src/com/android/launcher3/dragndrop/DragController.java - LeafOS-Project/android_packages_apps_Launcher3 - Gitiles

 /*
  * Copyright (C) 2008 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.launcher3.dragndrop;

 import static com.android.launcher3.Utilities.ATLEAST_Q;

 import android.content.ComponentName;
 import android.graphics.Point;
 import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
 import android.view.DragEvent;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
 import android.view.View;

 import androidx.annotation.Nullable;

 import com.android.launcher3.DragSource;
 import com.android.launcher3.DropTarget;
 import com.android.launcher3.logging.InstanceId;
 import com.android.launcher3.model.data.ItemInfo;
 import com.android.launcher3.model.data.WorkspaceItemInfo;
 import com.android.launcher3.util.ItemInfoMatcher;
 import com.android.launcher3.util.TouchController;
 import com.android.launcher3.views.ActivityContext;

 import java.util.ArrayList;
 import java.util.Optional;

 /**
  * Class for initiating a drag within a view or across multiple views.
  * @param <T>
  */
 public abstract class DragController<T extends ActivityContext>
         implements DragDriver.EventListener, TouchController {

     /**
      * When a drag is started from a deep press, you need to drag this much farther than normal to
      * end a pre-drag. See {@link DragOptions.PreDragCondition#shouldStartDrag(double)}.
      */
     private static final int DEEP_PRESS_DISTANCE_FACTOR = 3;

     protected final T mActivity;

     // temporaries to avoid gc thrash
     private final Rect mRectTemp = new Rect();
     private final int[] mCoordinatesTemp = new int[2];

     /**
      * Drag driver for the current drag/drop operation, or null if there is no active DND operation.
      * It's null during accessible drag operations.
      */
     protected DragDriver mDragDriver = null;

     /** Options controlling the drag behavior. */
     protected DragOptions mOptions;

     /** Coordinate for motion down event */
     protected final Point mMotionDown = new Point();
     /** Coordinate for last touch event **/
     protected final Point mLastTouch = new Point();

     private final Point mTmpPoint = new Point();

     protected DropTarget.DragObject mDragObject;

     /** Who can receive drop events */
     private final ArrayList<DropTarget> mDropTargets = new ArrayList<>();
     private final ArrayList<DragListener> mListeners = new ArrayList<>();

     protected DropTarget mLastDropTarget;

     private int mLastTouchClassification;
     protected int mDistanceSinceScroll = 0;

     protected boolean mIsInPreDrag;

     /**
      * Interface to receive notifications when a drag starts or stops
      */
     public interface DragListener {
         /**
          * A drag has begun
          *
          * @param dragObject The object being dragged
          * @param options Options used to start the drag
          */
         void onDragStart(DropTarget.DragObject dragObject, DragOptions options);

         /**
          * The drag has ended
          */
         void onDragEnd();
     }

     /**
      * Used to create a new DragLayer from XML.
      */
     public DragController(T activity) {
         mActivity = activity;
     }

     /**
      * Starts a drag.
      *
      * <p>When the drag is started, the UI automatically goes into spring loaded mode. On a
      * successful drop, it is the responsibility of the {@link DropTarget} to exit out of the spring
      * loaded mode. If the drop was cancelled for some reason, the UI will automatically exit out of
      * this mode.
      *
      * @param drawable The drawable to be displayed in the drag view.  It will be re-scaled to the
      *                 enlarged size.
      * @param originalView The source view (ie. icon, widget etc.) that is being dragged and which
      *                     the DragView represents
      * @param dragLayerX The x position in the DragLayer of the left-top of the bitmap.
      * @param dragLayerY The y position in the DragLayer of the left-top of the bitmap.
      * @param source An object representing where the drag originated
      * @param dragInfo The data associated with the object that is being dragged
      * @param dragRegion Coordinates within the bitmap b for the position of item being dragged.
      *                   Makes dragging feel more precise, e.g. you can clip out a transparent
      *                   border
      */
     public DragView startDrag(
             Drawable drawable,
             DraggableView originalView,
             int dragLayerX,
             int dragLayerY,
             DragSource source,
             ItemInfo dragInfo,
             Point dragOffset,
             Rect dragRegion,
             float initialDragViewScale,
             float dragViewScaleOnDrop,
             DragOptions options) {
         return startDrag(drawable, /* view= */ null, originalView, dragLayerX, dragLayerY,
                 source, dragInfo, dragOffset, dragRegion, initialDragViewScale, dragViewScaleOnDrop,
                 options);
     }

