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A picture is bytes where there is no file, and the clipboard is one way in

`Could not read that picture: _Namespace` was dart:io's filesystem saying it
is not there: the chooser handed back an XFile and `File.copy` tried to put it
in the app's storage, which a browser does not have. So `frq.pictures` is the
fifth seam, and what crosses it is a map with `:path` where there is a
filesystem and `:bytes` where there is not.

`frq.upload.core` already built the multipart body out of bytes, so only the
transport and the chooser ever differed — the browser posts that same body
over XMLHttpRequest, and reads `XFile.readAsBytes` instead of copying. The
`mem://` key it invents is not a place: `frq.main` tracks the attachment by
`:path` to know whether an upload that just landed is still the picture on
screen, and `discard!` hands it to a delete that finds nothing. Both wanted a
name, not a location.

Ctrl-V falls out of the same shape. A browser fires `paste` with the picture
in it, so listening costs nothing and lands in `attach!` by the same road the
chooser takes. A paste carrying no image is left entirely alone — no
preventDefault — because that is somebody pasting text into the composer.

And `preview-url`, which is where the pictures in the backlog come from: a
path on the targets that cache to disk, and the URL itself in a browser, which
has an image cache already and gets the bytes through the proxy the avatars
go through. A link in a message is a picture again.

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

nandi committed 2026-09-17T18:47:49-07:00 Browse files

f4d18a5 parent: c9d7b92

modified flutter/src/frq/main.cljd +21 -15 Viewed

@@ -58,8 +58,10 @@
58	58	[frq.replies :as replies]
59	59	[frq.profile :as profile]
60	60	[frq.avatars.dart :as avatars]
61		- ["package:image_picker/image_picker.dart" :as picker]
62		- [frq.upload.dart :as upload]
	61	+ [frq.pictures :as pictures]
	62	+ ;; The dart:io chooser and upload this entry point installs;
	63	+ ;; `frq.main-web` installs the browser's.
	64	+ [frq.pictures.dart :as pictures-dart]
63	65	[frq.irc.mutate :as mutate]
64	66	[frq.oauth.core :as oauth]
65	67	[frq.oauth.handoff :as handoff]
@@ -993,22 +995,27 @@
993	995	(discard! (:path a))))
994	996
995	997	(defn ^:async attach!
996		- "Hold the picture already copied to `path` against the next line, and start
997		- its upload.
	998	+ "Hold `picture` against the next line, and start its upload.
	999	+
	1000	+ What `frq.pictures/pick!` answers with, or what a paste handed over: a map
	1001	+ carrying `:path` where there is a filesystem, `:bytes` where there is not,
	1002	+ and a name either way. `:path` is the key the attachment is tracked by even
	1003	+ when it names nowhere.
998	1004
999	1005	The upload starts at once rather than at send, so by the time a line is
1000	1006	written the picture is usually already up. A failure lands in `error` like
1001	1007	any other and takes the attachment with it — there is nothing to send and
1002	1008	nothing to show."
1003		- [path filename]
	1009	+ [picture]
1004	1010	(let [did (:did @cells/session)
1005	1011	host-name (str @cells/form-host)
1006		- channel (str @cells/current)]
	1012	+ channel (str @cells/current)
	1013	+ path (:path picture)]
1007	1014	(reset! cells/error nil)
1008	1015	(clear-attachment!)
1009	1016	(reset! cells/attachment {:path path :status :uploading})
1010	1017	(try
1011		- (let [url (await (upload/upload! host-name did channel path filename))]
	1018	+ (let [url (await (pictures/upload! host-name did channel picture))]
1012	1019	;; Only if this is still the picture on screen: a reader who attached
1013	1020	;; another, or cleared it, has said what they want, and an upload
1014	1021	;; landing afterwards does not get to undo that.
@@ -1036,13 +1043,8 @@
1036	1043	to be ours — not the reader's own picture, sitting in their gallery."
1037	1044	[]
1038	1045	(try
1039		- (let [chosen (await (.pickImage (picker/ImagePicker)
1040		- .source picker/ImageSource.gallery))]
1041		- (when chosen
1042		- (let [copy (str (outgoing-dir) "/" (.-millisecondsSinceEpoch (DateTime/now))
1043		- ".png")]
1044		- (await (.copy (dio/File. (.-path chosen)) copy))
1045		- (await (attach! copy "picture.png")))))
	1046	+ (when-let [picture (await (pictures/pick! (outgoing-dir)))]
	1047	+ (await (attach! picture)))
1046	1048	(catch Object e
1047	1049	(reset! cells/error (str "Could not read that picture: " (or (ex-message e) e))))))
1048	1050
@@ -1359,7 +1361,10 @@
1359	1361	;; difference is what is behind them: a face is a CDN URL the network
1360	1362	;; will serve again, a picture in a message is whatever host a stranger
1361	1363	;; put a link to.
1362		- :image-path (fn [url] (media/path-when-ready url))
	1364	+ ;; Through the seam: a path on the targets that cache to disk, and the
	1365	+ ;; URL itself in a browser, which has its own image cache and nowhere to
	1366	+ ;; put a file. See `frq.pictures/preview-url`.
	1367	+ :image-path (fn [url] (pictures/preview-url url))
1363	1368	:wide? wide?
1364	1369	;; True where there is a pointer to hover with. Three Flutter targets
1365	1370	;; compile this file now, so it is asked rather than assumed: a window on
@@ -1481,4 +1486,5 @@
1481	1486	(net-dart/install!)
1482	1487	(oauth-dart/install!)
1483	1488	(atproto-dart/install!)
	1489	+ (pictures-dart/install!)
1484	1490	(await (start!)))

