1 files changed, 42 insertions, 1 deletions
diff --git a/src/ui/render/TreeRenderObject.cpp b/src/ui/render/TreeRenderObject.cpp
index 46965b7f..bb983ea5 100644
--- a/src/ui/render/TreeRenderObject.cpp
+++ b/src/ui/render/TreeRenderObject.cpp
@@ -1,4 +1,5 @@
 #include "cru/ui/render/TreeRenderObject.h"
+#include "cru/ui/render/MeasureRequirement.h"
 
 namespace cru::ui::render {
 TreeRenderObjectItem::TreeRenderObjectItem(TreeRenderObject* tree_render_object,
@@ -37,9 +38,49 @@ TreeRenderObject::TreeRenderObject() {
 
 TreeRenderObject::~TreeRenderObject() { delete root_item_; }
 
+void TreeRenderObject::SetTabWidth(float tab_width) {
+  if (tab_width == tab_width_) return;
+  tab_width_ = tab_width;
+  InvalidateLayout();
+}
+
+static Size MeasureTreeRenderObjectItem(MeasureSize max_size,
+                                        TreeRenderObjectItem* item,
+                                        float tab_width) {
+  item->GetRenderObject()->Measure(
+      MeasureRequirement(max_size, MeasureSize::NotSpecified()),
+      MeasureSize::NotSpecified());
+
+  auto item_size = item->GetRenderObject()->GetSize();
+
+  if (max_size.width.IsSpecified()) {
+    max_size.width = max_size.width.GetLengthOrUndefined() - tab_width;
+  }
+
+  if (max_size.height.IsSpecified()) {
+    max_size.height = max_size.height.GetLengthOrUndefined() - item_size.height;
+  }
+
+  Size result_size = item_size;
+
+  for (auto child : item->GetChildren()) {
+    auto child_size = MeasureTreeRenderObjectItem(max_size, child, tab_width);
+    if (child_size.width > result_size.width)
+      result_size.width = child_size.width;
+    result_size.height += child_size.height;
+  }
+
+  return result_size;
+}
+
 Size TreeRenderObject::OnMeasureContent(const MeasureRequirement& requirement,
                                         const MeasureSize& preferred_size) {
-  throw Exception(u"Not implemented.");
+  auto size =
+      MeasureTreeRenderObjectItem(requirement.max, root_item_, tab_width_);
+
+  size = Max(size, requirement.min.GetSizeOr0());
+
+  return size;
 }
 
 void TreeRenderObject::OnLayoutContent(const Rect& content_rect) {