designer/src/com/android/tools/idea/uibuilder/model/NlDropEvent.java

/*
 * Copyright (C) 2015 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.tools.idea.uibuilder.model;

import com.android.annotations.NonNull;

import java.awt.*;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DropTargetDragEvent;
import java.awt.dnd.DropTargetDropEvent;

/**
 * This class encapsulates either a {@see DropTargetDragEvent} or a {@see DropTargetDropEvent}
 * such that we can access either instance in code common for the 2 cases.
 * <p/>
 * Also ensure that accept is called before data is retrieved from a source that has text flavor but no designer flavor.
 */
public class NlDropEvent {
  private final DropTargetDragEvent myDragEvent;
  private final DropTargetDropEvent myDropEvent;
  private boolean myStatusSpecified;

  public NlDropEvent(@NonNull DropTargetDragEvent dragEvent) {
    myDragEvent = dragEvent;
    myDropEvent = null;
  }

  public NlDropEvent(@NonNull DropTargetDropEvent dropEvent) {
    myDragEvent = null;
    myDropEvent = dropEvent;
  }

  @NonNull
  public Point getLocation() {
    if (myDragEvent != null) {
      return myDragEvent.getLocation();
    }
    else {
      return myDropEvent.getLocation();
    }
  }

  public boolean isDataFlavorSupported(@NonNull DataFlavor flavor) {
    if (myDragEvent != null) {
      return myDragEvent.isDataFlavorSupported(flavor);
    }
    else {
      return myDropEvent.isDataFlavorSupported(flavor);
    }
  }

  public int getDropAction() {
    if (myDragEvent != null) {
      return myDragEvent.getDropAction();
    }
    else {
      return myDropEvent.getDropAction();
    }
  }

  @NonNull
  public Transferable getTransferable() {
    if (!myStatusSpecified &&
        !isDataFlavorSupported(ItemTransferable.DESIGNER_FLAVOR) &&
        isDataFlavorSupported(DataFlavor.stringFlavor)) {
      accept(DnDConstants.ACTION_COPY);
    }
    if (myDragEvent != null) {
      return myDragEvent.getTransferable();
    }
    else {
      return myDropEvent.getTransferable();
    }
  }

  public void accept(int dropAction) {
    if (!myStatusSpecified) {
      if (myDragEvent != null) {
        myDragEvent.acceptDrag(dropAction);
      }
      else {
        myDropEvent.acceptDrop(dropAction);
      }
      myStatusSpecified = true;
    }
  }

  public void reject() {
    if (!myStatusSpecified) {
      if (myDragEvent != null) {
        myDragEvent.rejectDrag();
      }
      else {
        myDropEvent.rejectDrop();
      }
      myStatusSpecified = true;
    }
  }

  public void complete() {
    if (myDropEvent != null) {
      myDropEvent.dropComplete(true);
    }
  }
}