     /**
      * Starts a drag.
      *
      * <p>When the drag is started, the UI automatically goes into spring loaded mode. On a
      * successful drop, it is the responsibility of the {@link DropTarget} to exit out of the spring
      * loaded mode. If the drop was cancelled for some reason, the UI will automatically exit out of
      * this mode.
      *
      * @param view The view to be displayed in the drag view.  It will be re-scaled to the
      *             enlarged size.
      * @param originalView The source view (ie. icon, widget etc.) that is being dragged and which
      *                     the DragView represents
      * @param dragLayerX The x position in the DragLayer of the left-top of the bitmap.
      * @param dragLayerY The y position in the DragLayer of the left-top of the bitmap.
      * @param source An object representing where the drag originated
      * @param dragInfo The data associated with the object that is being dragged
      * @param dragRegion Coordinates within the bitmap b for the position of item being dragged.
      *                   Makes dragging feel more precise, e.g. you can clip out a transparent
      *                   border
      */
     public DragView startDrag(
             View view,
             DraggableView originalView,
             int dragLayerX,
             int dragLayerY,
             DragSource source,
             ItemInfo dragInfo,
             Point dragOffset,
             Rect dragRegion,
             float initialDragViewScale,
             float dragViewScaleOnDrop,
             DragOptions options) {
         return startDrag(/* drawable= */ null, view, originalView, dragLayerX, dragLayerY,
                 source, dragInfo, dragOffset, dragRegion, initialDragViewScale, dragViewScaleOnDrop,
                 options);
     }

     protected abstract DragView startDrag(
             @Nullable Drawable drawable,
             @Nullable View view,
             DraggableView originalView,
             int dragLayerX,
             int dragLayerY,
             DragSource source,
             ItemInfo dragInfo,
             Point dragOffset,
             Rect dragRegion,
             float initialDragViewScale,
             float dragViewScaleOnDrop,
             DragOptions options);

     protected void callOnDragStart() {
         if (mOptions.preDragCondition != null) {
             mOptions.preDragCondition.onPreDragEnd(mDragObject, true /* dragStarted*/);
         }
         mIsInPreDrag = false;
         mDragObject.dragView.onDragStart();
         for (DragListener listener : new ArrayList<>(mListeners)) {
             listener.onDragStart(mDragObject, mOptions);
         }
     }

     public Optional<InstanceId> getLogInstanceId() {
         return Optional.ofNullable(mDragObject)
                 .map(dragObject -> dragObject.logInstanceId);
     }

     /**
      * Call this from a drag source view like this:
      *
      * <pre>
      *  @Override
      *  public boolean dispatchKeyEvent(KeyEvent event) {
      *      return mDragController.dispatchKeyEvent(this, event)
      *              || super.dispatchKeyEvent(event);
      * </pre>
      */
     public boolean dispatchKeyEvent(KeyEvent event) {
         return mDragDriver != null;
     }

     public boolean isDragging() {
         return mDragDriver != null || (mOptions != null && mOptions.isAccessibleDrag);
     }

     /**
      * Stop dragging without dropping.
      */
     public void cancelDrag() {
         if (isDragging()) {
             if (mLastDropTarget != null) {
                 mLastDropTarget.onDragExit(mDragObject);
             }
             mDragObject.deferDragViewCleanupPostAnimation = false;
             mDragObject.cancelled = true;
             mDragObject.dragComplete = true;
             if (!mIsInPreDrag) {
                 dispatchDropComplete(null, false);
             }
         }
         endDrag();
     }

     private void dispatchDropComplete(View dropTarget, boolean accepted) {
         if (!accepted) {
             // If it was not accepted, cleanup the state. If it was accepted, it is the
             // responsibility of the drop target to cleanup the state.
             exitDrag();
             mDragObject.deferDragViewCleanupPostAnimation = false;
         }

         mDragObject.dragSource.onDropCompleted(dropTarget, mDragObject, accepted);
     }

     protected abstract void exitDrag();

     public void onAppsRemoved(ItemInfoMatcher matcher) {
         // Cancel the current drag if we are removing an app that we are dragging
         if (mDragObject != null) {
             ItemInfo dragInfo = mDragObject.dragInfo;
             if (dragInfo instanceof WorkspaceItemInfo) {
                 ComponentName cn = dragInfo.getTargetComponent();
                 if (cn != null && matcher.matches(dragInfo, cn)) {
                     cancelDrag();
                 }
             }
         }
     }

     protected void endDrag() {
         if (isDragging()) {
             mDragDriver = null;
             boolean isDeferred = false;
             if (mDragObject.dragView != null) {
                 isDeferred = mDragObject.deferDragViewCleanupPostAnimation;
                 if (!isDeferred) {
                     mDragObject.dragView.remove();
                 } else if (mIsInPreDrag) {
                     animateDragViewToOriginalPosition(null, null, -1);
                 }
                 mDragObject.dragView = null;
             }

