expand method
Expand the given packet of pointer data into a sequence of framework pointer events.
The devicePixelRatio argument (usually given the value from
dart:ui.Window.devicePixelRatio) is used to convert the incoming data
from physical coordinates to logical pixels. See the discussion at
PointerEvent for more details on the PointerEvent coordinate space.
Implementation
static Iterable<PointerEvent> expand(Iterable<ui.PointerData> data, double devicePixelRatio) sync* {
for (ui.PointerData datum in data) {
final Offset position = Offset(datum.physicalX, datum.physicalY) / devicePixelRatio;
final double radiusMinor = _toLogicalPixels(datum.radiusMinor, devicePixelRatio);
final double radiusMajor = _toLogicalPixels(datum.radiusMajor, devicePixelRatio);
final double radiusMin = _toLogicalPixels(datum.radiusMin, devicePixelRatio);
final double radiusMax = _toLogicalPixels(datum.radiusMax, devicePixelRatio);
final Duration timeStamp = datum.timeStamp;
final PointerDeviceKind kind = datum.kind;
assert(datum.change != null);
switch (datum.change) {
case ui.PointerChange.add:
assert(!_pointers.containsKey(datum.device));
final _PointerState state = _ensureStateForPointer(datum, position);
assert(state.lastPosition == position);
yield PointerAddedEvent(
timeStamp: timeStamp,
kind: kind,
device: datum.device,
position: position,
obscured: datum.obscured,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distance: datum.distance,
distanceMax: datum.distanceMax,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt
);
break;
case ui.PointerChange.hover:
final bool alreadyAdded = _pointers.containsKey(datum.device);
final _PointerState state = _ensureStateForPointer(datum, position);
assert(!state.down);
if (!alreadyAdded) {
assert(state.lastPosition == position);
yield PointerAddedEvent(
timeStamp: timeStamp,
kind: kind,
device: datum.device,
position: position,
obscured: datum.obscured,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distance: datum.distance,
distanceMax: datum.distanceMax,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt
);
}
final Offset offset = position - state.lastPosition;
state.lastPosition = position;
yield PointerHoverEvent(
timeStamp: timeStamp,
kind: kind,
device: datum.device,
position: position,
delta: offset,
buttons: datum.buttons,
obscured: datum.obscured,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distance: datum.distance,
distanceMax: datum.distanceMax,
size: datum.size,
radiusMajor: radiusMajor,
radiusMinor: radiusMinor,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt
);
state.lastPosition = position;
break;
case ui.PointerChange.down:
final bool alreadyAdded = _pointers.containsKey(datum.device);
final _PointerState state = _ensureStateForPointer(datum, position);
assert(!state.down);
if (!alreadyAdded) {
assert(state.lastPosition == position);
yield PointerAddedEvent(
timeStamp: timeStamp,
kind: kind,
device: datum.device,
position: position,
obscured: datum.obscured,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distance: datum.distance,
distanceMax: datum.distanceMax,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt
);
}
if (state.lastPosition != position) {
// Not all sources of pointer packets respect the invariant that
// they hover the pointer to the down location before sending the
// down event. We restore the invariant here for our clients.
final Offset offset = position - state.lastPosition;
state.lastPosition = position;
yield PointerHoverEvent(
timeStamp: timeStamp,
kind: kind,
device: datum.device,
position: position,
delta: offset,
buttons: datum.buttons,
obscured: datum.obscured,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distance: datum.distance,
distanceMax: datum.distanceMax,
size: datum.size,
radiusMajor: radiusMajor,
radiusMinor: radiusMinor,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt,
synthesized: true,
);
state.lastPosition = position;
}
state.startNewPointer();
state.setDown();
yield PointerDownEvent(
timeStamp: timeStamp,
pointer: state.pointer,
kind: kind,
device: datum.device,
position: position,
buttons: datum.buttons,
obscured: datum.obscured,
pressure: datum.pressure,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distanceMax: datum.distanceMax,
size: datum.size,
radiusMajor: radiusMajor,
radiusMinor: radiusMinor,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt
);
break;
case ui.PointerChange.move:
// If the service starts supporting hover pointers, then it must also
// start sending us ADDED and REMOVED data points.
