commit f75283abf000d956d99336f5762c4ff215ef44fb
author Sam Sebree <sasebree@microsoft.com> Tue May 05 15:56:41 2020
committer Commit Bot <commit-bot@chromium.org> Tue May 05 15:56:41 2020
tree 471fc61ca432b73b21f648ab7b783cee8206ea70
parent 1a5c6f95a9253ed5c1aa6f2897dddc14af757a25

Bugfix: Clicking above number input's increment button displays click
of decrement button

The spinbutton is a single element (derives from HTMLDivElement) that
can be used to spin a value up or down.  Because its implemented as a
single element, but actually behaves like (and is painted as) two
scrollbar buttons stacked on top of each other, it has state
(up_down_state_) in addition to the normal hover and active flags to
determine which half of the spin button the hover and active flags
apply to.

The painting code for spinbutton uses the extra state like so:
if (active) {
  if (up) {
    // paint active state for up
  }
  else {
    // paint active state for down
  }
}

The code shown above isn't a problem so long as all active (or hover)
states are either up or down.  Because of some pixel snapped checks in
the spinbutton code, however, sometimes the up_down_state_ was set to
indeterminate while the spinbutton was still tagged as active or
hovered.  That's an error state.  If the spinbutton is hovered or
active, it should always indicate which side.

To fix the up_down_state_/hover/active misalignment bugs, all the
checks testing for whether the spinbutton contains the mouse events
delivered to it have been removed.  Mousedown/up/move events (excluding
when the mouse is explicitly captured) are only delivered to the
spinbutton element when they are over the spinbutton element - so the
checks in the current code were redundant in addition to being a source
of bugs.

Because the up_down_state_ is only used to influence painting and value
spinning while the spinbutton is in the hover or active states, it
makes the indeterminate value unnecessary - so it was removed as well
which simplifies some of the themeing code.

This fix also increases the touch-ability of the SpinButtonElement as
we can now press the up/down arrow, and drag our choice to the opposite
corresponding arrow, and the number input behaves as you would expect,
incrementing or decrementing as needed.

Bug: 419108
Change-Id: I9d25da6f2e553035076f1a85e786a5bf5be80aad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2163034
Commit-Queue: Sam Sebree <sasebree@microsoft.com>
Reviewed-by: Mason Freed <masonfreed@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#765569}