//! Geometric box-drawing: U+2500-259F synthesized as rects, lines, and //! arcs at EXACT cell bounds, the way dedicated terminals render them. //! Font glyphs are sized to the em box, not the padded cell, so borders //! drawn from glyphs show seams between rows and columns; a synthesized //! segment runs edge-to-edge and shares the same midline arithmetic in //! every cell, so adjacent pieces join seamlessly at any size. //! //! Coverage: the full light/heavy line set (dashes render solid), the //! pure-double lines and corners (corners as two NESTED L joins, the //! double frame a terminal face draws), double tees/crosses with the //! crossing bar riding through the joint rather than breaking (the one //! simplification; mixed single-double variants fall back to their //! single shapes), rounded corners as true quarter arcs, diagonals, //! half lines, block elements, shades, and quadrants. const std = @import("std"); const canvas = @import("root.zig"); const geometry = @import("geometry"); pub fn isBoxDrawing(cp: u21) bool { return cp >= 0x2500 and cp <= 0x259F; } /// A horizontal run of the SAME code point that draws one seamless /// full-width piece can merge into a single command. pub fn mergesHorizontally(cp: u21) bool { return switch (cp) { 0x2500, 0x2501, 0x2550 => true, // ─ ━ ═ 0x2580...0x2588 => true, // ▀ and the lower blocks ▁..█ 0x2591, 0x2592, 0x2593, 0x2594 => true, // shades and ▔ else => false, }; } const Weight = enum { none, light, heavy, double }; const Sides = struct { up: Weight = .none, down: Weight = .none, left: Weight = .none, right: Weight = .none, }; /// The two-bit weight patterns of the U+251C-254B tees and crosses /// follow no single formula; explicit tables keep them honest. fn lineSides(cp: u21) ?Sides { const L = Weight.light; const H = Weight.heavy; const D = Weight.double; return switch (cp) { 0x2500, 0x254C => .{ .left = L, .right = L }, // ─ ╌ 0x2501, 0x254D => .{ .left = H, .right = H }, // ━ ╍ 0x2502, 0x254E => .{ .up = L, .down = L }, // │ ╎ 0x2503, 0x254F => .{ .up = H, .down = H }, // ┃ ╏ 0x2504, 0x2508 => .{ .left = L, .right = L }, // dashed ─ 0x2505, 0x2509 => .{ .left = H, .right = H }, // dashed ━ 0x2506, 0x250A => .{ .up = L, .down = L }, // dashed │ 0x2507, 0x250B => .{ .up = H, .down = H }, // dashed ┃ 0x250C => .{ .down = L, .right = L }, // ┌ 0x250D => .{ .down = L, .right = H }, // ┍ 0x250E => .{ .down = H, .right = L }, // ┎ 0x250F => .{ .down = H, .right = H }, // ┏ 0x2510 => .{ .down = L, .left = L }, // ┐ 0x2511 => .{ .down = L, .left = H }, // ┑ 0x2512 => .{ .down = H, .left = L }, // ┒ 0x2513 => .{ .down = H, .left = H }, // ┓ 0x2514 => .{ .up = L, .right = L }, // └ 0x2515 => .{ .up = L, .right = H }, // ┕ 0x2516 => .{ .up = H, .right = L }, // ┖ 0x2517 => .{ .up = H, .right = H }, // ┗ 0x2518 => .{ .up = L, .left = L }, // ┘ 0x2519 => .{ .up = L, .left = H }, // ┙ 0x251A => .{ .up = H, .left = L }, // ┚ 0x251B => .{ .up = H, .left = H }, // ┛ 0x251C => .{ .up = L, .down = L, .right = L }, // ├ 0x251D => .{ .up = L, .down = L, .right = H }, // ┝ 0x251E => .{ .up = H, .down = L, .right = L }, // ┞ 0x251F => .{ .up = L, .down = H, .right = L }, // ┟ 0x2520 => .