timedDragFrom method
Attempts a series of PointerEvents to simulate a drag operation in the
duration
time.
This is the timed version of dragFrom. This may or may not result in a
flingFrom or ballistic animation, depending on the speed from
offset/duration
.
The move events are sent at a given frequency
in Hz (or events per
second). It defaults to 60Hz.
The movement is linear in time.
See also LiveTestWidgetsFlutterBindingFramePolicy.benchmarkLive for more accurate time control.
Implementation
Future<void> timedDragFrom(
Offset startLocation,
Offset offset,
Duration duration, {
int? pointer,
int buttons = kPrimaryButton,
double frequency = 60.0,
}) {
assert(frequency > 0);
final int intervals = duration.inMicroseconds * frequency ~/ 1E6;
assert(intervals > 1);
pointer ??= _getNextPointer();
final List<Duration> timeStamps = <Duration>[
for (int t = 0; t <= intervals; t += 1)
duration * t ~/ intervals,
];
final List<Offset> offsets = <Offset>[
startLocation,
for (int t = 0; t <= intervals; t += 1)
startLocation + offset * (t / intervals),
];
final List<PointerEventRecord> records = <PointerEventRecord>[
PointerEventRecord(Duration.zero, <PointerEvent>[
PointerAddedEvent(
position: startLocation,
),
PointerDownEvent(
position: startLocation,
pointer: pointer,
buttons: buttons,
),
]),
...<PointerEventRecord>[
for (int t = 0; t <= intervals; t += 1)
PointerEventRecord(timeStamps[t], <PointerEvent>[
PointerMoveEvent(
timeStamp: timeStamps[t],
position: offsets[t+1],
delta: offsets[t+1] - offsets[t],
pointer: pointer,
buttons: buttons,
),
]),
],
PointerEventRecord(duration, <PointerEvent>[
PointerUpEvent(
timeStamp: duration,
position: offsets.last,
pointer: pointer,
// The PointerData received from the engine with
// change = PointerChange.up, which translates to PointerUpEvent,
// doesn't provide the button field.
// buttons: buttons,
),
]),
];
return TestAsyncUtils.guard<void>(() async {
await handlePointerEventRecord(records);
});
}