1 files changed, 79 insertions, 0 deletions
diff --git a/src/ui/layout_base.cpp b/src/ui/layout_base.cpp
new file mode 100644
index 00000000..a26379a0
--- /dev/null
+++ b/src/ui/layout_base.cpp
@@ -0,0 +1,79 @@
+#include "layout_base.h"
+
+#include "application.h"
+#include "control.h"
+
+namespace cru::ui
+{
+    LayoutManager* LayoutManager::GetInstance()
+    {
+        static LayoutManager layout_manager;
+        return &layout_manager;
+    }
+
+    void LayoutManager::InvalidateControlPositionCache(Control * control)
+    {
+        if (cache_invalid_controls_.count(control) == 1)
+            return;
+
+        // find descendant then erase it; find ancestor then just return.
+        auto i = cache_invalid_controls_.cbegin();
+        while (i != cache_invalid_controls_.cend())
+        {
+            auto current_i = i++;
+            const auto result = IsAncestorOrDescendant(*current_i, control);
+            if (result == control)
+                cache_invalid_controls_.erase(current_i);
+            else if (result != nullptr)
+                return; // find a ancestor of "control", just return
+        }
+
+        cache_invalid_controls_.insert(control);
+
+        if (cache_invalid_controls_.size() == 1) // when insert just now and not repeat to "InvokeLater".
+        {
+            InvokeLater([this] {
+
+                RefreshInvalidControlPositionCache(); // first refresh position cache.
+                for (const auto i : cache_invalid_controls_) // traverse all descendants of position-invalid controls and notify position change event
+                    i->TraverseDescendants([](Control* control)
+                {
+                    control->CheckAndNotifyPositionChanged();
+                });
+                cache_invalid_controls_.clear(); // after update and notify, clear the set.
+
+            });
+        }
+    }
+
+    void LayoutManager::RefreshInvalidControlPositionCache()
+    {
+        for (const auto i : cache_invalid_controls_)
+            RefreshControlPositionCache(i);
+    }
+
+    void LayoutManager::RefreshControlPositionCache(Control * control)
+    {
+        auto point = Point::Zero();
+        auto parent = control;
+        while ((parent = parent->GetParent())) {
+            const auto p = parent->GetPositionRelative();
+            point.x += p.x;
+            point.y += p.y;
+        }
+        RefreshControlPositionCacheInternal(control, point);
+    }
+
+    void LayoutManager::RefreshControlPositionCacheInternal(Control * control, const Point & parent_lefttop_absolute)
+    {
+        const auto position = control->GetPositionRelative();
+        Point lefttop(
+            parent_lefttop_absolute.x + position.x,
+            parent_lefttop_absolute.y + position.y
+        );
+        control->position_cache_.lefttop_position_absolute = lefttop;
+        control->ForeachChild([lefttop](Control* c) {
+            RefreshControlPositionCacheInternal(c, lefttop);
+        });
+    }
+}