mod(renderer): dynamic clear of size for widgets to improve render performance

src/widget/Spacer.zig

@@ -12,6 +12,7 @@ pub fn Widget(comptime Event: type, comptime Renderer: type) type {
     }
     return struct {
         size: terminal.Size = undefined,
+        size_changed: bool = false,
 
         pub fn init() @This() {
             return .{};
@@ -25,6 +26,7 @@ pub fn Widget(comptime Event: type, comptime Renderer: type) type {
             switch (event) {
                 .resize => |size| {
                     this.size = size;
+                    this.size_changed = true;
                 },
                 else => {},
             }
@@ -32,7 +34,10 @@ pub fn Widget(comptime Event: type, comptime Renderer: type) type {
         }
 
         pub fn render(this: *@This(), renderer: *Renderer) !void {
-            try renderer.clear(this.size);
+            if (this.size_changed) {
+                try renderer.clear(this.size);
+                this.size_changed = false;
+            }
         }
     };
 }