              [frq.replies :as replies]
              [frq.profile :as profile]
              [frq.avatars.dart :as avatars]
--            ["package:image_picker/image_picker.dart" :as picker]
++            [frq.pictures :as pictures]
--            [frq.upload.dart :as upload]
++            ;; The dart:io chooser and upload this entry point installs;
++            ;; `frq.main-web` installs the browser's.
++            [frq.pictures.dart :as pictures-dart]
              [frq.irc.mutate :as mutate]
              [frq.oauth.core :as oauth]
              [frq.oauth.handoff :as handoff]
      (discard! (:path a))))
  (defn ^:async attach!
--  "Hold the picture already copied to `path` against the next line, and start
++  "Hold `picture` against the next line, and start its upload.
--  its upload.
++
++  What `frq.pictures/pick!` answers with, or what a paste handed over: a map
++  carrying `:path` where there is a filesystem, `:bytes` where there is not,
++  and a name either way. `:path` is the key the attachment is tracked by even
++  when it names nowhere.
    The upload starts at once rather than at send, so by the time a line is
    written the picture is usually already up. A failure lands in `error` like
    any other and takes the attachment with it — there is nothing to send and
    nothing to show."
--  [path filename]
++  [picture]
    (let [did (:did @cells/session)
          host-name (str @cells/form-host)
--        channel (str @cells/current)]
++        channel (str @cells/current)
++        path (:path picture)]
      (reset! cells/error nil)
      (clear-attachment!)
      (reset! cells/attachment {:path path :status :uploading})
      (try
--      (let [url (await (upload/upload! host-name did channel path filename))]
++      (let [url (await (pictures/upload! host-name did channel picture))]
          ;; Only if this is still the picture on screen: a reader who attached
          ;; another, or cleared it, has said what they want, and an upload
          ;; landing afterwards does not get to undo that.
    to be ours — not the reader's own picture, sitting in their gallery."
    []
    (try
--    (let [chosen (await (.pickImage (picker/ImagePicker)
++    (when-let [picture (await (pictures/pick! (outgoing-dir)))]
--                                    .source picker/ImageSource.gallery))]
++      (await (attach! picture)))
--      (when chosen
--        (let [copy (str (outgoing-dir) "/" (.-millisecondsSinceEpoch (DateTime/now))
--                        ".png")]
--          (await (.copy (dio/File. (.-path chosen)) copy))
--          (await (attach! copy "picture.png")))))
      (catch Object e
        (reset! cells/error (str "Could not read that picture: " (or (ex-message e) e))))))
        ;; difference is what is behind them: a face is a CDN URL the network
        ;; will serve again, a picture in a message is whatever host a stranger
        ;; put a link to.
--      :image-path (fn [url] (media/path-when-ready url))
++      ;; Through the seam: a path on the targets that cache to disk, and the
++      ;; URL itself in a browser, which has its own image cache and nowhere to
++      ;; put a file. See `frq.pictures/preview-url`.
++      :image-path (fn [url] (pictures/preview-url url))
        :wide? wide?
        ;; True where there is a pointer to hover with. Three Flutter targets
        ;; compile this file now, so it is asked rather than assumed: a window on
    (net-dart/install!)
    (oauth-dart/install!)
    (atproto-dart/install!)
++  (pictures-dart/install!)
    (await (start!)))

