viewport_manager.h

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#pragma once
 
#include "viewport_config.h"
#include <QObject>
#include <QSize>
#include <QPointF>
 
namespace CaptureMoment::UI {
namespace Display {
 
struct ScreenInfo {
    int physical_width{0};   
    int physical_height{0};  
    float dpr{1.0f};         
    
    [[nodiscard]] bool isValid() const noexcept {
        return physical_width > 0 && physical_height > 0 && dpr > 0.0f;
    }
};
 
struct ViewportCalculation {
    QSize downsample_size;       
    QSize display_size;          
    float fit_zoom{1.0f};        
    bool needs_downsample{false};
    size_t texture_memory_mb{0}; 
    
    [[nodiscard]] bool isValid() const noexcept {
        return downsample_size.isValid() && display_size.isValid();
    }
};
 
struct ViewportState {
    float zoom{1.0f};            
    QPointF pan{0.0, 0.0};       
    QPointF center_offset{0.0, 0.0}; 
};
 
class ViewportManager : public QObject {
    Q_OBJECT
 
public:
    // =========================================================================
    // Construction
    // =========================================================================
    
    explicit ViewportManager(QObject* parent = nullptr);
    ~ViewportManager() override = default;
    
    ViewportManager(const ViewportManager&) = delete;
    ViewportManager& operator=(const ViewportManager&) = delete;
    ViewportManager(ViewportManager&&) = default;
    ViewportManager& operator=(ViewportManager&&) = default;
 
    // =========================================================================
    // Initialization
    // =========================================================================
    
    void initialize(const QSize& viewport_logical, const ScreenInfo& screen);
    
    void setViewportSize(const QSize& viewport_logical);
    
    void setQualityMargin(float margin);
    
    void setMaxDownsample(int max_dim);
 
    // =========================================================================
    // Calculations
    // =========================================================================
    
    [[nodiscard]] ViewportCalculation calculateDisplay(const QSize& source_size) const;
    
    [[nodiscard]] float calculateFitZoom(const QSize& source_size) const noexcept;
    
    [[nodiscard]] QSize calculateDownsampleSize(const QSize& source_size) const;
    
    [[nodiscard]] ViewportState calculateFitToView(const QSize& display_size) const noexcept;
 
    // =========================================================================
    // Getters
    // =========================================================================
    
    [[nodiscard]] QSize viewportSize() const noexcept { return m_viewport_logical; }
 
    [[nodiscard]] QSize viewportPhysicalSize() const noexcept { return m_viewport_physical; }
 
    [[nodiscard]] ScreenInfo screenInfo() const noexcept { return m_screen; }
  
    [[nodiscard]] float devicePixelRatio() const noexcept { return m_screen.dpr; }
    
    [[nodiscard]] float qualityMargin() const noexcept { return m_quality_margin; }
  
    [[nodiscard]] int plafond() const noexcept { return m_plafond; }
    
    [[nodiscard]] int maxDownsample() const noexcept { return m_max_downsample; }
    
    [[nodiscard]] bool isInitialized() const noexcept { return m_initialized; }
 
signals:
    void viewportSizeChanged(const QSize& size);
    void maxDownsampleChanged(int max_dim);
 
private:
 
    void updateMaxDownsample();
 
    bool m_initialized{false}; 
 
    QSize m_viewport_logical;   
 
    QSize m_viewport_physical;
 
    ScreenInfo m_screen;
 
    float m_quality_margin{DisplayConfig::defaultQualityMargin()}; 
 
    int m_plafond{DisplayConfig::plafondSmallScreen()};
 
    int m_max_downsample{DisplayConfig::plafondSmallScreen()};
};
 
} // namespace Display
} // namespace CaptureMoment::UI