Q: How do I set the tab order for fields?
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A: Beginning with PDF 1.5, PDF producers may make the navigation order
explicit with the optional Tabs entry in a page object (see Table 30
in PDF Reference). The following are the possible values for this
entry:
- R (row order): Annotations shall be visited in rows running
horizontally across the page. The direction within a row shall be
determined by the Direction entry in the viewer preferences dictionary
(see 12.2, “Viewer Preferences”). The first annotation that shall be
visited is the first annotation in the topmost row. When the end of a
row is encountered, the first annotation in the next row shall be
visited.
- C (column order): Annotations shall be visited in columns running
vertically up and down the page. Columns shall be ordered by the
Direction entry in the viewer preferences dictionary (see 12.2,
“Viewer Preferences”). The first annotation that shall be visited is
the one at the top of the first column. When the end of a column is
encountered, the first annotation in the next column shall be visited.
- S (structure order): Annotations shall be visited in the order in
which they appear in the structure tree (see 14.7, “Logical
Structure”). The order for annotations that are not included in the
structure tree shall be determined in a manner of the conforming
reader's choosing.
For example to specify 'row' tab order for a given page you can use
the following line:
mypage.GetSDFObj().PutName("Tabs", "R");