modified flutter/src/frq/main_web.cljd +7 -1 Viewed

@@ -29,7 +29,8 @@
29	29	[frq.oauth.web :as oauth-web]
30	30	[frq.atproto.web :as atproto-web]
31	31	["dart:html" :as html]
32		- [frq.hiccup :as hiccup]))
	32	+ [frq.hiccup :as hiccup]
	33	+ [frq.pictures.web :as pictures-web]))
33	34
34	35	(defn ^:async main []
35	36	(app/bind!)
@@ -63,6 +64,11 @@
63	64	;; authorization server, and failing that was there a sign-in before today.
64	65	;; Either way what lands is a session in `frq.cells`, which is what
65	66	;; `frq.main/sign-in!` finds instead of starting the browser leg again.
	67	+ (pictures-web/install!)
	68	+ ;; Ctrl-V. The other two targets have no clipboard to listen to, and this is
	69	+ ;; the same attachment the chooser makes — `attach!` cannot tell which it
	70	+ ;; was handed.
	71	+ (pictures-web/listen-for-paste! (fn [picture] (app/attach! picture) nil))
66	72	(let [signed-in? (or (await (oauth-web/resume!)) (oauth-web/restore!))]
67	73	(await (app/start!))
68	74	;; A sign-in that has just completed should not then wait to be told to

              [frq.oauth.web :as oauth-web]
              [frq.atproto.web :as atproto-web]
              ["dart:html" :as html]
--            [frq.hiccup :as hiccup]))
++            [frq.hiccup :as hiccup]
++            [frq.pictures.web :as pictures-web]))
  (defn ^:async main []
    (app/bind!)
    ;; authorization server, and failing that was there a sign-in before today.
    ;; Either way what lands is a session in `frq.cells`, which is what
    ;; `frq.main/sign-in!` finds instead of starting the browser leg again.
++  (pictures-web/install!)
++  ;; Ctrl-V. The other two targets have no clipboard to listen to, and this is
++  ;; the same attachment the chooser makes — `attach!` cannot tell which it
++  ;; was handed.
++  (pictures-web/listen-for-paste! (fn [picture] (app/attach! picture) nil))
    (let [signed-in? (or (await (oauth-web/resume!)) (oauth-web/restore!))]
      (await (app/start!))
      ;; A sign-in that has just completed should not then wait to be told to

