Shared String Table

A workbook can contain thousands of cells containing string (non-numeric) data. Furthermore this data is very likely to be repeated across many rows or columns. The goal of implementing a single string table that is shared across the workbook is to improve performance and optimize the storage format.

For cells that contain a string, the cell value will contain an index into the shared string table, pointing to the actual string value. The shared string table is permitted to contain all the necessary information for displaying the string: the text, formatting properties, and phonetic properties (for East Asian languages).

Most strings in a workbook have formatting applied at the cell level, that is, the entire string in the cell has the same formatting applied. In these cases, the formatting for the cell is stored in the styles part, and the string for the cell can be stored in the shared strings table.

Some strings in the workbook can have formatting applied at a level that is more granular than the cell level. For instance, specific characters within the string can be bolded, have coloring, italicizing, etc. In these cases, the formatting is stored along with the text in the string table, and is treated as a unique entry in the table.

The following features of the shared strings table are supported by ImageGear:

Feature	Description	Comment
String Item	This element is the representation of an individual string in the shared strings table. If the string is just a simple string with formatting applied at the cell level, then the String Item should contain a single text element used to express the string. If the string has more complex formatting, then the String Item consists of multiple rich text runs.	Phonetic properties of string items are not supported by ImageGear.
Rich Text Run	This element represents a run of rich text.	Fully supported.
Run Font	This element is a string representing the name of the font assigned to display this run.	Fully supported.
Run Properties	This element represents a set of properties to apply to the contents of a rich text run	The following run properties are supported: Bold Font Family (Supported true type fonts only) Italic Font Strike Through Font Size Underline ImageGear does not support the vertical alignment of text, meaning that subscripts and superscripts will appear as normal text.

ImageGear uses Microsoft WPF for rendering fonts. For some particular font families, WPF may fail to load the correct typeface, although the specified font is present on the system - this is a known issue that has not yet been addressed. Due to this, the content displayed by ImageGear (font family/style, text layout, line spacing, etc.) may differ from the content displayed by Microsoft Office.