custom shader animation can be set to "always" to always remain active

Fixes #1225

The `custom-shader-animation` configuration can now be set to "always"
which keeps animation active even if the terminal is unfocused.

src/renderer/message.zig

@@ -1,6 +1,7 @@
 const std = @import("std");
 const assert = std.debug.assert;
 const Allocator = std.mem.Allocator;
+const configpkg = @import("../config.zig");
 const font = @import("../font/main.zig");
 const renderer = @import("../renderer.zig");
 const terminal = @import("../terminal/main.zig");
@@ -45,9 +46,42 @@ pub const Message = union(enum) {
     /// The derived configuration to update the renderer with.
     change_config: struct {
         alloc: Allocator,
-        ptr: *renderer.Renderer.DerivedConfig,
+        thread: *renderer.Thread.DerivedConfig,
+        impl: *renderer.Renderer.DerivedConfig,
     },
 
     /// Activate or deactivate the inspector.
     inspector: bool,
+
+    /// Initialize a change_config message.
+    pub fn initChangeConfig(alloc: Allocator, config: *const configpkg.Config) !Message {
+        const thread_ptr = try alloc.create(renderer.Thread.DerivedConfig);
+        errdefer alloc.destroy(thread_ptr);
+        const config_ptr = try alloc.create(renderer.Renderer.DerivedConfig);
+        errdefer alloc.destroy(config_ptr);
+
+        thread_ptr.* = renderer.Thread.DerivedConfig.init(config);
+        config_ptr.* = try renderer.Renderer.DerivedConfig.init(alloc, config);
+        errdefer config_ptr.deinit();
+
+        return .{
+            .change_config = .{
+                .alloc = alloc,
+                .thread = thread_ptr,
+                .impl = config_ptr,
+            },
+        };
+    }
+
+    pub fn deinit(self: *const Message) void {
+        switch (self.*) {
+            .change_config => |v| {
+                v.impl.deinit();
+                v.alloc.destroy(v.impl);
+                v.alloc.destroy(v.thread);
+            },
+
+            else => {},
+        }
+    }
 };