Source code
Revision control
Copy as Markdown
Other Tools
# bitmap strike must round its pen to nearest, not floor it with the sub-pixel
# bias.
#
# Proggy carries an embedded bitmap strike at ppem 11 (its outlines are empty,
# so `embedded-bitmaps: true` + size 11 selects the strike). A strike ignores the
# quantized sub-pixel offset its glyph key asks for and lands on the device grid,
# so the floor(pen + 0.125) bias - which only makes sense paired with an offset
# the rasterizer honours - just drags the glyph up to 0.875px to the left of
# where it was placed. Rounding to nearest instead keeps it within 0.5px, and on
# the same grid line as any nearest-snapped clip or mask edge.
#
# Each row draws 'w' at a fractional x; the reference draws it at round(x). Rows
# with a fraction below 0.5 (and at/above 0.875) round the same way either way
# and guard against the pen moving when it should not; rows in between move by a
# whole pixel and are what a pre-fix build gets wrong.
root:
items:
- type: rect
bounds: [0, 0, 240, 160]
color: white
# fraction < 0.5: rounds down, unchanged by the fix
- type: text
font: Proggy.ttf
size: 11
embedded-bitmaps: true
color: black
origin: [100.1, 24]
text: "w"
- type: text
font: Proggy.ttf
size: 11
embedded-bitmaps: true
color: black
origin: [100.3, 40]
text: "w"
# 0.5 <= fraction < 0.875: rounds up, floored down before the fix
- type: text
font: Proggy.ttf
size: 11
embedded-bitmaps: true
color: black
origin: [100.5, 56]
text: "w"
- type: text
font: Proggy.ttf
size: 11
embedded-bitmaps: true
color: black
origin: [100.6, 72]
text: "w"
- type: text
font: Proggy.ttf
size: 11
embedded-bitmaps: true
color: black
origin: [100.7, 88]
text: "w"
- type: text
font: Proggy.ttf
size: 11
embedded-bitmaps: true
color: black
origin: [100.8, 104]
text: "w"
# fraction >= 0.875: the floor bias already rounds up, unchanged by the fix
- type: text
font: Proggy.ttf
size: 11
embedded-bitmaps: true
color: black
origin: [100.9, 120]
text: "w"