             // Only end the drag if we are not deferred
             if (!isDeferred) {
                 callOnDragEnd();
             }
         }
     }

     public void animateDragViewToOriginalPosition(final Runnable onComplete,
             final View originalIcon, int duration) {
         Runnable onCompleteRunnable = new Runnable() {
             @Override
             public void run() {
                 if (originalIcon != null) {
                     originalIcon.setVisibility(View.VISIBLE);
                 }
                 if (onComplete != null) {
                     onComplete.run();
                 }
             }
         };
         mDragObject.dragView.animateTo(mMotionDown.x, mMotionDown.y, onCompleteRunnable, duration);
     }

     private void callOnDragEnd() {
         if (mIsInPreDrag && mOptions.preDragCondition != null) {
             mOptions.preDragCondition.onPreDragEnd(mDragObject, false /* dragStarted*/);
         }
         mIsInPreDrag = false;
         mOptions = null;
         for (DragListener listener : new ArrayList<>(mListeners)) {
             listener.onDragEnd();
         }
     }

     /**
      * This only gets called as a result of drag view cleanup being deferred in endDrag();
      */
     void onDeferredEndDrag(DragView dragView) {
         dragView.remove();

         if (mDragObject.deferDragViewCleanupPostAnimation) {
             // If we skipped calling onDragEnd() before, do it now
             callOnDragEnd();
         }
     }

     /**
      * Clamps the position to the drag layer bounds.
      */
     private Point getClampedDragLayerPos(float x, float y) {
         mActivity.getDragLayer().getLocalVisibleRect(mRectTemp);
         mTmpPoint.x = (int) Math.max(mRectTemp.left, Math.min(x, mRectTemp.right - 1));
         mTmpPoint.y = (int) Math.max(mRectTemp.top, Math.min(y, mRectTemp.bottom - 1));
         return mTmpPoint;
     }

     @Override
     public void onDriverDragMove(float x, float y) {
         Point dragLayerPos = getClampedDragLayerPos(x, y);
         handleMoveEvent(dragLayerPos.x, dragLayerPos.y);
     }

     @Override
     public void onDriverDragExitWindow() {
         if (mLastDropTarget != null) {
             mLastDropTarget.onDragExit(mDragObject);
             mLastDropTarget = null;
         }
     }

     @Override
     public void onDriverDragEnd(float x, float y) {
         if (!endWithFlingAnimation()) {
             drop(findDropTarget((int) x, (int) y, mCoordinatesTemp), null);
         }
         endDrag();
     }

     protected boolean endWithFlingAnimation() {
         return false;
     }

     @Override
     public void onDriverDragCancel() {
         cancelDrag();
     }

     /**
      * Call this from a drag source view.
      */
     @Override
     public boolean onControllerInterceptTouchEvent(MotionEvent ev) {
         if (mOptions != null && mOptions.isAccessibleDrag) {
             return false;
         }

         Point dragLayerPos = getClampedDragLayerPos(ev.getX(), ev.getY());
         mLastTouch.set(dragLayerPos.x,  dragLayerPos.y);
         if (ev.getAction() == MotionEvent.ACTION_DOWN) {
             // Remember location of down touch
             mMotionDown.set(dragLayerPos.x,  dragLayerPos.y);
         }

         if (ATLEAST_Q) {
             mLastTouchClassification = ev.getClassification();
         }
         return mDragDriver != null && mDragDriver.onInterceptTouchEvent(ev);
     }

     /**
      * Call this from a drag source view.
      */
     @Override
     public boolean onControllerTouchEvent(MotionEvent ev) {
         return mDragDriver != null && mDragDriver.onTouchEvent(ev);
     }

     /**
      * Call this from a drag source view.
      */
     public boolean onDragEvent(DragEvent event) {
         return mDragDriver != null && mDragDriver.onDragEvent(event);
     }

     protected void handleMoveEvent(int x, int y) {
         mDragObject.dragView.move(x, y);

         // Drop on someone?
         final int[] coordinates = mCoordinatesTemp;
         DropTarget dropTarget = findDropTarget(x, y, coordinates);
         mDragObject.x = coordinates[0];
         mDragObject.y = coordinates[1];
         checkTouchMove(dropTarget);

