renderer/Metal: change font size works again

src/Surface.zig

@@ -970,11 +970,26 @@ pub fn setFontSize(self: *Surface, size: font.face.DesiredSize) void {
     // Update our font size so future changes work
     self.font_size = size;
 
-    // Notify our render thread of the font size. This triggers everything else.
+    // We need to build up a new font stack for this font size.
+    const font_grid_key, const font_grid = self.app.font_grid_set.ref(
+        &self.config.font,
+        self.font_size,
+    ) catch unreachable;
+    errdefer self.app.font_grid_set.deref(font_grid_key);
+
+    // Notify our render thread of the new font stack
     _ = self.renderer_thread.mailbox.push(.{
-        .font_size = size,
+        .font_grid = .{
+            .grid = font_grid,
+            .set = &self.app.font_grid_set,
+            .old_key = self.font_grid_key,
+            .new_key = font_grid_key,
+        },
     }, .{ .forever = {} });
 
+    // Once we've sent the key we can replace our key
+    self.font_grid_key = font_grid_key;
+
     // Schedule render which also drains our mailbox
     self.queueRender() catch unreachable;
 }

src/renderer/Metal.zig

@@ -566,18 +566,17 @@ pub fn setFocus(self: *Metal, focus: bool) !void {
 /// Set the new font size.
 ///
 /// Must be called on the render thread.
-pub fn setFontSize(self: *Metal, size: font.face.DesiredSize) !void {
-    log.info("set font size={}", .{size});
-    if (true) @panic("TODO"); // TODO(fontmem)
-
-    // Set our new size, this will also reset our font atlas.
-    try self.font_group.setSize(size);
+pub fn setFontGrid(self: *Metal, grid: *font.SharedGrid) !void {
+    // Update our grid
+    self.font_grid = grid;
+    self.texture_greyscale_modified = 0;
+    self.texture_color_modified = 0;
 
     // Recalculate our metrics
     const metrics = metrics: {
-        const index = (try self.font_group.indexForCodepoint(self.alloc, 'M', .regular, .text)).?;
-        const face = try self.font_group.group.faceFromIndex(index);
-        break :metrics face.metrics;
+        grid.lock.lockShared();
+        defer grid.lock.unlockShared();
+        break :metrics grid.metrics;
     };
 
     // Update our uniforms
@@ -597,14 +596,6 @@ pub fn setFontSize(self: *Metal, size: font.face.DesiredSize) !void {
     if (std.meta.eql(self.grid_metrics, metrics)) return;
     self.grid_metrics = metrics;
 
-    // Set the sprite font up
-    self.font_group.group.sprite = font.sprite.Face{
-        .width = metrics.cell_width,
-        .height = metrics.cell_height,
-        .thickness = metrics.underline_thickness * @as(u32, if (self.config.font_thicken) 2 else 1),
-        .underline_position = metrics.underline_position,
-    };
-
     // Notify the window that the cell size changed.
     _ = self.surface_mailbox.push(.{
         .cell_size = .{

src/renderer/Thread.zig

@@ -321,8 +321,13 @@ fn drainMailbox(self: *Thread) !void {
                 }
             },
 
-            .font_size => |size| {
-                try self.renderer.setFontSize(size);
+            .font_grid => |grid| if (self.renderer.setFontGrid(grid.grid)) {
+                // Success, deref our old grid
+                grid.set.deref(grid.old_key);
+            } else |err| {
+                // Error, deref our new grid since we didn't use it.
+                grid.set.deref(grid.new_key);
+                return err;
             },
 
             .foreground_color => |color| {

src/renderer/message.zig

@@ -22,10 +22,21 @@ pub const Message = union(enum) {
     /// restarting the timer.
     reset_cursor_blink: void,
 
-    /// Change the font size. This should recalculate the grid size and
-    /// send a grid size change message back to the window thread if
-    /// the size changes.
-    font_size: font.face.DesiredSize,
+    /// Change the font grid. This can happen for any number of reasons
+    /// including a font size change, family change, etc.
+    font_grid: struct {
+        grid: *font.SharedGrid,
+        set: *font.SharedGridSet,
+
+        // The key for the new grid. If adopting the new grid fails for any
+        // reason, the old grid should be kept but the new key should be
+        // dereferenced.
+        new_key: font.SharedGridSet.Key,
+
+        // After accepting the new grid, the old grid must be dereferenced
+        // using the fields below.
+        old_key: font.SharedGridSet.Key,
+    },
 
     /// Change the foreground color. This can be done separately from changing
     /// the config file in response to an OSC 10 command.