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Merged
octalide merged 2 commits into from
Oct 1, 2026
Merged

fix(#198): a tab's label is cut with room to spare #199

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32b5e42
fix(#198): a label within a sixty-fourth of a pixel of its box is dra…
octalide Oct 1, 2026
4479987
fix(#198): a tab's room on the strip includes its separator
octalide Oct 1, 2026
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55 changes: 48 additions & 7 deletions src/tabs.mach
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -151,6 +151,7 @@ pub rec Event {
rec Geom {
rh: f32;
pad: f32;
sep: f32;
lh: f32;
x0: f32;
x1: f32;
Expand Down Expand Up @@ -366,6 +367,12 @@ fun width(ctx: *context.Context, g: *Geom, t: *Tab) f32 {
ret lo + (natural(ctx, g, t) - lo) * g.fit;
}

# the room a tab takes on the strip this frame: its body and the separator
# after it, which the body is drawn short of, so the body keeps its whole width
fun room(ctx: *context.Context, g: *Geom, t: *Tab) f32 {
ret width(ctx, g, t) + g.sep;
}

# the furthest the strip scrolls
fun most(g: *Geom) f32 {
ret maxf(g.total - (g.x1 - g.x0), 0.0::f32);
Expand All @@ -376,14 +383,15 @@ fun measure(ctx: *context.Context, tabs: *Tab, n: usize) Geom {
var g: Geom;
val ts: *theme.Style = context.look_of(ctx, theme.TAB);
g.pad = context.px(ctx, ts.inset.l);
g.sep = context.px(ctx, ts.margin.r);
g.lh = context.line_height(ctx);
g.rh = maxf(context.px(ctx, ts.min_h), g.lh + context.px(ctx, ts.inset.t + ts.inset.b));
var nat: f32 = 0.0::f32;
var lo: f32 = 0.0::f32;
var i: usize = 0;
for (i < n) {
nat = nat + natural(ctx, ?g, ?tabs[i]);
lo = lo + least(ctx, ?g, ?tabs[i]);
nat = nat + natural(ctx, ?g, ?tabs[i]) + g.sep;
lo = lo + least(ctx, ?g, ?tabs[i]) + g.sep;
i = i + 1;
}
val r: context.Area = widget.place(ctx, layout.fill(1.0::f32), layout.fit(), nat, g.rh);
Expand All @@ -404,7 +412,7 @@ fun measure(ctx: *context.Context, tabs: *Tab, n: usize) Geom {
g.total = 0.0::f32;
i = 0;
for (i < n) {
g.total = g.total + width(ctx, ?g, ?tabs[i]);
g.total = g.total + room(ctx, ?g, ?tabs[i]);
i = i + 1;
}
ret g;
Expand All @@ -415,7 +423,7 @@ fun reveal(ctx: *context.Context, g: *Geom, s: *State, tabs: *Tab, n: usize) {
var x: f32 = 0.0::f32;
var i: usize = 0;
for (i < n) {
val w: f32 = width(ctx, g, ?tabs[i]);
val w: f32 = room(ctx, g, ?tabs[i]);
if (i == s.index) {
val view: f32 = g.x1 - g.x0;
if (x < s.scroll) { s.scroll = x; }
Expand All @@ -435,7 +443,7 @@ fun step(ctx: *context.Context, g: *Geom, s: *State, tabs: *Tab, n: usize, right
var i: usize = 0;
val eps: f32 = 0.5::f32;
for (i < n) {
val w: f32 = width(ctx, g, ?tabs[i]);
val w: f32 = room(ctx, g, ?tabs[i]);
if (right && x + w > s.scroll + view + eps) { ret x + w - view; }
if (!right && x < s.scroll - eps) { to = x; }
x = x + w;
Expand Down Expand Up @@ -585,7 +593,7 @@ pub fun bar(ctx: *context.Context, key: str, tabs: *Tab, n: usize) Event {
var over: interact.Hit;
var slot: usize = n;
var mark: f32 = g.x0 + g.total - s.scroll;
val seps: f32 = context.px(ctx, context.look_of(ctx, theme.TAB).margin.r);
val seps: f32 = g.sep;
var x: f32 = g.x0 - s.scroll;
var i: usize = 0;
val grp: interact.Group = interact.begin_group(ctx, id, interact.ROW);
Expand All @@ -594,7 +602,7 @@ pub fun bar(ctx: *context.Context, key: str, tabs: *Tab, n: usize) Event {
for (i < n) {
val t: *Tab = ?tabs[i];
val x0: f32 = x;
val x1: f32 = x + width(ctx, ?g, t);
val x1: f32 = x + room(ctx, ?g, t);
x = x1;
val tid: u64 = tab_id(id, t.key);
val h: interact.Hit = interact.hit(ctx, tid, x0, g.y0, x1 - seps, g.y1, input.BUTTON_LEFT | input.BUTTON_MIDDLE | interact.FOCUS);
Expand Down Expand Up @@ -754,6 +762,39 @@ fun keys(a: *App) u64 {
ret k;
}

