mod: change interface for rendering of Layouts and Widgets to use a non-const pointer to the renderer instead

src/layout.zig

@@ -1,7 +1,7 @@
 //! Dynamic dispatch for layout implementations.
 //! Each layout should at last implement these functions:
 //! - handle(this: *@This(), event: Event) anyerror!*std.ArrayList(Event) {}
-//! - render(this: *@This(), renderer: Renderer) anyerror!void {}
+//! - render(this: *@This(), renderer: *Renderer) anyerror!void {}
 //! - deinit(this: *@This()) void {}
 //!
 //! Create a `Layout` using `createFrom(object: anytype)` and use them through
@@ -28,7 +28,7 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
 
         const VTable = struct {
             handle: *const fn (this: *LayoutType, event: Event) anyerror!*Events,
-            render: *const fn (this: *LayoutType, renderer: Renderer) anyerror!void,
+            render: *const fn (this: *LayoutType, renderer: *Renderer) anyerror!void,
             deinit: *const fn (this: *LayoutType) void,
         };
 
@@ -41,7 +41,7 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
         }
 
         // Render this `Layout` completely. This will render contained sub-elements too.
-        pub fn render(this: *LayoutType, renderer: Renderer) !void {
+        pub fn render(this: *LayoutType, renderer: *Renderer) !void {
             return try this.vtable.render(this, renderer);
         }
 
@@ -63,7 +63,7 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
                     }.handle,
                     .render = struct {
                         // Render the contents of this `Layout`.
-                        fn render(this: *LayoutType, renderer: Renderer) !void {
+                        fn render(this: *LayoutType, renderer: *Renderer) !void {
                             const layout: @TypeOf(object) = @ptrFromInt(this.object);
                             try layout.render(renderer);
                         }