1 files changed, 146 insertions, 0 deletions
diff --git a/src/ui/controls/scroll_control.cpp b/src/ui/controls/scroll_control.cpp
new file mode 100644
index 00000000..00969ab7
--- /dev/null
+++ b/src/ui/controls/scroll_control.cpp
@@ -0,0 +1,146 @@
+#include "scroll_control.hpp"
+
+#include <limits>
+
+#include "cru_debug.hpp"
+#include "format.hpp"
+
+namespace cru::ui::controls
+{
+    ScrollControl::ScrollControl(const bool container) : Control(container)
+    {
+        SetClipToPadding(true);
+    }
+
+    ScrollControl::~ScrollControl()
+    {
+
+    }
+
+    void ScrollControl::SetHorizontalScrollEnabled(const bool enable)
+    {
+        horizontal_scroll_enabled_ = enable;
+        InvalidateLayout();
+        InvalidateDraw();
+    }
+
+    void ScrollControl::SetVerticalScrollEnabled(const bool enable)
+    {
+        vertical_scroll_enabled_ = enable;
+        InvalidateLayout();
+        InvalidateDraw();
+    }
+
+    Control* ScrollControl::HitTest(const Point& point)
+    {
+
+    }
+
+    void ScrollControl::SetViewWidth(const float length)
+    {
+        view_width_ = length;
+    }
+
+    void ScrollControl::SetViewHeight(const float length)
+    {
+        view_height_ = length;
+    }
+
+    Size ScrollControl::OnMeasureContent(const Size& available_size)
+    {
+        const auto layout_params = GetLayoutParams();
+
+        auto available_size_for_children = available_size;
+        if (IsHorizontalScrollEnabled())
+        {
+            if (layout_params->width.mode == MeasureMode::Content)
+                debug::DebugMessage(L"ScrollView: Width measure mode is Content and horizontal scroll is enabled. So Stretch is used instead.");
+
+            for (auto child : GetChildren())
+            {
+                const auto child_layout_params = child->GetLayoutParams();
+                if (child_layout_params->width.mode == MeasureMode::Stretch)
+                    throw std::runtime_error(Format("ScrollView: Horizontal scroll is enabled but a child {} 's width measure mode is Stretch which may cause infinite length.", ToUtf8String(child->GetControlType())));
+            }
+
+            available_size_for_children.width = std::numeric_limits<float>::max();
+        }
+
+        if (IsVerticalScrollEnabled())
+        {
+            if (layout_params->height.mode == MeasureMode::Content)
+                debug::DebugMessage(L"ScrollView: Height measure mode is Content and vertical scroll is enabled. So Stretch is used instead.");
+
+            for (auto child : GetChildren())
+            {
+                const auto child_layout_params = child->GetLayoutParams();
+                if (child_layout_params->height.mode == MeasureMode::Stretch)
+                    throw std::runtime_error(Format("ScrollView: Vertical scroll is enabled but a child {} 's height measure mode is Stretch which may cause infinite length.", ToUtf8String(child->GetControlType())));
+            }
+
+            available_size_for_children.height = std::numeric_limits<float>::max();
+        }
+
+        auto max_child_size = Size::Zero();
+        for (auto control: GetChildren())
+        {
+            control->Measure(available_size_for_children);
+            const auto&& size = control->GetDesiredSize();
+            if (max_child_size.width < size.width)
+                max_child_size.width = size.width;
+            if (max_child_size.height < size.height)
+                max_child_size.height = size.height;
+        }
+
+        // coerce size fro stretch.
+        for (auto control: GetChildren())
+        {
+            auto size = control->GetDesiredSize();
+            const auto child_layout_params = control->GetLayoutParams();
+            if (child_layout_params->width.mode == MeasureMode::Stretch)
+                size.width = max_child_size.width;
+            if (child_layout_params->height.mode == MeasureMode::Stretch)
+                size.height = max_child_size.height;
+            control->SetDesiredSize(size);
+        }
+
+        auto result = max_child_size;
+        if (IsHorizontalScrollEnabled())
+        {
+            SetViewWidth(max_child_size.width);
+            result.width = available_size.width;
+        }
+        if (IsVerticalScrollEnabled())
+        {
+            SetViewHeight(max_child_size.height);
+            result.height = available_size.height;
+        }
+
+        return result;
+    }
+
+    void ScrollControl::OnLayoutContent(const Rect& rect)
+    {
+        auto layout_rect = rect;
+
+        if (IsHorizontalScrollEnabled())
+            layout_rect.width = GetViewWidth();
+        if (IsVerticalScrollEnabled())
+            layout_rect.height = GetViewHeight();
+
+        for (auto control: GetChildren())
+        {
+            const auto size = control->GetDesiredSize();
+            // Ignore alignment, always center aligned.
+            auto&& calculate_anchor = [](const float anchor, const float layout_length, const float control_length) -> float
+            {
+                return anchor + (layout_length - control_length) / 2;
+            };
+
+            control->Layout(Rect(Point(
+                calculate_anchor(rect.left, layout_rect.width, size.width),
+                calculate_anchor(rect.top, layout_rect.height, size.height)
+            ), size));
+        }
+    }
+}