test bar__a_tab_with_room_is_drawn_its_whole_width {
var al: allo.Allocator;
val made: err[allo.Error] = page.make(?al);
if (sel made.err) { ret 1; }
var a: App;
var d: driver.Driver;
if (!app(?d, ?al, ?a, 6, 1600.0::f32)) { ret 1; }
a.tabs[1].closable = false;
a.tabs[4].closable = false;
driver.step(?d);
driver.step(?d);
val ts: *theme.Style = context.look_of(?d.ctx, theme.TAB);
var g: Geom;
g.pad = context.px(?d.ctx, ts.inset.l);
g.sep = context.px(?d.ctx, ts.margin.r);
g.lh = context.line_height(?d.ctx);
g.fit = 1.0::f32;
if (g.sep <= 0.0::f32) { ret 2; }
# each tab's drawn rect, short of its separator, is its whole natural width,
# so its label box is exactly its label
val bid: u64 = context.id_of(?d.ctx, "tabs");
var i: usize = 0;
for (i < a.n) {
val r: opt[context.Area] = driver.rect(?d, tab_id(bid, a.tabs[i].key));
if (sel r.none) { ret 3; }
if (r.some.x1 - r.some.x0 != natural(?d.ctx, ?g, ?a.tabs[i])) { ret 4; }
i = i + 1;
}
val f: err[allo.Error] = driver.free(?d);
if (sel f.err) { ret 1; }
ret 0;
}

test bar__unshrunk_tabs_are_their_natural_width {
var al: allo.Allocator;
val made: err[allo.Error] = page.make(?al);
Expand Down
46 changes: 45 additions & 1 deletion src/text.mach
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Original file line number Diff line number Diff line change
Expand Up @@ -198,6 +198,11 @@ fun cut_at(ctx: *context.Context, s: str, n: usize, x: f32, y: f32, w: f32, mode
ret px - x;
}

# how far a label may overrun its box and still count as fitting: a box sized to
# its label is built from absolute coordinates, whose rounding far from the left
# edge leaves it a hair short, and a sixty-fourth of a pixel never shows
val FIT_SLACK: f32 = 0.015625;

# draw the first n bytes of a line of text with its line box's top-left at
# (x, y), as it is when it fits the box's span, else as the kind's overflow
# says: clipped to the box, or cut with an ellipsis at its end to fit the
Expand All @@ -218,7 +223,7 @@ fun cut_at(ctx: *context.Context, s: str, n: usize, x: f32, y: f32, w: f32, mode
pub fun fit_box(ctx: *context.Context, kind: u32, s: str, n: usize, x: f32, y: f32, b: context.Area, c: draw.Color) {
if (s == nil || n == 0) { ret; }
val w: f32 = maxf(b.x1 - b.x0, 0.0::f32);
if (context.text_width_n(ctx, s, n) <= w) {
if (context.text_width_n(ctx, s, n) <= w + FIT_SLACK) {
context.text_span(ctx, s, n, x, y, c);
ret;
}
Expand Down Expand Up @@ -338,6 +343,45 @@ pub fun spans_at(ctx: *context.Context, sp: *Span, n: usize, x: f32, y: f32) f32
ret px - x;
}

test text__a_label_sized_to_its_box_is_whole_anywhere {
var a: allo.Allocator;
val made: err[allo.Error] = page.make(?a);
if (sel made.err) { ret 1; }
var ctx: context.Context;
val ie: err[allo.Error] = context.init(?ctx, ?a);
if (sel ie.err) { ret 1; }
var in: input.Input;
context.begin(?ctx, in, 6000.0::f32, 100.0::f32);
val s: str = "Behavior";
val n: usize = str_len(s);
val lw: f32 = context.text_width(?ctx, s);
val white: draw.Color = draw.rgba(1.0::f32, 1.0::f32, 1.0::f32, 1.0::f32);
# boxes sized to the label as a tab or button builds them, from absolute
# coordinates far from the left edge with paddings off the pixel grid; each
# must draw the same glyphs as the label drawn whole
var k: u32 = 0;
for (k < 600) {
val x: f32 = 900.0::f32 + k::f32 * 7.31::f32;
val pad: f32 = 1.0::f32 + (k % 37)::f32 * 0.173::f32;
val b: context.Area = context.Area{x0: x + pad, y0: 0.0::f32, x1: (x + (pad * 2.0::f32 + lw)) - pad, y1: 20.0::f32};
val ref: usize = context.draw_count(?ctx);
context.text_span(?ctx, s, n, x + pad, 0.0::f32, white);
val at: usize = context.draw_count(?ctx);
fit_box(?ctx, 0, s, n, x + pad, 0.0::f32, b, white);
if (context.draw_count(?ctx) - at != at - ref) { ret 2; }
val p: *draw.Vert = context.draw_verts(?ctx);
var i: usize = 0;
for (i < at - ref) {
if (p[at + i].u != p[ref + i].u || p[at + i].v != p[ref + i].v) { ret 3; }
i = i + 1;
}
k = k + 1;
}
val freed: err[allo.Error] = context.free(?ctx);
if (sel freed.err) { ret 1; }
ret 0;
}

test text__cuts_and_spans {
var a: allo.Allocator;
val made: err[allo.Error] = page.make(?a);
Expand Down
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