added flutter/src/frq/pictures.cljd +57 -0 Viewed

new file mode 100644
@@ -0,0 +1,57 @@
	1	+(ns frq.pictures
	2	+ "Choosing a picture and sending it, named once for both Flutter targets.
	3	+
	4	+ The fifth seam, and it exists because a browser has no file. dart:io picks
	5	+ one with the system chooser, copies it into the app's own storage and
	6	+ uploads it by path; a browser is handed BYTES — from the chooser, or from
	7	+ the clipboard — and there is no path to copy to. `File.copy` on the web
	8	+ throws `Unsupported operation: _Namespace`, which is dart:io's filesystem
	9	+ saying it is not there, and what the reader saw was `Could not read that
	10	+ picture: _Namespace`.
	11	+
	12	+ So a picture here is a map, and either half of it may be missing: `:path`
	13	+ where there is a filesystem, `:bytes` where there is not, `:filename`
	14	+ always. `frq.upload.core` already builds the multipart body out of bytes, so
	15	+ only the transport and the chooser differ."
	16	+ (:refer-clojure :exclude [name]))
	17	+
	18	+(defonce ^:private impl (atom {}))
	19	+
	20	+(defn install! [m] (swap! impl merge m) nil)
	21	+
	22	+(defn ^:async pick!
	23	+ "Ask the reader for a picture. Nil when they chose none.
	24	+
	25	+ `dir` is where a copy belongs on the targets that have one — it is the
	26	+ caller's, because it comes from `frq.io/config-dir`, and the web backend
	27	+ ignores it."
	28	+ [dir]
	29	+ (if-let [f (:pick! @impl)]
	30	+ (await (f dir))
	31	+ (throw (ex-info "frq.pictures: no backend installed" {:op :pick!}))))
	32	+
	33	+(defn ^:async upload!
	34	+ "Send `picture` and answer the URL freeq serves it back at."
	35	+ [host did channel picture]
	36	+ (if-let [f (:upload! @impl)]
	37	+ (await (f host did channel picture))
	38	+ (throw (ex-info "frq.pictures: no backend installed" {:op :upload!}))))
	39	+
	40	+(defn preview-url
	41	+ "What the renderer should draw for the picture at `url`, or nil while there
	42	+ is nothing to draw yet.
	43	+
	44	+ Two different answers, and the browser's is the simpler one. dart:io
	45	+ downloads the picture into a cache and hands back a path, because a phone
	46	+ wants the bytes on disk and `frq.media` is the thing that puts them there.
	47	+ A browser already has an image loader with a cache in front of it, and no
	48	+ disk to put anything on — so the answer is the URL, which
	49	+ `frq.hiccup/src-url` then sends through the same proxy the avatars use.
	50	+
	51	+ Synchronous, because the screens call it while they build a row and read nil
	52	+ as \"not here yet\" — see `frq.media/path-when-ready`, which is the answer on
	53	+ the other two targets."
	54	+ [url]
	55	+ (if-let [f (:preview-url @impl)]
	56	+ (f url)
	57	+ nil))

++(ns frq.pictures
++  "Choosing a picture and sending it, named once for both Flutter targets.
++
++  The fifth seam, and it exists because a browser has no file. dart:io picks
++  one with the system chooser, copies it into the app's own storage and
++  uploads it by path; a browser is handed BYTES — from the chooser, or from
++  the clipboard — and there is no path to copy to. `File.copy` on the web
++  throws `Unsupported operation: _Namespace`, which is dart:io's filesystem
++  saying it is not there, and what the reader saw was `Could not read that
++  picture: _Namespace`.
++
++  So a picture here is a map, and either half of it may be missing: `:path`
++  where there is a filesystem, `:bytes` where there is not, `:filename`
++  always. `frq.upload.core` already builds the multipart body out of bytes, so
++  only the transport and the chooser differ."
++  (:refer-clojure :exclude [name]))
++
++(defonce ^:private impl (atom {}))
++
++(defn install! [m] (swap! impl merge m) nil)
++
++(defn ^:async pick!
++  "Ask the reader for a picture. Nil when they chose none.
++
++  `dir` is where a copy belongs on the targets that have one — it is the
++  caller's, because it comes from `frq.io/config-dir`, and the web backend
++  ignores it."
++  [dir]
++  (if-let [f (:pick! @impl)]
++    (await (f dir))
++    (throw (ex-info "frq.pictures: no backend installed" {:op :pick!}))))
++
++(defn ^:async upload!
++  "Send `picture` and answer the URL freeq serves it back at."
++  [host did channel picture]
++  (if-let [f (:upload! @impl)]
++    (await (f host did channel picture))
++    (throw (ex-info "frq.pictures: no backend installed" {:op :upload!}))))
++
++(defn preview-url
++  "What the renderer should draw for the picture at `url`, or nil while there
++  is nothing to draw yet.
++
++  Two different answers, and the browser's is the simpler one. dart:io
++  downloads the picture into a cache and hands back a path, because a phone
++  wants the bytes on disk and `frq.media` is the thing that puts them there.
++  A browser already has an image loader with a cache in front of it, and no
++  disk to put anything on — so the answer is the URL, which
++  `frq.hiccup/src-url` then sends through the same proxy the avatars use.
++
++  Synchronous, because the screens call it while they build a row and read nil
++  as \"not here yet\" — see `frq.media/path-when-ready`, which is the answer on
++  the other two targets."
++  [url]
++  (if-let [f (:preview-url @impl)]
++    (f url)
++    nil))

