nandi/jolt-native · 7d907d0

⑂ 7d907d0

Fill the window's height, and find a glyph the UI font has not got

Two things a screenshot showed.

THE GLYPHS. A UI font covers Latin and stops, and frq's chrome is icons
while its messages carry emoji — every one of them was the missing-glyph
box. SDL_ttf keeps a list of fallback faces and asks each in turn, so
Noto Color Emoji and Noto Sans Symbols are added behind the main face and
text the main face already has costs nothing. Per FACE and not per
family, so each size opens its own and holds them: SDL_ttf keeps the
pointer rather than copying the font.

THE HEIGHT, which took three wrong answers to get right and each one is
worth keeping.

A row is only as tall as what is in it, and frq marks the PANES with
:fill-height rather than the row holding them — egui hands a horizontal
layout the available height and the panes fill that, so there is nothing
there to mark. Here the row has to be told, and its own children are what
know: a row holding something that wants the height wants the height.

Then the viewport ASKED for the height instead of filling it — a minimum
of the whole column — and the column had nothing left for the separator
and the compose bar, which went off the bottom of the window. It reports
nothing now and takes what is left. An explicit :height is still a
demand, which is what the viewport test was already saying.

And its :expand was being overridden by the container default, :cross. A
viewport that fills only the width asks its column for no height, is
given none, and shows nothing at all — an empty backlog with a scrollbar
beside it, which is exactly what the window looked like. It is the one
container that always fills both ways, so it says so itself.

Every one of those was found by tracing the box chain rather than by
reading it: the numbers say which box stopped passing the slack on, and
all three times it was not the one I would have guessed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

nandi committed 2026-09-10T06:59:08-07:00 Browse files

7d907d0 parent: 5fcbb42

modified glimmer-backends/glimmer-jvui/src/glimmer_jvui/core.clj +29 -6 Viewed

@@ -70,9 +70,27 @@
70	70
71	71	(defn- num [v default] (if (number? v) (double v) default))
72	72
	73	+(defn- fills-height?
	74	+ "Does any child of `n` ask to fill the height?
	75	+
	76	+ A row is only as tall as what is in it, and frq marks the PANES with
	77	+ :fill-height rather than the row that holds them — egui gives a
	78	+ horizontal layout the available height and the panes fill that, so
	79	+ there is nothing there to mark. Here the row has to be told, and its
	80	+ own children are what know: a row holding something that wants the
	81	+ height wants the height.
	82	+
	83	+ Asked of the tree rather than inferred from the layout, because the
	84	+ layout answers a frame too late — a row that learns it should be tall
	85	+ from what happened last frame is a row that is the wrong height on
	86	+ the frame anybody looks at."
	87	+ [n]
	88	+ (boolean (some #(:fill-height (:props (deref %))) (:children (deref n)))))
	89	+
73	90	(defn- box-opts
74	91	"The container options shared by every container tag."
75		- [props key]
	92	+ ([props key] (box-opts props key false))
	93	+ ([props key fill-height?]
76	94	(cond-> {:key key
77	95	:dir (if (= :horizontal (:orientation props)) :horizontal :vertical)
78	96	;; A CONTAINER fills its parent's cross axis by default. Without
@@ -97,7 +115,7 @@
97	115	;; row it does not fill the width of is not what anyone means by it.
98	116	;; The panes that do NOT ask for it stay :cross and keep their own
99	117	;; size, which is what leaves the slack to be taken.
100		- (:fill-height props) (assoc :expand :both)
	118	+ (or (:fill-height props) fill-height?) (assoc :expand :both)
101	119	;; A minimum, not a size: the messages column asks for one only while
102	120	;; the people panel is beside it.
103	121	(:width-request props)
@@ -113,7 +131,7 @@
113	131	(:align props) (assoc :gravity (case (:align props)
114	132	(:center "center") [0.0 0.5]
115	133	(:end "end") [0.0 1.0]
116		- [0.0 0.0]))))
	134	+ [0.0 0.0])))))
117	135
118	136	(defn- fire! [n k & args]
119	137	(when-let [f (get (:props @n) k)] (apply f args)))
@@ -158,7 +176,11 @@
158	176	;; :height is a prop frq writes and this used to drop on the floor —
159	177	;; the chat did not follow new messages, and switching channels
160	178	;; carried the previous one's scroll across.
161		- :scroll (w/scroll* (cond-> (box-opts props key)
	179	+ ;; :expand is forced rather than left to box-opts, whose default is
	180	+ ;; :cross — and a viewport that fills only the width asks its column
	181	+ ;; for no height, is given none, and shows nothing at all. It is the
	182	+ ;; one container that always fills both ways.
	183	+ :scroll (w/scroll* (cond-> (assoc (box-opts props key) :expand :both)
162	184	(:height props)
163	185	(assoc :height (num (:height props) 200.0))
164	186	(:reserve props)
@@ -185,10 +207,11 @@
185	207	(fire! n :on-change (if at-end? "end" "away")))))
186	208	(emit-children! n))
187	209
188		- :hbox (c/box* (assoc (box-opts props key) :dir :horizontal)
	210	+ :hbox (c/box* (assoc (box-opts props key (fills-height? n)) :dir :horizontal)
189	211	(emit-children! n))
190	212
191		- (:vbox :box) (c/box* (box-opts props key) (emit-children! n))
	213	+ (:vbox :box) (c/box* (box-opts props key (fills-height? n))
	214	+ (emit-children! n))
192	215
193	216	;; ONE tag for both kinds of picture: `:feed` is live pixels pushed
194	217	;; in under a name and re-uploaded as they arrive, `:src` is a file

