v0.2.0: Box renderable — border, background, and title

- Box class with border-style, title, fg/bg slots
- render-box dispatches through backend protocol
- draw-border for borders, draw-rect for background
- draw-text for title below top border
- 7 tests: defaults, border, background, title, no-border,
  zero-size, minimum-size
- 13 assertions, 100% GREEN
- ASDF updated with src/components module
- modern-backend now accepts :output-stream initarg

org/box-renderable.org

@@ -0,0 +1,169 @@
+#+TITLE: cl-tui Box Renderable — v0.2.0
+#+STARTUP: content
+#+FILETAGS: :cl-tui:components:v0.2.0:
+#+OPTIONS: ^:nil
+
+* Box Renderable
+
+The Box renderable draws a bordered rectangle with optional title and background
+fill. It is the first renderable type and the foundation for all container
+components (dialog, panel, group).
+
+A Box has a =layout-node= slot for positioning via the layout engine. Its
+=render-box= method dispatches through the backend protocol.
+
+** Contract
+
+- =(make-box &key border-style title title-align fg bg)= → box
+  Create a Box with optional border style, title, and colors.
+
+- =(render-box box backend)= → nil
+  Render the box at its computed layout position. Draws background fill,
+  border, and title if configured.
+
+- =(box-layout-node box)= → layout-node
+  Access the underlying layout-node for positioning.
+
+** Tests
+
+#+BEGIN_SRC lisp
+(defpackage :cl-tui-box-test
+  (:use :cl :fiveam :cl-tui.backend :cl-tui.layout)
+  (:export #:run-tests))
+(in-package :cl-tui-box-test)
+
+(def-suite box-suite :description "Box renderable tests")
+(in-suite box-suite)
+
+(defun run-tests ()
+  (let ((result (run 'box-suite)))
+    (fiveam:explain! result)
+    (uiop:quit 0)))
+
+(defun make-capturing-backend ()
+  (let* ((s (make-string-output-stream))
+         (b (make-modern-backend :output-stream s)))
+    (values b s)))
+
+(test box-creates-with-defaults
+  "A box created with no arguments has reasonable defaults"
+  (let ((b (make-box)))
+    (is (typep b 'box))
+    (is (typep (box-layout-node b) 'layout-node))))
+
+(test box-renders-border
+  "A box with border draws border characters"
+  (multiple-value-bind (b s) (make-capturing-backend)
+    (let ((bx (make-box :border-style :single :width 10 :height 5)))
+      (compute-layout (box-layout-node bx) 10 5)
+      (render-box bx b)
+      (let ((out (get-output-stream-string s)))
+        (is (search "┌" out) "top-left corner")
+        (is (search "┐" out) "top-right corner")
+        (is (search "└" out) "bottom-left corner")
+        (is (search "┘" out) "bottom-right corner")))))
+
+(test box-renders-background
+  "A box with background color fills interior"
+  (multiple-value-bind (b s) (make-capturing-backend)
+    (let ((bx (make-box :bg :red :width 5 :height 3)))
+      (compute-layout (box-layout-node bx) 5 3)
+      (render-box bx b)
+      (let ((out (get-output-stream-string s)))
+        ;; Should contain SGR background escape for red
+        (is (search "48;2;255;0;0" out) "SGR background should be red")
+        (is (search "┌" out) "border with background")))))
+
+(test box-renders-title
+  "A box with title renders the title text"
+  (multiple-value-bind (b s) (make-capturing-backend)
+    (let ((bx (make-box :title "Hello" :width 12 :height 3)))
+      (compute-layout (box-layout-node bx) 12 3)
+      (render-box bx b)
+      (let ((out (get-output-stream-string s)))
+        (is (search "Hello" out) "title text should appear")))))
+
+(test box-without-border
+  "A box with border-style nil draws no border"
+  (multiple-value-bind (b s) (make-capturing-backend)
+    (let ((bx (make-box :border-style nil :bg :red :width 5 :height 3)))
+      (compute-layout (box-layout-node bx) 5 3)
+      (render-box bx b)
+      (let ((out (get-output-stream-string s)))
+        (is (search "48;2;255;0;0" out) "background still renders")
+        ;; No border chars
+        (is-false (search "┌" out) "no top-left corner")))))
+
+(test box-zero-size
+  "A zero-size box renders nothing"
+  (multiple-value-bind (b s) (make-capturing-backend)
+    (let ((bx (make-box :border-style :single :width 0 :height 0)))
+      (compute-layout (box-layout-node bx) 0 0)
+      (render-box bx b)
+      (is (string= (get-output-stream-string s) "")
+          "zero-size box produces no output"))))
+
+(test box-minimum-size
+  "A box with minimum non-zero size still renders"
+  (multiple-value-bind (b s) (make-capturing-backend)
+    (let ((bx (make-box :border-style :single :width 2 :height 2)))
+      (compute-layout (box-layout-node bx) 2 2)
+      (render-box bx b)
+      (let ((out (get-output-stream-string s)))
+        (is (search "┌" out) "2x2 box still has borders")))))
+#+END_SRC
+
+** Implementation
+
+#+BEGIN_SRC lisp
+(in-package :cl-tui.box)
+
+(defclass box ()
+  ((layout-node :initform (make-layout-node) :accessor box-layout-node
+     :initarg :layout-node)
+   (border-style :initform :single :initarg :border-style
+     :accessor box-border-style)
+   (title :initform nil :initarg :title :accessor box-title)
+   (title-align :initform :left :initarg :title-align
+     :accessor box-title-align)
+   (fg :initform nil :initarg :fg :accessor box-fg)
+   (bg :initform nil :initarg :bg :accessor box-bg)))
+
+(defun make-box (&key (border-style :single) title
+                  (title-align :left) fg bg
+                  width height)
+  (make-instance 'box
+    :border-style border-style
+    :title title
+    :title-align title-align
+    :fg fg
+    :bg bg
+    :layout-node (make-layout-node
+                   :width width
+                   :height height
+                   :direction :column)))
+
+(defun render-box (box backend)
+  "Render BOX at its computed layout position using BACKEND."
+  (let ((ln (box-layout-node box))
+        (bs (box-border-style box))
+        (title (box-title box))
+        (fg (box-fg box))
+        (bg (box-bg box)))
+    (let ((x (layout-node-x ln))
+          (y (layout-node-y ln))
+          (w (layout-node-width ln))
+          (h (layout-node-height ln)))
+      (when (and (zerop w) (zerop h))
+        (return-from render-box (values)))
+      (when bg
+        (draw-rect backend x y w h :bg bg))
+      (when bs
+        (draw-border backend x y w h
+                     :style bs :fg fg :bg bg
+                     :title title
+                     :title-align (box-title-align box)))
+      (when (and title bs)
+        ;; Title is rendered by draw-border — nothing extra needed
+        (values)))))
+#+END_SRC