), height: 256);
+      precacheImage(img128, context);
+      precacheImage(img256, context);
+    });
+  }
+
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  Widget build(BuildContext context) {
     final displayData = ref
         .watch(signatureViewModelProvider)
-        .getDisplaySignatureData(asset, graphicAdjust);
+        .getDisplaySignatureData(widget.asset, widget.graphicAdjust);
+    _maybePrecache(displayData.bytes);
     // Fit inside 96x64 with 6px padding using the shared rotated image widget
     const boxW = 96.0, boxH = 64.0, pad = 6.0;
+    // Hint decoder with small target size to reduce decode cost.
+    // The card shows inside 96x64 with 6px padding; request ~128px max.
     Widget coreImage = RotatedSignatureImage(
       bytes: displayData.bytes,
-      rotationDeg: rotationDeg,
+      rotationDeg: widget.rotationDeg,
+      // Only set one dimension to keep aspect ratio
+      cacheHeight: 128,
     );
     Widget img =
         (displayData.colorMatrix != null)
@@ -102,7 +125,7 @@ class SignatureCard extends ConsumerWidget {
               top: 0,
               child: IconButton(
                 icon: const Icon(Icons.close, size: 16),
-                onPressed: disabled ? null : onDelete,
+                onPressed: widget.disabled ? null : widget.onDelete,
                 tooltip: 'Remove',
                 padding: const EdgeInsets.all(2),
               ),
@@ -111,31 +134,29 @@ class SignatureCard extends ConsumerWidget {
         ),
       ),
     );
-    Widget child = onTap != null ? InkWell(onTap: onTap, child: base) : base;
+    Widget child =
+        widget.onTap != null ? InkWell(onTap: widget.onTap, child: base) : base;
     // Add context menu for adjust/delete on right-click or long-press
     child = GestureDetector(
       key: const Key('gd_signature_card_area'),
       behavior: HitTestBehavior.opaque,
       onSecondaryTapDown:
-          disabled
+          widget.disabled
               ? null
               : (details) => _showContextMenu(context, details.globalPosition),
       onLongPressStart:
-          disabled
+          widget.disabled
               ? null
               : (details) => _showContextMenu(context, details.globalPosition),
       child: child,
     );
-    if (disabled) return child;
+    if (widget.disabled) return child;
     return Draggable<SignatureDragData>(
-      data:
+      data: SignatureDragData(
-          useCurrentBytesForDrag
-              ? const SignatureDragData()
-              : SignatureDragData(
         card: domain.SignatureCard(
-                  asset: asset,
+          asset: widget.asset,
-                  rotationDeg: rotationDeg,
+          rotationDeg: widget.rotationDeg,
-                  graphicAdjust: graphicAdjust,
+          graphicAdjust: widget.graphicAdjust,
         ),
       ),
       onDragStarted: () {
@@ -166,12 +187,14 @@ class SignatureCard extends ConsumerWidget {
                         ),
                         child: RotatedSignatureImage(
                           bytes: displayData.bytes,
-                          rotationDeg: rotationDeg,
+                          rotationDeg: widget.rotationDeg,
+                          cacheHeight: 256,
                         ),
                       )
                       : RotatedSignatureImage(
                         bytes: displayData.bytes,
-                        rotationDeg: rotationDeg,
+                        rotationDeg: widget.rotationDeg,
+                        cacheHeight: 256,
                       ),
             ),
           ),

lib/ui/features/signature/widgets/signature_drag_data.dart

@@ -1,6 +1,6 @@
 import 'package:pdf_signature/domain/models/model.dart';
 
 class SignatureDragData {
-  final SignatureCard? card; // null means use current processed signature
+  final SignatureCard card; // null means use current processed signature
-  const SignatureDragData({this.card});
+  const SignatureDragData({required this.card});
 }

lib/ui/features/signature/widgets/signature_drawer.dart

@@ -6,9 +6,9 @@ import 'package:pdf_signature/l10n/app_localizations.dart';
 
 import 'package:pdf_signature/data/repositories/signature_asset_repository.dart';
 import 'package:pdf_signature/data/repositories/signature_card_repository.dart';
-import 'package:pdf_signature/domain/models/model.dart' hide SignatureCard;
+import 'package:pdf_signature/domain/models/signature_asset.dart';
 import 'image_editor_dialog.dart';
-import 'signature_card.dart';
+import 'signature_card_view.dart';
 import '../../pdf/view_model/pdf_view_model.dart';
 
