Description
Place glyph-run tab positions at the next strictly greater explicit stop, then repeat a supplied positive interval after the last stop; no text shaping.
A glyph’s advance moves the next placement origin; its ink box describes visible bounds relative to that origin. Ink can overhang the advance, and an unknown box differs from a known empty box. These tools use caller-supplied glyph IDs and metrics, placing a horizontal run by cumulative advances without shaping text.
Place glyph-run tab positions at the next strictly greater explicit stop, then repeat a supplied positive interval after the last stop; no text shaping.
When to use this tool
Use this tool to place glyph-run tab positions at the next strictly greater explicit stop, then repeat a supplied positive interval after the last stop; no text shaping.
How to use the tool and how it works
- Enter positions, tabStops, interval using the input definitions below.
- Run the operation. Resolve malformed-input errors before interpreting the result.
- Read result.positions. Interpret signs, units, ordering and null values using the rules below.
Require strictly increasing explicit tab stops and a positive repeat interval. For each position choose the first stop strictly greater than it; after the final stop, use origin + (floor((position−origin)/interval)+1)×interval, with origin the final stop or zero.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| positions | Current horizontal positions to advance to tab stops, in common metric units. | Dense list of at most 128 finite numbers, subject to the stated integer/shape rules. |
| tabStops | Strictly increasing explicit stop coordinates; may be empty. | Dense list of at most 128 finite numbers, subject to the stated integer/shape rules. |
| interval | Positive repeat distance after the final explicit stop, or after origin zero if no stops exist. | Finite number satisfying the stated comparisons. |
| Output field | Interpretation |
|---|---|
| result | Object containing the fields below. |
| result.positions | Next tab-stop coordinate for every supplied position. |
{
"input": {
"positions": [
0,
4,
10
],
"tabStops": [
4,
8
],
"interval": 4
},
"output": {
"result": {
"positions": [
4,
8,
12
]
}
}
}Limitations and assumptions
- Positions already on a stop advance to the next one. Tabs are placed geometrically without text measurement or font shaping.
- All advances, box coordinates, shifts and positional tolerances must share caller-defined metric units. Signed advances are accepted. Glyph records contain id, advance, integer cluster 0–8192 and box = null or [minX,minY,maxX,maxY] with ordered bounds.
- Every declared top-level input is required and unknown fields are rejected. Ordinary strings are limited to 8,192 UTF-16 code units and lists to 128 entries, with tighter operation-specific bounds where stated. JSON text has bounded nesting and node counts.
- Numeric outputs must be finite and within the absolute safe-integer magnitude; exact larger integers use decimal text. Source positions are zero-based UTF-16 offsets and span ends are exclusive unless a different convention is explicitly stated.
Alternative or Complementary methods
Obtain metrics and cluster mappings from the intended font/shaping system, then inspect the supplied observations. Use actual rendering when hinting, fallback choice or visible pixel extents matter.
References
Similar or alternative tools
- Glyph Advance Scale Transform
Scale explicit glyph advances and known box coordinates by a nonnegative uniform factor; no hinted rasterization or font metric inference.
- Glyph Box Run Extents
Union explicitly supplied glyph ink boxes placed by accumulated horizontal advances; missing boxes contribute no invented ink, no font shaping.