Android之上下滑动的引导页
前几天无意中看到一篇博文，名字叫Android 仿网易新闻v3.5:上下滑动的引导页，才知道原来应用的新手教学——即初次安装应用的引导程序，还能够上下滑动而不是左右滑动。今天就抽出时间把这个东西学习了一下，本案例是基于JakeWharton编写的类的改写。
（
在github上,有相关的开源项目
https://github.com/JakeWharton/Android-DirectionalViewPager
这个项目实际上是在ViewPager的基础上，做了一个扩展。增加了对上下方向滑动的支持
正如项目的名字。使用该项目，能够灵活的改变viewpager的方向,并且仅用一个简单的属性设置就能够做到,我仅仅对该项目提供的样例做了一些简单的修改，就做到了上下滑动引导页的效果.
）本project的文件夹结构例如以下图所看到的：
private MyPagerAdapter myPagerAdapter;//自己定义PagerAdapter
/**
* 把setAdapter简单封装一下。使得外部调用类仅仅需传递一个List<ImageView>就可以
* @param images 图片集合
*/
public void setImages(List<ImageView> images)
{
myPagerAdapter=new MyPagerAdapter(getContext(), images);
setAdapter(myPagerAdapter);
}
/**
* 自己定义PagerAdapter
* @author Android将军
*
*/
private class MyPagerAdapter extends PagerAdapter{
private Context context;
private List<ImageView> images;
public MyPagerAdapter(Context context,List<ImageView> images)
{
this.context=context;
this.images=images;
}
@Override
public void destroyItem(View container, int position, Object object) {
// TODO Auto-generated method stub
//((ViewPag.er)container).removeView((View)object);
((ViewPager)container).removeView(images.get(position));
}
@Override
public Object instantiateItem(View container, int position) {
// TODO Auto-generated method stub
((ViewPager)container).addView(images.get(position));
return images.get(position);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return images.size();
}
@Override
public boolean isViewFromObject(View arg0, Object arg1) {
// TODO Auto-generated method stub
return arg0 == arg1;
}
@Override
public void restoreState(Parcelable arg0, ClassLoader arg1) {
// TODO Auto-generated method stub
}
@Override
public Parcelable saveState() {
// TODO Auto-generated method stub
return null;
}
@Override
public void startUpdate(View arg0) {
// TODO Auto-generated method stub
}
@Override
public void finishUpdate(View arg0) {
// TODO Auto-generated method stub
}
}在Activity中像例如以下代码那样使用就可以：
package com.gc.testvercialviewpager;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
/**
*
* @author Android将军
*
*/
public class MainActivity extends Activity {
private List<ImageView> images;
private int[] imageUirs=new int[]{R.drawable.one,R.drawable.two,R.drawable.three};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setData();
DirectionalViewPager mDirectionalViewPager=(DirectionalViewPager)findViewById(R.id.myviewpager);
mDirectionalViewPager.setImages(images);
mDirectionalViewPager.setOrientation(DirectionalViewPager.VERTICAL);
}
public void setData()
{
images=new ArrayList<ImageView>();
for(int i=0;i<imageUirs.length;i++)
{
ImageView mImageView=new ImageView(this);
mImageView.setBackgroundResource(imageUirs[i]);
images.add(mImageView);
}
}
}
activity-main的布局文件代码例如以下：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<com.gc.testvercialviewpager.DirectionalViewPager
android:id="@+id/myviewpager"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</RelativeLayout>不知道大家有没有注意VerticalViewPagerCompat这个类，假设是使用这个类的话，该类必须放在android.support.v4.view包里，否则无法编译通过，但是到底为什么是这样才行。我如今也不清楚。希望有知道的能告诉我一下。假设拿来放在项目里，那岂不是还得专门为此文件建立一个包，这样显然不合理。于是乎我就把此文件给删除了，然后把DirectionalViewPager里面与这个类有关的代码都凝视掉。程序依旧能够执行，效果依旧和没有去除该类一样，去除该类之后的project项目结构例如以下图
package com.gc.testvercialviewpager;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.os.Build;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.v4.os.ParcelableCompat;
import android.support.v4.os.ParcelableCompatCreatorCallbacks;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.VelocityTrackerCompat;
//import android.support.v4.view.VerticalViewPagerCompat;
import android.support.v4.view.ViewConfigurationCompat;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.Scroller;
/**
* Layout manager that allows the user to flip horizontally or vertically
* through pages of data. You supply an implementation of a {@link PagerAdapter}
* to generate the pages that the view shows.
