improve parsing 3

lib/models/ocr_element.dart

@@ -22,16 +22,39 @@ class OcrElement {
   double get width => (right - left).abs();
 }
 
+/// One ML Kit text line with its word-level elements.
+class OcrLine {
+  const OcrLine({
+    required this.text,
+    required this.elements,
+    required this.left,
+    required this.top,
+    required this.right,
+    required this.bottom,
+  });
+
+  final String text;
+  final List<OcrElement> elements;
+  final double left;
+  final double top;
+  final double right;
+  final double bottom;
+
+  double get centerY => (top + bottom) / 2;
+}
+
 /// All positioned elements from one ML Kit recognition pass.
 class OcrDocument {
   const OcrDocument({
     required this.elements,
+    required this.lines,
     required this.imageWidth,
     required this.imageHeight,
     required this.flattenedText,
   });
 
   final List<OcrElement> elements;
+  final List<OcrLine> lines;
   final double imageWidth;
   final double imageHeight;
   final String flattenedText;