added flutter/src/frq/pictures/dart.cljd +31 -0 Viewed

new file mode 100644
@@ -0,0 +1,31 @@
	1	+(ns frq.pictures.dart
	2	+ "Pictures over dart:io: the system chooser, a copy, and `frq.upload.dart`.
	3	+
	4	+ What was in `frq.main` until the web needed the other half. Unchanged in
	5	+ substance — the chooser hands back a grant for the one picture chosen, and
	6	+ it is copied into our own storage because the send drops the file when it is
	7	+ done with it, and what it drops has to be ours."
	8	+ (:require ["dart:io" :as dio]
	9	+ ["package:image_picker/image_picker.dart" :as picker]
	10	+ [frq.media.dart :as media]
	11	+ [frq.pictures :as pictures]
	12	+ [frq.upload.dart :as upload]))
	13	+
	14	+(defn ^:async ^:private pick! [dir]
	15	+ (let [chosen (await (.pickImage (picker/ImagePicker)
	16	+ .source picker/ImageSource.gallery))]
	17	+ (when chosen
	18	+ (let [copy (str dir "/" (.-millisecondsSinceEpoch (DateTime/now)) ".png")]
	19	+ (await (.copy (dio/File. (.-path chosen)) copy))
	20	+ {:path copy :filename "picture.png"}))))
	21	+
	22	+(defn ^:async ^:private upload! [host did channel picture]
	23	+ (await (upload/upload! host did channel (:path picture)
	24	+ (or (:filename picture) "picture.png"))))
	25	+
	26	+(defn install! []
	27	+ (pictures/install! {:pick! pick!
	28	+ :upload! upload!
	29	+ ;; The cache does the work; this is only where the
	30	+ ;; screens ask whether it has finished.
	31	+ :preview-url media/path-when-ready}))

++(ns frq.pictures.dart
++  "Pictures over dart:io: the system chooser, a copy, and `frq.upload.dart`.
++
++  What was in `frq.main` until the web needed the other half. Unchanged in
++  substance — the chooser hands back a grant for the one picture chosen, and
++  it is copied into our own storage because the send drops the file when it is
++  done with it, and what it drops has to be ours."
++  (:require ["dart:io" :as dio]
++            ["package:image_picker/image_picker.dart" :as picker]
++            [frq.media.dart :as media]
++            [frq.pictures :as pictures]
++            [frq.upload.dart :as upload]))
++
++(defn ^:async ^:private pick! [dir]
++  (let [chosen (await (.pickImage (picker/ImagePicker)
++                                  .source picker/ImageSource.gallery))]
++    (when chosen
++      (let [copy (str dir "/" (.-millisecondsSinceEpoch (DateTime/now)) ".png")]
++        (await (.copy (dio/File. (.-path chosen)) copy))
++        {:path copy :filename "picture.png"}))))
++
++(defn ^:async ^:private upload! [host did channel picture]
++  (await (upload/upload! host did channel (:path picture)
++                         (or (:filename picture) "picture.png"))))
++
++(defn install! []
++  (pictures/install! {:pick! pick!
++                      :upload! upload!
++                      ;; The cache does the work; this is only where the
++                      ;; screens ask whether it has finished.
++                      :preview-url media/path-when-ready}))

