widget_skin_derive.hpp

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#pragma once
 
#include <pulp/canvas/canvas.hpp>
#include <cstdint>
#include <vector>
 
namespace pulp::view {


struct SkinImage {
    const uint8_t* pixels = nullptr;
    int width = 0;
    int height = 0;
    bool valid() const { return pixels && width > 0 && height > 0; }
};

struct FaderSkin {
    canvas::Color track_color{};
    canvas::Color fill_color{};
    canvas::Color thumb_color{};
    canvas::Color thumb_border_color{};
    // Outline of the empty track (the lighter edge the captured art draws
    // around the dark channel above the thumb). Recovered as the brightest
    // low-saturation column pixel found on a track row, when it is meaningfully
    // lighter than the track fill itself. Lets the skinned fader stroke the
    // track so it doesn't read as a flat dark slab.
    canvas::Color track_border_color{};
    bool has_track = false;
    bool has_fill = false;
    bool has_thumb = false;
    bool has_thumb_border = false;
    bool has_track_border = false;
    // Horizontal extents recovered from the captured art, in ASSET PIXELS
    // (the importer divides by the asset scale to get logical px). The track
    // is the thin low-saturation central column at a non-thumb row; the thumb
    // is the widest opaque row (the silver slab).
    float track_width_px = 0.0f;
    float thumb_width_px = 0.0f;
    bool has_track_width = false;
    bool has_thumb_width = false;
    // Height of the control housing (the tallest opaque run — the track + thumb),
    // in ASSET PIXELS. The captured PNG bakes the value-stack text below the
    // control, so the node's declared height spans control+labels; using it
    // verbatim stretches the fader to ~2× its real height. This is the real
    // control extent.
    float housing_height_px = 0.0f;
    bool has_housing_height = false;
    // Normalized thumb position recovered from the capture (0 = bottom, 1 =
    // top), i.e. where the design actually drew the thumb. An audio fader's
    // value→position map is non-linear (a taper), so a linear (value-min)/(max-
    // min) seed lands the thumb in the wrong place; seeding from the captured
    // position reproduces the design.
    float thumb_position = 0.0f;
    bool has_thumb_position = false;
    bool any() const { return has_track || has_fill || has_thumb || has_thumb_border; }
};

struct MeterSkin {
    std::vector<canvas::Color> gradient;  // low → high
    canvas::Color background{};
    bool has_background = false;
    // Horizontal extent of the colored bar, in ASSET PIXELS (the importer
    // divides by the asset scale to get logical px). Recovered from the bar's
    // own vertical region so faint label glyphs below it don't widen it.
    float bar_width_px = 0.0f;
    bool has_bar_width = false;
    // Height of the meter housing (the tallest opaque run — the dark channel +
    // colored fill), in ASSET PIXELS. Like the fader, the captured PNG bakes
    // the value-stack text below the control, so the declared height spans
    // control+labels; using it verbatim stretches the meter to ~2× its real
    // height (and doubles the absolute fill). This is the real control extent.
    float housing_height_px = 0.0f;
    bool has_housing_height = false;
    // Fraction of the housing's cross-axis width occupied by the colored fill
    // (colored-bar width / full housing width, 0..1). The captured meter recesses
    // a narrow colored bar inside a wider dark housing slot; this ratio lets the
    // skinned meter reproduce that inset instead of painting edge-to-edge. 1.0
    // when the fill spans the full housing.
    float bar_fill_ratio = 1.0f;
    bool has_bar_fill_ratio = false;
    // Normalized fill level recovered from the capture (0 = empty, 1 = full):
    // the height of the contiguous saturated fill from the bottom of the bar.
    // Like the fader, a meter's dB→position map is non-linear, so seed the
    // initial level from where the capture actually filled to.
    float fill_level = 0.0f;
    bool has_fill_level = false;
    bool valid() const { return gradient.size() >= 2; }
};

FaderSkin derive_fader_skin(const SkinImage& img);

MeterSkin derive_meter_skin(const SkinImage& img, int stop_count = 5);
 
}  // namespace pulp::view