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Commit 7899891e authored by Prabir Pradhan's avatar Prabir Pradhan
Browse files

ViewGroup: Send events to the child at the event's dispatch location 

A mouse event should always be dispatched to the cursor position,
regardless of the location of the pointers in the MotionEvent.

When there are touchpad gestures like a two finger
swipe or a pinch, we promote compatibility with apps by adding fake
pointers that emulate the same behavior on a touchscreen. For example,
two finger swipes turn into a one finger drag, and two finger pinch
emulates a pinch on the screen using two pointers.

The proper way for views to handle touchpad gestures is to look for the
new motion classifications added for touchpad gestures, and dispatch
events at the cursor position for these gestures. However, our API
is incomplete at the moment, becuase apps cannot query the cursor
position.

We can at least fix this in the UiToolkit by dispatching mouse events to
the cursor location.

Bug: 279444161
Test: manual
Test: atest FrameworksCoreTests:ViewGroupTest
Change-Id: I58a9c06b7651ebe97cd03447b083cc9887f863b1
parent 526d138b

core/java/android/view/MotionEvent.java

+34 −0
Original line number Diff line number Diff line
@@ -4166,6 +4166,40 @@ public final class MotionEvent extends InputEvent implements Parcelable { 
        nativeWriteToParcel(mNativePtr, out);

    }



    /**

     * Get the x coordinate of the location where the pointer should be dispatched.

     *

     * This is required because a mouse event, such as from a touchpad, may contain multiple

     * pointers that should all be dispatched to the cursor position.

     * @hide

     */

    public float getXDispatchLocation(int pointerIndex) {

        if (isFromSource(InputDevice.SOURCE_MOUSE)) {

            final float xCursorPosition = getXCursorPosition();

            if (xCursorPosition != INVALID_CURSOR_POSITION) {

                return xCursorPosition;

            }

        }

        return getX(pointerIndex);

    }



    /**

     * Get the y coordinate of the location where the pointer should be dispatched.

     *

     * This is required because a mouse event, such as from a touchpad, may contain multiple

     * pointers that should all be dispatched to the cursor position.

     * @hide

     */

    public float getYDispatchLocation(int pointerIndex) {

        if (isFromSource(InputDevice.SOURCE_MOUSE)) {

            final float yCursorPosition = getYCursorPosition();

            if (yCursorPosition != INVALID_CURSOR_POSITION) {

                return yCursorPosition;

            }

        }

        return getY(pointerIndex);

    }



    /**

     * Transfer object for pointer coordinates.

     *

core/java/android/view/ViewGroup.java

+17 −19
Original line number Diff line number Diff line
@@ -2040,8 +2040,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 


    @Override

    public PointerIcon onResolvePointerIcon(MotionEvent event, int pointerIndex) {

        final float x = event.getX(pointerIndex);

        final float y = event.getY(pointerIndex);

        final float x = event.getXDispatchLocation(pointerIndex);

        final float y = event.getYDispatchLocation(pointerIndex);

        if (isOnScrollbarThumb(x, y) || isDraggingScrollBar()) {

            return PointerIcon.getSystemIcon(mContext, PointerIcon.TYPE_ARROW);

        }
@@ -2125,8 +2125,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
        HoverTarget firstOldHoverTarget = mFirstHoverTarget;

        mFirstHoverTarget = null;

        if (!interceptHover && action != MotionEvent.ACTION_HOVER_EXIT) {

            final float x = event.getX();

            final float y = event.getY();

            final float x = event.getXDispatchLocation(0);

            final float y = event.getYDispatchLocation(0);

            final int childrenCount = mChildrenCount;

            if (childrenCount != 0) {

                final ArrayList<View> preorderedList = buildOrderedChildList();
@@ -2347,8 +2347,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
                // Check what the child under the pointer says about the tooltip.

                final int childrenCount = mChildrenCount;

                if (childrenCount != 0) {

                    final float x = event.getX();

                    final float y = event.getY();

                    final float x = event.getXDispatchLocation(0);

                    final float y = event.getYDispatchLocation(0);



                    final ArrayList<View> preorderedList = buildOrderedChildList();

                    final boolean customOrder = preorderedList == null
@@ -2443,8 +2443,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
    @Override

    protected boolean pointInHoveredChild(MotionEvent event) {

        if (mFirstHoverTarget != null) {

            return isTransformedTouchPointInView(event.getX(), event.getY(),

                mFirstHoverTarget.child, null);

            return isTransformedTouchPointInView(event.getXDispatchLocation(0),

                    event.getYDispatchLocation(0), mFirstHoverTarget.child, null);