         // Check if we are hovering over the scroll areas
         mDistanceSinceScroll += Math.hypot(mLastTouch.x - x, mLastTouch.y - y);
         mLastTouch.set(x, y);

         int distanceDragged = mDistanceSinceScroll;
         if (ATLEAST_Q && mLastTouchClassification == MotionEvent.CLASSIFICATION_DEEP_PRESS) {
             distanceDragged /= DEEP_PRESS_DISTANCE_FACTOR;
         }
         if (mIsInPreDrag && mOptions.preDragCondition != null
                 && mOptions.preDragCondition.shouldStartDrag(distanceDragged)) {
             callOnDragStart();
         }
     }

     public float getDistanceDragged() {
         return mDistanceSinceScroll;
     }

     public void forceTouchMove() {
         int[] placeholderCoordinates = mCoordinatesTemp;
         DropTarget dropTarget = findDropTarget(mLastTouch.x, mLastTouch.y, placeholderCoordinates);
         mDragObject.x = placeholderCoordinates[0];
         mDragObject.y = placeholderCoordinates[1];
         checkTouchMove(dropTarget);
     }

     private void checkTouchMove(DropTarget dropTarget) {
         if (dropTarget != null) {
             if (mLastDropTarget != dropTarget) {
                 if (mLastDropTarget != null) {
                     mLastDropTarget.onDragExit(mDragObject);
                 }
                 dropTarget.onDragEnter(mDragObject);
             }
             dropTarget.onDragOver(mDragObject);
         } else {
             if (mLastDropTarget != null) {
                 mLastDropTarget.onDragExit(mDragObject);
             }
         }
         mLastDropTarget = dropTarget;
     }

     /**
      * As above, since accessible drag and drop won't cause the same sequence of touch events,
      * we manually ensure appropriate drag and drop events get emulated for accessible drag.
      */
     public void completeAccessibleDrag(int[] location) {
         final int[] coordinates = mCoordinatesTemp;

         // We make sure that we prime the target for drop.
         DropTarget dropTarget = findDropTarget(location[0], location[1], coordinates);
         mDragObject.x = coordinates[0];
         mDragObject.y = coordinates[1];
         checkTouchMove(dropTarget);

         dropTarget.prepareAccessibilityDrop();
         // Perform the drop
         drop(dropTarget, null);
         endDrag();
     }

     protected void drop(DropTarget dropTarget, Runnable flingAnimation) {
         final int[] coordinates = mCoordinatesTemp;
         mDragObject.x = coordinates[0];
         mDragObject.y = coordinates[1];

         // Move dragging to the final target.
         if (dropTarget != mLastDropTarget) {
             if (mLastDropTarget != null) {
                 mLastDropTarget.onDragExit(mDragObject);
             }
             mLastDropTarget = dropTarget;
             if (dropTarget != null) {
                 dropTarget.onDragEnter(mDragObject);
             }
         }

         mDragObject.dragComplete = true;
         if (mIsInPreDrag) {
             if (dropTarget != null) {
                 dropTarget.onDragExit(mDragObject);
             }
             return;
         }

         // Drop onto the target.
         boolean accepted = false;
         if (dropTarget != null) {
             dropTarget.onDragExit(mDragObject);
             if (dropTarget.acceptDrop(mDragObject)) {
                 if (flingAnimation != null) {
                     flingAnimation.run();
                 } else {
                     dropTarget.onDrop(mDragObject, mOptions);
                 }
                 accepted = true;
             }
         }
         final View dropTargetAsView = dropTarget instanceof View ? (View) dropTarget : null;
         dispatchDropComplete(dropTargetAsView, accepted);
     }

     private DropTarget findDropTarget(int x, int y, int[] dropCoordinates) {
         mDragObject.x = x;
         mDragObject.y = y;

         final Rect r = mRectTemp;
         final ArrayList<DropTarget> dropTargets = mDropTargets;
         final int count = dropTargets.size();
         for (int i = count - 1; i >= 0; i--) {
             DropTarget target = dropTargets.get(i);
             if (!target.isDropEnabled())
                 continue;

             target.getHitRectRelativeToDragLayer(r);
             if (r.contains(x, y)) {
                 dropCoordinates[0] = x;
                 dropCoordinates[1] = y;
                 mActivity.getDragLayer().mapCoordInSelfToDescendant((View) target, dropCoordinates);
                 return target;
             }
         }
         // Pass all unhandled drag to workspace. Workspace finds the correct
         // cell layout to drop to in the existing drag/drop logic.
         dropCoordinates[0] = x;
         dropCoordinates[1] = y;
         return getDefaultDropTarget(dropCoordinates);
     }

     protected abstract DropTarget getDefaultDropTarget(int[] dropCoordinates);

     /**
      * Sets the drag listener which will be notified when a drag starts or ends.
      */
     public void addDragListener(DragListener l) {
         mListeners.add(l);
     }

     /**
      * Remove a previously installed drag listener.
      */
     public void removeDragListener(DragListener l) {
         mListeners.remove(l);
     }

     /**
      * Add a DropTarget to the list of potential places to receive drop events.
      */
     public void addDropTarget(DropTarget target) {
         mDropTargets.add(target);
     }