{ .up = H, .down = H, .right = L }, // ┠ 0x2521 => .{ .up = H, .down = L, .right = H }, // ┡ 0x2522 => .{ .up = L, .down = H, .right = H }, // ┢ 0x2523 => .{ .up = H, .down = H, .right = H }, // ┣ 0x2524 => .{ .up = L, .down = L, .left = L }, // ┤ 0x2525 => .{ .up = L, .down = L, .left = H }, // ┥ 0x2526 => .{ .up = H, .down = L, .left = L }, // ┦ 0x2527 => .{ .up = L, .down = H, .left = L }, // ┧ 0x2528 => .{ .up = H, .down = H, .left = L }, // ┨ 0x2529 => .{ .up = H, .down = L, .left = H }, // ┩ 0x252A => .{ .up = L, .down = H, .left = H }, // ┪ 0x252B => .{ .up = H, .down = H, .left = H }, // ┫ 0x252C => .{ .left = L, .right = L, .down = L }, // ┬ 0x252D => .{ .left = H, .right = L, .down = L }, // ┭ 0x252E => .{ .left = L, .right = H, .down = L }, // ┮ 0x252F => .{ .left = H, .right = H, .down = L }, // ┯ 0x2530 => .{ .left = L, .right = L, .down = H }, // ┰ 0x2531 => .{ .left = H, .right = L, .down = H }, // ┱ 0x2532 => .{ .left = L, .right = H, .down = H }, // ┲ 0x2533 => .{ .left = H, .right = H, .down = H }, // ┳ 0x2534 => .{ .left = L, .right = L, .up = L }, // ┴ 0x2535 => .{ .left = H, .right = L, .up = L }, // ┵ 0x2536 => .{ .left = L, .right = H, .up = L }, // ┶ 0x2537 => .{ .left = H, .right = H, .up = L }, // ┷ 0x2538 => .{ .left = L, .right = L, .up = H }, // ┸ 0x2539 => .{ .left = H, .right = L, .up = H }, // ┹ 0x253A => .{ .left = L, .right = H, .up = H }, // ┺ 0x253B => .{ .left = H, .right = H, .up = H }, // ┻ 0x253C => .{ .up = L, .down = L, .left = L, .right = L }, // ┼ 0x253D => .{ .up = L, .down = L, .left = H, .right = L }, // ┽ 0x253E => .{ .up = L, .down = L, .left = L, .right = H }, // ┾ 0x253F => .{ .up = L, .down = L, .left = H, .right = H }, // ┿ 0x2540 => .{ .up = H, .down = L, .left = L, .right = L }, // ╀ 0x2541 => .{ .up = L, .down = H, .left = L, .right = L }, // ╁ 0x2542 => .{ .up = H, .down = H, .left = L, .right = L }, // ╂ 0x2543 => .{ .up = H, .down = L, .left = H, .right = L }, // ╃ 0x2544 => .{ .up = H, .down = L, .left = L, .right = H }, // ╄ 0x2545 => .{ .up = L, .down = H, .left = H, .right = L }, // ╅ 0x2546 => .{ .up = L, .down = H, .left = L, .right = H }, // ╆ 0x2547 => .{ .up = H, .down = L, .left = H, .right = H }, // ╇ 0x2548 => .{ .up = L, .down = H, .left = H, .right = H }, // ╈ 0x2549 => .{ .up = H, .down = H, .left = H, .right = L }, // ╉ 0x254A => .{ .up = H, .down = H, .left = L, .right = H }, // ╊ 0x254B => .{ .up = H, .down = H, .left = H, .right = H }, // ╋ 0x2550 => .{ .left = D, .right = D }, // ═ 0x2551 => .{ .up = D, .down = D }, // ║ 0x2552 => .{ .down = L, .right = D }, // ╒ 0x2553 => .{ .down = D, .right = L }, // ╓ 0x2554 => .{ .down = D, .right = D }, // ╔ 0x2555 => .{ .down = L, .left = D }, // ╕ 0x2556 => .{ .down = D, .left = L }, // ╖ 0x2557 => .{ .down = D, .left = D }, // ╗ 0x2558 => .{ .up = L, .right = D }, // ╘ 0x2559 => .{ .up = D, .right = L }, // ╙ 0x255A => .{ .up = D, .right = D }, // ╚ 0x255B => .{ .up = L, .left = D }, // ╛ 0x255C => .{ .up = D, .left = L }, // ╜ 0x255D => .{ .up = D, .left = D }, // ╝ 0x255E => .{ .up = L, .down = L, .right = D }, // ╞ 0x255F => .{ .up = D, .down = D, .right = L }, // ╟ 0x2560 => .