Package com.inductiveautomation.rm.pdf.reader

Class PDFGlyphWidthTable

java.lang.Object
com.inductiveautomation.rm.pdf.reader.PDFGlyphWidthTable
public class PDFGlyphWidthTable extends 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 Details

    • PDFGlyphWidthTable

      public PDFGlyphWidthTable(List pdfwidths, 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 Details

    • getWidth

      public float getWidth(int cid)
      Binary search the list and return the width