Class RowLayout

Vertical positions of the body rows: the row heights as prefix sums plus optional extra heights behind single rows (the detail rows of master/detail). DOM-free; the table keeps one instance for its body (RenderScope.getBodyRowTop, RenderScope.getBodyRowIndexAtY).

• Constant row height: positions are computed (i * h), no array.
• Variable row heights: a Float64Array of rowCount + 1 prefix sums, built lazily on the first access after setRows – then getTop is O(1) and findIndexAt O(log n) (before 1.1.97 the table summed the heights of all rows above the viewport in every scroll frame).
• Extras: sorted row indices with their extra heights and the prefix sums of the extras (O(log k) per lookup, k = number of extras). Changing one extra height (setExtraHeight) costs O(k), not O(n).

The slot of a row is the row plus its extra height below it: getTop(i + 1) = getTop(i) + getRowHeight(i) + getExtraHeight(i).

Example

const layout = new RowLayout();
layout.setRows(1000, i => i % 2 ? 30 : 50);       // variable heights
layout.setExtras([12, 40], [180, 240]);            // details behind rows 12 and 40
const top = layout.getTop(41);                     // top of row 41 below both details
const row = layout.findIndexAt(5000);              // the row whose slot contains y = 5000
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Since

1.1.97