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 font.info attributes (since RoboFab 1.2)

font.info.postscriptBlueValues

(number list) A list of up to 14 integers or floats specifying the values that should be in the Type 1/CFF BlueValues field. This list must contain an even number of integers following the rules defined in the Type 1/CFF specification.

font.info.postscriptOtherBlues

(number list) A list of up to 10 integers or floats specifying the values that should be in the Type 1/CFF OtherBlues field. This list must contain an even number of integers following the rules defined in the Type 1/CFF specification.

font.info.postscriptFamilyBlues

(number list) A list of up to 14 integers or floats specifying the values that should be in the Type 1/CFF FamilyBlues field. This list must contain an even number of integers following the rules defined in the Type 1/CFF specification.

font.info.postscriptFamilyOtherBlues

(number list) A list of up to 10 integers or floats specifying the values that should be in the Type 1/CFF FamilyOtherBlues field. This list must contain an even number of integers following the rules defined in the Type 1/CFF specification.

font.info.postscriptStemSnapH

(number list) List of horizontal stems sorted in increasing order. Up to 12 integers or floats are possible. This corresponds to the Type 1/CFF StemSnapH field.

font.info.postscriptStemSnapV

(number list) List of vertical stems sorted in increasing order. Up to 12 integers or floats are possible. This corresponds to the Type 1/CFF StemSnapV field.

font.info.postscriptBlueFuzz

(integer or float) BlueFuzz value. This corresponds to the Type 1/CFF BlueFuzz field.

font.info.postscriptBlueShift

(integer or float) BlueShift value. This corresponds to the Type 1/CFF BlueShift field.

font.info.postscriptBlueScale

(float) BlueScale value. This corresponds to the Type 1/CFF BlueScale field.

font.info.postscriptForceBold

(boolean) Indicates how the Type 1/CFF ForceBold field should be set.

Example, some font.info blues attrs, usage

# example of accessing the postscript blues
# data using the font.info attributes.

from robofab.world import CurrentFont

f = CurrentFont()

print f.info.postscriptBlueValues
print f.info.postscriptOtherBlues
print f.info.postscriptFamilyBlues
print f.info.postscriptFamilyOtherBlues
[-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 adobe.com.

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 robofab.world 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 robofab.world import CurrentFont

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

# a math operation returns a new, unbound object
ps2 = f.psHints * .5       

# it needs to be rounded first
ps2.round()

# now you can add the values to the FL object
f.psHints.update(ps2)

# see those zones skip!
f.update()

Attributes

blueShift

Value for blue shift. Integer in FontLab, float or int in NoneLab.

blueScale

Value for blue scale. Float in FontLab and NoneLab.

blueFuzz

Value for blue fuzz. Integer in FontLab, float or int in NoneLab.

forceBold

Value for force bold. Boolean in FontLab and NoneLab.

blueValues

List of pairs of numbers indicating the primary alignment zones. Integers in FontLab, floats or ints in NoneLab.

otherBlues

List of pairs of numbers indicating the secondary alignment zones. Integers in FontLab, floats or ints in NoneLab.

familyBlues

List of pairs of numbers indicating the primary family alignment zones. Integers in FontLab, floats or ints in NoneLab.

familyOtherBlues

List of pairs of numbers indicating the secondary family alignment zones. Integers in FontLab, floats or ints in NoneLab.

vStems

List of numbers for the vertical stems. Integers in FontLab, floats or ints in NoneLab.

hStems

List of numbers for the horizontal stems. Integers in FontLab, floats or ints in NoneLab.

Methods

copy()

Returns a copy of the object. Both in FontLab and NoneLab the copy will be an objectsRF.PostScriptFontHintValues.

round()

Round the values to ints as much as the nature of the values allows. Note: blueScale is not rounded, it is a float, forceBold is set to False if -0.5 < value < 0.5. Otherwise it will be True, blueShift, blueFuzz are rounded to int, stems are rounded to int, blues are rounded to int.

asDict()

Returns a dictionary with all attributes and values of this object.

fromDict(aDict)

This will look for familiar attributes in aDict and assign the value to the object.

update(anotherPSHintsObject)

This will copy values from the other object.

Examples

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

from robofab.world 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
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