ClipView.h

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// Copyright (c) 2025 Dave R. Smith.
// Malena Framework — Licensed under PolyForm Noncommercial 1.0.0; commercial use requires a paid license. See LICENSE.
 
#ifndef MALENA_CLIPVIEW_H
#define MALENA_CLIPVIEW_H
 
#pragma once
 
#include <SFML/Graphics/RenderTarget.hpp>
#include <SFML/Graphics/View.hpp>
#include <SFML/Graphics/Rect.hpp>
 
namespace ml
{
    template<typename F>
    void withClipView(sf::RenderTarget& target, sf::FloatRect rect, F&& body)
    {
        if (rect.size.x <= 0.f || rect.size.y <= 0.f)
        {
            body();
            return;
        }
 
        const auto  sz = target.getSize();
        const float tw = static_cast<float>(sz.x);
        const float th = static_cast<float>(sz.y);
        const sf::View saved = target.getView();
 
        const sf::Vector2i tl = target.mapCoordsToPixel(rect.position, saved);
        const sf::Vector2i br = target.mapCoordsToPixel(
            {rect.position.x + rect.size.x, rect.position.y + rect.size.y}, saved);
 
        sf::View clip;
        clip.setCenter({rect.position.x + rect.size.x / 2.f,
                        rect.position.y + rect.size.y / 2.f});
        clip.setSize(rect.size);
        clip.setViewport(sf::FloatRect{
            {tl.x / tw, tl.y / th},
            {(br.x - tl.x) / tw, (br.y - tl.y) / th}
        });
 
        target.setView(clip);
        body();
        target.setView(saved);
    }
 
} // namespace ml
 
#endif // MALENA_CLIPVIEW_H