the gui wears any monospace font on the machine

1 files changed, 96 insertions, 3 deletions

diff --git a/src/gui/gui.zig b/src/gui/gui.zig
index 6280ab00..66812575 100644
--- a/src/gui/gui.zig
+++ b/src/gui/gui.zig
@@ -22,6 +22,7 @@ const config = @import("../config.zig");
 const look = @import("../look.zig");
 const deck = @import("deck.zig");
 const crt = @import("crt.zig");
+const fonts = @import("fonts.zig"); // the Font builtin's half of the seam
 
 const is_emscripten = builtin.os.tag == .emscripten;
 
@@ -780,6 +781,15 @@ const Gui = struct {
     overlay_vertices: []OverlayVertex,
 
     font: *c.UIFont,
+    /// the file behind `font`, when it is one the Font builtin loaded. Empty
+    /// for the font the binary ships with, which is @embedFile'd and not ours
+    /// to free — stb keeps a pointer into these bytes, so they outlive nothing.
+    font_bytes: []u8 = &.{},
+    /// the cell height the metrics are asked for, in pixels. A field and not
+    /// the local constant it used to be because refitFont reads it: changing
+    /// the FACE has to re-ask at the same size, and changing the SIZE (the
+    /// Ctrl+/Ctrl- this leaves the path for) is writing here and calling that.
+    px: f32,
     scale: f32,
     cell_w: u32,
     cell_h: u32,
@@ -1027,6 +1037,7 @@ fn runNative(init: std.process.Init, opts_in: pardes.Options) !void {
         .overlay_vxfer = overlay_vxfer,
         .overlay_vertices = overlay_vertices,
         .font = font,
+        .px = px,
         .scale = scale,
         .cell_w = cell_w,
         .cell_h = cell_h,
@@ -1037,6 +1048,7 @@ fn runNative(init: std.process.Init, opts_in: pardes.Options) !void {
         .capture_dir = capture_dir orelse "",
     };
     defer g.glyphs.deinit();
+    defer if (g.font_bytes.len != 0) gpa.free(g.font_bytes); // set by Font, if it ran
     defer gpa.free(g.scroll_edge); // grown on demand by stepScroll
     // slot (0,0) is the space glyph (blank cells sample alpha=0 → bg only)
     _ = c.ui_font_raster(font, scale, ' ', atlas_stage.ptr, @intCast(atlas_w), @intCast(cell_w), @intCast(cell_h), asc);
@@ -1179,12 +1191,35 @@ fn runNative(init: std.process.Init, opts_in: pardes.Options) !void {
             core.deinit();
             core = nc;
         }
+        // Font builtin: the core resolved a name to a path and asked for it —
+        // it cannot load a font itself, having no rasterizer, no atlas and no
+        // window. Inline here beside Restore because it is the same kind of
+        // thing and this is the flat loop.
+        if (fonts.want) |path| blk: {
+            fonts.want = null;
+            const bytes = look.readFile(gpa, path) catch break :blk;
+            const nf = c.ui_font_new(bytes.ptr, @intCast(bytes.len)) orelse {
+                // stb turned it down (an .otf whose outlines it cannot read).
+                // Keep wearing the one that works: a font pardes cannot
+                // rasterize is a blank window with no way back out of it.
+                log.err("ui_font_new failed: {s}", .{path});
+                gpa.free(bytes);
+                break :blk;
+            };
+            c.ui_font_free(g.font);
+            if (g.font_bytes.len != 0) gpa.free(g.font_bytes);
+            g.font = nf;
+            g.font_bytes = bytes; // stb reads them for as long as the font lives
+            refitFont(&g, core);
+        }
         // 5. live cwd for tags/look: cheap /proc readlink per pane, per frame
         pollCwds(core, &ptys);
-        // 6. the grid follows the window (covers WINDOW_RESIZED and test resizes)
+        // 6. the grid follows the window (covers WINDOW_RESIZED and test
+        // resizes). Off g.cell_w/h, not the init locals: a font change moves
+        // them, and this is the line that would go on dividing by the old cell.
         _ = c.SDL_GetWindowSizeInPixels(window, &pw, &ph);
-        const cols: u16 = @intCast(@max(1, @divTrunc(@as(u32, @intCast(@max(pw, 1))), cell_w)));
-        const rows: u16 = @intCast(@max(1, @divTrunc(@as(u32, @intCast(@max(ph, 1))), cell_h)));
+        const cols: u16 = @intCast(@max(1, @divTrunc(@as(u32, @intCast(@max(pw, 1))), g.cell_w)));
+        const rows: u16 = @intCast(@max(1, @divTrunc(@as(u32, @intCast(@max(ph, 1))), g.cell_h)));
         if (cols != core.screen_w or rows != core.screen_h)
             core.update(.{ .resize = .{ .cols = cols, .rows = rows } });
         // 7. render — the scroll animation steps LAST before it, while
@@ -1417,6 +1452,7 @@ fn runWeb(opts_in: pardes.Options) !void {
             .gl_overlay_vbo = overlay_vbo,
             .gl_u_atlas = c.glGetUniformLocation(program, "u_atlas"),
             .font = font,
+            .px = px,
             .scale = scale,
             .cell_w = cell_w,
             .cell_h = cell_h,
@@ -2794,6 +2830,63 @@ fn firstCp(s: []const u8) u32 {
     return std.unicode.utf8Decode(s[0..n]) catch ' ';
 }
 