 /// Data for drag-and-drop is in signature_drag_data.dart
@@ -49,7 +49,7 @@ class _SignatureDrawerState extends ConsumerState<SignatureDrawer> {
               margin: EdgeInsets.zero,
               child: Padding(
                 padding: const EdgeInsets.all(12),
-                child: SignatureCard(
+                child: SignatureCardView(
                   key: ValueKey('sig_card_${library.indexOf(card)}'),
                   asset: card.asset,
                   rotationDeg: card.rotationDeg,

lib/utils/rotation_utils.dart

@@ -0,0 +1,21 @@
+import 'dart:math' as math;
+
+/// Convert degrees to radians with counterclockwise as positive in screen space
+/// by inverting the sign (because screen Y axis points downwards).
+double ccwRadians(double degrees) => -degrees * math.pi / 180.0;
+
+/// Classic math convention: positive degrees rotate counterclockwise.
+/// No screen-space Y-inversion applied.
+double radians(double degrees) => degrees * math.pi / 180.0;
+
+/// Compute scale factor to keep a rotated rectangle of aspect ratio [ar]
+/// within a unit 1x1 box. If [ar] is null or <= 0, fall back to a square.
+/// Returns the scale to apply before rotation.
+double scaleToFitForAngle(double angleRad, {double? ar}) {
+  final double c = angleRad == 0.0 ? 1.0 : math.cos(angleRad).abs();
+  final double s = angleRad == 0.0 ? 0.0 : math.sin(angleRad).abs();
+  if (ar != null && ar > 0) {
+    return math.min(ar / (ar * c + s), 1.0 / (ar * s + c));
+  }
+  return 1.0 / (c + s).clamp(1.0, double.infinity);
+}

test/widget/pdf_page_area_early_jump_test.dart

@@ -42,11 +42,6 @@ void main() {
                 height: 520,
                 child: PdfPageArea(
                   pageSize: Size(676, 400),
-                  onDragSignature: _noopOffset,
-                  onResizeSignature: _noopOffset,
-                  onConfirmSignature: _noop,
-                  onClearActiveOverlay: _noop,
-                  onSelectPlaced: _noopInt,
                   controller: PdfViewerController(),
                 ),
               ),
@@ -75,6 +70,4 @@ void main() {
   });
 }
 
-void _noop() {}
+// No extra callbacks required in the new API
-void _noopInt(int? _) {}
-void _noopOffset(Offset _) {}

test/widget/pdf_page_area_jump_test.dart

@@ -43,11 +43,6 @@ void main() {
                   height: 520,
                   child: PdfPageArea(
                     pageSize: Size(676, 400),
-                    onDragSignature: _noopOffset,
-                    onResizeSignature: _noopOffset,
-                    onConfirmSignature: _noop,
-                    onClearActiveOverlay: _noop,
-                    onSelectPlaced: _noopInt,
                     controller: PdfViewerController(),
                   ),
                 ),
@@ -106,6 +101,4 @@ void main() {
   );
 }
 
-void _noop() {}
+// No extra callbacks required in the new API
-void _noopInt(int? _) {}
-void _noopOffset(Offset _) {}

test/widget/pdf_page_area_test.dart

@@ -43,11 +43,6 @@ void main() {
                 height: 520,
                 child: PdfPageArea(
                   pageSize: const Size(676, 400),
-                  onDragSignature: _noopOffset,
-                  onResizeSignature: _noopOffset,
-                  onConfirmSignature: _noop,
-                  onClearActiveOverlay: _noop,
-                  onSelectPlaced: _noopInt,
                   controller: PdfViewerController(),
                 ),
               ),
@@ -91,11 +86,6 @@ void main() {
                 // Keep aspect ratio consistent with uiPageSize
                 child: PdfPageArea(
                   pageSize: uiPageSize,
-                  onDragSignature: _noopOffset,
-                  onResizeSignature: _noopOffset,
-                  onConfirmSignature: _noop,
-                  onClearActiveOverlay: _noop,
-                  onSelectPlaced: _noopInt,
                   controller: PdfViewerController(),
                 ),
               ),
@@ -170,6 +160,4 @@ void main() {
   });
 }
 
-void _noop() {}
+// No extra callbacks required in the new API
-void _noopInt(int? _) {}
-void _noopOffset(Offset _) {}