Performance optimization & bugfix

Only depth sort if we need to.
Fixed a bug where if you left the highest ancestor of a slider and re-entered it would still be sliding.

include/JUI/Base/Widget.hpp

@@ -81,6 +81,9 @@ namespace JUI {
         std::vector<Widget*> GetDescendants();
         /// Returns a flat list of all nodes that are higher in the hierarchy list.
         std::vector<Widget*> GetAncestors();
+
+        /// @returns the highest ancestor which is not the scene root.
+        Widget* GetHighestNonRootAncestor();
         /// Returns the nodes directly descendant to this widget.
         std::vector<Widget*> GetChildren();
 
@@ -123,7 +126,7 @@ namespace JUI {
         /// @note The range of valid values is -MAX_INT to MAX_INT.
         /// @note This does not manipulate the OpenGL Z buffer, rather, when rendering,
         /// we sort the direct children of a widget widget and render.
-        int ZIndex() const;
+        [[nodiscard]] int ZIndex() const;
 
         /// Sets this widgets z-index.
         /// @see ZIndex().
@@ -384,6 +387,7 @@ namespace JUI {
         Widget* next = nullptr;
         Widget* prev = nullptr;
         int zindex = 0;
+        bool z_dirty = false;
         int layout_order = 0;
         Vector2 viewport_size{0,0};
 

src/JUI/Base/Widget.cpp

@@ -292,7 +292,10 @@ struct {
 zIndexSort;
 
 void Widget::DrawChildWidgets() {
-    std::sort(children.begin(), children.end(), zIndexSort);
+    if (z_dirty)
+        z_dirty = false,
+        std::sort(children.begin(), children.end(), zIndexSort);
+
     for (auto* child : children)
         child->Draw();
 }
@@ -419,7 +422,11 @@ void Widget::AnchorPoint(const Vector2& point) {
 
 int Widget::ZIndex() const { return zindex;}
 
-void Widget::ZIndex(int new_zindex) { zindex = new_zindex; }
+void Widget::ZIndex(int new_zindex) {
+zindex = new_zindex;
+    if (parent)
+        parent->z_dirty = true;
+}
 
 AABB2D Widget::GetActualRenderBounds() const {
     return {GetAbsolutePosition(), GetAbsoluteSize()};
@@ -652,4 +659,19 @@ float Widget::ComputeElementPadding(float size, const UDim &padding) {
     return padding.Pixels + (padding.Scale * size);
 }
 
+Widget* Widget::GetHighestNonRootAncestor() {
+    if (!parent)
+        return nullptr;
+
+    Widget* previous = this;
+    Widget* current = parent;
+
+    while (current->parent) {
+        previous = current;
+        current = current->parent;
+    }
+
+    return previous;
+}
+
 

src/JUI/Widgets/Slider.cpp

@@ -74,6 +74,12 @@ namespace JUI
             current = value;
             //std::cout << "slider value: " << value << std::endl;
         }
+
+        // TODO there is probably a more elegant fix for this.
+       // Fixes the slider not letting go - Redacted.
+       Widget* target = parent ? GetHighestNonRootAncestor() : this;
+       if (!target->IsMouseInside()) { dragging = false; mb_state = false; }
+
         Rect::Update(delta);
     }