*
* <p>
* Note this class is currently under early design and development. The API will
* likely change in later updates of the compatibility library, requiring
* changes to the source code of apps when they are compiled against the newer
* version.
* </p>
*/
public class DirectionalViewPager extends ViewPager {
private static final String TAG = "DirectionalViewPager";
private static final String XML_NS = "http://schemas.android.com/apk/res/android";
private static final boolean DEBUG = false;
private static final boolean USE_CACHE = false;
public static final int HORIZONTAL = 0;
public static final int VERTICAL = 1;
private MyPagerAdapter myPagerAdapter;//自己定义PagerAdapter
static class ItemInfo {
Object object;
int position;
boolean scrolling;
}
private final ArrayList<ItemInfo> mItems = new ArrayList<ItemInfo>();
private PagerAdapter mAdapter;
private int mCurItem; // Index of currently displayed page.
private int mRestoredCurItem = -1;
private Parcelable mRestoredAdapterState = null;
private ClassLoader mRestoredClassLoader = null;
private Scroller mScroller;
//private VerticalViewPagerCompat.DataSetObserver mObserver;
private int mChildWidthMeasureSpec;
private int mChildHeightMeasureSpec;
private boolean mInLayout;
private boolean mScrollingCacheEnabled;
private boolean mPopulatePending;
private boolean mScrolling;
private boolean mIsBeingDragged;
private boolean mIsUnableToDrag;
private int mTouchSlop;
private float mInitialMotion;
/**
* Position of the last motion event.
*/
private float mLastMotionX;
private float mLastMotionY;
private int mOrientation = HORIZONTAL;
/**
* ID of the active pointer. This is used to retain consistency during
* drags/flings if multiple pointers are used.
*/
private int mActivePointerId = INVALID_POINTER;
/**
* Sentinel value for no current active pointer. Used by
* {@link #mActivePointerId}.
*/
private static final int INVALID_POINTER = -1;
/**
* Determines speed during touch scrolling
*/
private VelocityTracker mVelocityTracker;
private int mMinimumVelocity;
private int mMaximumVelocity;
private OnPageChangeListener mOnPageChangeListener;
private int mScrollState = SCROLL_STATE_IDLE;
public DirectionalViewPager(Context context) {
super(context);
initViewPager();
}
public DirectionalViewPager(Context context, AttributeSet attrs) {
super(context, attrs);
initViewPager();
// We default to horizontal, only change if a value is explicitly
// specified
int orientation = attrs.getAttributeIntValue(XML_NS, "orientation", -1);
if (orientation != -1) {
setOrientation(orientation);
}
}
void initViewPager() {
setWillNotDraw(false);
mScroller = new Scroller(getContext());
final ViewConfiguration configuration = ViewConfiguration
.get(getContext());
mTouchSlop = ViewConfigurationCompat
.getScaledPagingTouchSlop(configuration);
mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
}
private void setScrollState(int newState) {
if (mScrollState == newState) {
return;
}
mScrollState = newState;
if (mOnPageChangeListener != null) {
mOnPageChangeListener.onPageScrollStateChanged(newState);
}
}
public void setAdapter(PagerAdapter adapter) {
if (mAdapter != null) {
//VerticalViewPagerCompat.setDataSetObserver(mAdapter, null);
}
mAdapter = adapter;
if (mAdapter != null) {
// if (mObserver == null) {
// mObserver = new DataSetObserver();
// }
// VerticalViewPagerCompat.setDataSetObserver(mAdapter, mObserver);
mPopulatePending = false;
if (mRestoredCurItem >= 0) {
mAdapter.restoreState(mRestoredAdapterState,
mRestoredClassLoader);
setCurrentItemInternal(mRestoredCurItem, false, true);
mRestoredCurItem = -1;
mRestoredAdapterState = null;
mRestoredClassLoader = null;
} else {
populate();
}
}
}
public PagerAdapter getAdapter() {
return mAdapter;
}
public void setCurrentItem(int item) {
mPopulatePending = false;
setCurrentItemInternal(item, true, false);
}
void setCurrentItemInternal(int item, boolean smoothScroll, boolean always) {
if (mAdapter == null || mAdapter.getCount() <= 0) {
setScrollingCacheEnabled(false);
return;
}
if (!always && mCurItem == item && mItems.size() != 0) {
setScrollingCacheEnabled(false);
return;
}
if (item < 0) {
item = 0;
} else if (item >= mAdapter.getCount()) {
item = mAdapter.getCount() - 1;
}
if (item > (mCurItem + 1) || item < (mCurItem - 1)) {
// We are doing a jump by more than one page. To avoid
// glitches, we want to keep all current pages in the view
// until the scroll ends.
