add debug mode

example/lib/app.dart

@@ -10,7 +10,7 @@ class App extends StatefulWidget {
 }
 
 class _AppState extends State<App> {
-  final CanvasController controller = CanvasController();
+  final CanvasController controller = CanvasController(debug: true);
 
   @override
   void initState() {

lib/core/controller.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:infinite_lazy_2d_grid/utils/conversions.dart';
+import 'package:infinite_lazy_2d_grid/utils/styles.dart';
 
 // ------------------------------ Public Types -------------------------------
 
@@ -25,6 +26,12 @@ class CanvasController with ChangeNotifier {
   int _nextId = 0; // surely we won't run out of IDs, Clueless
   Offset _gsTopLeftOffset = Offset.zero;
   final Map<int, _CanvasItem> _children = {}; // int for IDs
+  bool debug;
+
+  CanvasController({this.debug = false});
+
+  // -------------------- getters --------------------
+  Offset get offset => _gsTopLeftOffset;
 
   // -------------------- public functions --------------------
 
@@ -70,9 +77,38 @@ class CanvasController with ChangeNotifier {
   }
 
   List<(Offset, Widget)> widgetsWithScreenPositions() {
-    return _children.values.map((item) {
+    return _children.entries.map((entry) {
+      final item = entry.value;
       final ssPosition = gsToSs(item.gsPosition, _gsTopLeftOffset);
-      return (ssPosition, item.builder());
+      var child = item.builder();
+      if (debug) child = _Debug(id: entry.key, gs: item.gsPosition, ss: ssPosition, child: child);
+      return (ssPosition, child);
     }).toList();
   }
 }
+
+class _Debug extends StatelessWidget {
+  final int id;
+  final Offset gs, ss;
+  final Widget child;
+
+  const _Debug({required this.id, required this.gs, required this.ss, required this.child});
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+      clipBehavior: Clip.none,
+      children: [
+        child,
+        Positioned(
+          left: 0,
+          bottom: -60,
+          child: Text(
+            'ID: $id\nGS:(${gs.dx.toInt()},${gs.dy.toInt()})\nSS:(${ss.dx.toInt()},${ss.dy.toInt()})',
+            style: monospaceStyle,
+          ),
+        ),
+      ],
+    );
+  }
+}

lib/core/render.dart

@@ -1,6 +1,8 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:infinite_lazy_2d_grid/core/controller.dart';
+import 'package:infinite_lazy_2d_grid/utils/offset_extensions.dart';
+import 'package:infinite_lazy_2d_grid/utils/styles.dart';
 
 import 'background.dart';
 
@@ -28,11 +30,26 @@ class CanvasView extends StatelessWidget {
             final childrenWithPositions = controller.widgetsWithScreenPositions();
             final ssPositions = childrenWithPositions.map((e) => e.$1).toList();
             final children = childrenWithPositions.map((e) => e.$2).toList();
-            return _CanvasRenderObject(
+            final canvas = _CanvasRenderObject(
               canvasBackground: canvasBackground,
               ssPositions: ssPositions,
               children: children,
             );
+
+            if (controller.debug) {
+              return Stack(
+                children: [
+                  canvas,
+                  Positioned(
+                    top: 16,
+                    left: 16,
+                    child: Text('Offset: ${controller.offset.coord()}', style: monospaceStyle),
+                  ),
+                ],
+              );
+            } else {
+              return canvas;
+            }
           },
         ),
       ),

lib/utils/offset_extensions.dart

@@ -10,4 +10,8 @@ extension OffsetCartesionOps on Offset {
   Offset operator -(Offset other) {
     return Offset(dx - other.dx, dy - other.dy);
   }
+
+  String coord() {
+    return '(${dx.toStringAsFixed(2)}, ${dy.toStringAsFixed(2)})';
+  }
 }

lib/utils/styles.dart

@@ -0,0 +1,8 @@
+import 'package:flutter/material.dart';
+
+final TextStyle monospaceStyle = TextStyle(
+  color: Colors.black,
+  fontSize: 14,
+  fontWeight: FontWeight.bold,
+  fontFamily: 'monospace',
+);