++

packages/two_dimensional_scrollables/example/lib/main.dart

@@ -56,9 +56,9 @@ class _TableExampleState extends State<TableExample> {
           verticalDetails:
               ScrollableDetails.vertical(controller: _verticalController),
           cellBuilder: _buildCell,
-          columnCount: 20,
+          // columnCount: 20,
           columnBuilder: _buildColumnSpan,
-          rowCount: _rowCount,
+          // rowCount: _rowCount,
           rowBuilder: _buildRowSpan,
         ),
       ),

packages/two_dimensional_scrollables/lib/src/table_view/table.dart

@@ -129,17 +129,17 @@ class TableView extends TwoDimensionalScrollView {
     super.clipBehavior,
     int pinnedRowCount = 0,
     int pinnedColumnCount = 0,
-    required int columnCount,
-    required int rowCount,
+    int? columnCount,
+    int? rowCount,
     required TableSpanBuilder columnBuilder,
     required TableSpanBuilder rowBuilder,
     required TableViewCellBuilder cellBuilder,
   })  : assert(pinnedRowCount >= 0),
-        assert(rowCount >= 0),
-        assert(rowCount >= pinnedRowCount),
-        assert(columnCount >= 0),
+        assert(rowCount == null || rowCount >= 0),
+        assert(rowCount == null || rowCount >= pinnedRowCount),
+        assert(columnCount == null || columnCount >= 0),
         assert(pinnedColumnCount >= 0),
-        assert(columnCount >= pinnedColumnCount),
+        assert(columnCount == null || columnCount >= pinnedColumnCount),
         super(
           delegate: TableCellBuilderDelegate(
             columnCount: columnCount,
@@ -412,7 +412,7 @@ class RenderTableViewport extends RenderTwoDimensionalViewport {
   }
 
   // Updates the cached column metrics for the table.
-  void _updateColumnMetrics({int fromColumnIndex = 0, int? toColumnIndex,}) {
+  void _updateColumnMetrics({int fromColumnIndex = 0, int? toColumnIndex}) {
     _firstNonPinnedColumn = null;
     _lastNonPinnedColumn = null;
     double startOfRegularColumn = 0;
@@ -424,11 +424,11 @@ class RenderTableViewport extends RenderTwoDimensionalViewport {
       if (toColumnIndex != null) {
         // Column metrics should be computed up to the provided index.
         // Only relevant when we are filling in missing column metrics in an
-        //infinite context.
+        // infinite context.
         assert(delegate.columnCount == null);
         return newColumnMetrics.length > toColumnIndex;
       } else if (delegate.columnCount == null) {
-        // There are infinite columns, and no target index, computing metrics
+        // There are infinite columns, and no target index, compute metrics
         // up to what is visible and in the cache extent.
         return _lastNonPinnedColumn != null;
       }
@@ -454,9 +454,13 @@ class RenderTableViewport extends RenderTwoDimensionalViewport {
       final double leadingOffset =
           isPinned ? startOfPinnedColumn : startOfRegularColumn;
       _Span? span = _columnMetrics.remove(column);
-      final TableSpan configuration = needsDelegateRebuild || span == null
+      final TableSpan? configuration = needsDelegateRebuild
           ? delegate.buildColumn(column)
-          : span.configuration;
+          : span?.configuration;
+      if (configuration == null) {
+        // We have reached the end of columns.
+        break;
+      }
       span ??= _Span();
       span.update(
         isPinned: isPinned,
@@ -485,6 +489,7 @@ class RenderTableViewport extends RenderTwoDimensionalViewport {
       }
       column++;
     }
+
     assert(newColumnMetrics.length >= delegate.pinnedColumnCount);
     for (final _Span span in _columnMetrics.values) {
       span.dispose();
@@ -493,7 +498,7 @@ class RenderTableViewport extends RenderTwoDimensionalViewport {
   }
 