  (defn- num [v default] (if (number? v) (double v) default))
++(defn- fills-height?
++  "Does any child of `n` ask to fill the height?
++
++   A row is only as tall as what is in it, and frq marks the PANES with
++   :fill-height rather than the row that holds them — egui gives a
++   horizontal layout the available height and the panes fill that, so
++   there is nothing there to mark. Here the row has to be told, and its
++   own children are what know: a row holding something that wants the
++   height wants the height.
++
++   Asked of the tree rather than inferred from the layout, because the
++   layout answers a frame too late — a row that learns it should be tall
++   from what happened last frame is a row that is the wrong height on
++   the frame anybody looks at."
++  [n]
++  (boolean (some #(:fill-height (:props (deref %))) (:children (deref n)))))
++
  (defn- box-opts
    "The container options shared by every container tag."
--  [props key]
++  ([props key] (box-opts props key false))
++  ([props key fill-height?]
    (cond-> {:key key
             :dir (if (= :horizontal (:orientation props)) :horizontal :vertical)
             ;; A CONTAINER fills its parent's cross axis by default. Without
      ;; row it does not fill the width of is not what anyone means by it.
      ;; The panes that do NOT ask for it stay :cross and keep their own
      ;; size, which is what leaves the slack to be taken.
--    (:fill-height props) (assoc :expand :both)
++    (or (:fill-height props) fill-height?) (assoc :expand :both)
      ;; A minimum, not a size: the messages column asks for one only while
      ;; the people panel is beside it.
      (:width-request props)
      (:align props)   (assoc :gravity (case (:align props)
                                         (:center "center") [0.0 0.5]
                                         (:end "end")       [0.0 1.0]
--                                       [0.0 0.0]))))
++                                       [0.0 0.0])))))
  (defn- fire! [n k & args]
    (when-let [f (get (:props @n) k)] (apply f args)))
        ;; :height is a prop frq writes and this used to drop on the floor —
        ;; the chat did not follow new messages, and switching channels
        ;; carried the previous one's scroll across.
--      :scroll (w/scroll* (cond-> (box-opts props key)
++      ;; :expand is forced rather than left to box-opts, whose default is
++      ;; :cross — and a viewport that fills only the width asks its column
++      ;; for no height, is given none, and shows nothing at all. It is the
++      ;; one container that always fills both ways.
++      :scroll (w/scroll* (cond-> (assoc (box-opts props key) :expand :both)
                             (:height props)
                             (assoc :height (num (:height props) 200.0))
                             (:reserve props)
                                      (fire! n :on-change (if at-end? "end" "away")))))
                           (emit-children! n))
--      :hbox (c/box* (assoc (box-opts props key) :dir :horizontal)
++      :hbox (c/box* (assoc (box-opts props key (fills-height? n)) :dir :horizontal)
                      (emit-children! n))
--      (:vbox :box) (c/box* (box-opts props key) (emit-children! n))
++      (:vbox :box) (c/box* (box-opts props key (fills-height? n))
++                           (emit-children! n))
        ;; ONE tag for both kinds of picture: `:feed` is live pixels pushed
        ;; in under a name and re-uploaded as they arrive, `:src` is a file