// See also: https://github.com/flutter/flutter/issues/720
assert(_pointers.containsKey(datum.device));
final _PointerState state = _pointers[datum.device];
assert(state.down);
final Offset offset = position - state.lastPosition;
state.lastPosition = position;
yield PointerMoveEvent(
timeStamp: timeStamp,
pointer: state.pointer,
kind: kind,
device: datum.device,
position: position,
delta: offset,
buttons: datum.buttons,
obscured: datum.obscured,
pressure: datum.pressure,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distanceMax: datum.distanceMax,
size: datum.size,
radiusMajor: radiusMajor,
radiusMinor: radiusMinor,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt,
platformData: datum.platformData,
);
break;
case ui.PointerChange.up:
case ui.PointerChange.cancel:
assert(_pointers.containsKey(datum.device));
final _PointerState state = _pointers[datum.device];
assert(state.down);
if (position != state.lastPosition) {
// Not all sources of pointer packets respect the invariant that
// they move the pointer to the up location before sending the up
// event. For example, in the iOS simulator, of you drag outside the
// window, you'll get a stream of pointers that violates that
// invariant. We restore the invariant here for our clients.
final Offset offset = position - state.lastPosition;
state.lastPosition = position;
yield PointerMoveEvent(
timeStamp: timeStamp,
pointer: state.pointer,
kind: kind,
device: datum.device,
position: position,
delta: offset,
buttons: datum.buttons,
obscured: datum.obscured,
pressure: datum.pressure,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distanceMax: datum.distanceMax,
size: datum.size,
radiusMajor: radiusMajor,
radiusMinor: radiusMinor,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt,
synthesized: true,
);
state.lastPosition = position;
}
assert(position == state.lastPosition);
state.setUp();
if (datum.change == ui.PointerChange.up) {
yield PointerUpEvent(
timeStamp: timeStamp,
pointer: state.pointer,
kind: kind,
device: datum.device,
position: position,
buttons: datum.buttons,
obscured: datum.obscured,
pressure: datum.pressure,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distance: datum.distance,
distanceMax: datum.distanceMax,
size: datum.size,
radiusMajor: radiusMajor,
radiusMinor: radiusMinor,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt
);
} else {
yield PointerCancelEvent(
timeStamp: timeStamp,
pointer: state.pointer,
kind: kind,
device: datum.device,
position: position,
buttons: datum.buttons,
obscured: datum.obscured,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distance: datum.distance,
distanceMax: datum.distanceMax,
size: datum.size,
radiusMajor: radiusMajor,
radiusMinor: radiusMinor,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt
);
}
break;
case ui.PointerChange.remove:
assert(_pointers.containsKey(datum.device));
final _PointerState state = _pointers[datum.device];
if (state.down) {
yield PointerCancelEvent(
timeStamp: timeStamp,
pointer: state.pointer,
kind: kind,
device: datum.device,
position: position,
buttons: datum.buttons,
obscured: datum.obscured,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distance: datum.distance,
distanceMax: datum.distanceMax,
size: datum.size,
radiusMajor: radiusMajor,
radiusMinor: radiusMinor,
radiusMin: radiusMin,
radiusMax: radiusMax,
orientation: datum.orientation,
tilt: datum.tilt
);
}
_pointers.remove(datum.device);
yield PointerRemovedEvent(
timeStamp: timeStamp,
kind: kind,
device: datum.device,
obscured: datum.obscured,
pressureMin: datum.pressureMin,
pressureMax: datum.pressureMax,
distanceMax: datum.distanceMax,
radiusMin: radiusMin,
radiusMax: radiusMax
);
break;
}
}
}