The order one field leads to the next
Say the order the tab key walks a page's links and fields in: row by row, or column by column.
Summary
On a form filled in on screen, the tab key jumps from field to field — and something has to decide which field is « the next one ». On a form in two columns, going all the way down the left before crossing to the right is one reading; crossing the page row by row is another, and the two give a very different experience of the same sheet.
Technically
Written at the top level of a request, under
"page_tab_orders"
page_tab_orders writes /Tabs on the pages it names, which settles the order reading software walks everything a page carries as annotations: its links, its form fields and the rest. Five orders exist — by row, by column, by the structure tree, and the two the format only added at 2.0, which therefore ask the document to declare that version. A page no entry names leaves the order to the reading software; in a tagged document, a page carrying a link or a field states the structure order of its own accord.
Request schema
-
page_tab_orders— array, optional, empty by default. -
page_tab_orders[].page— integer ≥ 1, required. The page the entry is for. -
page_tab_orders[].order— string, required. Five values:row(across the page, then down it),column(down the page, then across it),structure(the order the structure tree reads the page in),annotations(the order the page lists its annotations in),widgets(the same, the fields first). -
annotationsandwidgetsask the request for"version": "2.0"; short of that the render is refused rather than write an order the declared version could not be read to hold.
An entry says how a page is walked, not that there is one. A page named twice takes the last order given for it.
A whole request that creates a PDF
{
"page_tab_orders": [{ "page": 1, "order": "row" }],
"standard_fonts": [{ "name": "sans", "face": "helvetica" }],
"items": [
{
"type": "text",
"rect": { "llx": 60, "lly": 740, "urx": 535, "ury": 760 },
"content": ["Two links, walked across the page"],
"font": "sans",
"font_size": 12
},
{
"type": "link",
"rect": { "llx": 60, "lly": 700, "urx": 160, "ury": 720 },
"to": { "uri": "https://hqf-pdf.com/" }
},
{
"type": "link",
"rect": { "llx": 200, "lly": 700, "urx": 300, "ury": 720 },
"to": { "uri": "https://hqf-pdf.com/en/" }
}
]
}Finding one's way through it
What a page sets off as reading software comes and goes What the document says it is made of The clickable contents down the side Landing places that have a name Following an article column by column How the document opens and prints
Where to go next
Every JSON key of a request, in one page The other forty-one settings of a request