new(xychart): add PointerEvent handlers to XYChart and *Series

[williaster]

TODO

• add tests in separate PR test(xychart): add PointerEvent tests #952

🚀 Enhancements

This PR

• adds the ability to set PointerEvent handlers on XYChart, or on individual *Series (previously the only mouse events which were handled were to show/hide tooltips)
  • onPointerMove/Out/Up are currently supported
    • hoping this will be compatible with focus/blur (a11y), and brush/zoom/pan in the future
• adds pointerEvents: boolean to all *Series, which enables users to prevent a Series from emitting, or responding to any PointerEvents (including tooltips; see demo below)
• all mousemove/out + touchmove/end references were simplified to pointermove/out
• updates the /xychart example to demonstrate onPointerUp => if you click on the chart, the Annotation will move to the nearest Datum in the nearest Series

Usage examples

// set handler on chart
// invoke for nearest Datum in _nearest_ `Series` to event, or nearest Datum in _all_ `Series`
<XYChart onPointerUp={() => ...} pointerEvents={'all' | 'nearest'}>
  <LineSeries {...} />
  <LineSeries {...} />
</XYChart>

// invoke handler for only a specific `Series`
// `XYChart` will capture and emit events when `captureEvents=true`, else Series DOM elements emit events
// note: Tooltips still work for Series regardless of `PointerEvent` handlers, unless pointerEvents={false}
<XYChart captureEvents={true | false}>
  <LineSeries onPointerMove={() => ...}  {...} />
  <LineSeries {...} />
</XYChart>

Implementation notes

• all events are dispatched through the EventEmitterContext rather than being handled within a given component.
  • In order to scope e.g., BarSeries events to that BarSeries, I added the notion of EventEmitter sources so that a Series can subscribe to only it's own events + events emitted by XYChart
• Series PointerEvent handlers are set on individual bars, glyphs, or paths (rather than a container to capture events on all of them) to prevent one Series blocking events for another series.

Demo of pointerEvents={false} for all Series except SF (therefore tooltip only contains SF, even though mouse is closer to other AreaSeries)

@kristw @hshoff

[williaster]

maybe should be called pointerEventDataKey 🤔

[williaster]

I guess this probably should mirror the implementation and could also support specific dataKey | dataKey[] as well.

EDIT: gonna punt on this until it's a feature request, makes the type-ing more error prone because string | 'all' becomes string.

[williaster]

because we have to always use the same # of hooks, we can't conditionally create this and have to do the check in the handler. we conditionally return the handler below, tho.

[coveralls]

Pull Request Test Coverage Report for Build 393068437

• 117 of 124 (94.35%) changed or added relevant lines in 16 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.007%) to 59.858%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/visx-xychart/src/hooks/usePointerEventEmitters.ts	5	8	62.5%
packages/visx-xychart/src/hooks/usePointerEventHandlers.ts	28	32	87.5%

Totals
Change from base Build 383897138:	-0.007%
Covered Lines:	1677
Relevant Lines:	2621

---

💛 - Coveralls

[williaster]

noting as a TODO that this logic was lost in this refactor

[coveralls]

Pull Request Test Coverage Report for Build 393068437

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 117 of 124 (94.35%) changed or added relevant lines in 16 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.006%) to 59.858%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/visx-xychart/src/hooks/usePointerEventEmitters.ts	5	8	62.5%
packages/visx-xychart/src/hooks/usePointerEventHandlers.ts	28	32	87.5%

Totals
Change from base Build 383897138:	-0.006%
Covered Lines:	1677
Relevant Lines:	2621

---

💛 - Coveralls