simple backend: ANSI colors, cursor positioning, bold — no longer a no-op

- draw-text: uses cursor-move-escape, sgr-fg/sgr-bg, sgr-attr for
  bold/italic/underline/reverse/dim/blink (was: just dumped string)
- draw-rect: fills with background color (was: complete no-op)
- draw-link: forwards to draw-text with fg/bg (was: ignored them)
- draw-ellipsis: uses positioned draw-text (was: newline+space)
- Added end-sync with finish-output (was: missing, output never flushed)

src/backend/simple.lisp

@@ -21,6 +21,9 @@
 (defmethod resume-backend ((b simple-backend))
   (values))
 
+(defmethod end-sync ((b simple-backend))
+  (finish-output (backend-output-stream b)))
+
 (defmethod backend-size ((b simple-backend))
   ;; Try ioctl on fd 0 (stdin), then stdout, then /dev/tty, then 80x24.
   ;; Use multiple-value-bind/values to preserve both cols and rows
@@ -79,8 +82,18 @@
 (defmethod draw-text ((b simple-backend) x y string fg bg
                       &key bold italic underline reverse dim blink
                       &allow-other-keys)
- (declare (ignore x y fg bg bold italic underline reverse dim blink))
- (backend-write b string))
+  (let* ((style-reset (format nil "~C[22;23;24;25;27m" #\Esc))
+         (parts (list (cursor-move-escape x y)
+                      (sgr-fg fg) (sgr-bg bg)
+                      (when bold (sgr-attr :bold))
+                      (when italic (sgr-attr :italic))
+                      (when underline (sgr-attr :underline))
+                      (when reverse (sgr-attr :reverse))
+                      (when dim (sgr-attr :dim))
+                      (when blink (sgr-attr :blink))
+                      string
+                      style-reset)))
+    (backend-write b (apply #'concatenate 'string parts))))
 
 (defun %simple-border-char (pos)
   "Return ASCII border character at POS.
@@ -142,19 +155,22 @@ POS is :top-left, :top-right, :bottom-left, :bottom-right,
 
 (defmethod draw-rect ((b simple-backend) x y width height
                       &key bg)
-  (declare (ignore x y width height bg))
-  ;; On simple backend, background fill is a no-op
-  (values))
+  (let* ((bg-esc (sgr-bg bg))
+         (style-reset (format nil "~C[22;23;24;25;27m" #\Esc))
+         (line (concatenate 'string
+                 bg-esc
+                 (make-string width :initial-element #\Space)
+                 style-reset (string #\Newline))))
+    (loop :for row :from 0 :below height :do
+      (backend-write b (cursor-move-escape x (+ y row)))
+      (backend-write b line))))
 
 (defmethod draw-link ((b simple-backend) x y string url
                       &key fg bg)
-  (declare (ignore url fg bg))
-  (draw-text b x y string nil nil))
+  (declare (ignore url))
+  (draw-text b x y string fg bg))
 
 (defmethod draw-ellipsis ((b simple-backend) x y width
                           &key fg bg)
-  (declare (ignore width fg bg))
-  ;; Position using newlines+spaces (simple-backend pattern)
-  (dotimes (row y) (backend-write b (string #\Newline)))
-  (backend-write b (make-string x :initial-element #\Space))
-  (backend-write b "..."))
+  (declare (ignore width))
+  (draw-text b x y "..." fg bg))