Implémentation du zoom et pan pour le mode ajout d'impact

corrigé les impactes en mode zoom

lib/features/crop/widgets/crop_overlay.dart

@@ -0,0 +1,178 @@
+/// Overlay visuel pour le recadrage d'image.
+///
+/// Affiche un masque semi-transparent avec une zone carrée transparente
+/// au centre pour indiquer la zone de recadrage.
+library;
+
+import 'package:flutter/material.dart';
+
+class CropOverlay extends StatelessWidget {
+  /// Taille du carré de recadrage (côté en pixels)
+  final double cropSize;
+
+  /// Afficher la grille des tiers
+  final bool showGrid;
+
+  const CropOverlay({
+    super.key,
+    required this.cropSize,
+    this.showGrid = true,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return CustomPaint(
+      size: Size.infinite,
+      painter: _CropOverlayPainter(
+        cropSize: cropSize,
+        showGrid: showGrid,
+      ),
+    );
+  }
+}
+
+class _CropOverlayPainter extends CustomPainter {
+  final double cropSize;
+  final bool showGrid;
+
+  _CropOverlayPainter({
+    required this.cropSize,
+    required this.showGrid,
+  });
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    // Calculer la position du carré centré
+    final cropRect = Rect.fromCenter(
+      center: Offset(size.width / 2, size.height / 2),
+      width: cropSize,
+      height: cropSize,
+    );
+
+    // Dessiner le masque semi-transparent
+    final maskPaint = Paint()
+      ..color = Colors.black.withValues(alpha: 0.6)
+      ..style = PaintingStyle.fill;
+
+    // Créer un path pour le masque (tout sauf le carré central)
+    final maskPath = Path()
+      ..addRect(Rect.fromLTWH(0, 0, size.width, size.height))
+      ..addRect(cropRect)
+      ..fillType = PathFillType.evenOdd;
+
+    canvas.drawPath(maskPath, maskPaint);
+
+    // Dessiner la bordure du carré de recadrage
+    final borderPaint = Paint()
+      ..color = Colors.white
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = 2;
+
+    canvas.drawRect(cropRect, borderPaint);
+
+    // Dessiner les coins accentués
+    _drawCorners(canvas, cropRect);
+
+    // Dessiner la grille des tiers si activée
+    if (showGrid) {
+      _drawGrid(canvas, cropRect);
+    }
+  }
+
+  void _drawCorners(Canvas canvas, Rect rect) {
+    final cornerPaint = Paint()
+      ..color = Colors.white
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = 4
+      ..strokeCap = StrokeCap.round;
+
+    const cornerLength = 20.0;
+
+    // Coin supérieur gauche
+    canvas.drawLine(
+      Offset(rect.left, rect.top + cornerLength),
+      Offset(rect.left, rect.top),
+      cornerPaint,
+    );
+    canvas.drawLine(
+      Offset(rect.left, rect.top),
+      Offset(rect.left + cornerLength, rect.top),
+      cornerPaint,
+    );
+
+    // Coin supérieur droit
+    canvas.drawLine(
+      Offset(rect.right - cornerLength, rect.top),
+      Offset(rect.right, rect.top),
+      cornerPaint,
+    );
+    canvas.drawLine(
+      Offset(rect.right, rect.top),
+      Offset(rect.right, rect.top + cornerLength),
+      cornerPaint,
+    );
+
+    // Coin inférieur gauche
+    canvas.drawLine(
+      Offset(rect.left, rect.bottom - cornerLength),
+      Offset(rect.left, rect.bottom),
+      cornerPaint,
+    );
+    canvas.drawLine(
+      Offset(rect.left, rect.bottom),
+      Offset(rect.left + cornerLength, rect.bottom),
+      cornerPaint,
+    );
+
+    // Coin inférieur droit
+    canvas.drawLine(
+      Offset(rect.right - cornerLength, rect.bottom),
+      Offset(rect.right, rect.bottom),
+      cornerPaint,
+    );
+    canvas.drawLine(
+      Offset(rect.right, rect.bottom),
+      Offset(rect.right, rect.bottom - cornerLength),
+      cornerPaint,
+    );
+  }
+
+  void _drawGrid(Canvas canvas, Rect rect) {
+    final gridPaint = Paint()
+      ..color = Colors.white.withValues(alpha: 0.4)
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = 1;
+
+    final thirdWidth = rect.width / 3;
+    final thirdHeight = rect.height / 3;
+
+    // Lignes verticales
+    canvas.drawLine(
+      Offset(rect.left + thirdWidth, rect.top),
+      Offset(rect.left + thirdWidth, rect.bottom),
+      gridPaint,
+    );
+    canvas.drawLine(
+      Offset(rect.left + thirdWidth * 2, rect.top),
+      Offset(rect.left + thirdWidth * 2, rect.bottom),
+      gridPaint,
+    );
+
+    // Lignes horizontales
+    canvas.drawLine(
+      Offset(rect.left, rect.top + thirdHeight),
+      Offset(rect.right, rect.top + thirdHeight),
+      gridPaint,
+    );
+    canvas.drawLine(
+      Offset(rect.left, rect.top + thirdHeight * 2),
+      Offset(rect.right, rect.top + thirdHeight * 2),
+      gridPaint,
+    );
+  }
+
+  @override
+  bool shouldRepaint(covariant _CropOverlayPainter oldDelegate) {
+    return cropSize != oldDelegate.cropSize || showGrid != oldDelegate.showGrid;
+  }
+}