+/// Re-measure the cell, throw the glyph atlas away, and re-fit the grid to the
+/// window. THE path for any change to what a cell LOOKS like: point g.font at
+/// a different face (the Font builtin, above) or write a different g.px (the
+/// Ctrl+/Ctrl- sizing this leaves the road open for) and call this — those are
+/// one line each, and everything that has to follow from them is here.
+///
+/// The atlas is the part that must not be skipped, and the reason the whole
+/// thing is a function rather than three lines at a call site. It is keyed by
+/// CODEPOINT ALONE — one face, one size, a pen walking rows of cell_w×cell_h
+/// slots — so after a change every slot in it holds the wrong picture at the
+/// wrong metrics, and every codepoint already in the map would keep being
+/// drawn from that slot forever, because ensureGlyph's first line is a cache
+/// hit. Clearing the map, zeroing the staging bitmap and rewinding the pen put
+/// it back to exactly what init built, and ensureGlyph refills it as the next
+/// frame draws. The zeroing is not tidiness: the upload is the WHOLE texture,
+/// the new cell size is a different grid over the same 2048², and a leftover
+/// bitmap no slot points at any more would still be sampled by whatever new
+/// slot overlaps it.
+fn refitFont(g: *Gui, core: *pardes.Pardes) void {
+    // Native rasters at the size it measures. Web MEASURES at the CSS size and
+    // RASTERS web_render_scale bigger, so text stays sharp on a scaled canvas
+    // and cellLayout scales the quads back down — the same two scales initGl
+    // takes, asked again because a different face answers differently.
+    const measure = c.ui_font_scale_for_height(g.font, g.px);
+    g.scale = if (is_emscripten) c.ui_font_scale_for_height(g.font, g.px * web_render_scale) else measure;
+    var cw: c_int = 10;
+    var chh: c_int = 20;
+    var asc: c_int = 16;
+    c.ui_font_cell_metrics(g.font, measure, &cw, &chh, &asc);
+    const grow: f32 = if (is_emscripten) web_render_scale else 1.0;
+    g.cell_w = @intFromFloat(@ceil(@as(f32, @floatFromInt(@max(cw, 1))) * grow));
+    g.cell_h = @intFromFloat(@ceil(@as(f32, @floatFromInt(@max(chh, 1))) * grow));
+    g.ascent = @intFromFloat(@ceil(@as(f32, @floatFromInt(@max(asc, 1))) * grow));
+
+    g.glyphs.clearRetainingCapacity();
+    @memset(g.atlas_stage, 0);
+    // slot (0,0) is the space glyph, exactly as init lays it out
+    _ = c.ui_font_raster(g.font, g.scale, ' ', g.atlas_stage.ptr, @intCast(atlas_w), @intCast(g.cell_w), @intCast(g.cell_h), g.ascent);
+    g.space_slot = .{ .u = 0, .v = 0 };
+    g.pen_x = g.cell_w;
+    g.pen_y = 0;
+    g.atlas_dirty = true;
+
+    // ...and the grid: the same window is a different number of cells now. The
+    // shells re-derive this every frame anyway, so this is only the frame the
+    // change happens on — but it is the frame the surface is about to be
+    // rendered for, and a stale screen_w here is a row of cells drawn off the
+    // right edge of the window.
+    var pw: c_int = 0;
+    var ph: c_int = 0;
+    _ = c.SDL_GetWindowSizeInPixels(g.window, &pw, &ph);
+    const cols: u16 = @intCast(@max(1, @divTrunc(@as(u32, @intCast(@max(pw, 1))), g.cell_w)));
+    const rows: u16 = @intCast(@max(1, @divTrunc(@as(u32, @intCast(@max(ph, 1))), g.cell_h)));
+    if (cols != core.screen_w or rows != core.screen_h)
+        core.update(.{ .resize = .{ .cols = cols, .rows = rows } });
+}
+
 fn ensureGlyph(g: *Gui, cp: u32) Slot {
     if (g.glyphs.get(cp)) |s| return s;
     if (g.pen_x + g.cell_w > atlas_w) {