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Reland "ChromeOS/Android trackpad gestures" (flutter#34060)
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* Android trackpad gestures

* Try to fix lint problem
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@moffatman
moffatman authored Jun 16, 2022
1 parent 3f0bc07 commit 27006fe
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Showing 2 changed files with 280 additions and 32 deletions.
103 changes: 71 additions & 32 deletions shell/platform/android/io/flutter/embedding/android/AndroidTouchProcessor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,12 @@
import android.view.MotionEvent;
import androidx.annotation.IntDef;
import androidx.annotation.NonNull;
import androidx.annotation.VisibleForTesting;
import io.flutter.embedding.engine.renderer.FlutterRenderer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.HashMap;
import java.util.Map;

/** Sends touch information from Android to Flutter in a format that Flutter understands. */
public class AndroidTouchProcessor {
Expand All @@ -26,7 +29,7 @@ public class AndroidTouchProcessor {
PointerChange.PAN_ZOOM_UPDATE,
PointerChange.PAN_ZOOM_END
})
private @interface PointerChange {
public @interface PointerChange {
int CANCEL = 0;
int ADD = 1;
int REMOVE = 2;
Expand All @@ -48,7 +51,7 @@ public class AndroidTouchProcessor {
PointerDeviceKind.TRACKPAD,
PointerDeviceKind.UNKNOWN
})
private @interface PointerDeviceKind {
public @interface PointerDeviceKind {
int TOUCH = 0;
int MOUSE = 1;
int STYLUS = 2;
Expand All @@ -59,15 +62,15 @@ public class AndroidTouchProcessor {

// Must match the PointerSignalKind enum in pointer.dart.
@IntDef({PointerSignalKind.NONE, PointerSignalKind.SCROLL, PointerSignalKind.UNKNOWN})
private @interface PointerSignalKind {
public @interface PointerSignalKind {
int NONE = 0;
int SCROLL = 1;
int UNKNOWN = 2;
}

// Must match the unpacking code in hooks.dart.
private static final int POINTER_DATA_FIELD_COUNT = 35;
private static final int BYTES_PER_FIELD = 8;
@VisibleForTesting static final int BYTES_PER_FIELD = 8;

// This value must match the value in framework's platform_view.dart.
// This flag indicates whether the original Android pointer events were batched together.
Expand All @@ -76,12 +79,12 @@ public class AndroidTouchProcessor {
@NonNull private final FlutterRenderer renderer;
@NonNull private final MotionEventTracker motionEventTracker;

private static final int _POINTER_BUTTON_PRIMARY = 1;

private static final Matrix IDENTITY_TRANSFORM = new Matrix();

private final boolean trackMotionEvents;

private final Map<Integer, float[]> ongoingPans = new HashMap<>();

/**
* Constructs an {@code AndroidTouchProcessor} that will send touch event data to the Flutter
* execution context represented by the given {@link FlutterRenderer}.
Expand Down Expand Up @@ -220,6 +223,28 @@ private void addPointerForIndex(
}

int pointerKind = getPointerDeviceTypeForToolType(event.getToolType(pointerIndex));
// We use this in lieu of using event.getRawX and event.getRawY as we wish to support
// earlier versions than API level 29.
float viewToScreenCoords[] = {event.getX(pointerIndex), event.getY(pointerIndex)};
transformMatrix.mapPoints(viewToScreenCoords);
long buttons;
if (pointerKind == PointerDeviceKind.MOUSE) {
buttons = event.getButtonState() & 0x1F;
if (buttons == 0
&& event.getSource() == InputDevice.SOURCE_MOUSE
&& pointerChange == PointerChange.DOWN) {
// Some implementations translate trackpad scrolling into a mouse down-move-up event
// sequence with buttons: 0, such as ARC on a Chromebook. See #11420, a legacy
// implementation that uses the same condition but converts differently.
ongoingPans.put(event.getPointerId(pointerIndex), viewToScreenCoords);
}
} else if (pointerKind == PointerDeviceKind.STYLUS) {
buttons = (event.getButtonState() >> 4) & 0xF;
} else {
buttons = 0;
}

boolean isTrackpadPan = ongoingPans.containsKey(event.getPointerId(pointerIndex));

int signalKind =
event.getActionMasked() == MotionEvent.ACTION_SCROLL
Expand All @@ -230,39 +255,31 @@ private void addPointerForIndex(