     /**
      * Don't send drop events to <em>target</em> any more.
      */
     public void removeDropTarget(DropTarget target) {
         mDropTargets.remove(target);
     }
 }
	/*
	* Copyright (C) 2008 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.launcher3.dragndrop;

	import static com.android.launcher3.Utilities.ATLEAST_Q;

	import android.content.ComponentName;
	import android.graphics.Point;
	import android.graphics.Rect;
	import android.graphics.drawable.Drawable;
	import android.view.DragEvent;
	import android.view.KeyEvent;
	import android.view.MotionEvent;
	import android.view.View;

	import androidx.annotation.Nullable;

	import com.android.launcher3.DragSource;
	import com.android.launcher3.DropTarget;
	import com.android.launcher3.logging.InstanceId;
	import com.android.launcher3.model.data.ItemInfo;
	import com.android.launcher3.model.data.WorkspaceItemInfo;
	import com.android.launcher3.util.ItemInfoMatcher;
	import com.android.launcher3.util.TouchController;
	import com.android.launcher3.views.ActivityContext;

	import java.util.ArrayList;
	import java.util.Optional;

	/**
	* Class for initiating a drag within a view or across multiple views.
	* @param <T>
	*/
	public abstract class DragController<T extends ActivityContext>
	implements DragDriver.EventListener, TouchController {

	/**
	* When a drag is started from a deep press, you need to drag this much farther than normal to
	* end a pre-drag. See {@link DragOptions.PreDragCondition#shouldStartDrag(double)}.
	*/
	private static final int DEEP_PRESS_DISTANCE_FACTOR = 3;

	protected final T mActivity;

	// temporaries to avoid gc thrash
	private final Rect mRectTemp = new Rect();
	private final int[] mCoordinatesTemp = new int[2];

	/**
	* Drag driver for the current drag/drop operation, or null if there is no active DND operation.
	* It's null during accessible drag operations.
	*/
	protected DragDriver mDragDriver = null;

	/** Options controlling the drag behavior. */
	protected DragOptions mOptions;

	/** Coordinate for motion down event */
	protected final Point mMotionDown = new Point();
	/ Coordinate for last touch event /
	protected final Point mLastTouch = new Point();

	private final Point mTmpPoint = new Point();

	protected DropTarget.DragObject mDragObject;

	/** Who can receive drop events */
	private final ArrayList<DropTarget> mDropTargets = new ArrayList<>();
	private final ArrayList<DragListener> mListeners = new ArrayList<>();

	protected DropTarget mLastDropTarget;

	private int mLastTouchClassification;
	protected int mDistanceSinceScroll = 0;

	protected boolean mIsInPreDrag;

	/**
	* Interface to receive notifications when a drag starts or stops
	*/
	public interface DragListener {
	/**
	* A drag has begun
	*
	* @param dragObject The object being dragged
	* @param options Options used to start the drag
	*/
	void onDragStart(DropTarget.DragObject dragObject, DragOptions options);

	/**
	* The drag has ended
	*/
	void onDragEnd();
	}

	/**
	* Used to create a new DragLayer from XML.
	*/
	public DragController(T activity) {
	mActivity = activity;
	}

	/**
	* Starts a drag.
	*
	* <p>When the drag is started, the UI automatically goes into spring loaded mode. On a
	* successful drop, it is the responsibility of the {@link DropTarget} to exit out of the spring
	* loaded mode. If the drop was cancelled for some reason, the UI will automatically exit out of
	* this mode.
	*
	* @param drawable The drawable to be displayed in the drag view. It will be re-scaled to the
	* enlarged size.
	* @param originalView The source view (ie. icon, widget etc.) that is being dragged and which
	* the DragView represents
	* @param dragLayerX The x position in the DragLayer of the left-top of the bitmap.
	* @param dragLayerY The y position in the DragLayer of the left-top of the bitmap.
	* @param source An object representing where the drag originated
	* @param dragInfo The data associated with the object that is being dragged
	* @param dragRegion Coordinates within the bitmap b for the position of item being dragged.
	* Makes dragging feel more precise, e.g. you can clip out a transparent
	* border
	*/
	public DragView startDrag(
	Drawable drawable,
	DraggableView originalView,
	int dragLayerX,
	int dragLayerY,
	DragSource source,
	ItemInfo dragInfo,
	Point dragOffset,
	Rect dragRegion,
	float initialDragViewScale,
	float dragViewScaleOnDrop,
	DragOptions options) {
	return startDrag(drawable, /* view= */ null, originalView, dragLayerX, dragLayerY,
	source, dragInfo, dragOffset, dragRegion, initialDragViewScale, dragViewScaleOnDrop,
	options);
	}

