WIP

src/Nazara/Widgets/BoxLayout.cpp

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+// Copyright (C) 2022 Jérôme "Lynix" Leclercq (lynix680@gmail.com)
+// This file is part of the "Nazara Engine - Widgets module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#if 0
+
+#include <Nazara/Widgets/BoxLayout.hpp>
+#include <Nazara/Core/Log.hpp>
+#include <Nazara/Core/StackVector.hpp>
+#include <kiwi/kiwi.h>
+#include <NDK/Widgets/BoxLayout.hpp>
+#include <cassert>
+#include <vector>
+#include <Nazara/Widgets/Debug.hpp>
+
+namespace Nz
+{
+	struct BoxLayout::State
+	{
+		std::vector<kiwi::Variable> sizeVar;
+		kiwi::Solver solver;
+	};
+
+	BoxLayout::BoxLayout(BaseWidget* parent, BoxLayoutOrientation orientation) :
+	BaseWidget(parent),
+	m_orientation(orientation),
+	m_spacing(5.f)
+	{
+		m_state = std::make_unique<State>();
+	}
+
+	BoxLayout::~BoxLayout() = default;
+
+	void BoxLayout::Layout()
+	{
+		BaseWidget::Layout();
+
+		std::size_t axis;
+
+		switch (m_orientation)
+		{
+			case BoxLayoutOrientation_Horizontal:
+				axis = 0; //< x
+				break;
+
+			case BoxLayoutOrientation_Vertical:
+				axis = 1; //< y
+				break;
+
+			default:
+				assert(false);
+				break;
+		}
+
+		//TODO: Keep solver state when widgets don't change
+		std::size_t widgetChildCount = GetWidgetChildCount();
+		if (widgetChildCount == 0)
+			return;
+
+		m_state->solver.reset();
+
+		m_state->sizeVar.clear();
+		m_state->sizeVar.reserve(widgetChildCount);
+
+		kiwi::Expression sizeSum;
+
+		Nz::Vector2f layoutSize = GetSize();
+		float availableSpace = layoutSize[axis] - m_spacing * (widgetChildCount - 1);
+		float perfectSpacePerWidget = availableSpace / widgetChildCount;
+
+		// Handle size
+		ForEachWidgetChild([&](BaseWidget* child)
+		{
+			if (!child->IsVisible())
+				return;
+
+			float maximumSize = child->GetMaximumSize()[axis];
+			float minimumSize = child->GetMinimumSize()[axis];
+
+			m_state->sizeVar.emplace_back();
+			auto& sizeVar = m_state->sizeVar.back();
+
+			m_state->solver.addConstraint({ sizeVar >= minimumSize | kiwi::strength::required });
+
+			if (maximumSize < std::numeric_limits<float>::infinity())
+				m_state->solver.addConstraint({ sizeVar <= maximumSize | kiwi::strength::required });
+
+			m_state->solver.addConstraint({ sizeVar >= perfectSpacePerWidget | kiwi::strength::medium });
+
+			sizeSum = sizeSum + sizeVar;
+		});
+
+		kiwi::Variable targetSize("LayoutSize");
+
+		m_state->solver.addConstraint(sizeSum <= targetSize | kiwi::strength::strong);
+
+		m_state->solver.addEditVariable(targetSize, kiwi::strength::strong);
+		m_state->solver.suggestValue(targetSize, availableSpace);
+
+		m_state->solver.updateVariables();
+
+		std::size_t varIndex = 0;
+
+		float remainingSize = availableSpace;
+
+		ForEachWidgetChild([&](BaseWidget* child)
+		{
+			if (!child->IsVisible())
+				return;
+
+			Nz::Vector2f newSize = layoutSize;
+			newSize[axis] = m_state->sizeVar[varIndex].value();
+
+			child->Resize(newSize);
+			remainingSize -= newSize[axis];
+
+			varIndex++;
+		});
+
+		float spacing = m_spacing + remainingSize / (widgetChildCount - 1);
+
+		// Handle position
+		float cursor = 0.f;
+		bool first = true;
+		ForEachWidgetChild([&](BaseWidget* child)
+		{
+			if (first)
+				first = false;
+			else
+				cursor += spacing;
+
+			Nz::Vector2f position = Nz::Vector2f(0.f, 0.f);
+			position[axis] = cursor;
+
+			child->SetPosition(position);
+
+			cursor += child->GetSize()[axis];
+		});
+	}
+}
+
+#endif