Fix auto canvas placeholder crashing in fixed-height scrollable canvases.

Author: SaadArdati

lib/src/transformers/node_transformers/passive_rectangle_transformer.dart

@@ -73,13 +73,16 @@ class PassiveRectangleWidget extends StatelessWidget {
   Widget build(BuildContext context) {
     final ScopedValues scopedValues = ScopedValues.of(context);
 
-    // final BaseNode? parent = node.id == kRootNode || node.parentID == kRootNode
-    //     ? null
-    //     : getNode(node.parentID);
+    final BaseNode? parent = node.id == kRootNode || node.parentID == kRootNode
+        ? null
+        : manager.getNode(node.parentID);
+    bool isPlaceholder =
+        parent is CanvasNode && parent.properties.bodyId == node.id;
 
     /// TODO Birju / Saad. Why does the commented out parent code below break published layouts only?
     /// Saad's note: The below code looks like AdaptiveNodeBox
-    final double? width = (node.horizontalFit == SizeFit.shrinkWrap)
+    final double? width = (node.horizontalFit == SizeFit.shrinkWrap ||
+            isPlaceholder)
         ? null
         : (node.horizontalFit ==
                 SizeFit
@@ -89,7 +92,8 @@ class PassiveRectangleWidget extends StatelessWidget {
             ? double.infinity
             : node.basicBoxLocal.width;
 
-    final double? height = (node.verticalFit == SizeFit.shrinkWrap)
+    final double? height = (node.verticalFit == SizeFit.shrinkWrap ||
+            isPlaceholder)
         ? null
         : (node.verticalFit ==
                 SizeFit
@@ -138,25 +142,11 @@ class PassiveRectangleWidget extends StatelessWidget {
           ...buildFills(
             node,
             useInk: false,
-            // useInk: node is BlendMixin &&
-            //     (node as BlendMixin).inkWell != null &&
-            //     settings.useInk,
             obscureImages: settings.obscureImages,
             settings: settings,
             scopedValues: scopedValues,
           ),
           ...buildStrokes(node, scopedValues),
-          // old
-          // ...wrapWithPaddingAndScroll(
-          //   node,
-          //   [
-          //     ...children,
-          //     if (portalWidget != null) portalWidget,
-          //   ],
-          //   stackAlignment: stackAlignment,
-          //   applyPadding: applyPadding,
-          // ),
-
           ...wrapWithInkWell(
             context,
             node,
@@ -170,37 +160,6 @@ class PassiveRectangleWidget extends StatelessWidget {
               applyPadding: applyPadding,
             ),
           ),
-
-          // Builder(builder: (context) {
-          //   final child = Stack(
-          //     children: [
-          //       ...wrapWithPaddingAndScroll(
-          //         node,
-          //         [
-          //           ...children,
-          //           if (portalWidget != null) portalWidget,
-          //         ],
-          //         stackAlignment: stackAlignment,
-          //         applyPadding: applyPadding,
-          //       ),
-          //     ],
-          //   );
-          //
-          //   if (node is BlendMixin && (node as BlendMixin).inkWell != null) {
-          //     return Material(
-          //       type: MaterialType.transparency,
-          //       child: InkWell(
-          //         onLongPress: () {},
-          //         onTap: () {
-          //           // TODO:
-          //         },
-          //         child: child,
-          //       ),
-          //     );
-          //   }
-          //
-          //   return child;
-          // }),
         ],
       ),
     );

lib/src/transformers/node_transformers/passive_row_column_transformer.dart

@@ -13,6 +13,7 @@ class PassiveRowColumnTransformer extends NodeWidgetTransformer<RowColumnNode> {
     required List<Widget> childrenWidgets,
     required List<BaseNode> childrenNodes,
     required bool withScroll,
+    required GetNode getNode,
   }) {
     assert(rowColumnNode is RowColumnMixin);
 
@@ -27,8 +28,22 @@ class PassiveRowColumnTransformer extends NodeWidgetTransformer<RowColumnNode> {
     } else if (rowColumnNode.verticalFit == SizeFit.shrinkWrap) {
       fixHeight = rowColumnNode.constraints.minHeight;
     } else {
-      fixHeight = rowColumnNode.constraints.maxHeight ?? double.infinity;
+      // If the node is a canvas node's body, it is likely a placeholder that
+      // expands to fill all available space, while the canvas is already meant
+      // to do that as a scroll view. In this case, we avoid setting the height
+      // to infinity at all costs.
+      final BaseNode? parent = rowColumnNode.parentID == kRootNode
+          ? null
+          : getNode(rowColumnNode.parentID);
+      bool isPlaceholder =
+          parent is CanvasNode && parent.properties.bodyId == rowColumnNode.id;
+      if (isPlaceholder) {
+        fixHeight = rowColumnNode.constraints.minHeight;
+      } else {
+        fixHeight = rowColumnNode.constraints.maxHeight ?? double.infinity;
+      }
     }
+
     if (rowColumnNode.horizontalFit == SizeFit.locked ||
         rowColumnNode.horizontalFit == SizeFit.fixed) {
       fixWidth = rowColumnNode.outerBoxLocal.width;
@@ -302,6 +317,7 @@ class PassiveRowColumnWidget extends StatelessWidget {
                   childrenWidgets: widgetChildren,
                   childrenNodes: children,
                   withScroll: true,
+                  getNode: manager.getNode,
                 )
               ],
               settings: settings,
@@ -311,6 +327,7 @@ class PassiveRowColumnWidget extends StatelessWidget {
             childrenWidgets: widgetChildren,
             childrenNodes: children,
             withScroll: true,
+            getNode: manager.getNode,
           );
 
     if (kIsTestLayout) {