up

main.rkt

@@ -37,10 +37,11 @@
 ;; h : exact-nonnegative-integer?
 ;; ! : (row col char -> void) row col -> void
 (struct rart (w h !))
-(define (draw row col x)
+(define (draw row col x #:clear? [clear? #t])
   (match-define (rart w h !) x)
-  (display (A:dec-soft-terminal-reset))
-  (display (A:clear-screen/home))
+  (display (A:dec-soft-terminal-reset))  
+  (when clear?
+    (display (A:clear-screen/home)))
   (set-drawing-parameters!)
   (! (λ (r c ch)
        (display (A:goto r c))

size.rkt

@@ -17,37 +17,69 @@
              [(== byte) empty]
              [next (cons next (loop))]))))
 
-(define (screen-size)
-  (define tty-str "/dev/tty")
+(define (bytes->number bs)
+  (string->number (bytes->string/utf-8 bs)))
+
+(define default-tty "/dev/tty")
+(struct term (f in out))
+(define (open-term #:tty [tty default-tty])
   (system* "/bin/stty"
            stty-minus-f-arg-string
-           tty-str
+           tty
            "raw"
            "-echo")
   (define-values (in out)
-    (open-input-output-file tty-str #:exists 'update))
-  (write-bytes #"\e[18t" out) (flush-output out)
-  (dynamic-wind
-    void
-    (λ ()
+    (open-input-output-file tty #:exists 'update))
+  (term tty in out))
+
+(define (close-term t)
+  (match-define (term f in out) t)
+  (close-input-port in)
+  (close-output-port out)
+  (system* "/bin/stty"
+           stty-minus-f-arg-string
+           f
+           "cooked"
+           "echo"))
+
+(define (with-term f #:tty [tty default-tty])
+  (define t (open-term #:tty tty))
+  (define (close!) (close-term t))
+  (with-handlers ([exn:fail? (λ (x) (close!) (raise x))])
+    (begin0 (f t) (close!))))
+
+(define (with-term* t f)
+  (if t (f t) (with-term f)))
+
+(define (screen-size [t #f])
+  (with-term* t
+    (λ (t)
+      (match-define (term _ in out) t)
+      (write-bytes #"\e[18t" out) (flush-output out)
       (match (read-until in #\;)
         [#"\e[8"
          (define row-s (read-until in #\;))
          (define col-s (read-until in #\t))
          (values (bytes->number row-s)
                  (bytes->number col-s))]
-        [_ (values #f #f)]))
-    (λ ()
-      (close-input-port in)
-      (close-output-port out)
-      (system* "/bin/stty"
-               stty-minus-f-arg-string
-               tty-str
-               "cooked"
-               "echo"))))
+        [x (error 'screen-size "Something weird happened, got ~e" x)]))))
 
-(define (bytes->number bs)
-  (string->number (bytes->string/utf-8 bs)))
+(define (cursor-position [t #f])
+  (with-term* t
+    (λ (t)
+      (match-define (term _ in out) t)
+      (display (position-report-request) out) (flush-output out)
+      (match (read-bytes 2 in)
+        [#"\e["
+         (define row-s (read-until in #\;))
+         (define col-s (read-until in #\R))
+         (values (bytes->number row-s)
+                 (bytes->number col-s))]
+        [x (error 'cursor-position "Something weird happened, got ~e" x)]))))
 
 (module+ main
-  (screen-size))
+  (with-term
+    (λ (t)
+      (screen-size t)
+      (cursor-position t))))
+