Set type on the pixel surfaces: the grid lays out, the fonts shape

vega_draw keeps what it wrote as spans (VegaSpan: a row, the columns it
was given, where its cells reached, its text and tone). A span written
where the same pen stopped follows the one before it (a field's name and
value, the help line, the prompt); one written after the pen moved (a
table's column, a list's label, a badge) starts afresh at its column, and
a badge sits flush with its end.

When the first font shapes, the pixels set type: a span and those
following it are one line of text, laid out as one paragraph in the font
stack (bidi and kerning cross the spans; each glyph takes the tone of the
span its character came from), from its column up to the nearest of its
spans' ends and the next span on the row, cut at a grapheme cluster
boundary with an ellipsis if it must be. The prompt gets a text cursor.
--symbols repeats: fonts in order of preference (at most 8); the cells,
when the first font does not shape, also fall back through them.

The check sets a label in one script, alone in its list, and holds it to
what the font that has it sets by itself (vega-symbols paragraph, which
now sizes itself to its text with width 0), pixel for pixel: Latin
kerning, Hangul, Arabic and Devanagari over DejaVu Sans, Noto Sans CJK KR
and FreeSans.

1 files changed, 47 insertions, 31 deletions

diff --git a/surfaces/main.c b/surfaces/main.c
index d58625a..6c7e368 100644
--- a/surfaces/main.c
+++ b/surfaces/main.c
@@ -21,10 +21,11 @@
  *   say              sentences (the first natural-language surface), driven by a script
  *   web [--listen ADDRESS] [--port N]
  *                    a web page (a GUI), on 127.0.0.1 unless another address is given
- *   pixels --symbols FONT.vsym [--size PX] --grid WxH --out PREFIX
- *                    the TUI's frames drawn with a font's glyphs, driven by a
- *                    script: each show writes PREFIX-N.ppm after the text
- *   display --symbols FONT.vsym [--size PX] [--card PATH] [--writeback WxH --out PREFIX]
+ *   pixels --symbols FONT.vsym... [--size PX] --grid WxH --out PREFIX
+ *                    the TUI's frames drawn in fonts (in order of preference;
+ *                    set as type when the first shapes), driven by a script:
+ *                    each show writes PREFIX-N.ppm after the text
+ *   display --symbols FONT.vsym... [--size PX] [--card PATH] [--writeback WxH --out PREFIX]
  *           [--live | --input EVENTS]
  *                    the same on a display through KMS, as many cells as fit,
  *                    driven by a script, or live: keyboards, mice and touch
@@ -865,22 +866,37 @@ static int script(Surface surface, unsigned width, unsigned height, bool paintin
 /* Surfaces that draw glyphs. */
 static bool glyphed(const char *surface) { return !strcmp(surface, "pixels") || !strcmp(surface, "display"); }
 
-/* The symbols a pixel surface draws with, read whole and kept. */
-static bool open_face(const char *path, float size) {
-    static VegaSymbols symbols;
-    FILE *f = fopen(path, "rb");
-    long length = f && !fseek(f, 0, SEEK_END) ? ftell(f) : -1;
-    unsigned char *bytes = length > 0 && !fseek(f, 0, SEEK_SET) ? malloc((size_t)length) : NULL;
-    bool ok = bytes && fread(bytes, 1, (size_t)length, f) == (size_t)length;
-    if (f) fclose(f);
-    char error[128] = "cannot read it";
-    ok = ok && vega_symbols_open(&symbols, bytes, (size_t)length, error, sizeof(error));
-    if (ok && !vega_face_open(&face, &symbols, size)) {
-        ok = false;
-        snprintf(error, sizeof(error), "no line and digit to lay a grid out with");
+/* The fonts a pixel surface draws with (--symbols, in order of
+ * preference), read whole and kept. */
+static const char *symbols_paths[VEGA_FACES];
+static unsigned symbols_count;
+static bool add_symbols(const char *path) {
+    if (symbols_count == VEGA_FACES) return false;
+    symbols_paths[symbols_count++] = path;
+    return true;
+}
+static bool open_face(float size) {
+    static VegaSymbols symbols[VEGA_FACES];
+    const VegaSymbols *opened[VEGA_FACES];
+    char error[160] = "cannot read it";
+    for (unsigned k = 0; k < symbols_count; ++k) {
+        const char *path = symbols_paths[k];
+        FILE *f = fopen(path, "rb");
+        long length = f && !fseek(f, 0, SEEK_END) ? ftell(f) : -1;
+        unsigned char *bytes = length > 0 && !fseek(f, 0, SEEK_SET) ? malloc((size_t)length) : NULL;
+        bool ok = bytes && fread(bytes, 1, (size_t)length, f) == (size_t)length;
+        if (f) fclose(f);
+        if (!ok || !vega_symbols_open(&symbols[k], bytes, (size_t)length, error, sizeof(error))) {
+            fprintf(stderr, "vega: %s: %s\n", path, error);
+            return false;
+        }
+        opened[k] = &symbols[k]; /* the bytes stay: the face reads them */
     }
-    if (!ok) fprintf(stderr, "vega: %s: %s\n", path, error);
-    return ok; /* the bytes stay: the face reads them */
+    if (!vega_face_open(&face, opened, symbols_count, size, error, sizeof(error))) {
+        fprintf(stderr, "vega: %s: %s\n", symbols_paths[0], error);
+        return false;
+    }
+    return true;
 }
 
