png/graphics/filled-rectangle: Add class printers

* modules/png/graphics/filled-rectangle.scm: Add class printers.
* tests/graphics.scm ("<filled-rectangle>: display"): New test.

modules/png/graphics/filled-rectangle.scm

@@ -1,6 +1,6 @@
 ;;; filled-rectangle.scm -- Filled rectangle implementation.
 
-;; Copyright (C) 2022 Artyom V. Poptsov <[email protected]>
+;; Copyright (C) 2022-2023 Artyom V. Poptsov <[email protected]>
 ;;
 ;; This program is free software: you can redistribute it and/or modify
 ;; it under the terms of the GNU General Public License as published by
@@ -26,6 +26,7 @@
 (define-module (png graphics filled-rectangle)
   #:use-module (oop goops)
   #:use-module (png image)
+  #:use-module (png core common)
   #:use-module (png graphics graphic)
   #:use-module (png graphics pixel)
   #:use-module (png graphics point)
@@ -42,6 +43,20 @@
 (define filled-rectangle-height   rectangle-height)
 (define filled-rectangle-width    rectangle-width)
 
+
+(define-method (%display (filled-rectangle <filled-rectangle>) (port <port>))
+  (format port "#<filled-rectangle position: ~a width: ~a height: ~a ~a>"
+          (filled-rectangle-position filled-rectangle)
+          (filled-rectangle-width filled-rectangle)
+          (filled-rectangle-height filled-rectangle)
+          (object-address/hex-string filled-rectangle)))
+
+(define-method (display (filled-rectangle <filled-rectangle>) (port <port>))
+  (%display filled-rectangle port))
+
+(define-method (write (filled-rectangle <filled-rectangle>) (port <port>))
+  (%display filled-rectangle port))
+
 
 (define-method (draw! (image <png-image>) (rectangle <filled-rectangle>))
   (let* ((position   (rectangle-position rectangle))

tests/graphics.scm

@@ -244,6 +244,18 @@
          #:width    50
          #:height   100)))))
 
+
+;; Filled rectangle.
+
+(test-assert "<filled-rectangle>: display"
+  (with-output-to-string
+    (lambda ()
+      (display
+       (make <filled-rectangle>
+         #:position (make <point> #:x 100 #:y 200)
+         #:width    50
+         #:height   100)))))
+
 
 ;; Multiline.