   // Updates the cached row metrics for the table.
-  void _updateRowMetrics({int fromRowIndex = 0, int? toRowIndex,}) {
+  void _updateRowMetrics({int fromRowIndex = 0, int? toRowIndex}) {
     _firstNonPinnedRow = null;
     _lastNonPinnedRow = null;
     double startOfRegularRow = 0;
@@ -507,7 +512,7 @@ class RenderTableViewport extends RenderTwoDimensionalViewport {
       _Span? span = _rowMetrics.remove(row);
       assert(needsDelegateRebuild || span != null);
       final TableSpan configuration =
-          needsDelegateRebuild ? delegate.buildRow(row) : span!.configuration;
+          needsDelegateRebuild ? delegate.buildRow(row) : span.configuration;
       span ??= _Span();
       span.update(
         isPinned: isPinned,
@@ -878,6 +883,16 @@ class RenderTableViewport extends RenderTwoDimensionalViewport {
             mergedColumnOffset = baseColumnOffset +
                 _columnMetrics[firstColumn]!.leadingOffset +
                 _columnMetrics[firstColumn]!.configuration.padding.leading;
+
+            if (delegate.columnCount == null && _columnMetrics[lastColumn] == null) {
+              // The number of columns is infinte, and we have not calculated
+              // the metrics to the full extent of the merged cell. Update the
+              // metrics so we have all the information for the merged area.
+              _updateColumnMetrics(
+                fromColumnIndex: _columnMetrics.length,
+                toColumnIndex: lastColumn,
+              );
+            }
             mergedColumnWidth = _columnMetrics[lastColumn]!.trailingOffset -
                 _columnMetrics[firstColumn]!.leadingOffset -
                 _columnMetrics[lastColumn]!.configuration.padding.trailing -

packages/two_dimensional_scrollables/lib/src/table_view/table_delegate.dart

@@ -14,14 +14,14 @@ import 'table_span.dart';
 /// Used by the [TableCellDelegateMixin.buildColumn] and
 /// [TableCellDelegateMixin.buildRow] to configure rows and columns in the
 /// [TableView].
-typedef TableSpanBuilder = TableSpan Function(int index);
+typedef TableSpanBuilder = TableSpan? Function(int index);
 
 /// Signature for a function that creates a child [TableViewCell] for a given
 /// [TableVicinity] in a [TableView], but may return null.
 ///
 /// Used by [TableCellBuilderDelegate.builder] to build cells on demand for the
 /// table.
-typedef TableViewCellBuilder = TableViewCell Function(
+typedef TableViewCellBuilder = TableViewCell? Function(
   BuildContext context,
   TableVicinity vicinity,
 );
@@ -45,6 +45,7 @@ mixin TableCellDelegateMixin on TwoDimensionalChildDelegate {
   ///
   /// If the value returned by this getter changes throughout the lifetime of
   /// the delegate object, [notifyListeners] must be called.
+  // TODO(Piinks): Update all docs where making nullable
   int? get columnCount;
 
   /// The number of rows that the table has content for.
@@ -102,13 +103,13 @@ mixin TableCellDelegateMixin on TwoDimensionalChildDelegate {
   ///
   /// The builder must return a valid [TableSpan] for all indices smaller than
   /// [columnCount].
-  TableSpan buildColumn(int index);
+  TableSpan? buildColumn(int index);
 
   /// Builds the [TableSpan] that describe the row at the provided index.
   ///
   /// The builder must return a valid [TableSpan] for all indices smaller than
   /// [rowCount].
-  TableSpan buildRow(int index);
+  TableSpan? buildRow(int index);
 }
 
 /// A delegate that supplies children for a [TableViewport] on demand using a
@@ -169,7 +170,7 @@ class TableCellBuilderDelegate extends TwoDimensionalChildBuilderDelegate
   /// [columnCount].
   final TableSpanBuilder _columnBuilder;
   @override
-  TableSpan buildColumn(int index) => _columnBuilder(index);
+  TableSpan? buildColumn(int index) => _columnBuilder(index);
 
   @override
   int get pinnedColumnCount => _pinnedColumnCount;
@@ -205,7 +206,7 @@ class TableCellBuilderDelegate extends TwoDimensionalChildBuilderDelegate
   /// [rowCount].
   final TableSpanBuilder _rowBuilder;
   @override
-  TableSpan buildRow(int index) => _rowBuilder(index);
+  TableSpan? buildRow(int index) => _rowBuilder(index);
 
   @override
   int get pinnedRowCount => _pinnedRowCount;
@@ -274,7 +275,13 @@ class TableCellListDelegate extends TwoDimensionalChildListDelegate
   /// [columnCount].
   final TableSpanBuilder _columnBuilder;
   @override
-  TableSpan buildColumn(int index) => _columnBuilder(index);
+  TableSpan? buildColumn(int index) {
+    if (index >= columnCount) {
+      // The list delegate has a finite number of columns.
+      return null;
+    }
+    return _columnBuilder(index);
+  }
 
   @override
   int get pinnedColumnCount => _pinnedColumnCount;
@@ -298,7 +305,13 @@ class TableCellListDelegate extends TwoDimensionalChildListDelegate
   /// [rowCount].
   final TableSpanBuilder _rowBuilder;
   @override
-  TableSpan buildRow(int index) => _rowBuilder(index);
+  TableSpan? buildRow(int index) {
+    if (index >= rowCount) {
+      // The list deleagte has a finite number of rows.
+      return null;
+    }
+    return _rowBuilder(index);
+  }
 
   @override
   int get pinnedRowCount => _pinnedRowCount;