Function updateOffset

packages/table-core/src/features/ColumnSizing.ts:375–416

(
          eventType: 'move' | 'end',
          clientXPos?: number,
        )

        const newColumnSizing: ColumnSizingState = {}

        const updateOffset = (
          eventType: 'move' | 'end',
          clientXPos?: number,
        ) => {
          if (typeof clientXPos !== 'number') {
            return
          }

          table.setColumnSizingInfo((old) => {
            const deltaDirection =
              table.options.columnResizeDirection === 'rtl' ? -1 : 1
            const deltaOffset =
              (clientXPos - (old?.startOffset ?? 0)) * deltaDirection
            const deltaPercentage = Math.max(
              deltaOffset / (old?.startSize ?? 0),
              -0.999999,
            )

            old.columnSizingStart.forEach(([columnId, headerSize]) => {
              newColumnSizing[columnId] =
                Math.round(
                  Math.max(headerSize + headerSize * deltaPercentage, 0) * 100,
                ) / 100
            })

            return {
              ...old,
              deltaOffset,
              deltaPercentage,
            }
          })

          if (
            table.options.columnResizeMode === 'onChange' ||
            eventType === 'end'
          ) {
            table.setColumnSizing((old) => ({
              ...old,
              ...newColumnSizing,
            }))
          }
        }

        const onMove = (clientXPos?: number) => updateOffset('move', clientXPos)