{ .up = D, .down = D, .right = D }, // ╠ 0x2561 => .{ .up = L, .down = L, .left = D }, // ╡ 0x2562 => .{ .up = D, .down = D, .left = L }, // ╢ 0x2563 => .{ .up = D, .down = D, .left = D }, // ╣ 0x2564 => .{ .left = D, .right = D, .down = L }, // ╤ 0x2565 => .{ .left = L, .right = L, .down = D }, // ╥ 0x2566 => .{ .left = D, .right = D, .down = D }, // ╦ 0x2567 => .{ .left = D, .right = D, .up = L }, // ╧ 0x2568 => .{ .left = L, .right = L, .up = D }, // ╨ 0x2569 => .{ .left = D, .right = D, .up = D }, // ╩ 0x256A => .{ .up = L, .down = L, .left = D, .right = D }, // ╪ 0x256B => .{ .up = D, .down = D, .left = L, .right = L }, // ╫ 0x256C => .{ .up = D, .down = D, .left = D, .right = D }, // ╬ 0x2574 => .{ .left = L }, // ╴ 0x2575 => .{ .up = L }, // ╵ 0x2576 => .{ .right = L }, // ╶ 0x2577 => .{ .down = L }, // ╷ 0x2578 => .{ .left = H }, // ╸ 0x2579 => .{ .up = H }, // ╹ 0x257A => .{ .right = H }, // ╺ 0x257B => .{ .down = H }, // ╻ 0x257C => .{ .left = L, .right = H }, // ╼ 0x257D => .{ .up = L, .down = H }, // ╽ 0x257E => .{ .left = H, .right = L }, // ╾ 0x257F => .{ .up = H, .down = L }, // ╿ else => null, }; } /// Paint one box-drawing cell (or a merged horizontal run of the same /// The MOST commands `paint` can emit for one code point — the per-cell /// charge the grid painter's row preflight uses, kept adjacent to the /// paint switch so the two cannot drift. Pure lines emit one bar (two /// for a double), joints emit per side (two per double side), nested /// double corners four, rounded corners a path plus its straight run, /// the crossing diagonal two, quadrants one rect per lit quarter, and /// every block/shade/fraction one. pub fn maxCommands(cp: u21) usize { if (doubleCorner(cp) != null) return 4; if (lineSides(cp)) |sides| { // The pure-line shortcuts emit one bar (two for a double). if (sides.up == .none and sides.down == .none and sides.left == sides.right and sides.left != .none) { return if (sides.left == .double) 2 else 1; } if (sides.left == .none and sides.right == .none and sides.up == sides.down and sides.up != .none) { return if (sides.up == .double) 2 else 1; } var total: usize = 0; for ([_]Weight{ sides.up, sides.down, sides.left, sides.right }) |weight| { total += switch (weight) { .none => 0, .light, .heavy => 1, .double => 2, }; } return total; } return switch (cp) { 0x256D, 0x256E, 0x256F, 0x2570 => 2, // arc + straight run 0x2573 => 2, // the crossing diagonal 0x2596...0x259F => 3, // at most three lit quarters in the set else => 1, // lines, blocks, shades, fractions }; } /// A pure-double corner's turn: which vertical and horizontal side the /// two nested L joins open toward. const DoubleCorner = struct { down: bool, right: bool }; fn doubleCorner(cp: u21) ?DoubleCorner { return switch (cp) { 0x2554 => .{ .down = true, .right = true }, // ╔ 0x2557 => .{ .down = true, .right = false }, // ╗ 0x255A => .{ .down = false, .right = true }, // ╚ 0x255D => .