core: font size changes work

src/Surface.zig

@@ -642,8 +642,6 @@ pub fn handleMessage(self: *Surface, msg: Message) !void {
             try self.rt_surface.setMouseShape(shape);
         },
 
-        .cell_size => |size| try self.setCellSize(size),
-
         .clipboard_read => |clipboard| {
             if (self.config.clipboard_read == .deny) {
                 log.info("application attempted to read clipboard, but 'clipboard-read' is set to deny", .{});
@@ -966,18 +964,25 @@ fn setCellSize(self: *Surface, size: renderer.CellSize) !void {
 /// Change the font size.
 ///
 /// This can only be called from the main thread.
-pub fn setFontSize(self: *Surface, size: font.face.DesiredSize) void {
+pub fn setFontSize(self: *Surface, size: font.face.DesiredSize) !void {
     // Update our font size so future changes work
     self.font_size = size;
 
     // 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(
+    const font_grid_key, const font_grid = try 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
+    // Set our cell size
+    try self.setCellSize(.{
+        .width = font_grid.metrics.cell_width,
+        .height = font_grid.metrics.cell_height,
+    });
+
+    // Notify our render thread of the new font stack. The renderer
+    // MUST accept the new font grid and deref the old.
     _ = self.renderer_thread.mailbox.push(.{
         .font_grid = .{
             .grid = font_grid,
@@ -988,7 +993,6 @@ pub fn setFontSize(self: *Surface, size: font.face.DesiredSize) void {
     }, .{ .forever = {} });
 
     // Once we've sent the key we can replace our key
-    // TODO(fontmem): we should not store this anymore
     self.font_grid_key = font_grid_key;
 
     // Schedule render which also drains our mailbox
@@ -1699,7 +1703,7 @@ pub fn contentScaleCallback(self: *Surface, content_scale: apprt.ContentScale) !
         return;
     }
 
-    self.setFontSize(size);
+    try self.setFontSize(size);
 
     // Update our padding which is dependent on DPI.
     self.padding = padding: {
@@ -2998,7 +3002,7 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
 
             var size = self.font_size;
             size.points +|= delta;
-            self.setFontSize(size);
+            try self.setFontSize(size);
         },
 
         .decrease_font_size => |delta| {
@@ -3006,7 +3010,7 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
 
             var size = self.font_size;
             size.points = @max(1, size.points -| delta);
-            self.setFontSize(size);
+            try self.setFontSize(size);
         },
 
         .reset_font_size => {
@@ -3014,7 +3018,7 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
 
             var size = self.font_size;
             size.points = self.config.original_font_size;
-            self.setFontSize(size);
+            try self.setFontSize(size);
         },
 
         .clear_screen => {

src/apprt/glfw.zig

@@ -246,7 +246,7 @@ pub const App = struct {
         // If we have a parent, inherit some properties
         if (self.config.@"window-inherit-font-size") {
             if (parent_) |parent| {
-                surface.core_surface.setFontSize(parent.font_size);
+                try surface.core_surface.setFontSize(parent.font_size);
             }
         }
 

src/apprt/surface.zig

@@ -21,9 +21,6 @@ pub const Message = union(enum) {
     /// Set the mouse shape.
     set_mouse_shape: terminal.MouseShape,
 
-    /// Change the cell size.
-    cell_size: renderer.CellSize,
-
     /// Read the clipboard and write to the pty.
     clipboard_read: apprt.Clipboard,
 

src/renderer/Metal.zig

@@ -566,18 +566,16 @@ pub fn setFocus(self: *Metal, focus: bool) !void {
 /// Set the new font size.
 ///
 /// Must be called on the render thread.
-pub fn setFontGrid(self: *Metal, grid: *font.SharedGrid) !void {
+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
+    // Get our metrics from the grid. This doesn't require a lock because
-    const metrics = metrics: {
+    // the metrics are never recalculated.
-        grid.lock.lockShared();
+    const metrics = grid.metrics;
-        defer grid.lock.unlockShared();
+    self.grid_metrics = metrics;
-        break :metrics grid.metrics;
-    };
 
     // Update our uniforms
     self.uniforms = .{
@@ -590,19 +588,6 @@ pub fn setFontGrid(self: *Metal, grid: *font.SharedGrid) !void {
         .strikethrough_thickness = @floatFromInt(metrics.strikethrough_thickness),
         .min_contrast = self.uniforms.min_contrast,
     };
-
-    // Recalculate our cell size. If it is the same as before, then we do
-    // nothing since the grid size couldn't have possibly changed.
-    if (std.meta.eql(self.grid_metrics, metrics)) return;
-    self.grid_metrics = metrics;
-
-    // Notify the window that the cell size changed.
-    _ = self.surface_mailbox.push(.{
-        .cell_size = .{
-            .width = metrics.cell_width,
-            .height = metrics.cell_height,
-        },
-    }, .{ .forever = {} });
 }
 
 /// Update the frame data.

src/renderer/Options.zig

@@ -8,7 +8,7 @@ const Config = @import("../config.zig").Config;
 /// The derived configuration for this renderer implementation.
 config: renderer.Renderer.DerivedConfig,
 
-/// The font grid that should be used.
+/// The font grid that should be used along with the key for deref-ing.
 font_grid: *font.SharedGrid,
 
 /// Padding options for the viewport.

src/renderer/Thread.zig

@@ -321,13 +321,9 @@ fn drainMailbox(self: *Thread) !void {
                 }
             },
 
-            .font_grid => |grid| if (self.renderer.setFontGrid(grid.grid)) {
+            .font_grid => |grid| {
-                // Success, deref our old grid
+                self.renderer.setFontGrid(grid.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| {