From 649fe208ca96891faf249b7fb0a884a5d9d40b58 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sat, 21 Apr 2018 20:07:38 -0400
Subject: render: font: Add font-line-width procedure.

* chickadee/render/font.scm (font-line-width): New procedure.
---
 chickadee/render/font.scm | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/chickadee/render/font.scm b/chickadee/render/font.scm
index 1a01ad4..f63450b 100644
--- a/chickadee/render/font.scm
+++ b/chickadee/render/font.scm
@@ -42,6 +42,7 @@
             font?
             font-face
             font-line-height
+            font-line-width
             font-bold?
             font-italic?
             draw-text*
@@ -75,6 +76,17 @@
 
 (set-record-type-printer! <font> display-font)
 
+(define (font-line-width font text)
+  "Return the width of TEXT when rendered with FONT."
+  (let loop ((width 0.0)
+             (i 0))
+    (if (< i (string-length text))
+        (let ((char (or (font-ref font (string-ref text i))
+                        (font-ref font #\?))))
+          (loop (+ width (font-char-advance char))
+                (+ i 1)))
+        width)))
+
 (define* (load-tile-font file tile-width tile-height characters #:key
                          (face "untitled") (margin 0) (spacing 0))
   "Load the font named FACE from FILE, a bitmap image containing the
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