Estimate fixed-layout column widths

Per-column width in px, from the header parts and the formatted cell strings, for tables rendered with table-layout: fixed (the blockr table preview and blockr.viz's html tables). Computing widths server-side keeps the layout independent of measuring the DOM - the measure-and-lock approach reads 0 whenever a render lands while a dock panel is hidden or mid-relayout, crushing the columns.

Usage

column_widths_px(
  col_names,
  col_labels = character(length(col_names)),
  col_types = character(length(col_names)),
  formatted = rep(list(character(0)), length(col_names)),
  col_na = lapply(formatted, is.na),
  wrap_names = FALSE
)

Arguments

col_names

Character vector of column header texts (plain text, strip any HTML before calling).

col_labels

Optional secondary header line per column (the preview's ADaM labels); "" for none.

col_types

Optional type-tag line per column ("<dbl>" etc.); "" for none.

formatted

List of character vectors: the display strings of each column's cells (only the rows being rendered).

col_na

List of logical vectors flagging cells rendered as the NA marker instead of their display string.

wrap_names

Measure each header by its longest word rather than its full length. A header is free to wrap (nothing pins it to one line), it simply never has to when the estimate buys it a full line - so a long title sets the column width outright and the table sprawls. Measuring the longest word instead gives the narrowest column that still never breaks a word, and the header wraps into it by itself. FALSE (the default) keeps the historical one-line estimate.

Value

Integer vector of pixel widths, one per column, including the two 16px cell paddings, clamped to [60, 320].

Details

Deliberately px, not font-relative units: ch tracks the width of the digit 0, which in some font stacks runs 40% narrower than average text, so ch-sized columns clip hard exactly where fonts differ. 8px/char at the 14px table font (the constant the header min-width heuristic used for years) over-estimates almost every UI font, so the estimate degrades to slightly roomy columns - or, at worst, mild ellipsis with the title tooltip - never to crushed ones.