{ .down = false, .right = false }, // ╝ else => null, }; } /// Two nested L joins: the OUTER horizontal bar (the one on the closed /// side of the turn) meets the OUTER vertical bar at the outer /// intersection and the inner pair meets at the inner one, so `╔═╗` /// renders the double frame a terminal face draws — no bar rides /// through the joint, no inward stubs. Four bars, four commands. fn paintDoubleCorner(builder: *canvas.Builder, id_base: u64, keyed: bool, rect: geometry.RectF, corner: DoubleCorner, t: f32, color: canvas.Color) !void { const cx = rect.x + rect.width / 2; const cy = rect.y + rect.height / 2; // Bar centerlines: vertical bars at cx +- t, horizontal at cy +- t. // The OUTER pair sits opposite the openings (a down+right corner's // outer bars are the top horizontal and the left vertical). const outer_x = if (corner.right) cx - t else cx + t; const inner_x = if (corner.right) cx + t else cx - t; const outer_y = if (corner.down) cy - t else cy + t; const inner_y = if (corner.down) cy + t else cy - t; var id = id_base; // Horizontal bars run toward the horizontal opening, starting at // their matching vertical bar's far edge so each joint is solid. for ([2][2]f32{ .{ outer_y, outer_x }, .{ inner_y, inner_x } }) |pair| { const bar_y = pair[0]; const from_x = pair[1]; const x0 = if (corner.right) from_x - t / 2 else rect.x; const x1 = if (corner.right) rect.x + rect.width else from_x + t / 2; try builder.fillRect(.{ .id = if (keyed) id else 0, .rect = geometry.RectF.init(x0, bar_y - t / 2, x1 - x0, t), .fill = .{ .color = color }, }); id +%= 1; } // Vertical bars run toward the vertical opening the same way. for ([2][2]f32{ .{ outer_x, outer_y }, .{ inner_x, inner_y } }) |pair| { const bar_x = pair[0]; const from_y = pair[1]; const y0 = if (corner.down) from_y - t / 2 else rect.y; const y1 = if (corner.down) rect.y + rect.height else from_y + t / 2; try builder.fillRect(.{ .id = if (keyed) id else 0, .rect = geometry.RectF.init(bar_x - t / 2, y0, t, y1 - y0), .fill = .{ .color = color }, }); id +%= 1; } } /// seamless code point) as geometry filling `rect` edge-to-edge. Emits /// at most four commands with ids `id_base..id_base+3`; `thickness` is /// the light-line weight in canvas points. pub fn paint( builder: *canvas.Builder, id_base: u64, rect: geometry.RectF, cp: u21, color: canvas.Color, thickness: f32, ) !void { const t = @max(1, thickness); const cx = rect.x + rect.width / 2; const cy = rect.y + rect.height / 2; // The anonymous-id convention (`widgetPartId` returns 0 for id 0): // a zero base emits EVERY command with id 0 — no derived 1..3 ids // that would collide across an identity-less grid's cells. const keyed = id_base != 0; // Pure-double corners draw as two NESTED L joins — the outer pair of // bars turning at the outer intersection, the inner pair at the // inner one — the shape a real terminal face draws, instead of both // bars riding through the joint (which reads as a hash crossing with // inward stubs). if (doubleCorner(cp)) |corner| { try paintDoubleCorner(builder, id_base, keyed, rect, corner, t, color); return; } if (lineSides(cp)) |sides| { var id = id_base; // Pure horizontals and verticals emit ONE edge-to-edge bar (two // for a double): the common border pieces cost a single command // and are seamless by construction. if (sides.up == .none and sides.down == .none and sides.left == sides.right and sides.left != .none) { _ = try paintSegment(builder, id, keyed, sides.left, t, .