	/**
	* Starts a drag.
	*
	* <p>When the drag is started, the UI automatically goes into spring loaded mode. On a
	* successful drop, it is the responsibility of the {@link DropTarget} to exit out of the spring
	* loaded mode. If the drop was cancelled for some reason, the UI will automatically exit out of
	* this mode.
	*
	* @param view The view to be displayed in the drag view. It will be re-scaled to the
	* enlarged size.
	* @param originalView The source view (ie. icon, widget etc.) that is being dragged and which
	* the DragView represents
	* @param dragLayerX The x position in the DragLayer of the left-top of the bitmap.
	* @param dragLayerY The y position in the DragLayer of the left-top of the bitmap.
	* @param source An object representing where the drag originated
	* @param dragInfo The data associated with the object that is being dragged
	* @param dragRegion Coordinates within the bitmap b for the position of item being dragged.
	* Makes dragging feel more precise, e.g. you can clip out a transparent
	* border
	*/
	public DragView startDrag(
	View view,
	DraggableView originalView,
	int dragLayerX,
	int dragLayerY,
	DragSource source,
	ItemInfo dragInfo,
	Point dragOffset,
	Rect dragRegion,
	float initialDragViewScale,
	float dragViewScaleOnDrop,
	DragOptions options) {
	return startDrag(/* drawable= */ null, view, originalView, dragLayerX, dragLayerY,
	source, dragInfo, dragOffset, dragRegion, initialDragViewScale, dragViewScaleOnDrop,
	options);
	}

	protected abstract DragView startDrag(
	@Nullable Drawable drawable,
	@Nullable View view,
	DraggableView originalView,
	int dragLayerX,
	int dragLayerY,
	DragSource source,
	ItemInfo dragInfo,
	Point dragOffset,
	Rect dragRegion,
	float initialDragViewScale,
	float dragViewScaleOnDrop,
	DragOptions options);

	protected void callOnDragStart() {
	if (mOptions.preDragCondition != null) {
	mOptions.preDragCondition.onPreDragEnd(mDragObject, true /* dragStarted*/);
	}
	mIsInPreDrag = false;
	mDragObject.dragView.onDragStart();
	for (DragListener listener : new ArrayList<>(mListeners)) {
	listener.onDragStart(mDragObject, mOptions);
	}
	}

	public Optional<InstanceId> getLogInstanceId() {
	return Optional.ofNullable(mDragObject)
	.map(dragObject -> dragObject.logInstanceId);
	}

	/**
	* Call this from a drag source view like this:
	*
	* <pre>
	* @Override
	* public boolean dispatchKeyEvent(KeyEvent event) {
	* return mDragController.dispatchKeyEvent(this, event)
	* \|\| super.dispatchKeyEvent(event);
	* </pre>
	*/
	public boolean dispatchKeyEvent(KeyEvent event) {
	return mDragDriver != null;
	}

	public boolean isDragging() {
	return mDragDriver != null \|\| (mOptions != null && mOptions.isAccessibleDrag);
	}

	/**
	* Stop dragging without dropping.
	*/
	public void cancelDrag() {
	if (isDragging()) {
	if (mLastDropTarget != null) {
	mLastDropTarget.onDragExit(mDragObject);
	}
	mDragObject.deferDragViewCleanupPostAnimation = false;
	mDragObject.cancelled = true;
	mDragObject.dragComplete = true;
	if (!mIsInPreDrag) {
	dispatchDropComplete(null, false);
	}
	}
	endDrag();
	}

	private void dispatchDropComplete(View dropTarget, boolean accepted) {
	if (!accepted) {
	// If it was not accepted, cleanup the state. If it was accepted, it is the
	// responsibility of the drop target to cleanup the state.
	exitDrag();
	mDragObject.deferDragViewCleanupPostAnimation = false;
	}

	mDragObject.dragSource.onDropCompleted(dropTarget, mDragObject, accepted);
	}

	protected abstract void exitDrag();

	public void onAppsRemoved(ItemInfoMatcher matcher) {
	// Cancel the current drag if we are removing an app that we are dragging
	if (mDragObject != null) {
	ItemInfo dragInfo = mDragObject.dragInfo;
	if (dragInfo instanceof WorkspaceItemInfo) {
	ComponentName cn = dragInfo.getTargetComponent();
	if (cn != null && matcher.matches(dragInfo, cn)) {
	cancelDrag();
	}
	}
	}
	}

	protected void endDrag() {
	if (isDragging()) {
	mDragDriver = null;
	boolean isDeferred = false;
	if (mDragObject.dragView != null) {
	isDeferred = mDragObject.deferDragViewCleanupPostAnimation;
	if (!isDeferred) {
	mDragObject.dragView.remove();
	} else if (mIsInPreDrag) {
	animateDragViewToOriginalPosition(null, null, -1);
	}
	mDragObject.dragView = null;
	}

