screenshot_compare.hpp

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#pragma once

 
#include <string>
#include <vector>
#include <cstdint>
 
namespace pulp::view {

inline constexpr float kDefaultSimilarityThreshold = 0.85f;

struct CompareResult {
    bool valid = false;           
    float similarity = 0.0f;     
    uint32_t total_pixels = 0;   
    uint32_t diff_pixels = 0;    
    float mean_error = 0.0f;     
    std::string error;           

    bool passes(float threshold = kDefaultSimilarityThreshold) const {
        return valid && similarity >= threshold;
    }
};

struct DiffBounds {
    bool valid = false;
    uint32_t x = 0;
    uint32_t y = 0;
    uint32_t width = 0;
    uint32_t height = 0;
    uint32_t diff_pixels = 0;
};

struct ScreenshotContentStats {
    bool valid = false;
    uint32_t width = 0;
    uint32_t height = 0;
    uint32_t total_pixels = 0;
    uint32_t unique_colors = 0;  
    bool unique_colors_capped = false;
    double luminance_mean = 0.0;
    double luminance_stddev = 0.0;
    double alpha_mean = 0.0;
    double opaque_coverage = 0.0;
    double non_background_coverage = 0.0;
    std::string error;
 
    bool passes_content_floor(uint32_t min_unique_colors = 16,
                              double min_luminance_stddev = 1.0,
                              double min_non_background_coverage = 0.05,
                              double min_opaque_coverage = 0.95) const {
        return valid &&
               unique_colors >= min_unique_colors &&
               luminance_stddev >= min_luminance_stddev &&
               non_background_coverage >= min_non_background_coverage &&
               opaque_coverage >= min_opaque_coverage;
    }
};

struct PngMetadata {
    bool valid = false;
    uint32_t width = 0;
    uint32_t height = 0;
};
 
PngMetadata inspect_png_metadata(const std::vector<uint8_t>& png);

CompareResult compare_screenshots(
    const std::vector<uint8_t>& reference_png,
    const std::vector<uint8_t>& rendered_png,
    uint8_t tolerance = 32
);

CompareResult compare_screenshot_files(
    const std::string& reference_path,
    const std::string& rendered_path,
    uint8_t tolerance = 32
);

std::vector<uint8_t> generate_diff_image(
    const std::vector<uint8_t>& reference_png,
    const std::vector<uint8_t>& rendered_png,
    uint8_t tolerance = 32
);

std::vector<uint8_t> crop_png(
    const std::vector<uint8_t>& png,
    uint32_t x,
    uint32_t y,
    uint32_t width,
    uint32_t height
);

DiffBounds diff_bounds(
    const std::vector<uint8_t>& reference_png,
    const std::vector<uint8_t>& rendered_png,
    uint8_t tolerance = 32
);

ScreenshotContentStats analyze_screenshot_content(const std::vector<uint8_t>& png);
 
} // namespace pulp::view