A container's draw asked it once per child by searching the list of children
it had added so far, and four other per-child steps searched a list too, so
one draw cost the square of its children: 70% of a 1,600-child redraw was
those searches. A draw takes a DrawId and leaves it on every widget it asks
about; one note per widget is enough because the handle a container holds a
child by cannot be cloned. tests/children_cost.rs is the rig that shows it,
and it is the only one here that varies width: 3.680 ms to 0.811 ms at 1,600
children, and flat per child.
Beside it, the rest of the fourteenth sweep of #19: a mask's rectangle
resolved once per fragment instead of once per instance, which takes the
storage buffers out of the fragment stage and is 8.8x on a screenful of
deeply nested clips; TextBuffer::shape copying its attrs before the check
that would not need them, which allocated once per named-family text per
frame; a should_panic test on a debug assertion that made cargo test
--release fail; Fixed::div, reached only by its own test; Moves::remove
re-uploading an array it cannot have changed; and two comments the branch
itself falsified.
docs/LAYOUT_LOG.md has all eight with their measurements, the five things
looked at and left, and what was verified.
iris-ai
97fca76108