        }

        return false;

    }
@@ -2513,8 +2513,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
    public boolean onInterceptHoverEvent(MotionEvent event) {

        if (event.isFromSource(InputDevice.SOURCE_MOUSE)) {

            final int action = event.getAction();

            final float x = event.getX();

            final float y = event.getY();

            final float x = event.getXDispatchLocation(0);

            final float y = event.getYDispatchLocation(0);

            if ((action == MotionEvent.ACTION_HOVER_MOVE

                    || action == MotionEvent.ACTION_HOVER_ENTER) && isOnScrollbar(x, y)) {

                return true;
@@ -2535,8 +2535,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
        // Send the event to the child under the pointer.

        final int childrenCount = mChildrenCount;

        if (childrenCount != 0) {

            final float x = event.getX();

            final float y = event.getY();

            final float x = event.getXDispatchLocation(0);

            final float y = event.getXDispatchLocation(0);



            final ArrayList<View> preorderedList = buildOrderedChildList();

            final boolean customOrder = preorderedList == null
@@ -2700,10 +2700,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 


                    final int childrenCount = mChildrenCount;

                    if (newTouchTarget == null && childrenCount != 0) {

                        final float x =

                                isMouseEvent ? ev.getXCursorPosition() : ev.getX(actionIndex);

                        final float y =

                                isMouseEvent ? ev.getYCursorPosition() : ev.getY(actionIndex);

                        final float x = ev.getXDispatchLocation(actionIndex);

                        final float y = ev.getYDispatchLocation(actionIndex);

                        // Find a child that can receive the event.

                        // Scan children from front to back.

                        final ArrayList<View> preorderedList = buildTouchDispatchChildList();
@@ -2757,8 +2755,8 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
                                } else {

                                    mLastTouchDownIndex = childIndex;

                                }

                                mLastTouchDownX = ev.getX();

                                mLastTouchDownY = ev.getY();

                                mLastTouchDownX = x;

                                mLastTouchDownY = y;

                                newTouchTarget = addTouchTarget(child, idBitsToAssign);

                                alreadyDispatchedToNewTouchTarget = true;

                                break;
@@ -3287,7 +3285,7 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
        if (ev.isFromSource(InputDevice.SOURCE_MOUSE)

                && ev.getAction() == MotionEvent.ACTION_DOWN

                && ev.isButtonPressed(MotionEvent.BUTTON_PRIMARY)

                && isOnScrollbarThumb(ev.getX(), ev.getY())) {

                && isOnScrollbarThumb(ev.getXDispatchLocation(0), ev.getYDispatchLocation(0))) {

            return true;

        }

        return false;

core/tests/coretests/src/android/view/ViewGroupTest.java

+8 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ import static androidx.test.platform.app.InstrumentationRegistry.getInstrumentat 


import static org.junit.Assert.assertEquals;

import static org.mockito.ArgumentMatchers.any;

import static org.mockito.ArgumentMatchers.anyInt;

import static org.mockito.Mockito.doReturn;

import static org.mockito.Mockito.never;

import static org.mockito.Mockito.spy;
@@ -87,6 +88,9 @@ public class ViewGroupTest { 
        viewGroup.dispatchTouchEvent(event);

        verify(viewB).dispatchTouchEvent(event);



        viewGroup.onResolvePointerIcon(event, 0 /* pointerIndex */);

        verify(viewB).onResolvePointerIcon(event, 0);



        event = MotionEvent.obtain(0 /* downTime */, 0 /* eventTime */,

                MotionEvent.ACTION_POINTER_DOWN | (1 << MotionEvent.ACTION_POINTER_INDEX_SHIFT),

                2 /* pointerCount */, properties, coords, 0 /* metaState */, 0 /* buttonState */,
@@ -95,7 +99,11 @@ public class ViewGroupTest { 
        viewGroup.dispatchTouchEvent(event);

        verify(viewB).dispatchTouchEvent(event);



        viewGroup.onResolvePointerIcon(event, 1 /* pointerIndex */);

        verify(viewB).onResolvePointerIcon(event, 1);



        verify(viewA, never()).dispatchTouchEvent(any());

        verify(viewA, never()).onResolvePointerIcon(any(), anyInt());

    }



    /**