box_shadow_cache.hpp

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#pragma once

 
#ifdef PULP_HAS_SKIA
 
#include <cmath>
#include <cstddef>
#include <cstdint>
#include <functional>
 
#include "include/core/SkRefCnt.h"
 
class SkImage;
 
#include <pulp/canvas/canvas.hpp>  // Color (for the test-render helper)
 
namespace pulp::canvas {

struct BoxShadowKey {
    std::int32_t w = 0;
    std::int32_t h = 0;
    std::int32_t dx = 0;
    std::int32_t dy = 0;
    std::int32_t blur = 0;
    std::int32_t spread = 0;
    std::int32_t corner_radius = 0;
    std::int32_t scale = 0;
 
    bool operator==(const BoxShadowKey& o) const noexcept {
        return w == o.w && h == o.h && dx == o.dx && dy == o.dy &&
               blur == o.blur && spread == o.spread &&
               corner_radius == o.corner_radius && scale == o.scale;
    }
 
    static std::int32_t q(float v) noexcept {
        // static_cast<int32_t> of a non-finite or out-of-range float is UB, and
        // a parsed/animated shadow param can reach inf/NaN. Map non-finite to a
        // fixed bucket and clamp so the *4 and the cast can't overflow int32.
        if (!std::isfinite(v)) return 0;
        constexpr float kLimit = 4.0e8f;  // *4 ≈ 1.6e9, well inside int32 range
        if (v > kLimit) v = kLimit;
        else if (v < -kLimit) v = -kLimit;
        return static_cast<std::int32_t>(v * 4.0f + (v < 0 ? -0.5f : 0.5f));
    }
};
 
class BoxShadowCache {
public:
    static BoxShadowCache& instance();

    sk_sp<SkImage> get_or_render(const BoxShadowKey& key,
                                 const std::function<sk_sp<SkImage>()>& render);
 
    struct Stats {
        std::uint64_t hits = 0;     
        std::uint64_t renders = 0;  
        std::size_t size = 0;       
    };
    Stats stats() const;
    void reset_stats();
    void clear();

    void set_enabled(bool enabled);
    bool enabled() const;
 
    void set_capacity(std::size_t capacity);
 
private:
    BoxShadowCache() = default;
    struct Impl;
    // Defined in box_shadow_cache.cpp; stateful members live there to keep this
    // header free of <mutex>/<list>/<unordered_map>.
    static Impl& impl();
};
 
// ── Test-only render helper ─────────────────────────────────────────────────
// Renders a single box shadow into an RGBA8888 (unpremultiplied) raster buffer
// of px_w x px_h via the real SkiaCanvas path, so tests can pixel-compare the
// cached vs. uncached output without including Skia headers themselves. Returns
// the pixel buffer (size px_w*px_h*4).
std::vector<std::uint8_t> render_box_shadow_to_rgba(
    int px_w, int px_h, float scale,
    float x, float y, float w, float h,
    float dx, float dy, float blur, float spread,
    Color color, float corner_radius, bool inset);
 
}  // namespace pulp::canvas
 
#endif  // PULP_HAS_SKIA