Android中实现水平滑动（横向滑动）ListView示例

/**
* 横向的ListView
*
* * @author scd
*
*/
public class HorizontalListView extends AdapterView<ListAdapter> {
 
public boolean mAlwaysOverrideTouch = true;
protected ListAdapter mAdapter;
private int mLeftViewIndex = -1;
private int mRightViewIndex = 0;
protected int mCurrentX;
protected int mNextX;
private int mMaxX = Integer.MAX_VALUE;
private int mDisplayOffset = 0;
protected Scroller mScroller;
private GestureDetector mGesture;
private Queue<View> mRemovedViewQueue = new LinkedList<View>();
private OnItemSelectedListener mOnItemSelected;
private OnItemClickListener mOnItemClicked;
private OnItemLongClickListener mOnItemLongClicked;
private boolean mDataChanged = false;
 
public HorizontalListView(Context context, AttributeSet attrs) {
super(context, attrs);
initView();
}
 
private synchronized void initView() {
mLeftViewIndex = -1;
mRightViewIndex = 0;
mDisplayOffset = 0;
mCurrentX = 0;
mNextX = 0;
mMaxX = Integer.MAX_VALUE;
mScroller = new Scroller(getContext());
mGesture = new GestureDetector(getContext(), mOnGesture);
}
 
@Override
public void setOnItemSelectedListener(
AdapterView.OnItemSelectedListener listener) {
mOnItemSelected = listener;
}
 
@Override
public void setOnItemClickListener(AdapterView.OnItemClickListener listener) {
mOnItemClicked = listener;
}
 
@Override
public void setOnItemLongClickListener(
AdapterView.OnItemLongClickListener listener) {
mOnItemLongClicked = listener;
}
 
private DataSetObserver mDataObserver = new DataSetObserver() {
 
@Override
public void onChanged() {
synchronized (HorizontalListView.this) {
mDataChanged = true;
}
invalidate();
requestLayout();
}
 
@Override
public void onInvalidated() {
reset();
invalidate();
requestLayout();
}
 
};
 
@Override
public ListAdapter getAdapter() {
return mAdapter;
}
 
@Override
public View getSelectedView() {
// TODO: implement
return null;
}
 
@Override
public void setAdapter(ListAdapter adapter) {
if (mAdapter != null) {
mAdapter.unregisterDataSetObserver(mDataObserver);
}
mAdapter = adapter;
mAdapter.registerDataSetObserver(mDataObserver);
reset();
}
 
private synchronized void reset() {
initView();
removeAllViewsInLayout();
requestLayout();
}
 
@Override
public void setSelection(int position) {
// TODO: implement
}
 
private void addAndMeasureChild(final View child, int viewPos) {
LayoutParams params = child.getLayoutParams();
if (params == null) {
params = new LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.FILL_PARENT);
}
 
addViewInLayout(child, viewPos, params, true);
child.measure(
MeasureSpec.makeMeasureSpec(getWidth(), MeasureSpec.AT_MOST),
MeasureSpec.makeMeasureSpec(getHeight(), MeasureSpec.AT_MOST));
}
 
@Override
protected synchronized void onLayout(boolean changed, int left, int top,
int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
 
if (mAdapter == null) {
return;
}
 
if (mDataChanged) {
int oldCurrentX = mCurrentX;
initView();
removeAllViewsInLayout();
mNextX = oldCurrentX;
mDataChanged = false;
}
 
if (mScroller.computeScrollOffset()) {
int scrollx = mScroller.getCurrX();
mNextX = scrollx;
}
 
if (mNextX <= 0) {
mNextX = 0;
mScroller.forceFinished(true);
}
if (mNextX >= mMaxX) {
mNextX = mMaxX;
mScroller.forceFinished(true);
}
 
int dx = mCurrentX - mNextX;
 
removeNonVisibleItems(dx);
fillList(dx);
positionItems(dx);
 
mCurrentX = mNextX;
 
if (!mScroller.isFinished()) {
post(new Runnable() {
@Override
public void run() {
requestLayout();
}
});
 
}
}
 
private void fillList(final int dx) {
int edge = 0;
View child = getChildAt(getChildCount() - 1);
if (child != null) {
edge = child.getRight();
}
fillListRight(edge, dx);
 
edge = 0;
child = getChildAt(0);
if (child != null) {
edge = child.getLeft();
}
fillListLeft(edge, dx);
 
}
 
private void fillListRight(int rightEdge, final int dx) {
while (rightEdge + dx < getWidth()
&& mRightViewIndex < mAdapter.getCount()) {
 
View child = mAdapter.getView(mRightViewIndex,
mRemovedViewQueue.poll(), this);
addAndMeasureChild(child, -1);
rightEdge += child.getMeasuredWidth();
 
if (mRightViewIndex == mAdapter.getCount() - 1) {
mMaxX = mCurrentX + rightEdge - getWidth();
}
 
if (mMaxX < 0) {
mMaxX = 0;
}
mRightViewIndex++;
}
 
}
 
private void fillListLeft(int leftEdge, final int dx) {
while (leftEdge + dx > 0 && mLeftViewIndex >= 0) {
View child = mAdapter.getView(mLeftViewIndex,
mRemovedViewQueue.poll(), this);
addAndMeasureChild(child, 0);
leftEdge -= child.getMeasuredWidth();
mLeftViewIndex--;
mDisplayOffset -= child.getMeasuredWidth();
}
}
 
private void removeNonVisibleItems(final int dx) {
View child = getChildAt(0);
while (child != null && child.getRight() + dx <= 0) {
mDisplayOffset += child.getMeasuredWidth();
mRemovedViewQueue.offer(child);
removeViewInLayout(child);
mLeftViewIndex++;
child = getChildAt(0);
 
