1 files changed, 255 insertions, 0 deletions
diff --git a/include/cru/ui/render/ScrollBar.h b/include/cru/ui/render/ScrollBar.h
new file mode 100644
index 00000000..84d4375b
--- /dev/null
+++ b/include/cru/ui/render/ScrollBar.h
@@ -0,0 +1,255 @@
+#pragma once
+#include "Base.h"
+#include "cru/common/Base.h"
+#include "cru/common/Event.h"
+#include "cru/platform/graphics/Base.h"
+#include "cru/platform/graphics/Brush.h"
+#include "cru/platform/graphics/Geometry.h"
+#include "cru/platform/graphics/Painter.h"
+#include "cru/platform/gui/Cursor.h"
+#include "cru/platform/gui/TimerHelper.h"
+#include "cru/platform/gui/UiApplication.h"
+#include "cru/ui/Base.h"
+#include "cru/ui/controls/Control.h"
+#include "cru/ui/helper/ClickDetector.h"
+
+#include <gsl/pointers>
+#include <memory>
+#include <optional>
+#include <unordered_map>
+
+namespace cru::ui::render {
+class ScrollRenderObject;
+
+enum class ScrollKind { Absolute, Relative, Page, Line };
+
+struct Scroll {
+  Direction direction;
+  ScrollKind kind;
+  // For absolute, the new scroll position. Otherwise, offset.
+  float value;
+};
+
+enum class ScrollBarAreaKind {
+  UpArrow,    // Line up
+  DownArrow,  // Line down
+  UpSlot,     // Page up
+  DownSlot,   // Page down
+  Thumb
+};
+
+enum class ScrollBarBrushUsageKind { Arrow, ArrowBackground, Slot, Thumb };
+enum class ScrollBarBrushStateKind { Normal, Hover, Press, Disable };
+
+String CRU_UI_API GenerateScrollBarThemeColorKey(ScrollBarBrushUsageKind usage,
+                                                 ScrollBarBrushStateKind state);
+
+class CRU_UI_API ScrollBar : public Object {
+ public:
+  ScrollBar(gsl::not_null<ScrollRenderObject*> render_object,
+            Direction direction);
+
+  CRU_DELETE_COPY(ScrollBar)
+  CRU_DELETE_MOVE(ScrollBar)
+
+  ~ScrollBar() override;
+
+ public:
+  Direction GetDirection() const { return direction_; }
+
+  bool IsEnabled() const { return is_enabled_; }
+  void SetEnabled(bool value);
+
+  bool IsExpanded() const { return is_expanded_; }
+  void SetExpanded(bool value);
+
+  void Draw(platform::graphics::IPainter* painter);
+
+  IEvent<Scroll>* ScrollAttemptEvent() { return &scroll_attempt_event_; }
+
+  void InstallHandlers(controls::Control* control);
+  void UninstallHandlers() { InstallHandlers(nullptr); }
+
+  gsl::not_null<std::shared_ptr<platform::graphics::IBrush>>
+  GetCollapsedThumbBrush();
+  // Brush could be nullptr to use the theme brush.
+  void SetCollapsedThumbBrush(
+      std::shared_ptr<platform::graphics::IBrush> brush);
+  gsl::not_null<std::shared_ptr<platform::graphics::IBrush>> GetBrush(
+      ScrollBarBrushUsageKind usage, ScrollBarBrushStateKind state);
+  // Brush could be nullptr to use the theme brush.