for (int i = 0; i < mItems.size(); i++) {
mItems.get(i).scrolling = true;
}
}
final boolean dispatchSelected = mCurItem != item;
mCurItem = item;
populate();
if (smoothScroll) {
if (mOrientation == HORIZONTAL) {
smoothScrollTo(getWidth() * item, 0);
} else {
smoothScrollTo(0, getHeight() * item);
}
if (dispatchSelected && mOnPageChangeListener != null) {
mOnPageChangeListener.onPageSelected(item);
}
} else {
if (dispatchSelected && mOnPageChangeListener != null) {
mOnPageChangeListener.onPageSelected(item);
}
completeScroll();
if (mOrientation == HORIZONTAL) {
scrollTo(getWidth() * item, 0);
} else {
scrollTo(0, getHeight() * item);
}
}
}
public void setOnPageChangeListener(OnPageChangeListener listener) {
mOnPageChangeListener = listener;
}
/**
* Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
*
* @param dx
* the number of pixels to scroll by on the X axis
* @param dy
* the number of pixels to scroll by on the Y axis
*/
void smoothScrollTo(int x, int y) {
if (getChildCount() == 0) {
// Nothing to do.
setScrollingCacheEnabled(false);
return;
}
int sx = getScrollX();
int sy = getScrollY();
int dx = x - sx;
int dy = y - sy;
if (dx == 0 && dy == 0) {
completeScroll();
return;
}
setScrollingCacheEnabled(true);
mScrolling = true;
setScrollState(SCROLL_STATE_SETTLING);
mScroller.startScroll(sx, sy, dx, dy);
invalidate();
}
void addNewItem(int position, int index) {
ItemInfo ii = new ItemInfo();
ii.position = position;
ii.object = mAdapter.instantiateItem(this, position);
if (index < 0) {
mItems.add(ii);
} else {
mItems.add(index, ii);
}
}
void dataSetChanged() {
// This method only gets called if our observer is attached, so mAdapter
// is non-null.
boolean needPopulate = mItems.isEmpty() && mAdapter.getCount() > 0;
int newCurrItem = -1;
for (int i = 0; i < mItems.size(); i++) {
final ItemInfo ii = mItems.get(i);
final int newPos = mAdapter.getItemPosition(ii.object);
if (newPos == PagerAdapter.POSITION_UNCHANGED) {
continue;
}
if (newPos == PagerAdapter.POSITION_NONE) {
mItems.remove(i);
i--;
mAdapter.destroyItem(this, ii.position, ii.object);
needPopulate = true;
if (mCurItem == ii.position) {
// Keep the current item in the valid range
newCurrItem = Math.max(0,
Math.min(mCurItem, mAdapter.getCount() - 1));
}
continue;
}
if (ii.position != newPos) {
if (ii.position == mCurItem) {
// Our current item changed position. Follow it.
newCurrItem = newPos;
}
ii.position = newPos;
needPopulate = true;
}
}
if (newCurrItem >= 0) {
// TODO This currently causes a jump.
setCurrentItemInternal(newCurrItem, false, true);
needPopulate = true;
}
if (needPopulate) {
populate();
requestLayout();
}
}
void populate() {
if (mAdapter == null) {
return;
}
// Bail now if we are waiting to populate. This is to hold off
// on creating views from the time the user releases their finger to
// fling to a new position until we have finished the scroll to
// that position, avoiding glitches from happening at that point.
if (mPopulatePending) {
if (DEBUG)
Log.i(TAG, "populate is pending, skipping for now...");
return;
}
// Also, don't populate until we are attached to a window. This is to
// avoid trying to populate before we have restored our view hierarchy
// state and conflicting with what is restored.
if (getWindowToken() == null) {
return;
}
mAdapter.startUpdate(this);
final int startPos = mCurItem > 0 ? mCurItem - 1 : mCurItem;
final int count = mAdapter.getCount();
final int endPos = mCurItem < (count - 1) ? mCurItem + 1 : count - 1;
if (DEBUG)
Log.v(TAG, "populating: startPos=" + startPos + " endPos=" + endPos);
// Add and remove pages in the existing list.