	// Only end the drag if we are not deferred
	if (!isDeferred) {
	callOnDragEnd();
	}
	}
	}

	public void animateDragViewToOriginalPosition(final Runnable onComplete,
	final View originalIcon, int duration) {
	Runnable onCompleteRunnable = new Runnable() {
	@Override
	public void run() {
	if (originalIcon != null) {
	originalIcon.setVisibility(View.VISIBLE);
	}
	if (onComplete != null) {
	onComplete.run();
	}
	}
	};
	mDragObject.dragView.animateTo(mMotionDown.x, mMotionDown.y, onCompleteRunnable, duration);
	}

	private void callOnDragEnd() {
	if (mIsInPreDrag && mOptions.preDragCondition != null) {
	mOptions.preDragCondition.onPreDragEnd(mDragObject, false /* dragStarted*/);
	}
	mIsInPreDrag = false;
	mOptions = null;
	for (DragListener listener : new ArrayList<>(mListeners)) {
	listener.onDragEnd();
	}
	}

	/**
	* This only gets called as a result of drag view cleanup being deferred in endDrag();
	*/
	void onDeferredEndDrag(DragView dragView) {
	dragView.remove();

	if (mDragObject.deferDragViewCleanupPostAnimation) {
	// If we skipped calling onDragEnd() before, do it now
	callOnDragEnd();
	}
	}

	/**
	* Clamps the position to the drag layer bounds.
	*/
	private Point getClampedDragLayerPos(float x, float y) {
	mActivity.getDragLayer().getLocalVisibleRect(mRectTemp);
	mTmpPoint.x = (int) Math.max(mRectTemp.left, Math.min(x, mRectTemp.right - 1));
	mTmpPoint.y = (int) Math.max(mRectTemp.top, Math.min(y, mRectTemp.bottom - 1));
	return mTmpPoint;
	}

	@Override
	public void onDriverDragMove(float x, float y) {
	Point dragLayerPos = getClampedDragLayerPos(x, y);
	handleMoveEvent(dragLayerPos.x, dragLayerPos.y);
	}

	@Override
	public void onDriverDragExitWindow() {
	if (mLastDropTarget != null) {
	mLastDropTarget.onDragExit(mDragObject);
	mLastDropTarget = null;
	}
	}

	@Override
	public void onDriverDragEnd(float x, float y) {
	if (!endWithFlingAnimation()) {
	drop(findDropTarget((int) x, (int) y, mCoordinatesTemp), null);
	}
	endDrag();
	}

	protected boolean endWithFlingAnimation() {
	return false;
	}

	@Override
	public void onDriverDragCancel() {
	cancelDrag();
	}

	/**
	* Call this from a drag source view.
	*/
	@Override
	public boolean onControllerInterceptTouchEvent(MotionEvent ev) {
	if (mOptions != null && mOptions.isAccessibleDrag) {
	return false;
	}

	Point dragLayerPos = getClampedDragLayerPos(ev.getX(), ev.getY());
	mLastTouch.set(dragLayerPos.x, dragLayerPos.y);
	if (ev.getAction() == MotionEvent.ACTION_DOWN) {
	// Remember location of down touch
	mMotionDown.set(dragLayerPos.x, dragLayerPos.y);
	}

	if (ATLEAST_Q) {
	mLastTouchClassification = ev.getClassification();
	}
	return mDragDriver != null && mDragDriver.onInterceptTouchEvent(ev);
	}

	/**
	* Call this from a drag source view.
	*/
	@Override
	public boolean onControllerTouchEvent(MotionEvent ev) {
	return mDragDriver != null && mDragDriver.onTouchEvent(ev);
	}

	/**
	* Call this from a drag source view.
	*/
	public boolean onDragEvent(DragEvent event) {
	return mDragDriver != null && mDragDriver.onDragEvent(event);
	}

	protected void handleMoveEvent(int x, int y) {
	mDragObject.dragView.move(x, y);

	// Drop on someone?
	final int[] coordinates = mCoordinatesTemp;
	DropTarget dropTarget = findDropTarget(x, y, coordinates);
	mDragObject.x = coordinates[0];
	mDragObject.y = coordinates[1];
	checkTouchMove(dropTarget);

