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1 files changed, 79 insertions, 0 deletions

diff --git a/include/cru/ui/render/MeasureRequirement.hpp b/include/cru/ui/render/MeasureRequirement.hpp
new file mode 100644
index 00000000..83de255d
--- /dev/null
+++ b/include/cru/ui/render/MeasureRequirement.hpp
@@ -0,0 +1,79 @@
+#pragma once
+#include "Base.hpp"
+
+#include <limits>
+
+namespace cru::ui::render {
+class MeasureLength {
+ public:
+  struct tag_infinate_t {};
+  constexpr static tag_infinate_t tag_infinate{};
+
+  constexpr MeasureLength() : MeasureLength(0) {}
+  constexpr MeasureLength(tag_infinate_t) : length_(-1) {}
+  constexpr MeasureLength(float length) : length_(length) {
+    Expects(length >= 0);
+  }
+
+  MeasureLength(const MeasureLength& other) = default;
+  MeasureLength& operator=(const MeasureLength& other) = default;
+  MeasureLength& operator=(float length) {
+    Expects(length >= 0);
+    length_ = length;
+    return *this;
+  }
+
+  ~MeasureLength() = default;
+
+  constexpr static MeasureLength Infinate() {
+    return MeasureLength{tag_infinate};
+  }
+
+  constexpr bool IsInfinate() const { return length_ < 0; }
+  constexpr float GetLength() const {
+    return length_ < 0 ? std::numeric_limits<float>::max() : length_;
+  }
+
+  constexpr bool operator==(MeasureLength other) const {
+    return (length_ < 0 && other.length_ < 0) || length_ == other.length_;
+  }
+
+  constexpr bool operator!=(MeasureLength other) const {
+    return !operator==(other);
+  }
+
+ private:
+  // -1 for infinate
+  float length_;
+};
+
+struct MeasureRequirement {
+  MeasureLength max_width;
+  MeasureLength max_height;
+
+  constexpr MeasureRequirement() = default;
+  constexpr MeasureRequirement(MeasureLength max_width,
+                               MeasureLength max_height)
+      : max_width(max_width), max_height(max_height) {}
+
+  constexpr MeasureRequirement(const Size& max_size)
+      : max_width(max_size.width), max_height(max_size.height) {}
+
+  constexpr bool Satisfy(const Size& size) const {
+    if (!max_width.IsInfinate() && max_width.GetLength() < size.width)
+      return false;
+    if (!max_height.IsInfinate() && max_height.GetLength() < size.height)
+      return false;
+    return true;
+  }
+
+  constexpr Size GetMaxSize() const {
+    return Size{max_width.GetLength(), max_height.GetLength()};
+  }
+
+  constexpr static MeasureRequirement Infinate() {
+    return MeasureRequirement{MeasureLength::Infinate(),
+                              MeasureLength::Infinate()};
+  }
+};
+}  // namespace cru::ui::render