window cell size event for changing cell size

src/Window.zig

@@ -527,9 +527,34 @@ pub fn handleMessage(self: *Window, msg: Message) !void {
             log.debug("changing title \"{s}\"", .{slice});
             try self.window.setTitle(slice.ptr);
         },
+
+        .cell_size => |size| try self.setCellSize(size),
     }
 }
 
+/// Change the cell size for the terminal grid. This can happen as
+/// a result of changing the font size at runtime.
+fn setCellSize(self: *Window, size: renderer.CellSize) !void {
+    // Update our new cell size for future calcs
+    self.cell_size = size;
+
+    // Update our grid_size
+    self.grid_size = renderer.GridSize.init(
+        self.screen_size.subPadding(self.padding),
+        self.cell_size,
+    );
+
+    // Notify the terminal
+    _ = self.io_thread.mailbox.push(.{
+        .resize = .{
+            .grid_size = self.grid_size,
+            .screen_size = self.screen_size,
+            .padding = self.padding,
+        },
+    }, .{ .forever = {} });
+    self.io_thread.wakeup.send() catch {};
+}
+
 /// This queues a render operation with the renderer thread. The render
 /// isn't guaranteed to happen immediately but it will happen as soon as
 /// practical.

src/renderer/OpenGL.zig

@@ -18,6 +18,7 @@ const trace = @import("tracy").trace;
 const math = @import("../math.zig");
 const lru = @import("../lru.zig");
 const DevMode = @import("../DevMode.zig");
+const Window = @import("../Window.zig");
 
 const log = std.log.scoped(.grid);
 
@@ -80,6 +81,9 @@ focused: bool,
 /// Padding options
 padding: renderer.Options.Padding,
 
+/// The mailbox for communicating with the window.
+window_mailbox: Window.Mailbox,
+
 /// The raw structure that maps directly to the buffer sent to the vertex shader.
 /// This must be "extern" so that the field order is not reordered by the
 /// Zig compiler.
@@ -293,6 +297,7 @@ pub fn init(alloc: Allocator, options: renderer.Options) !OpenGL {
         .foreground = .{ .r = 255, .g = 255, .b = 255 },
         .focused = true,
         .padding = options.padding,
+        .window_mailbox = options.window_mailbox,
     };
 }
 
@@ -476,8 +481,12 @@ pub fn setFontSize(self: *OpenGL, size: font.face.DesiredSize) !void {
     // nothing since the grid size couldn't have possibly changed.
     const new_cell_size = .{ .width = metrics.cell_width, .height = metrics.cell_height };
     if (std.meta.eql(self.cell_size, new_cell_size)) return;
+    self.cell_size = new_cell_size;
 
     // Notify the window that the cell size changed.
+    _ = self.window_mailbox.push(.{
+        .cell_size = new_cell_size,
+    }, .{ .forever = {} });
 }
 
 /// Reload the font metrics, recalculate cell size, and send that all

src/window/message.zig

@@ -9,6 +9,9 @@ pub const Message = union(enum) {
     /// the termio message so that we can more efficiently send strings
     /// of any length
     set_title: [256]u8,
+
+    /// Change the cell size.
+    cell_size: renderer.CellSize,
 };
 
 /// A window mailbox.