int lastPos = -1;
for (int i = 0; i < mItems.size(); i++) {
ItemInfo ii = mItems.get(i);
if ((ii.position < startPos || ii.position > endPos)
&& !ii.scrolling) {
if (DEBUG)
Log.i(TAG, "removing: " + ii.position + " @ " + i);
mItems.remove(i);
i--;
mAdapter.destroyItem(this, ii.position, ii.object);
} else if (lastPos < endPos && ii.position > startPos) {
// The next item is outside of our range, but we have a gap
// between it and the last item where we want to have a page
// shown. Fill in the gap.
lastPos++;
if (lastPos < startPos) {
lastPos = startPos;
}
while (lastPos <= endPos && lastPos < ii.position) {
if (DEBUG)
Log.i(TAG, "inserting: " + lastPos + " @ " + i);
addNewItem(lastPos, i);
lastPos++;
i++;
}
}
lastPos = ii.position;
}
// Add any new pages we need at the end.
lastPos = mItems.size() > 0 ? mItems.get(mItems.size() - 1).position
: -1;
if (lastPos < endPos) {
lastPos++;
lastPos = lastPos > startPos ? lastPos : startPos;
while (lastPos <= endPos) {
if (DEBUG)
Log.i(TAG, "appending: " + lastPos);
addNewItem(lastPos, -1);
lastPos++;
}
}
if (DEBUG) {
Log.i(TAG, "Current page list:");
for (int i = 0; i < mItems.size(); i++) {
Log.i(TAG, "#" + i + ": page " + mItems.get(i).position);
}
}
mAdapter.finishUpdate(this);
}
public static class SavedState extends BaseSavedState {
int position;
Parcelable adapterState;
ClassLoader loader;
public SavedState(Parcelable superState) {
super(superState);
}
@Override
public void writeToParcel(Parcel out, int flags) {
super.writeToParcel(out, flags);
out.writeInt(position);
out.writeParcelable(adapterState, flags);
}
@Override
public String toString() {
return "FragmentPager.SavedState{"
+ Integer.toHexString(System.identityHashCode(this))
+ " position=" + position + "}";
}
public static final Parcelable.Creator<SavedState> CREATOR = ParcelableCompat
.newCreator(new ParcelableCompatCreatorCallbacks<SavedState>() {
@Override
public SavedState createFromParcel(Parcel in,
ClassLoader loader) {
return new SavedState(in, loader);
}
@Override
public SavedState[] newArray(int size) {
return new SavedState[size];
}
});
SavedState(Parcel in, ClassLoader loader) {
super(in);
if (loader == null) {
loader = getClass().getClassLoader();
}
position = in.readInt();
adapterState = in.readParcelable(loader);
this.loader = loader;
}
}
@Override
public Parcelable onSaveInstanceState() {
try
{
Parcelable superState = (Parcelable)super.onSaveInstanceState();
System.out.println("GGGGG333");
System.out.println("GGGGG");
SavedState ss = new SavedState(superState);
ss.position = mCurItem;
ss.adapterState = mAdapter.saveState();
return ss;
}catch(Exception e)
{
e.printStackTrace();
return null;
}
}
@Override
public void onRestoreInstanceState(Parcelable state) {
if (!(state instanceof SavedState)) {
super.onRestoreInstanceState(state);
return;
}
SavedState ss = (SavedState) state;
super.onRestoreInstanceState(ss.getSuperState());
if (mAdapter != null) {
mAdapter.restoreState(ss.adapterState, ss.loader);
setCurrentItemInternal(ss.position, false, true);
} else {
mRestoredCurItem = ss.position;
mRestoredAdapterState = ss.adapterState;
mRestoredClassLoader = ss.loader;
}
}
public int getOrientation() {
return mOrientation;
}
public void setOrientation(int orientation) {
switch (orientation) {
case HORIZONTAL:
case VERTICAL:
break;
default:
throw new IllegalArgumentException(
"Only HORIZONTAL and VERTICAL are valid orientations.");
}
if (orientation == mOrientation) {
return;
}
// Complete any scroll we are currently in the middle of
completeScroll();
// Reset values
mInitialMotion = 0;
mLastMotionX = 0;
mLastMotionY = 0;
if (mVelocityTracker != null) {
mVelocityTracker.clear();
}
// Adjust scroll for new orientation
mOrientation = orientation;
if (mOrientation == HORIZONTAL) {
scrollTo(mCurItem * getWidth(), 0);
} else {
scrollTo(0, mCurItem * getHeight());
}
requestLayout();
}
@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
if (mInLayout) {
addViewInLayout(child, index, params);
child.measure(mChildWidthMeasureSpec, mChildHeightMeasureSpec);
} else {
super.addView(child, index, params);
}
if (USE_CACHE) {
if (child.getVisibility() != GONE) {
child.setDrawingCacheEnabled(mScrollingCacheEnabled);
} else {
child.setDrawingCacheEnabled(false);
}
}
}
ItemInfo infoForChild(View child) {
for (int i = 0; i < mItems.size(); i++) {
ItemInfo ii = mItems.get(i);
if (mAdapter.isViewFromObject(child, ii.object)) {
return ii;
}
}
return null;
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
if (mAdapter != null) {
populate();
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// For simple implementation, or internal size is always 0.
