Documentation for module t1lib

Object-oriented interface to the t1lib Type1 font rasterizer.

This is the interface that should actually be used; _t1lib is the actual C extension which exposes the low-level interface.

Constants

LOG_ERROR

Log only serious errors. This can include such events as memory allocation failures.

LOG_WARNING

Log anything that might be useful in diagnosing misbehavior in a debugged application. This can include such information as missing font metrics (AFM) files.

LOG_STATISTIC

Various informational messages are included in the log; this can include memory consumption information.

LOG_DEBUG

Logging level to support debugging. All sorts of mess gets included in the log. This should be used primarily when debugging t1lib or tracking really nasty memory problems.

Exception T1Error

Raised by primitive t1lib operations that fail.

The string value describes what went wrong.

Exception UnknownFontError

Raised when a requested fontname is not recognized.

Public Members

fontname

requested font name

Exception EncodingFormatError

Raised when a font encoding file has a formatting error.

Class BBox

A bounding box.

Public Members

llx

lower-left x coordinate

lly

lower-left y coordinate

urx

upper-right x coordinate

ury

upper-right y coordinate

All values are measured in character space units.

Constructor

bbox

getHeight()

Return the height of the region.

getWidth()

Return the width of the region.

Class MetricsInfo

Metrics information derived from AFM data.

Public Members

width

bbox

bounding box of the glyph which would be generated for string

numchars

number of characters in the string measured

charpos

vector of numchars integers; see below

string

the string measured

All values are measured in character space units.

The charpos vector contains values which represent the horizontal escapement of string[:i + 1], where i is an index into string.

Constructor

metrics

string

Class Glyph

A rasterized bitmap.

Public Members

bits

string representing the bitmap as generated by t1lib

ascent

number of pixels image rises above the baseline

descent

number of pixels image descends below the baseline

leftSideBearing

number of pixels between the origin of the glyph and the leftmost bitmap pixel

rightSideBearing

number of pixels between the origin of the glyph and the rightmost bitmap pixel

characterWidth

width of the glyph, including character margins; this is the amount of horizontal movement needed before placing a subsequent bitmap

bpp

number of data bits per pixel

Constructor

Initialize a Glyph instance.

bits

string containing the bitmaps as generated by t1lib

metrics

5-tuple representing the metrics field of a t1lib GLYPH structure

bpp

bits per pixel

See the t1lib documentation for information on the format of the bits field.

getHeight()

Return the height of the bitmap.

Character margin areas are not included.

getWidth()

Return the width of the bitmap.

Character margin areas are not included.

Class T1Font

A font.

Instances of this class should not be created explicitly in user code.

isLogical()

Return true iff this font is a t1lib 'logical' font.

isPhysical()

Return true iff this font is a t1lib 'physical' font.

getLogicalPeers()

Return sequence of all logical fonts generated from the physical font associated with this font.

getPhysicalFont()

Return the t1lib 'physical' font associated with this font.

getUnderlinePosition()

Return the underline position of this font.

If no AFM data is available, return 0.

getUnderlineThickness()

Return the underline thickness of this font.

If no AFM data is available, return 0.

getPostScriptName()

Return the PostScript name for this font.

getCharName()

Return the PostScript name of a character in the current encoding.

char

character for which the name is desired

getEncodingIndex()

Return the index of a character in the current encoding.

charname

PostScript character name

If the character is not present in the current encoding, a T1Error exception is raised.

getLigatures()

char

getKerning()

Return the kerning for a character pair.

char1

char2

The value returned is measured in character space units. If no AFM data is available, 0 is returned.

getEncoding()

Return the current encoding vector.

setEncoding()

Change the encoding vector.

encoding = None

new encoding vector

If the new encoding vector is different from the old vector, the bitmap cache is cleared.

getExtension()

Return the current extension factor for the font.

setExtension()

Change the extension of the font.

extend

the new extension factor

The new slant replaces the old extension; it is not a modifier. If the new extension factor is different from the old factor, the bitmap cache is cleared.

getSlant()

Return the current slant factor for the font.

setSlant()

Change the slant of the font.

slant

the new slant factor

The new slant replaces the old slant; it is not a modifier. If the new slant factor is different from the old facter, the bitmap cache is cleared.

copy()

Return a new logical font based on the same physical font as this font.

reset()

Delete all cached bitmaps for this font.

delete()

Attempt to free all memory used by this font.

If this is a physical font still referenced by any logical fonts, a T1Error exception will be raised.

Class FontSetter

Constructor

Initialize a FontSetter instance.

font

T1Font instance

size

point size of the rasterized characters

angle = 0.0

rotation angle of the rasterized image (measured counter-clockwise)

spaceoff = 0.0

kerning = 0

flag indicating whether pairwise kerning should be used

bpp = 1

bits-per-pixel for the generated rasterizations

setChar()

Rasterize a single character.

char

the character to rasterize

Returns a Glyph instance.

setString()

Rasterize a string.

string

the string to rasterize

Returns a Glyph instance.

getMetrics()

Return metrics information for a string.

string

the string to compute metrics information for.

getWidth()

Return the width of a string in character space units.

string

the string to measure

getBBox()

Return the bounding box for a string.

string

string to compute the bounding box for

Returns a BBox instance.

setBitsPerPixel()

Set the number of bits per pixel for the resulting glyphs.

bpp

new bit depth

If bpp is not 1, 8, 16, 24, or 32, ValueError is raised.

newGlyph()

Return a glyph object for the specified information.

bits

string representing the raw bitmap generated by t1lib

metrics

bpp

bits-per-pixel for the bitmap

resetSize()

Clear bitmap cache in underlying t1lib.

Functions

init()

Initialize the library.

logging = 0

flag to indicate whether logging should be enabled

Use of this function is only necessary to enable logging. In that case, this must be called before any other calls to this module have been made.

printLog()

Add an entry to the t1lib.log file.

message

string containing the text to write out

level = LOG_WARNING

severity level; one of LOG_ERROR, LOG_WARNING, LOG_STATISTIC, or LOG_DEBUG

The name of the calling function or method is determined automatically and cannot be supplied by the caller.

setLogLevel()

Set the level of severity at which log entries are written to the log.

level

severity level; one of LOG_ERROR, LOG_WARNING, LOG_STATISTIC, or LOG_DEBUG

setDeviceResolutions()

Set the resolution of the output device in dots-per-inch.

xres

horizontal DPI

yres

vertical DPI

setAAGrayValues()

Set the values used for each level of gray for anti-aliasing.

white

gray75

gray50

gray25

black

Each value is interpreted as an unsigned 32-bit integer. Long integers may be used.

getFont()

Return a font object for a named font.

fontname

PostScript name of the font to be located

If the named font is not found, an UnknownFontError exception is raised. The fontname value is case-sensitive.

Font objects returned by this function will always refer to 'physical' fonts in t1lib terminology; logical fonts generated from the same physical base may exist.

loadEncoding()

Return an encoding vector read from a file.

fp_or_filename

either a file-like object or the name of a disk file

If a string is passed in, it will be used as a filename and passed to open(), otherwise fp_or_filename will be treated as any file-like object and assumed to have a readline() method.