 #ifdef VEGA_SURFACE
@@ -899,7 +915,7 @@ __attribute__((visibility("default"))) int pure_surface_run(const PureSurface *s
         fputs("vega: this surface was built for another Pure\n", stderr);
         return 2;
     }
-    const char *symbols_path = NULL, *card = "/dev/dri/card1", *recorded = NULL;
+    const char *card = "/dev/dri/card1", *recorded = NULL;
     unsigned width = 0, height = 0;
     float size = 16;
     bool on_display = argc > 1 && !strcmp(argv[1], "display"), pixels = argc > 1 && !strcmp(argv[1], "pixels");
@@ -911,7 +927,7 @@ __attribute__((visibility("default"))) int pure_surface_run(const PureSurface *s
             continue;
         }
         if (i + 1 >= argc) usage = true;
-        else if (!strcmp(argv[i], "--symbols")) symbols_path = argv[i + 1];
+        else if (!strcmp(argv[i], "--symbols")) usage = !add_symbols(argv[i + 1]);
         else if (!strcmp(argv[i], "--size") && sscanf(argv[i + 1], "%f", &size) == 1) {}
         else if (!strcmp(argv[i], "--card") && on_display) card = argv[i + 1];
         else if (!strcmp(argv[i], "--input")) recorded = argv[i + 1];
@@ -922,15 +938,15 @@ __attribute__((visibility("default"))) int pure_surface_run(const PureSurface *s
             writeback = on_display;
         } else usage = true;
     }
-    if (usage || !symbols_path || (writeback && !frames_prefix) || (pixels && (!width || !frames_prefix)) ||
+    if (usage || !symbols_count || (writeback && !frames_prefix) || (pixels && (!width || !frames_prefix)) ||
         (live_input && recorded)) {
-        fputs("vega-surface.so display --symbols FONT.vsym [--size PX] [--card PATH] [--writeback WIDTHxHEIGHT --out PREFIX]\n"
+        fputs("vega-surface.so display --symbols FONT.vsym... [--size PX] [--card PATH] [--writeback WIDTHxHEIGHT --out PREFIX]\n"
               "                        [--live | --input EVENTS]\n"
-              "vega-surface.so pixels --symbols FONT.vsym [--size PX] --grid WIDTHxHEIGHT --out PREFIX [--input EVENTS]\n",
+              "vega-surface.so pixels --symbols FONT.vsym... [--size PX] --grid WIDTHxHEIGHT --out PREFIX [--input EVENTS]\n",
               stderr);
         return 2;
     }
-    if (!open_face(symbols_path, size)) return 2;
+    if (!open_face(size)) return 2;
     unsigned columns = width, rows = height, pixels_across = width * (unsigned)face.cell_width,
              pixels_down = height * (unsigned)face.cell_height;
     if (on_display) {
@@ -967,7 +983,7 @@ __attribute__((visibility("default"))) int pure_surface_run(const PureSurface *s
 #else
 int main(int argc, char **argv) {
     unsigned width = 0, height = 0, port = 8080;
-    const char *symbols_path = NULL, *card = "/dev/dri/card1";
+    const char *card = "/dev/dri/card1";
     float size = 16;
     bool writeback = false, live_input = false;
     const char *recorded = NULL;
@@ -1003,24 +1019,24 @@ int main(int argc, char **argv) {
             writeback = true;
         else if (!strcmp(argv[i], "--card") && !strcmp(argv[1], "display")) card = argv[i + 1];
         else if (!strcmp(argv[i], "--input") && !strcmp(argv[1], "display")) recorded = argv[i + 1];
-        else if (!strcmp(argv[i], "--symbols") && glyphed(argv[1])) symbols_path = argv[i + 1];
+        else if (!strcmp(argv[i], "--symbols") && glyphed(argv[1])) usage = !add_symbols(argv[i + 1]);
         else if (!strcmp(argv[i], "--out") && glyphed(argv[1])) frames_prefix = argv[i + 1];
         else if (!strcmp(argv[i], "--size") && glyphed(argv[1]) && sscanf(argv[i + 1], "%f", &size) == 1) {}
         else usage = true;
     }
     bool pixels = argc > 1 && !strcmp(argv[1], "pixels"), on_display = argc > 1 && !strcmp(argv[1], "display");
     if (usage || (dumped && strcmp(argv[1], "tui") && !pixels) || (!strcmp(argv[1], "check") && argc != 3) ||
-        (pixels && (!dumped || !symbols_path || !frames_prefix)) || (on_display && (!symbols_path || (writeback && !frames_prefix)))) {
+        (pixels && (!dumped || !symbols_count || !frames_prefix)) || (on_display && (!symbols_count || (writeback && !frames_prefix)))) {
         fputs("vega tui|cli|say MODULE.pmod [--store PATH]\n"
               "vega tui MODULE.pmod [--store PATH] [--watch] | --dump|--paint WIDTHxHEIGHT < script\n"
               "vega web MODULE.pmod [--store PATH] [--listen ADDRESS] [--port N] [--watch]\n"
-              "vega pixels MODULE.pmod [--store PATH] --symbols FONT.vsym [--size PX] --grid WIDTHxHEIGHT --out PREFIX < script\n"
-              "vega display MODULE.pmod [--store PATH] --symbols FONT.vsym [--size PX] [--card PATH]\n"
+              "vega pixels MODULE.pmod [--store PATH] --symbols FONT.vsym... [--size PX] --grid WIDTHxHEIGHT --out PREFIX < script\n"
+              "vega display MODULE.pmod [--store PATH] --symbols FONT.vsym... [--size PX] [--card PATH]\n"
               "             [--writeback WIDTHxHEIGHT --out PREFIX] [--live | --input EVENTS] [--access] [< script]\n"
               "vega check MODULE.pmod\n", stderr);
         return 2;
     }
-    if ((pixels || on_display) && !open_face(symbols_path, size)) return 2;
+    if ((pixels || on_display) && !open_face(size)) return 2;
     if (on_display) {
         char error[256];
         if (!(display = vega_display_open(card, writeback, writeback ? width : 0, writeback ? height : 0, error, sizeof(error)))) {