// We depend on the container to specify the layout size of
// our view. We can't really know what it is since we will be
// adding and removing different arbitrary views and do not
// want the layout to change as this happens.
setMeasuredDimension(getDefaultSize(0, widthMeasureSpec),
getDefaultSize(0, heightMeasureSpec));
// Children are just made to fill our space.
mChildWidthMeasureSpec = MeasureSpec.makeMeasureSpec(getMeasuredWidth()
- getPaddingLeft() - getPaddingRight(), MeasureSpec.EXACTLY);
mChildHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
MeasureSpec.EXACTLY);
// Make sure we have created all fragments that we need to have shown.
mInLayout = true;
populate();
mInLayout = false;
// Make sure all children have been properly measured.
final int size = getChildCount();
for (int i = 0; i < size; ++i) {
final View child = getChildAt(i);
if (child.getVisibility() != GONE) {
if (DEBUG)
Log.v(TAG, "Measuring #" + i + " " + child + ": "
+ mChildWidthMeasureSpec + " x "
+ mChildHeightMeasureSpec);
child.measure(mChildWidthMeasureSpec, mChildHeightMeasureSpec);
}
}
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
// Make sure scroll position is set correctly.
if (mOrientation == HORIZONTAL) {
int scrollPos = mCurItem * w;
if (scrollPos != getScrollX()) {
completeScroll();
scrollTo(scrollPos, getScrollY());
}
} else {
int scrollPos = mCurItem * h;
if (scrollPos != getScrollY()) {
completeScroll();
scrollTo(getScrollX(), scrollPos);
}
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
mInLayout = true;
populate();
mInLayout = false;
final int count = getChildCount();
final int size = (mOrientation == HORIZONTAL) ? r - l : b - t;
for (int i = 0; i < count; i++) {
View child = getChildAt(i);
ItemInfo ii;
if (child.getVisibility() != GONE
&& (ii = infoForChild(child)) != null) {
int off = size * ii.position;
int childLeft = getPaddingLeft();
int childTop = getPaddingTop();
if (mOrientation == HORIZONTAL) {
childLeft += off;
} else {
childTop += off;
}
if (DEBUG)
Log.v(TAG,
"Positioning #" + i + " " + child + " f="
+ ii.object + ":" + childLeft + ","
+ childTop + " " + child.getMeasuredWidth()
+ "x" + child.getMeasuredHeight());
child.layout(childLeft, childTop,
childLeft + child.getMeasuredWidth(),
childTop + child.getMeasuredHeight());
}
}
}
@Override
public void computeScroll() {
if (DEBUG)
Log.i(TAG, "computeScroll: finished=" + mScroller.isFinished());
if (!mScroller.isFinished()) {
if (mScroller.computeScrollOffset()) {
if (DEBUG)
Log.i(TAG, "computeScroll: still scrolling");
int oldX = getScrollX();
int oldY = getScrollY();
int x = mScroller.getCurrX();
int y = mScroller.getCurrY();
if (oldX != x || oldY != y) {
scrollTo(x, y);
}
if (mOnPageChangeListener != null) {
int size;
int value;
if (mOrientation == HORIZONTAL) {
size = getWidth();
value = x;
} else {
size = getHeight();
value = y;
}
final int position = value / size;
final int offsetPixels = value % size;
final float offset = (float) offsetPixels / size;
mOnPageChangeListener.onPageScrolled(position, offset,
offsetPixels);
}
// Keep on drawing until the animation has finished.
