Show what would act on a screen as a picture on every surface, and keep a value's bidi within it

Speech wrote a value's C1 controls (U+009B is a CSI to some terminals),
DEL, line separators and bidi overrides as they were; the CLI and the
TUI wrote line separators (a pipe's reader may break its line there) and
the controls that turn text around (a terminal then reverses the rest of
its line, other values' cells too); the web page showed controls as they
were and let a label's override reverse its badge. Now every surface
shows controls, DEL, C1 and line and paragraph separators as pictures
(vega_visible); a terminal's cells show embeddings, overrides and
isolates as U+FFFD too (vega_cell); speech says a space for the one and
nothing for the other; the page shows the pictures and isolates each
value, while /screen's JSON keeps values as they are. screen_meaning
checks the CLI, the TUI, speech and the JSON against that rule, and that
nothing a value holds reaches any output as a control; the browser check
sees the page show it.

1 files changed, 28 insertions, 8 deletions

diff --git a/surfaces/draw.c b/surfaces/draw.c
index ec0b536..3135705 100644
--- a/surfaces/draw.c
+++ b/surfaces/draw.c
@@ -6,15 +6,16 @@ static const char *const tone_names[VEGA_TONES] = {"normal", "muted", "accent",
 
 /* ---- CLI ------------------------------------------------------------ */
 
-/* Text for a pipe: control characters become their pictures so a value never
- * breaks a line. */
+/* Text for a pipe: what would act on the output instead of being shown
+ * becomes its picture (vega_cell), so a value never breaks a line nor turns
+ * one around. */
 static void put_text(FILE *out, const char *text, size_t length) {
     for (size_t at = 0; at < length;) {
         uint32_t codepoint;
         size_t size = vega_decode(text, length, at, &codepoint);
-        if (vega_visible(codepoint) == codepoint) fwrite(text + at, 1, size, out);
+        if (vega_cell(codepoint) == codepoint) fwrite(text + at, 1, size, out);
         else {
-            uint32_t picture = vega_visible(codepoint);
+            uint32_t picture = vega_cell(codepoint);
             fputc(0xE0 | (int)(picture >> 12), out);
             fputc(0x80 | (int)(picture >> 6 & 0x3F), out);
             fputc(0x80 | (int)(picture & 0x3F), out);
@@ -125,10 +126,29 @@ void vega_print(FILE *out, PureApp *app, const VegaScreen *screen, bool color) {
 
 /* ---- NUI ------------------------------------------------------------ */
 
-/* Spoken text: control characters become spaces, and trailing ones go. */
+/* A code point as it is said: what would act on the output (controls, line
+ * and paragraph separators) as a space, the controls that turn text around
+ * not at all (0), else itself. */
+static uint32_t spoken(uint32_t codepoint) {
+    if (vega_visible(codepoint) != codepoint) return ' ';
+    return vega_cell(codepoint) != codepoint ? 0 : codepoint;
+}
+
+/* Spoken text: as spoken says, without the spaces it ends with. */
 static void speak(FILE *out, const char *text, size_t length) {
-    while (length && ((unsigned char)text[length - 1] <= 0x20)) --length;
-    for (size_t i = 0; i < length; ++i) fputc((unsigned char)text[i] < 0x20 ? ' ' : text[i], out);
+    size_t end = 0;
+    for (size_t at = 0; at < length;) {
+        uint32_t codepoint, said;
+        at += vega_decode(text, length, at, &codepoint);
+        if ((said = spoken(codepoint)) && said != ' ') end = at;
+    }
+    for (size_t at = 0; at < end;) {
+        uint32_t codepoint, said;
+        size_t size = vega_decode(text, end, at, &codepoint);
+        if ((said = spoken(codepoint)) == ' ') fputc(' ', out);
+        else if (said) fwrite(text + at, 1, size, out);
+        at += size;
+    }
 }
 
 /* "Item 2 of 3: milk, done." Tones other than normal and muted are said. */
@@ -292,7 +312,7 @@ static void put_cells(Pen *pen, const char *text, size_t length) {
     for (size_t at = 0; at < length;) {
         uint32_t codepoint;
         at += vega_decode(text, length, at, &codepoint);
-        codepoint = vega_visible(codepoint);
+        codepoint = vega_cell(codepoint);
         unsigned width = vega_width(codepoint);
         if (!width) {
             if (pen->column && !line[pen->column - 1].mark) {