modified jvui/src/jvui/font.clj +38 -1 Viewed

@@ -13,7 +13,8 @@
13	13	with a colour-mod at draw time, so one cached texture serves a label in
14	14	every colour it is ever drawn in, and a static page uploads nothing at all
15	15	after its first frame."
16		- (:require [jvui.sdl :as sdl]))
	16	+ (:require [clojure.string]
	17	+ [jvui.sdl :as sdl]))
17	18
18	19	(def ^:private candidates
19	20	["/usr/share/fonts/noto/NotoSans-Regular.ttf"
@@ -35,6 +36,31 @@
35	36
36	37	(defn- ffi-null? [p] (or (nil? p) (and (number? p) (zero? p))))
37	38
	39	+(def ^:private fallbacks
	40	+ "Faces to try for what the UI font has no glyph for.
	41	+
	42	+ A UI font covers Latin and stops. frq's chrome is icons and its
	43	+ messages carry emoji, and every one of those was coming out as the
	44	+ missing-glyph box — which is what the reader sees as \"the glyphs are
	45	+ broken\". SDL_ttf keeps a list of fallback faces and asks each in turn,
	46	+ so this costs nothing for text that the main face already has.
	47	+
	48	+ Emoji first: a face that has both a symbol and its emoji presentation
	49	+ should give the emoji one, which is what a message means by it.
	50	+ JVUI_FALLBACK_FONTS overrides, colon-separated, for a machine whose
	51	+ fonts live somewhere else."
	52	+ ["/usr/share/fonts/noto/NotoColorEmoji.ttf"
	53	+ "/usr/share/fonts/truetype/noto/NotoColorEmoji.ttf"
	54	+ "/run/current-system/sw/share/X11/fonts/NotoColorEmoji.ttf"
	55	+ "/usr/share/fonts/noto/NotoSansSymbols2-Regular.ttf"
	56	+ "/usr/share/fonts/noto/NotoSansSymbols-Regular.ttf"
	57	+ "/usr/share/fonts/truetype/noto/NotoSansSymbols2-Regular.ttf"])
	58	+
	59	+(defn- fallback-paths []
	60	+ (if-let [env (System/getenv "JVUI_FALLBACK_FONTS")]
	61	+ (remove clojure.string/blank? (clojure.string/split env #":"))
	62	+ (filter #(.exists (java.io.File. %)) fallbacks)))
	63	+
38	64	(defn open
39	65	"A font cache over `path`. Sizes are opened lazily and kept."
40	66	[path]
@@ -47,6 +73,17 @@
47	73	(let [f (sdl/open-font (:path @cache) (float size))]
48	74	(when (or (nil? f) (and (number? f) (zero? f)))
49	75	(throw (ex-info (str "TTF_OpenFont " (:path @cache) ": " (sdl/error)) {})))
	76	+ ;; Fallbacks are per FACE, not per family, so each size opens its
	77	+ ;; own and they are kept for as long as the face is — SDL_ttf
	78	+ ;; holds the pointer and does not copy the font.
	79	+ (let [fbs (into []
	80	+ (keep (fn [path]
	81	+ (let [g (sdl/open-font path (float size))]
	82	+ (when-not (ffi-null? g)
	83	+ (sdl/add-fallback-font! f g)
	84	+ g))))
	85	+ (fallback-paths))]
	86	+ (swap! cache update :fallbacks (fnil into []) fbs))
50	87	(swap! cache assoc-in [:faces k] f)
51	88	f))))
52	89

