1 files changed, 75 insertions, 18 deletions

diff --git a/include/cru/ui/render/ScrollBar.hpp b/include/cru/ui/render/ScrollBar.hpp
index a9be49a3..e3dabb57 100644
--- a/include/cru/ui/render/ScrollBar.hpp
+++ b/include/cru/ui/render/ScrollBar.hpp
@@ -15,25 +15,27 @@
 namespace cru::ui::render {
 class ScrollRenderObject;
 
-enum class ScrollKind { Absolute, Page, Line };
+enum class ScrollKind { Absolute, Relative, Page, Line };
 
 struct Scroll {
   Direction direction;
   ScrollKind kind;
-  float offset;
+  // For absolute, the new scroll position. Otherwise, offset.
+  float value;
 };
 
 enum class ScrollBarAreaKind {
   UpArrow,    // Line up
   DownArrow,  // Line down
-  UpThumb,    // Page up
-  DownThumb,  // Page down
+  UpSlot,     // Page up
+  DownSlot,   // Page down
   Thumb
 };
 
 class ScrollBar : public Object {
  public:
-  explicit ScrollBar(gsl::not_null<ScrollRenderObject*> render_object);
+  ScrollBar(gsl::not_null<ScrollRenderObject*> render_object,
+            Direction direction);
 
   CRU_DELETE_COPY(ScrollBar)
   CRU_DELETE_MOVE(ScrollBar)
@@ -41,12 +43,15 @@ class ScrollBar : public Object {
   ~ScrollBar() override = default;
 
  public:
+  Direction GetDirection() const { return direction_; }
+
   bool IsEnabled() const { return is_enabled_; }
   void SetEnabled(bool value);
 
-  void Draw(platform::graphics::IPainter* painter);
+  bool IsExpanded() const { return is_expanded_; }
+  void SetExpanded(bool value);
 
-  virtual std::optional<ScrollBarAreaKind> HitTest(const Point& point) = 0;
+  void Draw(platform::graphics::IPainter* painter);
 
   IEvent<Scroll>* ScrollAttemptEvent() { return &scroll_attempt_event_; }
 
@@ -54,20 +59,54 @@ class ScrollBar : public Object {
   void UninstallHandlers() { InstallHandlers(nullptr); }
 
   gsl::not_null<std::shared_ptr<platform::graphics::IBrush>>
-  GetCollapseThumbBrush() const;
+  GetCollapsedThumbBrush() const;
+  gsl::not_null<std::shared_ptr<platform::graphics::IBrush>>
+  GetExpandedThumbBrush() const;
+  gsl::not_null<std::shared_ptr<platform::graphics::IBrush>>
+  GetExpandedSlotBrush() const;
+  gsl::not_null<std::shared_ptr<platform::graphics::IBrush>>
+  GetExpandedArrowBrush() const;
+  gsl::not_null<std::shared_ptr<platform::graphics::IBrush>>
+  GetExpandedArrowBackgroundBrush() const;
 
  protected:
-  virtual void OnDraw(platform::graphics::IPainter* painter, bool expand) = 0;
+  void OnDraw(platform::graphics::IPainter* painter, bool expand);
+
+  virtual void DrawUpArrow(platform::graphics::IPainter* painter,
+                           const Rect& area) = 0;
+  virtual void DrawDownArrow(platform::graphics::IPainter* painter,
+                             const Rect& area) = 0;
+
+  std::optional<ScrollBarAreaKind> ExpandedHitTest(const Point& point);
+
+  virtual bool IsShowBar() = 0;
+
+  virtual std::optional<Rect> GetExpandedAreaRect(
+      ScrollBarAreaKind area_kind) = 0;
+  virtual std::optional<Rect> GetCollapsedTriggerExpandAreaRect() = 0;
+  virtual std::optional<Rect> GetCollapsedThumbRect() = 0;
+
+  virtual float CalculateNewScrollPosition(const Rect& thumb_original_rect,
+                                           const Point& mouse_offset) = 0;
 
  protected:
   gsl::not_null<ScrollRenderObject*> render_object_;
 
  private:
+  Direction direction_;
+
   bool is_enabled_ = true;
 
   bool is_expanded_ = false;
 
-  std::shared_ptr<platform::graphics::IBrush> collapse_thumb_brush_;
+  std::shared_ptr<platform::graphics::IBrush> collapsed_thumb_brush_;
+  std::shared_ptr<platform::graphics::IBrush> expanded_thumb_brush_;
+  std::shared_ptr<platform::graphics::IBrush> expanded_slot_brush_;
+  std::shared_ptr<platform::graphics::IBrush> expanded_arrow_brush_;
+  std::shared_ptr<platform::graphics::IBrush> expanded_arrow_background_brush_;
+
+  Rect move_thumb_thumb_original_rect_;
+  std::optional<Point> move_thumb_start_;
 
   EventRevokerListGuard event_guard_;
 
@@ -84,11 +123,20 @@ class HorizontalScrollBar : public ScrollBar {
 
   ~HorizontalScrollBar() override = default;
 
- public:
-  std::optional<ScrollBarAreaKind> HitTest(const Point& point) override;
-
  protected:
-  void OnDraw(platform::graphics::IPainter* painter, bool expand) override;
+  void DrawUpArrow(platform::graphics::IPainter* painter,
+                   const Rect& area) override;
+  void DrawDownArrow(platform::graphics::IPainter* painter,
+                     const Rect& area) override;
+
+  bool IsShowBar() override;
+
+  std::optional<Rect> GetExpandedAreaRect(ScrollBarAreaKind area_kind) override;
+  std::optional<Rect> GetCollapsedTriggerExpandAreaRect() override;
+  std::optional<Rect> GetCollapsedThumbRect() override;
+
+  float CalculateNewScrollPosition(const Rect& thumb_original_rect,
+                                   const Point& mouse_offset) override;
 };
 
 class VerticalScrollBar : public ScrollBar {
@@ -100,11 +148,20 @@ class VerticalScrollBar : public ScrollBar {
 
   ~VerticalScrollBar() override = default;
 
- public:
-  std::optional<ScrollBarAreaKind> HitTest(const Point& point) override;
-
  protected:
-  void OnDraw(platform::graphics::IPainter* painter, bool expand) override;
+  void DrawUpArrow(platform::graphics::IPainter* painter,
+                   const Rect& area) override;
+  void DrawDownArrow(platform::graphics::IPainter* painter,
+                     const Rect& area) override;
+
+  bool IsShowBar() override;
+
+  std::optional<Rect> GetExpandedAreaRect(ScrollBarAreaKind area_kind) override;
+  std::optional<Rect> GetCollapsedTriggerExpandAreaRect() override;
+  std::optional<Rect> GetCollapsedThumbRect() override;
+
+  float CalculateNewScrollPosition(const Rect& thumb_original_rect,
+                                   const Point& mouse_offset) override;
 };
 
 // A delegate to draw scrollbar and register related events.