com.inductiveautomation.rm.pdf.reader

Class PDFGlyphWidthTable

java.lang.Object

com.inductiveautomation.rm.pdf.reader.PDFGlyphWidthTable

public class PDFGlyphWidthTable
extends java.lang.Object

This class is used to map cids to widths. Widths are always indexed by character code. For single byte fonts, we allocate a single 256 entry array for quick character code -> width lookup. Instead of using a 64K entry array for 2 byte fonts, widths are represented by a sorted array of WidthTableEntries.

The pdf format for widths looks like: [cid [w1 w2 w3] cidfirst cidlast w4 cid2 [w5 w6 w7 w8]]

so the widths for a range of cids can be specified as an array of widths, or by a single width that applies to every cid in the range.

All WidthTableEntries have a startcid & endcid range and can then hold either a) an array of endcid-startcid+1 floats b) a single float

The widthtable can then do a binary search through the table to find the specific widthtable entry. The worst possible case would be a table of 64k entries, each describing a single glyph, and a search for a glyph through this would take log2(65536) = 16 hops through a huge table. Any fontlist this large would actually just revert to a single entry with 64k widths, so there would be no searching. Average case would be a much smaller, especially since this is often used for font subsets.

Constructor Summary

Constructors

Constructor and Description
PDFGlyphWidthTable(java.util.List pdfwidths, java.lang.Object defwidth) Main constructor.

Method Summary

Modifier and Type	Method and Description
float	getWidth(int cid) Binary search the list and return the width

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PDFGlyphWidthTable

public PDFGlyphWidthTable(java.util.List pdfwidths,
                          java.lang.Object defwidth)

Main constructor. pdfwidths is the array from the CIDfont's /W entry, and defwidth is the /DW entry. Both entries are optional, in which case all the widths are 1000.

Method Detail

getWidth

public float getWidth(int cid)

Binary search the list and return the width