{ .x = rect.x, .y = cy, .len = rect.width, .horizontal = true }, color); return; } if (sides.left == .none and sides.right == .none and sides.up == sides.down and sides.up != .none) { _ = try paintSegment(builder, id, keyed, sides.up, t, .{ .x = cx, .y = rect.y, .len = rect.height, .horizontal = false }, color); return; } // Doubles draw as two parallel light lines at center +/- t; the // single weights draw one centered bar (heavy at double width). // Every segment overlaps the cell center so joints are solid, // and runs to the cell edge so neighbors abut exactly. if (sides.left != .none) id = try paintSegment(builder, id, keyed, sides.left, t, .{ .x = rect.x, .y = cy, .len = cx - rect.x + barHalf(sides.left, t), .horizontal = true }, color); if (sides.right != .none) id = try paintSegment(builder, id, keyed, sides.right, t, .{ .x = cx - barHalf(sides.right, t), .y = cy, .len = rect.x + rect.width - cx + barHalf(sides.right, t), .horizontal = true }, color); if (sides.up != .none) id = try paintSegment(builder, id, keyed, sides.up, t, .{ .x = cx, .y = rect.y, .len = cy - rect.y + barHalf(sides.up, t), .horizontal = false }, color); if (sides.down != .none) id = try paintSegment(builder, id, keyed, sides.down, t, .{ .x = cx, .y = cy - barHalf(sides.down, t), .len = rect.y + rect.height - cy + barHalf(sides.down, t), .horizontal = false }, color); return; } switch (cp) { // Rounded corners: a true quarter arc joining the two cell // edges through the center, the shape box-heavy TUIs lean on. 0x256D, 0x256E, 0x256F, 0x2570 => { const r = @min(rect.width, rect.height) / 2; // Allocated from the builder's OWN path-element store, never // a stack local: `strokePath` retains the slice by reference // (it never copies), so a stack array would dangle the moment // this frame returns and the retained/diffed renderer read it // back as overwritten memory. const elements = try builder.allocPathElements(3); switch (cp) { // ╭ bottom edge to right edge 0x256D => { elements[0] = .{ .verb = .move_to, .points = .{ .{ .x = cx, .y = rect.y + rect.height }, geometry.PointF.zero(), geometry.PointF.zero() } }; elements[1] = .{ .verb = .line_to, .points = .{ .{ .x = cx, .y = cy + r / 2 }, geometry.PointF.zero(), geometry.PointF.zero() } }; elements[2] = .{ .verb = .quad_to, .points = .{ .{ .x = cx, .y = cy }, .{ .x = cx + r / 2, .y = cy }, geometry.PointF.zero() } }; }, // ╮ bottom edge to left edge 0x256E => { elements[0] = .{ .verb = .move_to, .points = .{ .{ .x = cx, .y = rect.y + rect.height }, geometry.PointF.zero(), geometry.PointF.zero() } }; elements[1] = .{ .verb = .line_to, .points = .{ .{ .x = cx, .y = cy + r / 2 }, geometry.PointF.zero(), geometry.PointF.zero() } }; elements[2] = .{ .verb = .quad_to, .points = .{ .{ .x = cx, .y = cy }, .{ .x = cx - r / 2, .y = cy }, geometry.PointF.zero() } }; }, // ╯ top edge to left edge 0x256F => { elements[0] = .{ .verb = .move_to, .points = .{ .{ .x = cx, .y = rect.y }, geometry.PointF.zero(), geometry.PointF.zero() } }; elements[1] = .{ .verb = .line_to, .points = .{ .{ .x = cx, .y = cy - r / 2 }, geometry.PointF.zero(), geometry.PointF.zero() } }; elements[2] = .