       with a colour-mod at draw time, so one cached texture serves a label in
       every colour it is ever drawn in, and a static page uploads nothing at all
       after its first frame."
--  (:require [jvui.sdl :as sdl]))
++  (:require [clojure.string]
++            [jvui.sdl :as sdl]))
  (def ^:private candidates
    ["/usr/share/fonts/noto/NotoSans-Regular.ttf"
  (defn- ffi-null? [p] (or (nil? p) (and (number? p) (zero? p))))
++(def ^:private fallbacks
++  "Faces to try for what the UI font has no glyph for.
++
++   A UI font covers Latin and stops. frq's chrome is icons and its
++   messages carry emoji, and every one of those was coming out as the
++   missing-glyph box — which is what the reader sees as \"the glyphs are
++   broken\". SDL_ttf keeps a list of fallback faces and asks each in turn,
++   so this costs nothing for text that the main face already has.
++
++   Emoji first: a face that has both a symbol and its emoji presentation
++   should give the emoji one, which is what a message means by it.
++   JVUI_FALLBACK_FONTS overrides, colon-separated, for a machine whose
++   fonts live somewhere else."
++  ["/usr/share/fonts/noto/NotoColorEmoji.ttf"
++   "/usr/share/fonts/truetype/noto/NotoColorEmoji.ttf"
++   "/run/current-system/sw/share/X11/fonts/NotoColorEmoji.ttf"
++   "/usr/share/fonts/noto/NotoSansSymbols2-Regular.ttf"
++   "/usr/share/fonts/noto/NotoSansSymbols-Regular.ttf"
++   "/usr/share/fonts/truetype/noto/NotoSansSymbols2-Regular.ttf"])
++
++(defn- fallback-paths []
++  (if-let [env (System/getenv "JVUI_FALLBACK_FONTS")]
++    (remove clojure.string/blank? (clojure.string/split env #":"))
++    (filter #(.exists (java.io.File. %)) fallbacks)))
++
  (defn open
    "A font cache over `path`. Sizes are opened lazily and kept."
    [path]
          (let [f (sdl/open-font (:path @cache) (float size))]
            (when (or (nil? f) (and (number? f) (zero? f)))
              (throw (ex-info (str "TTF_OpenFont " (:path @cache) ": " (sdl/error)) {})))
++          ;; Fallbacks are per FACE, not per family, so each size opens its
++          ;; own and they are kept for as long as the face is — SDL_ttf
++          ;; holds the pointer and does not copy the font.
++          (let [fbs (into []
++                          (keep (fn [path]
++                                  (let [g (sdl/open-font path (float size))]
++                                    (when-not (ffi-null? g)
++                                      (sdl/add-fallback-font! f g)
++                                      g))))
++                          (fallback-paths))]
++            (swap! cache update :fallbacks (fnil into []) fbs))
            (swap! cache assoc-in [:faces k] f)
            f))))

modified jvui/src/jvui/sdl.clj +3 -0 Viewed

@@ -67,6 +67,9 @@
67	67	(ffi/defcfn open-font "TTF_OpenFont" [:string :float] :pointer)
68	68	(ffi/defcfn close-font! "TTF_CloseFont" [:pointer] :void)
69	69	(ffi/defcfn font-height "TTF_GetFontHeight" [:pointer] :int)
	70	+;; A face to try for characters the main one has no glyph for. SDL_ttf keeps
	71	+;; a list of them and asks each in turn.
	72	+(ffi/defcfn add-fallback-font! "TTF_AddFallbackFont" [:pointer :pointer] :bool)
70	73	(ffi/defcfn ^:private raw-string-size "TTF_GetStringSize"
71	74	[:pointer :string :ulong :pointer :pointer] :bool)
72	75	(ffi/defcfn ^:private raw-render-blended "TTF_RenderText_Blended"

  (ffi/defcfn open-font     "TTF_OpenFont"                [:string :float] :pointer)
  (ffi/defcfn close-font!   "TTF_CloseFont"               [:pointer] :void)
  (ffi/defcfn font-height   "TTF_GetFontHeight"           [:pointer] :int)
++;; A face to try for characters the main one has no glyph for. SDL_ttf keeps
++;; a list of them and asks each in turn.
++(ffi/defcfn add-fallback-font! "TTF_AddFallbackFont"    [:pointer :pointer] :bool)
  (ffi/defcfn ^:private raw-string-size "TTF_GetStringSize"
    [:pointer :string :ulong :pointer :pointer] :bool)
  (ffi/defcfn ^:private raw-render-blended "TTF_RenderText_Blended"