added flutter/src/frq/pictures/web.cljd +133 -0 Viewed

new file mode 100644
@@ -0,0 +1,133 @@
	1	+(ns frq.pictures.web
	2	+ "Pictures in a browser: bytes from the chooser or the clipboard, and an
	3	+ XMLHttpRequest to carry them.
	4	+
	5	+ No copy and no path, because there is no filesystem to copy to — that is the
	6	+ whole of the difference, and `File.copy` saying `_Namespace` is dart:io
	7	+ telling us so. The chooser hands back an `XFile` over a blob URL; what is
	8	+ useful about it is `readAsBytes`.
	9	+
	10	+ And the clipboard, which the other targets have no equivalent for: a browser
	11	+ fires `paste` with the picture in it, so Ctrl-V is a way to attach one that
	12	+ costs nothing but listening."
	13	+ (:require ["dart:async" :as async]
	14	+ ["dart:html" :as html]
	15	+ ["dart:typed_data" :as td]
	16	+ ["package:image_picker/image_picker.dart" :as picker]
	17	+ [frq.pictures :as pictures]
	18	+ [frq.upload.core :as core]))
	19	+
	20	+(defn- ^td/Uint8List byte-list
	21	+ "A cljd vector of byte values as the typed list Dart wants.
	22	+
	23	+ Built element by element rather than handed over: what
	24	+ `frq.upload.core/request` answers with is a PersistentVector, and cljd does
	25	+ not bridge one to a `List<int>` — `frq.upload.dart` walks into a BytesBuilder
	26	+ for the same reason, and got \"PersistentVector<dynamic> is not a subtype of
	27	+ List<int>\" on screen before it did."
	28	+ [bs]
	29	+ (let [n (count bs)
	30	+ out (td/Uint8List. n)]
	31	+ (loop [s (seq bs) i 0]
	32	+ (if (nil? s)
	33	+ out
	34	+ (do (aset out i (first s))
	35	+ (recur (next s) (inc i)))))))
	36	+
	37	+(defn ^:async ^:private upload! [host did channel picture]
	38	+ (let [{p :path ct :content-type body :body}
	39	+ (core/request did channel (or (:filename picture) "picture.png")
	40	+ (vec (:bytes picture)))
	41	+ url (str "https://" host p)
	42	+ req (html/HttpRequest.)
	43	+ done (async/Completer.)]
	44	+ (.open req "POST" url)
	45	+ (.setRequestHeader req "accept" "application/json")
	46	+ (.setRequestHeader req "content-type" ct)
	47	+ (.addEventListener req "load"
	48	+ (fn [_]
	49	+ (when-not (.-isCompleted done)
	50	+ (let [status (.-status req)
	51	+ payload (str (.-responseText req))]
	52	+ (if (and (>= status 200) (< status 300))
	53	+ (.complete done (core/url-of payload))
	54	+ (.completeError
	55	+ done
	56	+ (Exception. (core/error-message (str status)
	57	+ payload))))))
	58	+ nil))
	59	+ (.addEventListener req "error"
	60	+ (fn [_]
	61	+ (when-not (.-isCompleted done)
	62	+ (.completeError
	63	+ done (Exception. (str "Could not reach " host))))
	64	+ nil))
	65	+ (.send req (byte-list body))
