draw565: Improve line wrapping

Currently the final word of wrapped text will always appear as a single
word on its own line. Fix this by rearranging the break cases to avoid
searching for the most recent space when we get to the end of the text.

Fixes: #230
Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>

wasp/boards/simulator/test_unit.py

@@ -57,3 +57,16 @@ def test_font_width(draw):
 
         if f.max_ch() >= 90:
             assert draw.bounding_box('IIII')[0] < draw.bounding_box('WWWW')[0]
+
+@pytest.mark.parametrize("input,expected", (
+    ('abc', [0, 3]),
+    ('one.two', [0, 7]),
+    ('one two', [0, 7]),
+    ('one two three', [0, 13]),
+    ('abcdefghijklmnopqrstuvwxyz', [0, 17, 26]),
+    ('abcdefghijklm nopqrstuvwxyz', [0, 14, 27]),
+    ('abcde fghij klmno pqrst uvwxyz', [0, 18, 30]),
+
+))
+def test_wrap(draw, input, expected):
+    assert draw.wrap(input, 240) == expected

wasp/draw565.py

@@ -366,12 +366,15 @@ class Draw565(object):
             l = 0
 
             for i in range(start, max+1):
-                if i >= len(s):
+                if i >= max:
+                    end = i
                     break
                 ch = s[i]
                 (_, h, w) = font.get_ch(ch)
                 l += w + 1
                 if l > width:
+                    if end <= start:
+                        end = i
                     break
 
                 # Break the line immediately if requested
@@ -382,8 +385,6 @@ class Draw565(object):
                 # Remember the right-most place we can cleanly break the line
                 if ch == ' ':
                     end = i+1
-            if end <= start:
-                end = i
             chunks.append(end)
 
         return chunks