自己重写Android下的拥有拖拽功能的Gallery

/* * Copyright (C) 2007 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 seker.mygallery.view; import seker.mygallery.R; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Rect; import android.util.AttributeSet; import android.view.GestureDetector; import android.view.Gravity; import android.view.HapticFeedbackConstants; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.SoundEffectConstants; import android.view.ContextMenu.ContextMenuInfo; import android.view.animation.Transformation; import android.widget.Scroller; /** * A view that shows items in a center-locked, horizontally scrolling list. * <p> * The default values for the Gallery assume you will be using * {@link android.R.styleable#Theme_galleryItemBackground} as the background for * each View given to the Gallery from the Adapter. If you are not doing this, * you may need to adjust some Gallery properties, such as the spacing. * <p> * Views given to the Gallery should use {@link MyGallery.LayoutParams} as their * layout parameters type. * * @attr ref android.R.styleable#Gallery_animationDuration * @attr ref android.R.styleable#Gallery_spacing * @attr ref android.R.styleable#Gallery_gravity */ //@Widget //mItemCount ---->getCount() //mFirstPosition---->getFirstVisiblePosition() public class MyGallery extends MyAbsSpinner implements GestureDetector.OnGestureListener { //dynamic center private int mDynamicCenter = -1; // private boolean isSingleTapUp = false; private static final byte RIGHT_DIRECTION = -1; private static final byte INVALID_DIRECTION = 0; private static final byte LEFT_DIRECTION = 1; private byte m_GestureDirection = INVALID_DIRECTION; /** * Duration in milliseconds from the start of a scroll during which we're * unsure whether the user is scrolling or flinging. */ private static final int SCROLL_TO_FLING_UNCERTAINTY_TIMEOUT = 250; /** * Horizontal spacing between items. */ private int mSpacing = 0; /** * How long the transition animation should run when a child view changes * position, measured in milliseconds. */ private int mAnimationDuration = 400; /** * The alpha of items that are not selected. */ private float mUnselectedAlpha; private int mGravity; /** * Helper for detecting touch gestures. */ private GestureDetector mGestureDetector; /** * The position of the item that received the user's down touch. */ private int mDownTouchPosition; /** * The view of the item that received the user's down touch. */ private View mDownTouchView; /** * Executes the delta scrolls from a fling or scroll movement. */ private FlingRunnable mFlingRunnable = new FlingRunnable(); /** * Sets mSuppressSelectionChanged = false. This is used to set it to false * in the future. It will also trigger a selection changed. */ private Runnable mDisableSuppressSelectionChangedRunnable = new Runnable() { public void run() { mSuppressSelectionChanged = false; selectionChanged(); } }; /** * When fling runnable runs, it resets this to false. Any method along the * path until the end of its run() can set this to true to abort any * remaining fling. For example, if we've reached either the leftmost or * rightmost item, we will set this to true. */ private boolean mShouldStopFling; /** * The currently selected item's child. */ private View mSelectedChild; /** * Whether to continuously callback on the item selected listener during a * fling. */ private boolean mShouldCallbackDuringFling = true; /** * Whether to callback when an item that is not selected is clicked. */ private boolean mShouldCallbackOnUnselectedItemClick = true; /** * If true, do not callback to item selected listener. */ private boolean mSuppressSelectionChanged; /** * If true, we have received the "invoke" (center or enter buttons) key * down. This is checked before we action on the "invoke" key up, and is * subsequently cleared. */ private boolean mReceivedInvokeKeyDown; private AdapterContextMenuInfo mContextMenuInfo; /** * If true, this onScroll is the first for this user's drag (remember, a * drag sends many onScrolls). */ private boolean mIsFirstScroll; public MyGallery(Context context) { this(context, null); } public MyGallery(Context context, AttributeSet attrs) { this(context, attrs, R.attr.galleryStyle); } public MyGallery(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); mGestureDetector = new GestureDetector(context, this); mGestureDetector.setIsLongpressEnabled(true); TypedArray a = context.obtainStyledAttributes( attrs, R.styleable.MyGallery, defStyle, 0); int index = a.getInt(R.styleable.MyGallery_gravity, -1); if (index >= 0) { setGravity(index); } int animationDuration = a.getInt(R.styleable.MyGallery_animationDuration, -1); if (animationDuration > 0) { setAnimationDuration(animationDuration); } int spacing = a.getDimensionPixelOffset(R.styleable.MyGallery_spacing, 0); setSpacing(spacing); float unselectedAlpha = a.getFloat( R.styleable.MyGallery_unselectedAlpha, 0.5f); setUnselectedAlpha(unselectedAlpha); a.recycle(); /* // We draw the selected item last (because otherwise the item to the // right overlaps it) mGroupFlags |= FLAG_USE_CHILD_DRAWING_ORDER; mGroupFlags |= FLAG_SUPPORT_STATIC_TRANSFORMATIONS; //*/ } /** * Whether or not to callback on any {@link #getOnItemSelectedListener()} * while the items are being flinged. If false, only the final selected item * will cause the callback. If true, all items between the first and the * final will cause callbacks. * * @param shouldCallback Whether or not to callback on the listener while * the items are being flinged. */ public void setCallbackDuringFling(boolean shouldCallback) { mShouldCallbackDuringFling = shouldCallback; } /** * Whether or not to callback when an item that is not selected is clicked. * If false, the item will become selected (and re-centered). If true, the * {@link #getOnItemClickListener()} will get the callback. * * @param shouldCallback Whether or not to callback on the listener when a * item that is not selected is clicked. * @hide */ public void setCallbackOnUnselectedItemClick(boolean shouldCallback) {