update example

Author: hackw

example/staggered_grid.dart

@@ -48,9 +48,6 @@ class StaggeredGridExample extends StatelessWidget {
               id: ConstraintId('horizontalList'),
               left: parent.left,
               top: parent.top,
-              margin: const EdgeInsets.only(
-                left: 100,
-              ),
               itemCount: 50,
               columnCount: columnCount,
               itemBuilder: (index) {

lib/src/constraint_layout.dart

@@ -138,7 +138,7 @@ List<Widget> constraintGrid({
   int currentRowUsedSpanCount = columnCount + 1;
   int totalUsedSpanCount = 0;
   late int currentRowBarrierCount;
-  Map<int, ConstraintId> currentSpanSlot = HashMap();
+  List<ConstraintId?> currentSpanSlot = List.filled(columnCount + 1, null);
   for (int i = 0; i < itemCount; i++) {
     ConstraintId itemId = ConstraintId(id.id + '_grid_item_$i');
     allChildIds.add(itemId);