improve parsing 2

lib/models/ocr_element.dart

@@ -0,0 +1,38 @@
+/// One OCR text fragment with pixel bounding box on the receipt image.
+library;
+
+class OcrElement {
+  const OcrElement({
+    required this.text,
+    required this.left,
+    required this.top,
+    required this.right,
+    required this.bottom,
+  });
+
+  final String text;
+  final double left;
+  final double top;
+  final double right;
+  final double bottom;
+
+  double get centerX => (left + right) / 2;
+  double get centerY => (top + bottom) / 2;
+  double get height => (bottom - top).abs();
+  double get width => (right - left).abs();
+}
+
+/// All positioned elements from one ML Kit recognition pass.
+class OcrDocument {
+  const OcrDocument({
+    required this.elements,
+    required this.imageWidth,
+    required this.imageHeight,
+    required this.flattenedText,
+  });
+
+  final List<OcrElement> elements;
+  final double imageWidth;
+  final double imageHeight;
+  final String flattenedText;
+}