127 lines
6.7 KiB
C++
127 lines
6.7 KiB
C++
#pragma once
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#include "core/ui/rect.h"
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// tab_strip — the REAPER-free layout + hit-test math behind the bank_panel's
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// named-banks tab strip (Phase B, Wave 4 — B4). The named-banks region of the
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// vertical-split bank window is a LICE-drawn tab strip (one tab per named bank,
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// NOT a SWELL-native tab control), and — from the start — it must scroll when the
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// tabs overflow the strip width (a naive fixed-width strip breaks down at ~8–12
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// tabs). What is NOT DAW-bound — how N fixed-width tabs tile a strip of a given
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// pixel width, where the overflow chevrons sit, which tab/chevron a click lands in,
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// and how far the strip may scroll — lives here so it is unit-tested outside the
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// DAW (CLAUDE.md §load-bearing split). The panel shell (bank_panel.cpp) owns the
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// SWELL window, LICE drawing, and the live BankBook read; it calls into this seam
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// for every rect and every hit. Mirror of mode_switch / bank_grid.
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//
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// PURE MODULE: NO REAPER types, NO SWELL, NO vendor/ includes. Standard library
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// only. Builds and unit-tests without REAPER.
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#include <vector>
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namespace reasampler::ui {
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// The strip the tabs are drawn into, top-left origin (SWELL/LICE convention).
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// (x, y) is the top-left corner; width/height are the strip extents. The panel
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// reserves this as a fixed-height band at the top of the named-banks region.
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using TabStripRect = Rect; // Q-W1: the shared concrete ui::Rect (core/ui/rect.h), role-aliased
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// Fixed inputs that shape the strip. tabWidth is the pixel width of each tab (fixed
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// so the strip reads as a uniform segmented control and overflow math stays simple —
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// labels ellipsize within the tab, they do not resize it). chevronWidth is the width
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// reserved at each end for the scroll affordance WHEN the tabs overflow; when they
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// fit, no chevron is reserved and the tabs use the full strip width.
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struct TabStripSpec {
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int tabWidth = 96;
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int chevronWidth = 20;
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};
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// One tab's pixel rectangle within the strip, top-left origin, ALREADY translated
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// by the current scroll offset and clipped to the visible track. `index` is the
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// tab's index in the caller's list (ordinal order) so the shell can label/light it
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// without re-deriving. A tab scrolled fully out of view is omitted from the result
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// (the shell only draws what computeTabRects returns), so every returned rect is at
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// least partially visible.
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struct TabRect {
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int index = 0;
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int x = 0;
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int y = 0;
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int width = 0;
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int height = 0;
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bool operator==(const TabRect& o) const {
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return index == o.index && x == o.x && y == o.y &&
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width == o.width && height == o.height;
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}
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};
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// The scrollable track's geometry: where the tabs may be drawn (between the
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// chevrons when overflowing, or the whole strip when they fit) and whether each
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// chevron is present. Derived once and shared by layout + hit-testing so both agree.
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struct TabStripLayout {
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bool overflow = false; // true iff N tabs at tabWidth exceed the track width
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int trackX = 0; // left edge of the tab track (past the left chevron)
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int trackWidth = 0; // width available to tabs (strip minus both chevrons)
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int maxScroll = 0; // largest valid scroll offset (0 when no overflow)
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bool leftChevron = false; // a left-scroll affordance is reserved this frame
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bool rightChevron = false;// a right-scroll affordance is reserved this frame
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};
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// Computes the strip layout for `tabCount` tabs of `spec.tabWidth` in `strip`,
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// given the current `scrollOffset`. Pure geometry:
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// * No overflow (all tabs fit the strip width): overflow=false, no chevrons, the
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// track IS the strip, maxScroll=0.
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// * Overflow: both chevrons are reserved (chevronWidth each), the track is the
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// strip minus both chevrons, and maxScroll is the pixels by which the tab run
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// exceeds the track (so the last tab's right edge can reach the track's right
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// edge but not scroll past it). Chevrons are always both present under overflow
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// (a fixed affordance is simpler and unambiguous than hiding one at an end;
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// clicking a chevron at a scroll limit is a harmless no-op the shell clamps).
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// tabCount <= 0 or a non-positive strip width returns a zeroed layout (no overflow,
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// track == strip, maxScroll 0).
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TabStripLayout computeTabStripLayout(const TabStripRect& strip, int tabCount,
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const TabStripSpec& spec, int scrollOffset);
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// Clamps a desired scroll offset into [0, maxScroll] for the given layout. The shell
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// calls this after a chevron click / wheel so the strip never scrolls past either
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// end. maxScroll is 0 when the tabs fit, so a fitting strip always clamps to 0.
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int clampTabScroll(int desiredOffset, const TabStripLayout& layout);
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// Tiles `tabCount` fixed-width tabs left-to-right into the layout's track, shifted
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// left by `scrollOffset`, and returns the rects that are at least partially visible
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// (in tab-index order). Each tab i sits at trackX + i*tabWidth - scrollOffset; a tab
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// whose visible extent is empty (fully left of or right of the track) is omitted.
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// Returned rects are CLIPPED to the track horizontally so a partially-scrolled tab
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// does not draw under a chevron. The caller passes the SAME scrollOffset it passed
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// to computeTabStripLayout (the shell clamps once, then uses the clamped value for
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// both). tabCount <= 0 -> empty.
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std::vector<TabRect> computeTabRects(const TabStripRect& strip, int tabCount,
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const TabStripSpec& spec, int scrollOffset);
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// What a point in the strip resolves to.
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enum class TabHitKind {
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None, // outside the strip, or in dead space between visible tabs
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Tab, // a tab — `index` is the tab's index in the caller's list
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ScrollLeft, // the left overflow chevron
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ScrollRight, // the right overflow chevron
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};
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// The outcome of hit-testing a point against the strip. For Tab, `index` is the tab
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// index; for the chevrons and None it is -1.
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struct TabHit {
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TabHitKind kind = TabHitKind::None;
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int index = -1;
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bool operator==(const TabHit& o) const {
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return kind == o.kind && index == o.index;
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}
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};
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// Hit-tests a point (SWELL/LICE top-left client coords) against the strip laid out
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// for `tabCount` tabs at `scrollOffset`. Chevrons take precedence over tabs at the
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// strip ends (a click in the reserved chevron band is a scroll, never a tab), and a
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// point outside the strip band, or in the track but not on any visible tab, is None.
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// Half-open bounds match computeTabRects / the chevron bands so no pixel is claimed
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// twice. The shell passes the SAME clamped scrollOffset it drew with.
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TabHit hitTestTabStrip(int px, int py, const TabStripRect& strip, int tabCount,
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const TabStripSpec& spec, int scrollOffset);
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} // namespace reasampler::ui
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