# Bitmap-data helper modules

## Overview:

The modules documented on this page are helpers for `fontTools.ttLib` that implement lower-level support for various table converters that need to interact with bitmapped data. The `BitmapGlyphMetrics` module is used for the `EBDT`/`EBLC` and `CBDT`/`CBLC` tables, and `sbixGlyph` and `sbixStrike` are used for the `sbix` table.

## fontTools.ttLib.tables.BitmapGlyphMetrics

class fontTools.ttLib.tables.BitmapGlyphMetrics.BitmapGlyphMetrics

  Bases: `object`

  toXML(writer, ttFont)
  fromXML(name, attrs, content, ttFont)

class fontTools.ttLib.tables.BitmapGlyphMetrics.BigGlyphMetrics

  Bases: `BitmapGlyphMetrics`

  binaryFormat = '\n > # big endian\n height: B\n width: B\n horiBearingX: b\n horiBearingY: b\n horiAdvance: B\n vertBearingX: b\n vertBearingY: b\n vertAdvance: B\n'

class fontTools.ttLib.tables.BitmapGlyphMetrics.SmallGlyphMetrics

  Bases: `BitmapGlyphMetrics`

  binaryFormat = '\n > # big endian\n height: B\n width: B\n BearingX: b\n BearingY: b\n Advance: B\n'

## fontTools.ttLib.tables.sbixGlyph

class fontTools.ttLib.tables.sbixGlyph.Glyph(glyphName=None, referenceGlyphName=None, originOffsetX=0, originOffsetY=0, graphicType=None, imageData=None, rawdata=None, gid=0)

  Bases: `object`

  is_reference_type()

    Returns True if this glyph is a reference to another glyph’s image data.

  decompile(ttFont)
  compile(ttFont)
  toXML(xmlWriter, ttFont)
  fromXML(name, attrs, content, ttFont)

## fontTools.ttLib.tables.sbixStrike

class fontTools.ttLib.tables.sbixStrike.Strike(rawdata=None, ppem=0, resolution=72)

  Bases: `object`

  decompile(ttFont)
  compile(ttFont)
  toXML(xmlWriter, ttFont)
  fromXML(name, attrs, content, ttFont)