	66	+ (await (.-future done))))
	67	+
	68	+(defn ^:async ^:private pick! [_dir]
	69	+ (let [chosen (await (.pickImage (picker/ImagePicker)
	70	+ .source picker/ImageSource.gallery))]
	71	+ (when chosen
	72	+ (let [bytes (await (.readAsBytes chosen))]
	73	+ ;; `:path` is a name and not a place: `frq.main` keys the attachment on
	74	+ ;; it — to know whether the upload that just landed is still the
	75	+ ;; picture on screen — and `discard!` hands it to `frq.io/delete-file!`,
	76	+ ;; which on the web is a localStorage key that was never written. So it
	77	+ ;; has to be unique and it has to be harmless, and this is both.
	78	+ {:path (str "mem://" (.-millisecondsSinceEpoch (DateTime/now)) ".png")
	79	+ :bytes (vec bytes)
	80	+ :filename (or (.-name chosen) "picture.png")}))))
	81	+
	82	+(defn ^:async ^:private blob-bytes
	83	+ "One clipboard file's bytes."
	84	+ [blob]
	85	+ (let [reader (html/FileReader.)
	86	+ done (async/Completer.)]
	87	+ (.addEventListener reader "loadend"
	88	+ (fn [_]
	89	+ (when-not (.-isCompleted done)
	90	+ (.complete done (.-result reader)))
	91	+ nil))
	92	+ (.readAsArrayBuffer reader blob)
	93	+ (await (.-future done))))
	94	+
	95	+(defn listen-for-paste!
	96	+ "Ctrl-V, as a way to attach a picture.
	97	+
	98	+ `on-picture` is called with the same map `pick!` answers with, so the paste
	99	+ and the chooser land in exactly the same place.
	100	+
	101	+ A paste carrying no picture is left entirely alone — no preventDefault, no
	102	+ error — because it is somebody pasting text into the composer, which is the
	103	+ overwhelmingly common case and must keep working."
	104	+ [on-picture]
	105	+ (.addEventListener
	106	+ html/document "paste"
	107	+ (fn [e]
	108	+ (let [data (.-clipboardData e)
	109	+ files (when data (.-files data))]
	110	+ (when (and files (pos? (.-length files)))
	111	+ (let [f (.item files 0)]
	112	+ (when (.startsWith (str (.-type f)) "image/")
	113	+ (.preventDefault e)
	114	+ (.then ^async/Future (blob-bytes f)
	115	+ (fn [buf]
	116	+ (on-picture
	117	+ {:path (str "mem://" (.-millisecondsSinceEpoch (DateTime/now))
	118	+ ".png")
	119	+ :bytes (vec (td/Uint8List.view buf))
	120	+ :filename (or (.-name f) "paste.png")})
	121	+ nil))))))
	122	+ nil))
	123	+ nil)
	124	+
	125	+(defn install! []
	126	+ (pictures/install! {:pick! pick!
	127	+ :upload! upload!
	128	+ ;; No download and no cache: the browser has both, and
	129	+ ;; `frq.hiccup/src-url` puts the URL through the proxy so
	130	+ ;; the bytes are allowed in. A picture is shown the
	131	+ ;; moment its link is on screen rather than after a
	132	+ ;; round trip this target never needed to make.
	133	+ :preview-url identity}))

