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RoboFab and PostScript font hint values

The font.psHints object, introduced in RoboFab 1.1.3 rev.89 showed it was useful to have access to the various PostScript blues values. But it also proved it was necessary to store them elsewhere. So in RoboFab 1.2 rev.172, the blues values found a permanent home in the new RInfo object. The font.psHints object is still functional, all fields are rerouted to their new places. The font.psHint attribute might be deprecated in the future.

Note on accessing blues data in FontLab Studio

A bug in FontLab's own Python attributes relating to blues, otherBlues, familyBlues and familyOtherBlues fields, makes it impossible to set the full number of zones using Python. The actual number of zones which can be set from Python is one less than the number in the Adobe specification. A warning will be printed when a zone will be dropped. Using the FontLab font info dialog, all zones can be set.

The attributes (since RoboFab 1.2)

Example, some blues attrs, usage

# example of accessing the postscript blues
# data using the attributes.
from import CurrentFont

f = CurrentFont()

>> [-8, 0, 200, 208, 214, 114]

>> [-136, -128, -86, -84, 376, 386]

>> [-8, 0, 200, 208, 214, 224]

>> [-136, -128, -86, -84, 376, 386]

Description of the font.psHint object

PostScriptFontHintValues is the class of the object found at font.psHints. It has a couple of attributes of its own which give you access to the font level PostScript hinting information. For exact information on the meaning and usage of these values, please refer to the developer resources at
The PostScriptFontHintValues objects, in FontLab and NoneLab flavor, can respond to add, sub, mul, rmul, div and rdiv, so you can do math with them, for instance interpolations. Available since ChangeSet 44.

Example, the font.psHints object, usage

# example of accessing the hint data,
    # using the font.psHints object.
    from import CurrentFont

    f = CurrentFont()
    print f.psHints.asDict()

    >>>{ 'forceBold': False,
    'blueScale': 0.25,
    'blueFuzz': 0,
    'blueShift': 4,
    'hStems': [24, 50],
    'vStems': [66, 4, 30, 72, 50],
    'blueValues': [[-8, 0], [200, 208], [214, 224]],
    'otherBlues': [[-136, -128], [-86, -84], [376, 386]],
    'familyOtherBlues': [[-136, -128], [-86, -84], [376, 386]],
    'familyBlues': [[-8, 0], [200, 208], [214, 224]], }
# example of scaling the hint data.
    from import CurrentFont

    f = CurrentFont()
    print f.psHints.asDict()

    ps2 = f.psHints * .5    # a math operation returns a new, unbound object
    ps2.round()                # it needs to be rounded first

    f.psHints.update(ps2)    # now you can add the values to the FL object
    f.update()                # see those zones skip!




#FLM: Get and set font level PostScript hint data.
from import CurrentFont

    This script shows the way to get to the font level postscript hint values.
    These values were available from the fl layer, but not in RoboFab.
    Now they're available in RoboFab in a slightly easier to use format.
    The values also export to UFO and import from UFO.
    Check the FontLab FontInfo panel / Hinting Settings


f = CurrentFont()

# the fontlevel postscript hint data is accessible through the psHints attribute

print "This script shows the attributes of psHints:", f.psHints

# now let's have a look at the values
# blueScale, blueShift, blueFuzz and forceBold are all single values.

print "blueScale", f.psHints.blueScale
f.psHints.blueScale = .5
print "blueScale changed", f.psHints.blueScale

print "blueShift", f.psHints.blueShift
f.psHints.blueShift = 5
print "blueShift changed", f.psHints.blueShift

print "blueFuzz", f.psHints.blueFuzz
f.psHints.blueFuzz = 0
print "blueFuzz changed", f.psHints.blueFuzz

print "forceBold", f.psHints.forceBold
f.psHints.forceBold = 1
print "forceBold changed", f.psHints.forceBold

# the following values are represented as lists.
# Important Note: you can only set the whole list, not individual items.
# So get the list, make changes to it, then set the list
# Zones are represented as tuples of integers, so it's easier to
# see which values belong together. FL stores the values as
# a single list of numbers.

# T1 spec says blueValues, FL says Primary Alignment Zones, under "Set Local Alignment Zones".
print "blueValues", f.psHints.blueValues
# remove the last zone
f.psHints.blueValues = f.psHints.blueValues[:-1]
print "blueValues changed", f.psHints.blueValues
# add a new zone
f.psHints.blueValues = f.psHints.blueValues + [(750, 770)]
print "blueValues changed", f.psHints.blueValues

# T1 spec says otherBlues, FL says Secondary Alignment Zones, under "Set Local Alignment Zones".
print "otherBlues", f.psHints.otherBlues
# remove the last zone
f.psHints.otherBlues = f.psHints.otherBlues[:-1]
print "otherBlues changed", f.psHints.otherBlues
# add a new zone
f.psHints.otherBlues = f.psHints.otherBlues + [(750, 770)]
print "otherBlues changed", f.psHints.otherBlues

# T1 spec says familyBlues, FL says Primary Alignment Zones, under "Set Family Alignment Zones".
print "familyBlues", f.psHints.familyBlues
# remove the last zone
f.psHints.familyBlues = f.psHints.familyBlues[:-1]
print "familyBlues changed", f.psHints.familyBlues
# add a new zone
f.psHints.familyBlues = f.psHints.familyBlues + [(750, 770)]
print "familyBlues changed", f.psHints.familyBlues

# T1 spec says familyOtherBlues, FL says Seconday Alignment Zones, under "Set Family Alignment Zones".
print "familyOtherBlues", f.psHints.familyOtherBlues
# remove the last zone
f.psHints.familyOtherBlues = f.psHints.familyOtherBlues[:-1]
print "familyOtherBlues changed", f.psHints.familyOtherBlues
# add a new zone
f.psHints.familyOtherBlues = f.psHints.familyOtherBlues + [(750, 770)]
print "familyOtherBlues changed", f.psHints.familyOtherBlues

# The horizontal stems are represented as a list of single values.
print "hStems", f.psHints.hStems
f.psHints.hStems = f.psHints.hStems[:-1]
print "hStems changed", f.psHints.hStems
# add a new stem
f.psHints.hStems = f.psHints.hStems + [100]
print "hStems changed", f.psHints.hStems

# The vertical stems are represented as a list of single values.
print "vStems", f.psHints.vStems
f.psHints.vStems = f.psHints.vStems[:-1]
print "vStems changed", f.psHints.vStems
# add a new stem
f.psHints.vStems = f.psHints.vStems + [100]
print "vStems changed", f.psHints.vStems

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