2011.06.21（3）——— android 1.6 launcher研究之Drag&Drop模型
2011.06.21（3）——— android 1.6 launcher研究之Drag&Drop模型
参考：http://blog.csdn.net/stonecao/archive/2011/06/02/6462357.aspx
http://blog.csdn.net/hmg25/archive/2011/03/02/6217659.aspx
研究了launcher的拖拽模型 里面重要的类 如下：
DragLayer：
public class DragLayer extends FrameLayout implements DragController { }/* * 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.lp.launcher;import android.view.View;/** * Interface for initiating a drag within a view or across multiple views. * */public interface DragController { /** * Interface to receive notifications when a drag starts or stops */ interface DragListener { /** * A drag has begun * * @param v The view that is being dragged * @param source An object representing where the drag originated * @param info The data associated with the object that is being dragged * @param dragAction The drag action: either {@link DragController#DRAG_ACTION_MOVE} * or {@link DragController#DRAG_ACTION_COPY} */ void onDragStart(View v, DragSource source, Object info, int dragAction); /** * The drag has eneded */ void onDragEnd(); } /** * Indicates the drag is a move. */ public static int DRAG_ACTION_MOVE = 0; /** * Indicates the drag is a copy. */ public static int DRAG_ACTION_COPY = 1; /** * Starts a drag * * @param v The view that is being dragged * @param source An object representing where the drag originated * @param info The data associated with the object that is being dragged * @param dragAction The drag action: either {@link #DRAG_ACTION_MOVE} or * {@link #DRAG_ACTION_COPY} */ void startDrag(View v, DragSource source, Object info, int dragAction); /** * Sets the drag listner which will be notified when a drag starts or ends. */ void setDragListener(DragListener l); /** * Remove a previously installed drag listener. */ void removeDragListener(DragListener l);}/* * 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.lp.launcher;import android.view.View;/** * Interface defining an object that can originate a drag. * */public interface DragSource { void setDragger(DragController dragger); void onDropCompleted(View target, boolean success);}/* * 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.lp.launcher;import android.graphics.Rect;/** * Interface defining an object that can receive a drag. * */public interface DropTarget { /** * Handle an object being dropped on the DropTarget * * @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 dragInfo Data associated with the object being dragged * */ void onDrop(DragSource source, int x, int y, int xOffset, int yOffset, Object dragInfo); void onDragEnter(DragSource source, int x, int y, int xOffset, int yOffset, Object dragInfo); void onDragOver(DragSource source, int x, int y, int xOffset, int yOffset, Object dragInfo); void onDragExit(DragSource source, int x, int y, int xOffset, int yOffset, 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 dragInfo Data associated with the object being dragged * @return True if the drop will be accepted, false otherwise. */ boolean acceptDrop(DragSource source, int x, int y, int xOffset, int yOffset, Object dragInfo); /** * 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 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. */ Rect estimateDropLocation(DragSource source, int x, int y, int xOffset, int yOffset, Object dragInfo, Rect recycle);}