invalidate();
return;
}
}
// Done with scroll, clean up state.
completeScroll();
}
private void completeScroll() {
boolean needPopulate;
if ((needPopulate = mScrolling)) {
// Done with scroll, no longer want to cache view drawing.
setScrollingCacheEnabled(false);
mScroller.abortAnimation();
int oldX = getScrollX();
int oldY = getScrollY();
int x = mScroller.getCurrX();
int y = mScroller.getCurrY();
if (oldX != x || oldY != y) {
scrollTo(x, y);
}
setScrollState(SCROLL_STATE_IDLE);
}
mPopulatePending = false;
mScrolling = false;
for (int i = 0; i < mItems.size(); i++) {
ItemInfo ii = mItems.get(i);
if (ii.scrolling) {
needPopulate = true;
ii.scrolling = false;
}
}
if (needPopulate) {
populate();
}
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
/*
* This method JUST determines whether we want to intercept the motion.
* If we return true, onMotionEvent will be called and we do the actual
* scrolling there.
*/
final int action = ev.getAction() & MotionEventCompat.ACTION_MASK;
// Always take care of the touch gesture being complete.
if (action == MotionEvent.ACTION_CANCEL
|| action == MotionEvent.ACTION_UP) {
// Release the drag.
if (DEBUG)
Log.v(TAG, "Intercept done!");
mIsBeingDragged = false;
mIsUnableToDrag = false;
mActivePointerId = INVALID_POINTER;
return false;
}
// Nothing more to do here if we have decided whether or not we
// are dragging.
if (action != MotionEvent.ACTION_DOWN) {
if (mIsBeingDragged) {
if (DEBUG)
Log.v(TAG, "Intercept returning true!");
return true;
}
if (mIsUnableToDrag) {
if (DEBUG)
Log.v(TAG, "Intercept returning false!");
return false;
}
}
switch (action) {
case MotionEvent.ACTION_MOVE: {
/*
* mIsBeingDragged == false, otherwise the shortcut would have
* caught it. Check whether the user has moved far enough from his
* original down touch.
*/
/*
* Locally do absolute value. mLastMotionY is set to the y value of
* the down event.
*/
final int activePointerId = mActivePointerId;
if (activePointerId == INVALID_POINTER
&& Build.VERSION.SDK_INT > Build.VERSION_CODES.DONUT) {
// If we don't have a valid id, the touch down wasn't on
// content.
break;
}
final int pointerIndex = MotionEventCompat.findPointerIndex(ev,
activePointerId);
final float x = MotionEventCompat.getX(ev, pointerIndex);
final float y = MotionEventCompat.getY(ev, pointerIndex);
final float xDiff = Math.abs(x - mLastMotionX);
final float yDiff = Math.abs(y - mLastMotionY);
float primaryDiff;
float secondaryDiff;
if (mOrientation == HORIZONTAL) {
primaryDiff = xDiff;
secondaryDiff = yDiff;
} else {
primaryDiff = yDiff;
secondaryDiff = xDiff;
}
if (DEBUG)
Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + ","
+ yDiff);
if (primaryDiff > mTouchSlop && primaryDiff > secondaryDiff) {
if (DEBUG)
Log.v(TAG, "Starting drag!");
mIsBeingDragged = true;
setScrollState(SCROLL_STATE_DRAGGING);
if (mOrientation == HORIZONTAL) {
mLastMotionX = x;
} else {
mLastMotionY = y;
}
setScrollingCacheEnabled(true);
} else {
if (secondaryDiff > mTouchSlop) {
// The finger has moved enough in the vertical
// direction to be counted as a drag... abort
// any attempt to drag horizontally, to work correctly
// with children that have scrolling containers.
if (DEBUG)
Log.v(TAG, "Starting unable to drag!");
mIsUnableToDrag = true;
}
}
break;
}
case MotionEvent.ACTION_DOWN: {
/*
* Remember location of down touch. ACTION_DOWN always refers to
* pointer index 0.