packet.putLong(motionEventId); // motionEventId
packet.putLong(timeStamp); // time_stamp
packet.putLong(pointerChange); // change
packet.putLong(pointerKind); // kind
if (isTrackpadPan) {
packet.putLong(getPointerChangeForPanZoom(pointerChange)); // change
packet.putLong(PointerDeviceKind.TRACKPAD); // kind
} else {
packet.putLong(pointerChange); // change
packet.putLong(pointerKind); // kind
}
packet.putLong(signalKind); // signal_kind
packet.putLong(event.getPointerId(pointerIndex)); // device
packet.putLong(0); // pointer_identifier, will be generated in pointer_data_packet_converter.cc.

// We use this in lieu of using event.getRawX and event.getRawY as we wish to support
// earlier versions than API level 29.
float viewToScreenCoords[] = {event.getX(pointerIndex), event.getY(pointerIndex)};
transformMatrix.mapPoints(viewToScreenCoords);
packet.putDouble(viewToScreenCoords[0]); // physical_x
packet.putDouble(viewToScreenCoords[1]); // physical_y
if (isTrackpadPan) {
float[] panStart = ongoingPans.get(event.getPointerId(pointerIndex));
packet.putDouble(panStart[0]);
packet.putDouble(panStart[1]);
} else {
packet.putDouble(viewToScreenCoords[0]); // physical_x
packet.putDouble(viewToScreenCoords[1]); // physical_y
}

packet.putDouble(
0.0); // physical_delta_x, will be generated in pointer_data_packet_converter.cc.
packet.putDouble(
0.0); // physical_delta_y, will be generated in pointer_data_packet_converter.cc.

long buttons;
if (pointerKind == PointerDeviceKind.MOUSE) {
buttons = event.getButtonState() & 0x1F;
// TODO(dkwingsmt): Remove this fix after implementing touchpad gestures
// https://github.com/flutter/flutter/issues/23604#issuecomment-524471152
if (buttons == 0
&& event.getSource() == InputDevice.SOURCE_MOUSE
&& (pointerChange == PointerChange.DOWN || pointerChange == PointerChange.MOVE)) {
buttons = _POINTER_BUTTON_PRIMARY;
}
} else if (pointerKind == PointerDeviceKind.STYLUS) {
buttons = (event.getButtonState() >> 4) & 0xF;
} else {
buttons = 0;
}
packet.putLong(buttons); // buttons

packet.putLong(0); // obscured
Expand Down Expand Up @@ -317,12 +334,22 @@ private void addPointerForIndex(
packet.putDouble(0.0); // scroll_delta_x
}

packet.putDouble(0.0); // pan_x
packet.putDouble(0.0); // pan_y
if (isTrackpadPan) {
float[] panStart = ongoingPans.get(event.getPointerId(pointerIndex));
packet.putDouble(viewToScreenCoords[0] - panStart[0]);
packet.putDouble(viewToScreenCoords[1] - panStart[1]);
} else {
packet.putDouble(0.0); // pan_x
packet.putDouble(0.0); // pan_y
}
packet.putDouble(0.0); // pan_delta_x
packet.putDouble(0.0); // pan_delta_y
packet.putDouble(1.0); // scale
packet.putDouble(0.0); // rotation

if (isTrackpadPan && getPointerChangeForPanZoom(pointerChange) == PointerChange.PAN_ZOOM_END) {
ongoingPans.remove(event.getPointerId(pointerIndex));
}
}

@PointerChange
Expand Down Expand Up @@ -354,7 +381,19 @@ private int getPointerChangeForAction(int maskedAction) {
if (maskedAction == MotionEvent.ACTION_SCROLL) {
return PointerChange.HOVER;
}
return -1;
throw new AssertionError("Unexpected masked action");
}

@PointerChange
private int getPointerChangeForPanZoom(int pointerChange) {
if (pointerChange == PointerChange.DOWN) {
return PointerChange.PAN_ZOOM_START;
} else if (pointerChange == PointerChange.MOVE) {
return PointerChange.PAN_ZOOM_UPDATE;
} else if (pointerChange == PointerChange.UP || pointerChange == PointerChange.CANCEL) {
return PointerChange.PAN_ZOOM_END;
}
throw new AssertionError("Unexpected pointer change");
}

@PointerDeviceKind
Expand Down
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