	// Check if we are hovering over the scroll areas
	mDistanceSinceScroll += Math.hypot(mLastTouch.x - x, mLastTouch.y - y);
	mLastTouch.set(x, y);

	int distanceDragged = mDistanceSinceScroll;
	if (ATLEAST_Q && mLastTouchClassification == MotionEvent.CLASSIFICATION_DEEP_PRESS) {
	distanceDragged /= DEEP_PRESS_DISTANCE_FACTOR;
	}
	if (mIsInPreDrag && mOptions.preDragCondition != null
	&& mOptions.preDragCondition.shouldStartDrag(distanceDragged)) {
	callOnDragStart();
	}
	}

	public float getDistanceDragged() {
	return mDistanceSinceScroll;
	}

	public void forceTouchMove() {
	int[] placeholderCoordinates = mCoordinatesTemp;
	DropTarget dropTarget = findDropTarget(mLastTouch.x, mLastTouch.y, placeholderCoordinates);
	mDragObject.x = placeholderCoordinates[0];
	mDragObject.y = placeholderCoordinates[1];
	checkTouchMove(dropTarget);
	}

	private void checkTouchMove(DropTarget dropTarget) {
	if (dropTarget != null) {
	if (mLastDropTarget != dropTarget) {
	if (mLastDropTarget != null) {
	mLastDropTarget.onDragExit(mDragObject);
	}
	dropTarget.onDragEnter(mDragObject);
	}
	dropTarget.onDragOver(mDragObject);
	} else {
	if (mLastDropTarget != null) {
	mLastDropTarget.onDragExit(mDragObject);
	}
	}
	mLastDropTarget = dropTarget;
	}

	/**
	* As above, since accessible drag and drop won't cause the same sequence of touch events,
	* we manually ensure appropriate drag and drop events get emulated for accessible drag.
	*/
	public void completeAccessibleDrag(int[] location) {
	final int[] coordinates = mCoordinatesTemp;

	// We make sure that we prime the target for drop.
	DropTarget dropTarget = findDropTarget(location[0], location[1], coordinates);
	mDragObject.x = coordinates[0];
	mDragObject.y = coordinates[1];
	checkTouchMove(dropTarget);

	dropTarget.prepareAccessibilityDrop();
	// Perform the drop
	drop(dropTarget, null);
	endDrag();
	}

	protected void drop(DropTarget dropTarget, Runnable flingAnimation) {
	final int[] coordinates = mCoordinatesTemp;
	mDragObject.x = coordinates[0];
	mDragObject.y = coordinates[1];

	// Move dragging to the final target.
	if (dropTarget != mLastDropTarget) {
	if (mLastDropTarget != null) {
	mLastDropTarget.onDragExit(mDragObject);
	}
	mLastDropTarget = dropTarget;
	if (dropTarget != null) {
	dropTarget.onDragEnter(mDragObject);
	}
	}

	mDragObject.dragComplete = true;
	if (mIsInPreDrag) {
	if (dropTarget != null) {
	dropTarget.onDragExit(mDragObject);
	}
	return;
	}

	// Drop onto the target.
	boolean accepted = false;
	if (dropTarget != null) {
	dropTarget.onDragExit(mDragObject);
	if (dropTarget.acceptDrop(mDragObject)) {
	if (flingAnimation != null) {
	flingAnimation.run();
	} else {
	dropTarget.onDrop(mDragObject, mOptions);
	}
	accepted = true;
	}
	}
	final View dropTargetAsView = dropTarget instanceof View ? (View) dropTarget : null;
	dispatchDropComplete(dropTargetAsView, accepted);
	}

	private DropTarget findDropTarget(int x, int y, int[] dropCoordinates) {
	mDragObject.x = x;
	mDragObject.y = y;

	final Rect r = mRectTemp;
	final ArrayList<DropTarget> dropTargets = mDropTargets;
	final int count = dropTargets.size();
	for (int i = count - 1; i >= 0; i--) {
	DropTarget target = dropTargets.get(i);
	if (!target.isDropEnabled())
	continue;

	target.getHitRectRelativeToDragLayer(r);
	if (r.contains(x, y)) {
	dropCoordinates[0] = x;
	dropCoordinates[1] = y;
	mActivity.getDragLayer().mapCoordInSelfToDescendant((View) target, dropCoordinates);
	return target;
	}
	}
	// Pass all unhandled drag to workspace. Workspace finds the correct
	// cell layout to drop to in the existing drag/drop logic.
	dropCoordinates[0] = x;
	dropCoordinates[1] = y;
	return getDefaultDropTarget(dropCoordinates);
	}

	protected abstract DropTarget getDefaultDropTarget(int[] dropCoordinates);

	/**
	* Sets the drag listener which will be notified when a drag starts or ends.
	*/
	public void addDragListener(DragListener l) {
	mListeners.add(l);
	}

	/**
	* Remove a previously installed drag listener.
	*/
	public void removeDragListener(DragListener l) {
	mListeners.remove(l);
	}

	/**
	* Add a DropTarget to the list of potential places to receive drop events.
	*/
	public void addDropTarget(DropTarget target) {
	mDropTargets.add(target);
	}

	/**
	* Don't send drop events to <em>target</em> any more.
	*/
	public void removeDropTarget(DropTarget target) {
	mDropTargets.remove(target);
	}
	}