reasampler/src/vst/knob_deck.h

// knob_deck.h — PURE knob-deck layout + hit-test for the r11 Sample-face recomposition
// (Wave B, FB1). NO VST3, NO REAPER, NO SWELL/LICE types at the boundary, and — like
// param_slider — NO engine types: cells and toggles carry opaque shell-owned control ids.
// The mirror of action_bar / param_slider: the fiddly group-box / caption-row / cell-grid
// arithmetic lives here, unit-tested outside the DAW, while the editor shell draws each
// group (fence, caption, compact toggles, knobs) through the L1 kit and routes clicks/drags
// via the hit-test. The KNOB PRIMITIVE itself (value<->needle-angle, vertical drag) is
// param_slider's (FA4); a knob cell here is just a rect — the shell composes the two.
//
// THE DECK (CONTEXT.md §S-VIEW r11). A horizontal run of FENCED GROUPS, left -> right, each
// a hairline-bordered bg/panel box with a CAPTION ROW (micro-caps caption left; the group's
// compact mode toggle right-anchored IN the caption row — this is where the not-full-width
// toggles live) over a KNOB ROW of fixed 48x58 cells (28px knob centered, 12px label band
// beneath). A group may additionally place one 18px-tall two-segment toggle IN the knob row
// after its cells (the VOICE group's Retrig|Legato — same Mono/Stereo segment grammar,
// vertically centered). Groups that must keep stable geometry across a mode flip reserve
// blank cells (id -1): the AMP ENVELOPE group always spans 5 cells so Gate<->Trigger never
// reflows its neighbours.
//
// WRAP (deterministic): groups place left-to-right with kDeckGroupGap between; a group that
// does not fit the remaining width starts a new deck row (whole groups only, never split).
// The first group of a row always places even if wider than the row (degenerate width).
// deckHeight() exposes the resulting height so the shell can bottom-anchor the deck band and
// give the ELASTIC HERO the rest (r11 band order).

#pragma once

#include <vector>

#include "editor_geometry.h"  // Rect, contains — the shared geometry idiom

namespace reasampler::vst {

// Fixed deck metrics (spec r11), exposed so the shell and tests agree.
inline constexpr int kDeckCellW = 48;         // one knob cell
inline constexpr int kDeckCellH = 58;
inline constexpr int kDeckKnobSize = 28;      // knob diameter inside the cell
inline constexpr int kDeckCellLabelH = 12;    // the Micro label band under the knob
inline constexpr int kDeckCaptionH = 20;      // the group caption row
inline constexpr int kDeckToggleH = 18;       // compact toggle segment height
inline constexpr int kDeckGroupPadX = 6;      // group box horizontal inner padding
inline constexpr int kDeckGroupPadY = 4;      // group box vertical inner padding
inline constexpr int kDeckCaptionGap = 2;     // caption row -> knob row gap
inline constexpr int kDeckToggleGap = 4;      // caption text -> toggle / cells -> row toggle gap
inline constexpr int kDeckGroupGap = 12;      // gap between groups on a row
inline constexpr int kDeckRowGap = 8;         // gap between wrapped deck rows
// One group box: padding + caption + gap + cell row + padding.
inline constexpr int kDeckGroupH =
    kDeckGroupPadY + kDeckCaptionH + kDeckCaptionGap + kDeckCellH + kDeckGroupPadY;

// A two-segment compact toggle (always 2 segments — the Mono/Stereo grammar). id -1 = absent.
struct DeckToggleDesc {
    int id = -1;        // shell control id returned by the hit-test; -1 = no toggle
    int segWidth = 44;  // px per segment
};

// One fenced group, in deck order. `cellIds` are the knob cells left-to-right; an id of -1
// is a RESERVED BLANK cell (geometry held, never hit — the AMP ENVELOPE Trigger face).
// `captionWidth` is the px the shell reserves for the caption text (this module does not
// measure text — the house constant-metrics pattern).
struct DeckGroupDesc {
    int id = 0;                    // shell group id (opaque here)
    int captionWidth = 60;
    DeckToggleDesc captionToggle;  // right-anchored in the caption row; id -1 = none
    std::vector<int> cellIds;      // knob cells; -1 = blank reserve
    DeckToggleDesc rowToggle;      // in the knob row after the cells; id -1 = none
};

// --- Laid-out geometry ---------------------------------------------------------------

struct DeckToggleLayout {
    int id = -1;
    Rect seg0;  // left segment
    Rect seg1;  // right segment
};

struct DeckCellLayout {
    int id = -1;
    Rect cell;   // the full 48x58 cell
    Rect knob;   // the centered kDeckKnobSize square (the knob circle inscribes it)
    Rect label;  // the 12px label band beneath the knob
};

struct DeckGroupLayout {
    int id = 0;
    Rect box;                       // the fenced group box
    Rect caption;                   // caption text rect (left part of the caption row)
    DeckToggleLayout captionToggle; // id -1 when absent (rects empty)
    std::vector<DeckCellLayout> cells;
    DeckToggleLayout rowToggle;     // id -1 when absent
};

struct DeckLayout {
    std::vector<DeckGroupLayout> groups;
    int rowCount = 0;
    int height = 0;  // rowCount * kDeckGroupH + (rowCount-1) * kDeckRowGap; 0 for no groups
};

// The width of one group box: the wider of its caption row (caption + gap + toggle) and its
// knob row (cells + gap + row toggle), plus the horizontal padding. Pure.
int deckGroupWidth(const DeckGroupDesc& g);

// The number of deck rows the groups occupy at `availWidth` under the greedy whole-group
// wrap (a group that does not fit the remaining row width starts a new row; the first group
// of a row always places). 0 for an empty group list. Pure — the wrap is deterministic.
int deckRowCount(const std::vector<DeckGroupDesc>& groups, int availWidth);

// The total deck height at `availWidth` (rows * kDeckGroupH + inter-row gaps). 0 for an
// empty list. The shell bottom-anchors a band of exactly this height. Pure.
int deckHeight(const std::vector<DeckGroupDesc>& groups, int availWidth);

// Lay the groups out from (left, top) within `availWidth`, wrapping per deckRowCount's rule.
// Every rect is absolute. Pure — same inputs, same layout.
DeckLayout layoutDeck(const std::vector<DeckGroupDesc>& groups, int left, int top,
                      int availWidth);

// --- Hit-test --------------------------------------------------------------------------

enum class DeckHitKind { None, Knob, CaptionToggle, RowToggle };

struct DeckHit {
    DeckHitKind kind = DeckHitKind::None;
    int id = -1;       // the control id of the hit element (cell id / toggle id)
    int segment = -1;  // 0/1 for a toggle hit; -1 otherwise
};

// The deck element a point lands on: a knob CELL (the whole 48x58 cell — friendlier than the
// bare knob circle; the shell anchors the vertical drag wherever the grab lands), a caption-
// toggle segment, or a row-toggle segment. Blank cells (id -1) and everything else miss.
// Pure — the shell's routing entry point.
DeckHit hitTestDeck(const DeckLayout& layout, int x, int y);

}  // namespace reasampler::vst