...

2 files changed, 34 insertions, 22 deletions

diff --git a/include/cru/ui/render/ScrollRenderObject.hpp b/include/cru/ui/render/ScrollRenderObject.hpp
index 43e6d7f9..0c1fb16b 100644
--- a/include/cru/ui/render/ScrollRenderObject.hpp
+++ b/include/cru/ui/render/ScrollRenderObject.hpp
@@ -4,6 +4,14 @@
 #include "cru/platform/graph/util/Painter.hpp"
 
 namespace cru::ui::render {
+// Measure logic:
+// Measure child with unspecified min and max size.
+// If parent's preferred size is specified, then it is used as measure result.
+// Or child's size is coerced into requirement and then used as result.
+// If no child, then use the preferred size if set or min size if set or 0.
+// Layout logic:
+// If child is smaller than content area, layout at lefttop.
+// Or layout by scroll state.
 class ScrollRenderObject : public RenderObject {
  public:
   ScrollRenderObject() : RenderObject(ChildMode::Single) {}
diff --git a/src/ui/render/ScrollRenderObject.cpp b/src/ui/render/ScrollRenderObject.cpp
index aab8c003..a367afd9 100644
--- a/src/ui/render/ScrollRenderObject.cpp
+++ b/src/ui/render/ScrollRenderObject.cpp
@@ -69,30 +69,34 @@ void ScrollRenderObject::SetScrollOffset(const Point& offset) {
 
 Size ScrollRenderObject::OnMeasureContent(const MeasureRequirement& requirement,
                                           const MeasureSize& preferred_size) {
-  // TODO: Rewrite this.
-  CRU_UNUSED(requirement);
-  CRU_UNUSED(preferred_size);
-  throw std::runtime_error("Not implemented.");
-
-  // if (const auto child = GetSingleChild()) {
-  //   child->Measure(MeasureRequirement::Infinate());
-  //   const auto preferred_size = child->GetMeasuredSize();
-  //   return Min(preferred_size, requirement.GetMaxSize());
-  // } else {
-  //   return Size{};
-  // }
+  if (const auto child = GetSingleChild()) {
+    child->Measure(MeasureRequirement{MeasureSize::NotSpecified(),
+                                      MeasureSize::NotSpecified()},
+                   MeasureSize::NotSpecified());
+
+    Size result = requirement.Coerce(child->GetSize());
+    if (preferred_size.width.IsSpecified()) {
+      result.width = preferred_size.width.GetLengthOrUndefined();
+    }
+    if (preferred_size.height.IsSpecified()) {
+      result.height = preferred_size.height.GetLengthOrUndefined();
+    }
+    return result;
+  } else {
+    Size result{preferred_size.width.IsSpecified()
+                    ? preferred_size.width.GetLengthOrUndefined()
+                    : requirement.min.width.GetLengthOr0(),
+                preferred_size.height.IsSpecified()
+                    ? preferred_size.height.GetLengthOrUndefined()
+                    : requirement.min.height.GetLengthOr0()};
+    return result;
+  }
 }  // namespace cru::ui::render
 
 void ScrollRenderObject::OnLayoutContent(const Rect& content_rect) {
-  // TODO: Rewrite this.
-  CRU_UNUSED(content_rect);
-  throw std::runtime_error("Not implemented.");
-
-  // if (const auto child = GetSingleChild()) {
-  //   const auto child_size = child->GetMeasuredSize();
-  //   const auto true_scroll =
-  //       CoerceScroll(scroll_offset_, content_rect.GetSize(), child_size);
-  //   child->Layout(Rect{content_rect.GetLeftTop() - true_scroll, child_size});
-  // }
+  if (const auto child = GetSingleChild()) {
+    const auto child_size = child->GetSize();
+    child->Layout(content_rect.GetLeftTop() - GetScrollOffset());
+  }
 }
 }  // namespace cru::ui::render