*/
if (mOrientation == HORIZONTAL) {
mLastMotionX = mInitialMotion = ev.getX();
mLastMotionY = ev.getY();
} else {
mLastMotionX = ev.getX();
mLastMotionY = mInitialMotion = ev.getY();
}
mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
if (mScrollState == SCROLL_STATE_SETTLING) {
// Let the user 'catch' the pager as it animates.
mIsBeingDragged = true;
mIsUnableToDrag = false;
setScrollState(SCROLL_STATE_DRAGGING);
} else {
completeScroll();
mIsBeingDragged = false;
mIsUnableToDrag = false;
}
if (DEBUG)
Log.v(TAG, "Down at " + mLastMotionX + "," + mLastMotionY
+ " mIsBeingDragged=" + mIsBeingDragged
+ "mIsUnableToDrag=" + mIsUnableToDrag);
break;
}
case MotionEventCompat.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mIsBeingDragged;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {
// Don't handle edge touches immediately -- they may actually belong
// to one of our
// descendants.
return false;
}
if (mAdapter == null || mAdapter.getCount() == 0) {
// Nothing to present or scroll; nothing to touch.
return false;
}
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
final int action = ev.getAction();
switch (action & MotionEventCompat.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
/*
* If being flinged and user touches, stop the fling. isFinished
* will be false if being flinged.
*/
completeScroll();
// Remember where the motion event started
if (mOrientation == HORIZONTAL) {
mLastMotionX = mInitialMotion = ev.getX();
} else {
mLastMotionY = mInitialMotion = ev.getY();
}
mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
break;
}
case MotionEvent.ACTION_MOVE:
if (!mIsBeingDragged) {
final int pointerIndex = MotionEventCompat.findPointerIndex(ev,
mActivePointerId);
final float x = MotionEventCompat.getX(ev, pointerIndex);
final float y = MotionEventCompat.getY(ev, pointerIndex);
final float xDiff = Math.abs(x - mLastMotionX);
final float yDiff = Math.abs(y - mLastMotionY);
float primaryDiff;
float secondaryDiff;
if (mOrientation == HORIZONTAL) {
primaryDiff = xDiff;
secondaryDiff = yDiff;
} else {
primaryDiff = yDiff;
secondaryDiff = xDiff;
}
if (DEBUG)
Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff
+ "," + yDiff);
if (primaryDiff > mTouchSlop && primaryDiff > secondaryDiff) {
if (DEBUG)
Log.v(TAG, "Starting drag!");
mIsBeingDragged = true;
if (mOrientation == HORIZONTAL) {
mLastMotionX = x;
} else {
mLastMotionY = y;
}
setScrollState(SCROLL_STATE_DRAGGING);
setScrollingCacheEnabled(true);
}
}
if (mIsBeingDragged) {
// Scroll to follow the motion event
final int activePointerIndex = MotionEventCompat
.findPointerIndex(ev, mActivePointerId);
final float x = MotionEventCompat.getX(ev, activePointerIndex);
final float y = MotionEventCompat.getY(ev, activePointerIndex);
int size;
float scroll;
if (mOrientation == HORIZONTAL) {
size = getWidth();
scroll = getScrollX() + (mLastMotionX - x);
mLastMotionX = x;
} else {
size = getHeight();
scroll = getScrollY() + (mLastMotionY - y);
mLastMotionY = y;
}
final float lowerBound = Math.max(0, (mCurItem - 1) * size);
final float upperBound = Math.min(mCurItem + 1,
mAdapter.getCount() - 1)
* size;
if (scroll < lowerBound) {
scroll = lowerBound;
} else if (scroll > upperBound) {
scroll = upperBound;
}
if (mOrientation == HORIZONTAL) {
// Don't lose the rounded component
mLastMotionX += scroll - (int) scroll;
scrollTo((int) scroll, getScrollY());
} else {
// Don't lose the rounded component
mLastMotionY += scroll - (int) scroll;
scrollTo(getScrollX(), (int) scroll);
}
if (mOnPageChangeListener != null) {
final int position = (int) scroll / size;
final int positionOffsetPixels = (int) scroll % size;
final float positionOffset = (float) positionOffsetPixels
/ size;
mOnPageChangeListener.onPageScrolled(position,
positionOffset, positionOffsetPixels);
}
}
break;
case MotionEvent.ACTION_UP:
if (mIsBeingDragged) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int initialVelocity;
float lastMotion;
int sizeOverThree;
if (mOrientation == HORIZONTAL) {
initialVelocity = (int) VelocityTrackerCompat.getXVelocity(