modified jvui/src/jvui/widgets.clj +22 -13 Viewed

@@ -426,20 +426,24 @@
426	426	leaves the end"
427	427	[opts body]
428	428	(let [{:keys [scroll-key reserve stick-to-bottom scroll-to-bottom on-at-end]} opts
429		- avail (c/avail-height)
430		- h (double (cond
431		- (:height opts) (:height opts)
432		- ;; With no height of its own a viewport takes what the
433		- ;; column has left, less whatever must stay behind for
434		- ;; the compose bar under it. Two hundred is only the
435		- ;; answer before anything has a size — on the first
436		- ;; frame, when the column does not know its own height
437		- ;; yet.
438		- (pos? avail) (max 0.0 (- avail (double (or reserve 0.0))))
439		- :else 200.0))
440	429	id (c/next-id (:key opts))
441	430	area (or scroll-key id)
442	431	prev (c/data id)
	432	+ ;; A viewport with no height of its own FILLS what is left rather
	433	+ ;; than ASKING for it. Asking is what it did first — a minimum of
	434	+ ;; the whole column — and then the column had nothing left for
	435	+ ;; the separator and compose bar under it, which went off the
	436	+ ;; bottom of the window.
	437	+ ;;
	438	+ ;; So the height is the one it was GIVEN last frame, and it
	439	+ ;; reports a minimum of nothing. Two hundred is the answer on the
	440	+ ;; first frame only, before it has been given anything.
	441	+ given (nth (:rect prev) 3 nil)
	442	+ h (double (cond
	443	+ (:height opts) (:height opts)
	444	+ (and given (pos? (double given)))
	445	+ (max 0.0 (- (double given) (double (or reserve 0.0))))
	446	+ :else 200.0))
443	447	content-h (second (or (:content-min prev) [0.0 0.0]))
444	448	view (or (:rect prev) [0.0 0.0 0.0 0.0])
445	449	maxoff (max 0.0 (- content-h h))
@@ -470,8 +474,13 @@
470	474	stick? maxoff
471	475	:else wheeled)
472	476	r (c/box* (merge {:dir :vertical
473		- :expand :horizontal
474		- :min-size [0.0 h]
	477	+ :expand :both
	478	+ ;; An explicit :height IS a demand and is
	479	+ ;; reported as one. Without it the viewport
	480	+ ;; fills what is left and asks for nothing —
	481	+ ;; asking is what left the compose bar off the
	482	+ ;; bottom of the window.
	483	+ :min-size [0.0 (if (:height opts) h 0.0)]
475	484	:fixed true
476	485	:clip? true
477	486	:spacing (c/th :spacing)

                         leaves the end"
    [opts body]
    (let [{:keys [scroll-key reserve stick-to-bottom scroll-to-bottom on-at-end]} opts
--        avail (c/avail-height)
--        h (double (cond
--                    (:height opts) (:height opts)
--                    ;; With no height of its own a viewport takes what the
--                    ;; column has left, less whatever must stay behind for
--                    ;; the compose bar under it. Two hundred is only the
--                    ;; answer before anything has a size — on the first
--                    ;; frame, when the column does not know its own height
--                    ;; yet.
--                    (pos? avail) (max 0.0 (- avail (double (or reserve 0.0))))
--                    :else 200.0))
          id (c/next-id (:key opts))
          area (or scroll-key id)
          prev (c/data id)
++        ;; A viewport with no height of its own FILLS what is left rather
++        ;; than ASKING for it. Asking is what it did first — a minimum of
++        ;; the whole column — and then the column had nothing left for
++        ;; the separator and compose bar under it, which went off the
++        ;; bottom of the window.
++        ;;
++        ;; So the height is the one it was GIVEN last frame, and it
++        ;; reports a minimum of nothing. Two hundred is the answer on the
++        ;; first frame only, before it has been given anything.
++        given (nth (:rect prev) 3 nil)
++        h (double (cond
++                    (:height opts) (:height opts)
++                    (and given (pos? (double given)))
++                    (max 0.0 (- (double given) (double (or reserve 0.0))))
++                    :else 200.0))
          content-h (second (or (:content-min prev) [0.0 0.0]))
          view (or (:rect prev) [0.0 0.0 0.0 0.0])
          maxoff (max 0.0 (- content-h h))
                stick? maxoff
                :else wheeled)
          r (c/box* (merge {:dir :vertical
--                          :expand :horizontal
++                          :expand :both
--                          :min-size [0.0 h]
++                          ;; An explicit :height IS a demand and is
++                          ;; reported as one. Without it the viewport
++                          ;; fills what is left and asks for nothing —
++                          ;; asking is what left the compose bar off the
++                          ;; bottom of the window.
++                          :min-size [0.0 (if (:height opts) h 0.0)]
                            :fixed true
                            :clip? true
                            :spacing (c/th :spacing)