{ .verb = .quad_to, .points = .{ .{ .x = cx, .y = cy }, .{ .x = cx - r / 2, .y = cy }, geometry.PointF.zero() } }; }, // ╰ top edge to right edge else => { elements[0] = .{ .verb = .move_to, .points = .{ .{ .x = cx, .y = rect.y }, geometry.PointF.zero(), geometry.PointF.zero() } }; elements[1] = .{ .verb = .line_to, .points = .{ .{ .x = cx, .y = cy - r / 2 }, geometry.PointF.zero(), geometry.PointF.zero() } }; elements[2] = .{ .verb = .quad_to, .points = .{ .{ .x = cx, .y = cy }, .{ .x = cx + r / 2, .y = cy }, geometry.PointF.zero() } }; }, } try builder.strokePath(.{ .id = if (keyed) id_base else 0, .elements = elements, .stroke = .{ .fill = .{ .color = color }, .width = t }, .cap = .butt }); // The straight remainder to the horizontal edge. const run: geometry.RectF = switch (cp) { 0x256D => geometry.RectF.init(cx + r / 2, cy - t / 2, rect.x + rect.width - (cx + r / 2), t), 0x256E => geometry.RectF.init(rect.x, cy - t / 2, cx - r / 2 - rect.x, t), 0x256F => geometry.RectF.init(rect.x, cy - t / 2, cx - r / 2 - rect.x, t), else => geometry.RectF.init(cx + r / 2, cy - t / 2, rect.x + rect.width - (cx + r / 2), t), }; try builder.fillRect(.{ .id = if (keyed) id_base +% 1 else 0, .rect = run, .fill = .{ .color = color } }); }, // Diagonals. 0x2571 => try builder.drawLine(.{ .id = if (keyed) id_base else 0, .from = .{ .x = rect.x, .y = rect.y + rect.height }, .to = .{ .x = rect.x + rect.width, .y = rect.y }, .stroke = .{ .fill = .{ .color = color }, .width = t } }), 0x2572 => try builder.drawLine(.{ .id = if (keyed) id_base else 0, .from = .{ .x = rect.x, .y = rect.y }, .to = .{ .x = rect.x + rect.width, .y = rect.y + rect.height }, .stroke = .{ .fill = .{ .color = color }, .width = t } }), 0x2573 => { try builder.drawLine(.{ .id = if (keyed) id_base else 0, .from = .{ .x = rect.x, .y = rect.y + rect.height }, .to = .{ .x = rect.x + rect.width, .y = rect.y }, .stroke = .{ .fill = .{ .color = color }, .width = t } }); try builder.drawLine(.{ .id = if (keyed) id_base +% 1 else 0, .from = .{ .x = rect.x, .y = rect.y }, .to = .{ .x = rect.x + rect.width, .y = rect.y + rect.height }, .stroke = .{ .fill = .{ .color = color }, .width = t } }); }, // Block elements: fractional rects, edge-to-edge. 0x2580 => try fillFraction(builder, id_base, rect, color, 1, .top, 0.5), 0x2581...0x2588 => try fillFraction(builder, id_base, rect, color, 1, .bottom, @as(f32, @floatFromInt(cp - 0x2580)) / 8.0), 0x2589...0x258F => try fillFraction(builder, id_base, rect, color, 1, .left, @as(f32, @floatFromInt(0x2590 - cp)) / 8.0), 0x2590 => try fillFraction(builder, id_base, rect, color, 1, .right, 0.5), 0x2591 => try fillFraction(builder, id_base, rect, color, 0.25, .bottom, 1), 0x2592 => try fillFraction(builder, id_base, rect, color, 0.5, .bottom, 1), 0x2593 => try fillFraction(builder, id_base, rect, color, 0.75, .bottom, 1), 0x2594 => try fillFraction(builder, id_base, rect, color, 1, .top, 0.125), 0x2595 => try fillFraction(builder, id_base, rect, color, 1, .right, 0.125), // Quadrants: one rect per lit quarter. 