+  void SetBrush(ScrollBarBrushUsageKind usage, ScrollBarBrushStateKind state,
+                std::shared_ptr<platform::graphics::IBrush> brush);
+
+ protected:
+  void OnDraw(platform::graphics::IPainter* painter, bool expand);
+
+  virtual void DrawUpArrow(
+      platform::graphics::IPainter* painter, const Rect& area,
+      gsl::not_null<platform::graphics::IBrush*> arrow_brush,
+      gsl::not_null<platform::graphics::IBrush*> background_brush) = 0;
+  virtual void DrawDownArrow(
+      platform::graphics::IPainter* painter, const Rect& area,
+      gsl::not_null<platform::graphics::IBrush*> arrow_brush,
+      gsl::not_null<platform::graphics::IBrush*> background_brush) = 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;
+
+  virtual bool CanScrollUp() = 0;
+  virtual bool CanScrollDown() = 0;
+
+ private:
+  void SetCursor();
+  void RestoreCursor();
+
+  void BeginAutoCollapseTimer();
+  void StopAutoCollapseTimer();
+
+  void OnMouseLeave();
+
+  ScrollBarBrushStateKind GetState(ScrollBarAreaKind area);
+
+ protected:
+  gsl::not_null<ScrollRenderObject*> render_object_;
+
+  std::unique_ptr<platform::graphics::IGeometry> arrow_geometry_;
+
+ private:
+  Direction direction_;
+
+  bool is_enabled_ = true;
+
+  bool is_expanded_ = false;
+
+  std::shared_ptr<platform::graphics::IBrush> collapsed_thumb_brush_;
+  std::unordered_map<
+      ScrollBarBrushUsageKind,
+      std::unordered_map<ScrollBarBrushStateKind,
+                         std::shared_ptr<platform::graphics::IBrush>>>
+      brushes_;
+
+  Rect move_thumb_thumb_original_rect_;
+  std::optional<Point> move_thumb_start_;
+
+  std::optional<ScrollBarAreaKind> mouse_hover_;
+  std::optional<ScrollBarAreaKind> mouse_press_;
+
+  EventRevokerListGuard event_guard_;
+
+  Event<Scroll> scroll_attempt_event_;
+
+  bool cursor_overrided_ = false;
+
+  platform::gui::TimerAutoCanceler auto_collapse_timer_canceler_;
+};
+
+class CRU_UI_API HorizontalScrollBar : public ScrollBar {
+ public:
+  explicit HorizontalScrollBar(
+      gsl::not_null<ScrollRenderObject*> render_object);
+
+  CRU_DELETE_COPY(HorizontalScrollBar)
+  CRU_DELETE_MOVE(HorizontalScrollBar)
+
+  ~HorizontalScrollBar() override = default;
+
+ protected:
+  void DrawUpArrow(
+      platform::graphics::IPainter* painter, const Rect& area,
+      gsl::not_null<platform::graphics::IBrush*> arrow_brush,
+      gsl::not_null<platform::graphics::IBrush*> background_brush) override;
+  void DrawDownArrow(
+      platform::graphics::IPainter* painter, const Rect& area,
+      gsl::not_null<platform::graphics::IBrush*> arrow_brush,
+      gsl::not_null<platform::graphics::IBrush*> background_brush) 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;
+
+  bool CanScrollUp() override;
+  bool CanScrollDown() override;
+};
+
+class CRU_UI_API VerticalScrollBar : public ScrollBar {
+ public:
+  explicit VerticalScrollBar(gsl::not_null<ScrollRenderObject*> render_object);
+
+  CRU_DELETE_COPY(VerticalScrollBar)
+  CRU_DELETE_MOVE(VerticalScrollBar)
+
+  ~VerticalScrollBar() override = default;
+
+ protected:
+  void DrawUpArrow(
+      platform::graphics::IPainter* painter, const Rect& area,
+      gsl::not_null<platform::graphics::IBrush*> arrow_brush,
+      gsl::not_null<platform::graphics::IBrush*> background_brush) override;
+  void DrawDownArrow(
+      platform::graphics::IPainter* painter, const Rect& area,
+      gsl::not_null<platform::graphics::IBrush*> arrow_brush,
+      gsl::not_null<platform::graphics::IBrush*> background_brush) 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;
+
+  bool CanScrollUp() override;
+  bool CanScrollDown() override;
+};
+
+// A delegate to draw scrollbar and register related events.
+class CRU_UI_API ScrollBarDelegate : public Object {
+ public:
+  explicit ScrollBarDelegate(gsl::not_null<ScrollRenderObject*> render_object);
+
+  CRU_DELETE_COPY(ScrollBarDelegate)
+  CRU_DELETE_MOVE(ScrollBarDelegate)
+
+  ~ScrollBarDelegate() override = default;
+
+ public:
+  bool IsHorizontalBarEnabled() const { return horizontal_bar_.IsEnabled(); }
+  void SetHorizontalBarEnabled(bool value) {
+    horizontal_bar_.SetEnabled(value);
+  }
+
+  bool IsVerticalBarEnabled() const { return horizontal_bar_.IsEnabled(); }
+  void SetVerticalBarEnabled(bool value) { horizontal_bar_.SetEnabled(value); }
+
+  IEvent<Scroll>* ScrollAttemptEvent() { return &scroll_attempt_event_; }
+
+  void DrawScrollBar(platform::graphics::IPainter* painter);
+
+  void InstallHandlers(controls::Control* control);
+  void UninstallHandlers() { InstallHandlers(nullptr); }
+
+ private:
+  gsl::not_null<ScrollRenderObject*> render_object_;
+
+  HorizontalScrollBar horizontal_bar_;
+  VerticalScrollBar vertical_bar_;
+
+  Event<Scroll> scroll_attempt_event_;
+};
+}  // namespace cru::ui::render