fix: image_canvas correctness + RAM fixes (v1.3.0)

- _imageSize reset on image switch (wrong swap threshold on nav)
- downsample caps both dims (tall images no longer full-res decode)
- single _readImageSize instead of leaking loadingBuilder listeners
- evict old downsample provider on full-res swap
- remove imageCache.clear() that dropped live image (gallery flash)

lib/services/image_manager.dart

@@ -69,8 +69,6 @@ class ImageManager extends ChangeNotifier {
     }
     if (_currentIndex < 0) _currentIndex = 0;
 
-    // Eski klasörün decode edilmiş görsellerini bırak; canlı görsel korunur
-    PaintingBinding.instance.imageCache.clear();
     notifyListeners();
   }
 

lib/widgets/image_canvas.dart

@@ -156,6 +156,7 @@ class _ImageCanvasState extends State<ImageCanvas> {
   void dispose() {
     HardwareKeyboard.instance.removeHandler(_onHardwareKey);
     _renderTick.dispose();
+    _imageSizeStream?.removeListener(_imageSizeListener!);
     super.dispose();
   }
 
@@ -200,6 +201,7 @@ class _ImageCanvasState extends State<ImageCanvas> {
     _tx = 0; _ty = 0; _sc = 1.0; _isFilled = true;
     _angle = 0; _contrast = 1.0; _saturation = 1.0; _brightness = 0;
     _usingFullRes = false;
+    _imageSize = Size.zero;
     _markRenderDirty();
   }
 
@@ -387,12 +389,27 @@ class _ImageCanvasState extends State<ImageCanvas> {
   ImageProvider<Object>? _cachedProvider;
   String? _cachedPath;
   int? _cachedCacheWidth;
+  ImageStream? _imageSizeStream;
+  ImageStreamListener? _imageSizeListener;
+
+  /// Provider değiştiğinde boyutu tek sefer oku (listener sızıntısı olmadan).
+  void _readImageSize(ImageProvider<Object> provider) {
+    _imageSizeStream?.removeListener(_imageSizeListener!);
+    _imageSizeStream = provider.resolve(const ImageConfiguration());
+    _imageSizeListener = ImageStreamListener((info, _) {
+      if (mounted) {
+        _imageSize = Size(info.image.width.toDouble(), info.image.height.toDouble());
+      }
+    });
+    _imageSizeStream!.addListener(_imageSizeListener!);
+  }
 
   void _checkFullResSwap() {
     if (_usingFullRes || _imageSize.isEmpty) return;
     final double stretchX = _vpSize.width * _sc / _imageSize.width;
     final double stretchY = _vpSize.height * _sc / _imageSize.height;
     if (math.max(stretchX, stretchY) >= 1.5) {
+      _cachedProvider?.evict(); // eski downsample provider'ı cache'ten at
       setState(() {
         _usingFullRes = true;
         _cachedProvider = _cachedFileImage;
@@ -409,8 +426,9 @@ class _ImageCanvasState extends State<ImageCanvas> {
       _cachedCacheWidth = effectiveWidth;
       _cachedFileImage = FileImage(File(widget.filePath));
       _cachedProvider = effectiveWidth != null
-          ? ResizeImage.resizeIfNeeded(effectiveWidth, null, _cachedFileImage!)
+          ? ResizeImage.resizeIfNeeded(effectiveWidth, effectiveWidth, _cachedFileImage!)
           : _cachedFileImage;
+      _readImageSize(_cachedProvider!);
     }
     final ImageProvider<Object> provider = _cachedProvider ?? _cachedFileImage!;
     return Image(
@@ -420,18 +438,6 @@ class _ImageCanvasState extends State<ImageCanvas> {
       filterQuality: FilterQuality.high,
       gaplessPlayback: true,
       errorBuilder: (_, _, _) => _errorWidget(),
-      loadingBuilder: (context, child, loadingProgress) {
-        if (loadingProgress == null && _imageSize.isEmpty) {
-          provider.resolve(const ImageConfiguration()).addListener(
-            ImageStreamListener((info, _) {
-              if (_imageSize.isEmpty) {
-                _imageSize = Size(info.image.width.toDouble(), info.image.height.toDouble());
-              }
-            }),
-          );
-        }
-        return child;
-      },
     );
   }