velocityTracker, mActivePointerId);
lastMotion = mLastMotionX;
sizeOverThree = getWidth() / 3;
} else {
initialVelocity = (int) VelocityTrackerCompat.getYVelocity(
velocityTracker, mActivePointerId);
lastMotion = mLastMotionY;
sizeOverThree = getHeight() / 3;
}
mPopulatePending = true;
if ((Math.abs(initialVelocity) > mMinimumVelocity)
|| Math.abs(mInitialMotion - lastMotion) >= sizeOverThree) {
if (lastMotion > mInitialMotion) {
setCurrentItemInternal(mCurItem - 1, true, true);
} else {
setCurrentItemInternal(mCurItem + 1, true, true);
}
} else {
setCurrentItemInternal(mCurItem, true, true);
}
mActivePointerId = INVALID_POINTER;
endDrag();
}
break;
case MotionEvent.ACTION_CANCEL:
if (mIsBeingDragged) {
setCurrentItemInternal(mCurItem, true, true);
mActivePointerId = INVALID_POINTER;
endDrag();
}
break;
case MotionEventCompat.ACTION_POINTER_DOWN: {
final int index = MotionEventCompat.getActionIndex(ev);
if (mOrientation == HORIZONTAL) {
mLastMotionX = MotionEventCompat.getX(ev, index);
} else {
mLastMotionY = MotionEventCompat.getY(ev, index);
}
mActivePointerId = MotionEventCompat.getPointerId(ev, index);
break;
}
case MotionEventCompat.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
final int index = MotionEventCompat.findPointerIndex(ev,
mActivePointerId);
if (mOrientation == HORIZONTAL) {
mLastMotionX = MotionEventCompat.getX(ev, index);
} else {
mLastMotionY = MotionEventCompat.getY(ev, index);
}
break;
}
return true;
}
private void onSecondaryPointerUp(MotionEvent ev) {
final int pointerIndex = MotionEventCompat.getActionIndex(ev);
final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ?
1 : 0;
if (mOrientation == HORIZONTAL) {
mLastMotionX = MotionEventCompat.getX(ev, newPointerIndex);
} else {
mLastMotionY = MotionEventCompat.getY(ev, newPointerIndex);
}
mActivePointerId = MotionEventCompat.getPointerId(ev,
newPointerIndex);
if (mVelocityTracker != null) {
mVelocityTracker.clear();
}
}
}
private void endDrag() {
mIsBeingDragged = false;
mIsUnableToDrag = false;
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
private void setScrollingCacheEnabled(boolean enabled) {
if (mScrollingCacheEnabled != enabled) {
mScrollingCacheEnabled = enabled;
if (USE_CACHE) {
final int size = getChildCount();
for (int i = 0; i < size; ++i) {
final View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.setDrawingCacheEnabled(enabled);
}
}
}
}
}
// private class DataSetObserver implements
// VerticalViewPagerCompat.DataSetObserver {
// @Override
// public void onDataSetChanged() {
// dataSetChanged();
// }
// }
/**
* 把setAdapter简单封装一下，使得外部调用类仅仅需传递一个List<ImageView>就可以
* @param images 图片集合
*/
public void setImages(List<ImageView> images)
{
myPagerAdapter=new MyPagerAdapter(getContext(), images);
setAdapter(myPagerAdapter);
}
/**
* 自己定义PagerAdapter
* @author Android将军
*
*/
private class MyPagerAdapter extends PagerAdapter{
private Context context;
private List<ImageView> images;
public MyPagerAdapter(Context context,List<ImageView> images)
{
this.context=context;
this.images=images;
}
@Override
public void destroyItem(View container, int position, Object object) {
// TODO Auto-generated method stub
//((ViewPag.er)container).removeView((View)object);
((ViewPager)container).removeView(images.get(position));
}
@Override
public Object instantiateItem(View container, int position) {
// TODO Auto-generated method stub
((ViewPager)container).addView(images.get(position));
return images.get(position);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return images.size();
}
@Override
public boolean isViewFromObject(View arg0, Object arg1) {
// TODO Auto-generated method stub
return arg0 == arg1;
}
@Override
public void restoreState(Parcelable arg0, ClassLoader arg1) {
// TODO Auto-generated method stub
}
@Override
public Parcelable saveState() {
// TODO Auto-generated method stub
return null;
}
@Override
public void startUpdate(View arg0) {
// TODO Auto-generated method stub
}
@Override
public void finishUpdate(View arg0) {
// TODO Auto-generated method stub
}
}
}
执行效果截图例如以下：