++(ns frq.pictures.web
++  "Pictures in a browser: bytes from the chooser or the clipboard, and an
++  XMLHttpRequest to carry them.
++
++  No copy and no path, because there is no filesystem to copy to — that is the
++  whole of the difference, and `File.copy` saying `_Namespace` is dart:io
++  telling us so. The chooser hands back an `XFile` over a blob URL; what is
++  useful about it is `readAsBytes`.
++
++  And the clipboard, which the other targets have no equivalent for: a browser
++  fires `paste` with the picture in it, so Ctrl-V is a way to attach one that
++  costs nothing but listening."
++  (:require ["dart:async" :as async]
++            ["dart:html" :as html]
++            ["dart:typed_data" :as td]
++            ["package:image_picker/image_picker.dart" :as picker]
++            [frq.pictures :as pictures]
++            [frq.upload.core :as core]))
++
++(defn- ^td/Uint8List byte-list
++  "A cljd vector of byte values as the typed list Dart wants.
++
++  Built element by element rather than handed over: what
++  `frq.upload.core/request` answers with is a PersistentVector, and cljd does
++  not bridge one to a `List<int>` — `frq.upload.dart` walks into a BytesBuilder
++  for the same reason, and got \"PersistentVector<dynamic> is not a subtype of
++  List<int>\" on screen before it did."
++  [bs]
++  (let [n (count bs)
++        out (td/Uint8List. n)]
++    (loop [s (seq bs) i 0]
++      (if (nil? s)
++        out
++        (do (aset out i (first s))
++            (recur (next s) (inc i)))))))
++
++(defn ^:async ^:private upload! [host did channel picture]
++  (let [{p :path ct :content-type body :body}
++        (core/request did channel (or (:filename picture) "picture.png")
++                      (vec (:bytes picture)))
++        url (str "https://" host p)
++        req (html/HttpRequest.)
++        done (async/Completer.)]
++    (.open req "POST" url)
++    (.setRequestHeader req "accept" "application/json")
++    (.setRequestHeader req "content-type" ct)
++    (.addEventListener req "load"
++                       (fn [_]
++                         (when-not (.-isCompleted done)
++                           (let [status (.-status req)
++                                 payload (str (.-responseText req))]
++                             (if (and (>= status 200) (< status 300))
++                               (.complete done (core/url-of payload))
++                               (.completeError
++                                done
++                                (Exception. (core/error-message (str status)
++                                                                payload))))))
++                         nil))
++    (.addEventListener req "error"
++                       (fn [_]
++                         (when-not (.-isCompleted done)
++                           (.completeError
++                            done (Exception. (str "Could not reach " host))))
++                         nil))
++    (.send req (byte-list body))
++    (await (.-future done))))
++
++(defn ^:async ^:private pick! [_dir]
++  (let [chosen (await (.pickImage (picker/ImagePicker)
++                                  .source picker/ImageSource.gallery))]
++    (when chosen
++      (let [bytes (await (.readAsBytes chosen))]
++        ;; `:path` is a name and not a place: `frq.main` keys the attachment on
++        ;; it — to know whether the upload that just landed is still the
++        ;; picture on screen — and `discard!` hands it to `frq.io/delete-file!`,
++        ;; which on the web is a localStorage key that was never written. So it
++        ;; has to be unique and it has to be harmless, and this is both.
++        {:path (str "mem://" (.-millisecondsSinceEpoch (DateTime/now)) ".png")
++         :bytes (vec bytes)
++         :filename (or (.-name chosen) "picture.png")}))))
++
++(defn ^:async ^:private blob-bytes
++  "One clipboard file's bytes."
++  [blob]
++  (let [reader (html/FileReader.)
++        done (async/Completer.)]
++    (.addEventListener reader "loadend"
++                       (fn [_]
++                         (when-not (.-isCompleted done)
++                           (.complete done (.-result reader)))
++                         nil))
++    (.readAsArrayBuffer reader blob)
++    (await (.-future done))))
++
++(defn listen-for-paste!
++  "Ctrl-V, as a way to attach a picture.
++
++  `on-picture` is called with the same map `pick!` answers with, so the paste
++  and the chooser land in exactly the same place.
++
++  A paste carrying no picture is left entirely alone — no preventDefault, no
++  error — because it is somebody pasting text into the composer, which is the
++  overwhelmingly common case and must keep working."
++  [on-picture]
++  (.addEventListener
++   html/document "paste"
++   (fn [e]
++     (let [data (.-clipboardData e)
++           files (when data (.-files data))]
++       (when (and files (pos? (.-length files)))
++         (let [f (.item files 0)]
++           (when (.startsWith (str (.-type f)) "image/")
++             (.preventDefault e)
++             (.then ^async/Future (blob-bytes f)
++                    (fn [buf]
++                      (on-picture
++                       {:path (str "mem://" (.-millisecondsSinceEpoch (DateTime/now))
++                                   ".png")
++                        :bytes (vec (td/Uint8List.view buf))
++                        :filename (or (.-name f) "paste.png")})
++                      nil))))))
++     nil))
++  nil)
++
++(defn install! []
++  (pictures/install! {:pick! pick!
++                      :upload! upload!
++                      ;; No download and no cache: the browser has both, and
++                      ;; `frq.hiccup/src-url` puts the URL through the proxy so
++                      ;; the bytes are allowed in. A picture is shown the
++                      ;; moment its link is on screen rather than after a
++                      ;; round trip this target never needed to make.
++                      :preview-url identity}))