draw565: Handle empty strings when calculating the bounding box

Currently the empty string cannot be drawn into a fixed width box.
Fix this by adding a special case for empty strings.

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>

1 files changed, 3 insertions, 0 deletions

diff --git a/wasp/draw565.py b/wasp/draw565.py
index f55977d..842b533 100644
--- a/wasp/draw565.py
+++ b/wasp/draw565.py
@@ -65,6 +65,9 @@ def _fill(mv, color: int, count: int, offset: int):
         p[x] = color
 
 def _bounding_box(s, font):
+    if not s:
+        return (0, font.height())
+
     w = 0
     for ch in s:
         (_, h, wc) = font.get_ch(ch)