DragLayer.java

/*
 * This is a modified version of a class from the Android Open Source Project. 
 * The original copyright and license information follows.
 * 
 * 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.esfoo.drag;

import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Toast;

/**
 * A ViewGroup that coordinates dragging across its dscendants.
 *
 * <p> This class used DragLayer in the Android Launcher activity as a model.
 * It is a bit different in several respects:
 * (1) It extends MyAbsoluteLayout rather than FrameLayout; (2) it implements DragSource and DropTarget methods
 * that were done in a separate Workspace class in the Launcher.
 */
public class DragLayer extends MyAbsoluteLayout 
    implements DragSource, DropTarget
{
    DragController mDragController;

    /**
     * Used to create a new DragLayer from XML.
     *
     * @param context The application's context.
     * @param attrs The attribtues set containing the Workspace's customization values.
     */
    public DragLayer (Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void setDragController(DragController controller) {
        mDragController = controller;
    }
    
    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        return mDragController.dispatchKeyEvent(event) || super.dispatchKeyEvent(event);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return mDragController.onInterceptTouchEvent(ev);
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        return mDragController.onTouchEvent(ev);
    }

    @Override
    public boolean dispatchUnhandledMove(View focused, int direction) {
        return mDragController.dispatchUnhandledMove(focused, direction);
    }

/**
 */
// DragSource interface methods

/**
 * setDragController
 *
 */

 /* setDragController is already defined. See above. */

/**
 * onDropCompleted
 *
 */

public void onDropCompleted (View target, boolean success)
{
    toast ("DragLayer2.onDropCompleted: " + target.getId () + " Check that the view moved.");
}

/**
 */
// DropTarget interface implementation

/**
 * Handle an object being dropped on the DropTarget.
 * This is the where a dragged view gets repositioned at the end of a drag.
 * 
 * @param source DragSource where the drag started
 * @param x X coordinate of the drop location
 * @param y Y coordinate of the drop location
 * @param xOffset Horizontal offset with the object being dragged where the original
 *          touch happened
 * @param yOffset Vertical offset with the object being dragged where the original
 *          touch happened
 * @param dragView The DragView that's being dragged around on screen.
 * @param dragInfo Data associated with the object being dragged
 * 
 */
public void onDrop(DragSource source, int x, int y, int xOffset, int yOffset,
        DragView dragView, Object dragInfo)
{
    View v = (View) dragInfo;
    toast ("DragLayer2.onDrop accepts view: " + v.getId ()
          + "x, y, xO, yO :" + new Integer (x) + ", " + new Integer (y) + ", "
          + new Integer (xOffset) + ", " + new Integer (yOffset));

    int w = v.getWidth ();
    int h = v.getHeight ();
    int left = x - xOffset;
    int top = y - yOffset;
    DragLayer.LayoutParams lp = new DragLayer.LayoutParams (w, h, left, top);
    this.updateViewLayout(v, lp);
}

public void onDragEnter(DragSource source, int x, int y, int xOffset, int yOffset,
        DragView dragView, Object dragInfo)
{
}

public void onDragOver(DragSource source, int x, int y, int xOffset, int yOffset,
        DragView dragView, Object dragInfo)
{
}

public void onDragExit(DragSource source, int x, int y, int xOffset, int yOffset,
        DragView dragView, Object dragInfo)
{
}

/**
 * Check if a drop action can occur at, or near, the requested location.
 * This may be called repeatedly during a drag, so any calls should return
 * quickly.
 * 
 * @param source DragSource where the drag started
 * @param x X coordinate of the drop location
 * @param y Y coordinate of the drop location
 * @param xOffset Horizontal offset with the object being dragged where the
 *            original touch happened
 * @param yOffset Vertical offset with the object being dragged where the
 *            original touch happened
 * @param dragView The DragView that's being dragged around on screen.
 * @param dragInfo Data associated with the object being dragged
 * @return True if the drop will be accepted, false otherwise.
 */
public boolean acceptDrop(DragSource source, int x, int y, int xOffset, int yOffset,
        DragView dragView, Object dragInfo)
{
    return true;
}

/**
 * Estimate the surface area where this object would land if dropped at the
 * given location.
 * 
 * @param source DragSource where the drag started
 * @param x X coordinate of the drop location
 * @param y Y coordinate of the drop location
 * @param xOffset Horizontal offset with the object being dragged where the
 *            original touch happened
 * @param yOffset Vertical offset with the object being dragged where the
 *            original touch happened
 * @param dragView The DragView that's being dragged around on screen.
 * @param dragInfo Data associated with the object being dragged
 * @param recycle {@link Rect} object to be possibly recycled.
 * @return Estimated area that would be occupied if object was dropped at
 *         the given location. Should return null if no estimate is found,
 *         or if this target doesn't provide estimations.
 */
public Rect estimateDropLocation(DragSource source, int x, int y, int xOffset, int yOffset,
            DragView dragView, Object dragInfo, Rect recycle)
{
    return null;
}

/**
 */
// More methods

/**
 * Show a string on the screen via Toast.
 * 
 * @param msg String
 * @return void
 */

public void toast (String msg)
{
    if (!DragActivity.Debugging) return;
    Toast.makeText (getContext (), msg, Toast.LENGTH_SHORT).show ();
} // end toast


} // end class