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Microsoft Typography | Developer information | Hinting tutorial | Spacing


Basic hinting philosophies and TrueType instructions


Spacing

Controlling the bitmap's placement in the advance width at all ppem sizes is an extremely important part of hinting. The method I've used to hint our example uc O - from the sidebearings - means we have a good chance of maintaining the actual position and keeping the glyph's bitmap from expanding outside its advance width. But we risk having the bitmap collapse and lose the white space in the counter. Because this glyph was sufficiently wide that was not a problem.

This hinting method is not an active method of spacing. It preserves spacing but to insure all sizes are spaced properly deltas would probably have to be used at some sizes to move the bitmap left or right. One method of controlling spacing is the use of sidebearing cvts which would give some type of consistency to all glyphs. When hinting inward another method would be to force a minimum of one pixel of white space on the right side of all glyphs. In our uc O example, a MDRP was used from the sidebearing with the second argument set not to maintain minimum distance. If we set that argument to maintain minimum distance, we would always have one pixel on the right of the bitmap.

When spacing glyphs, the type engineer looks at individual glyphs and glyphs in combination with other group members. They check spacing at each ppem size between control characters. For the uppercase group the control characters are commonly the uc O, uc H or uc I.

HAHBHCHDH OAOBOCODO

A more active way to control spacing is to write functions that measure distances and move portions of entire glyphs left or right.


Next section, Composite glyphs and functions.



this page was last updated 30 June 1997
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Microsoft Typography | Developer information | Hinting tutorial | Spacing