0x2596...0x259F => { const quads: u4 = switch (cp) { // bits: 1=upper-left 2=upper-right 4=lower-left 8=lower-right 0x2596 => 0b0100, // ▖ 0x2597 => 0b1000, // ▗ 0x2598 => 0b0001, // ▘ 0x2599 => 0b1101, // ▙ 0x259A => 0b1001, // ▚ 0x259B => 0b0111, // ▛ 0x259C => 0b1011, // ▜ 0x259D => 0b0010, // ▝ 0x259E => 0b0110, // ▞ else => 0b1110, // ▟ }; const hw = rect.width / 2; const hh = rect.height / 2; var id = id_base; if (quads & 0b0001 != 0) { try builder.fillRect(.{ .id = if (keyed) id else 0, .rect = geometry.RectF.init(rect.x, rect.y, hw, hh), .fill = .{ .color = color } }); id +%= 1; } if (quads & 0b0010 != 0) { try builder.fillRect(.{ .id = if (keyed) id else 0, .rect = geometry.RectF.init(rect.x + hw, rect.y, hw, hh), .fill = .{ .color = color } }); id +%= 1; } if (quads & 0b0100 != 0) { try builder.fillRect(.{ .id = if (keyed) id else 0, .rect = geometry.RectF.init(rect.x, rect.y + hh, hw, hh), .fill = .{ .color = color } }); id +%= 1; } if (quads & 0b1000 != 0) { try builder.fillRect(.{ .id = if (keyed) id else 0, .rect = geometry.RectF.init(rect.x + hw, rect.y + hh, hw, hh), .fill = .{ .color = color } }); } }, else => {}, } } const Fraction = enum { top, bottom, left, right }; fn fillFraction(builder: *canvas.Builder, id: u64, rect: geometry.RectF, color: canvas.Color, opacity: f32, side: Fraction, fraction: f32) !void { const shaded = canvas.Color.rgba(color.r, color.g, color.b, color.a * opacity); const filled: geometry.RectF = switch (side) { .top => geometry.RectF.init(rect.x, rect.y, rect.width, rect.height * fraction), .bottom => geometry.RectF.init(rect.x, rect.y + rect.height * (1 - fraction), rect.width, rect.height * fraction), .left => geometry.RectF.init(rect.x, rect.y, rect.width * fraction, rect.height), .right => geometry.RectF.init(rect.x + rect.width * (1 - fraction), rect.y, rect.width * fraction, rect.height), }; try builder.fillRect(.{ .id = id, .rect = filled, .fill = .{ .color = shaded } }); } const Segment = struct { x: f32, y: f32, len: f32, horizontal: bool }; /// The half-extent a crossing bar must overlap at the cell center so /// perpendicular joints are solid. fn barHalf(weight: Weight, t: f32) f32 { return switch (weight) { .none => 0, .light => t / 2, .heavy => t, .double => t * 1.5, }; } fn paintSegment(builder: *canvas.Builder, id: u64, keyed: bool, weight: Weight, t: f32, seg: Segment, color: canvas.Color) !u64 { switch (weight) { .none => return id, .light, .heavy => { const w = if (weight == .heavy) t * 2 else t; const rect = if (seg.horizontal) geometry.RectF.init(seg.x, seg.y - w / 2, seg.len, w) else geometry.RectF.init(seg.x - w / 2, seg.y, w, seg.len); try builder.fillRect(.{ .id = if (keyed) id else 0, .rect = rect, .fill = .{ .color = color } }); return id +% 1; }, .double => { // Two parallel light bars at center +/- t: pure double runs // (═ ║ and the pure-double corners) join seamlessly because // every cell computes the same offsets. var next = id; for ([2]f32{ -t, t }) |offset| { const rect = if (seg.horizontal) geometry.RectF.init(seg.x, seg.y + offset - t / 2, seg.len, t) else geometry.RectF.init(seg.x + offset - t / 2, seg.y, t, seg.len); try builder.fillRect(.{ .id = if (keyed) next else 0, .rect = rect, .fill = .{ .color = color } }); next +%= 1; } return next; }, } }