Layout.hpp

#pragma once
#include <vector>
#include <cmath>
#include <functional>
#include <algorithm>
 
namespace vex {
 
class VexUI;
 
enum class FlexDirection { Row, Column };
enum class PositionType { Relative, Absolute };
enum class Justify { FlexStart, Center, FlexEnd, SpaceBetween };
enum class Align { Auto, FlexStart, Center, FlexEnd, Stretch, Baseline };
enum class FlexWrap { NoWrap, Wrap, WrapReverse };

struct FlexValue {
    float v = NAN; 
    bool isPercent = false; 

    float resolve(float parent) const {
        if (std::isnan(v)) return NAN;
        return isPercent ? (v / 100.0f) * parent : v;
    }

    float resolveOr(float parent, float fallback) const {
        float res = resolve(parent);
        return std::isnan(res) ? fallback : res;
    }
};

struct LayoutNode {
    LayoutNode* parent = nullptr; 
    std::vector<LayoutNode*> children; 
    void* context = nullptr; 

    FlexValue width; 
    FlexValue height; 

    FlexValue left; 
    FlexValue top; 
    FlexValue right; 
    FlexValue bottom; 

    FlexValue marginLeft; 
    FlexValue marginTop; 
    FlexValue marginRight; 
    FlexValue marginBottom; 

    FlexValue paddingLeft; 
    FlexValue paddingTop; 
    FlexValue paddingRight; 
    FlexValue paddingBottom; 

    FlexValue borderWidth; 

    float flexGrow = 0.0f; 
    float flexShrink = 1.0f; 

    FlexDirection flexDirection = FlexDirection::Column; 
    PositionType positionType = PositionType::Relative; 
    Justify justifyContent = Justify::FlexStart; 
    Align alignItems = Align::Stretch; 
    Align alignSelf = Align::Auto; 
    FlexWrap flexWrap = FlexWrap::NoWrap; 

    std::function<void(LayoutNode*, float, float)> measureFunc = nullptr;

    float computedLeft = 0.0f; 
    float computedTop = 0.0f; 
    float computedWidth = 0.0f; 
    float computedHeight = 0.0f; 

    void insertChild(LayoutNode* child, size_t index) {
        child->parent = this;
        children.insert(children.begin() + index, child);
    }
};

void calculateLayout(LayoutNode* node, float parentWidth, float parentHeight, bool isRoot = false, const VexUI* ui = nullptr, float forcedW = NAN, float forcedH = NAN);
} // namespace vex