}
 
child = getChildAt(getChildCount() - 1);
while (child != null && child.getLeft() + dx >= getWidth()) {
mRemovedViewQueue.offer(child);
removeViewInLayout(child);
mRightViewIndex--;
child = getChildAt(getChildCount() - 1);
}
}
 
private void positionItems(final int dx) {
if (getChildCount() > 0) {
mDisplayOffset += dx;
int left = mDisplayOffset;
for (int i = 0; i < getChildCount(); i++) {
View child = getChildAt(i);
int childWidth = child.getMeasuredWidth();
child.layout(left, 0, left + childWidth,
child.getMeasuredHeight());
left += childWidth + child.getPaddingRight();
}
}
}
 
public synchronized void scrollTo(int x) {
mScroller.startScroll(mNextX, 0, x - mNextX, 0);
requestLayout();
}
 
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
boolean handled = super.dispatchTouchEvent(ev);
handled |= mGesture.onTouchEvent(ev);
return handled;
}
 
protected boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
synchronized (HorizontalListView.this) {
mScroller.fling(mNextX, 0, (int) -velocityX, 0, 0, mMaxX, 0, 0);
}
requestLayout();
 
return true;
}
 
protected boolean onDown(MotionEvent e) {
mScroller.forceFinished(true);
return true;
}
 
private OnGestureListener mOnGesture = new GestureDetector.SimpleOnGestureListener() {
 
@Override
public boolean onDown(MotionEvent e) {
return HorizontalListView.this.onDown(e);
}
 
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
return HorizontalListView.this
.onFling(e1, e2, velocityX, velocityY);
}
 
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
 
synchronized (HorizontalListView.this) {
mNextX += (int) distanceX;
}
requestLayout();
 
return true;
}
 
@Override
public boolean onSingleTapConfirmed(MotionEvent e) {
for (int i = 0; i < getChildCount(); i++) {
View child = getChildAt(i);
if (isEventWithinView(e, child)) {
if (mOnItemClicked != null) {
mOnItemClicked.onItemClick(HorizontalListView.this,
child, mLeftViewIndex + 1 + i,
mAdapter.getItemId(mLeftViewIndex + 1 + i));
}
if (mOnItemSelected != null) {
mOnItemSelected.onItemSelected(HorizontalListView.this,
child, mLeftViewIndex + 1 + i,
mAdapter.getItemId(mLeftViewIndex + 1 + i));
}
break;
}
 
}
return true;
}
 
@Override
public void onLongPress(MotionEvent e) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (isEventWithinView(e, child)) {
if (mOnItemLongClicked != null) {
mOnItemLongClicked.onItemLongClick(
HorizontalListView.this, child, mLeftViewIndex
+ 1 + i,
mAdapter.getItemId(mLeftViewIndex + 1 + i));
}
break;
}
}
}
 
private boolean isEventWithinView(MotionEvent e, View child) {
Rect viewRect = new Rect();
int[] childPosition = new int[2];
child.getLocationOnScreen(childPosition);
int left = childPosition[0];
int right = left + child.getWidth();
int top = childPosition[1];
int bottom = top + child.getHeight();
viewRect.set(left, top, right, bottom);
return viewRect.contains((int) e.getRawX(), (int) e.getRawY());
}
};
 
}

public class HorizontalListViewAdapter extends BaseAdapter {
/** 上下文 */
private Context mContext;
/** 图像数据源 */
private ArrayList<Map<String, Integer>> mImageList;
 
/** 数据源 */
private ArrayList<Map<String, Integer>> mTextList;
/** Image */
private static String IMAGE = "ic_";
 
private Map<String, Integer> mMap = null;
 
/** 构造方法 */
public HorizontalListViewAdapter(Context context) {
this.mContext = context;
initData();
}
 
/** 初始化数据 */
public void initData() {
mImageList = new ArrayList<Map<String, Integer>>();
/*
* 反射技术
*/
Class<?> imageClzz = R.drawable.class;
R.drawable instance = new R.drawable();
// 取得drawable类中所有的字段
Field[] fields = imageClzz.getDeclaredFields();
for (Field field : fields) {
// 获得字段的名字
String name = field.getName();
if (name != null && name.startsWith(IMAGE)) {
try {
mMap = new HashMap<String, Integer>();
mMap.put(IMAGE, (Integer) field.get(instance));
mImageList.add(mMap);
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
 
}
}
 
 
@Override
public int getCount() {
return mImageList.size();
}
 
@Override
public Map<String, Integer> getItem(int position) {
 
return mImageList == null ? null : mImageList.get(position);
}
 
@Override
public long getItemId(int position) {
return position;
}
 
@Override
public View getView(int position, View convertView, ViewGroup parent) {
 
ViewHolder holder;
if (convertView == null) {
holder = new ViewHolder();
convertView = LayoutInflater.from(mContext).inflate(
R.layout.horizontal_list_item, null);
holder.mImage = (ImageView) convertView
.findViewById(R.id.iv_list_item);
holder.mTitle = (TextView) convertView
.findViewById(R.id.tv_list_item);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
 
if (position == mSelectIndex) {
convertView.setSelected(true);
} else {
convertView.setSelected(false);
}
holder.mImage.setImageResource(getItem(position).get(IMAGE));
return convertView;
}
 
private class ViewHolder {
/** 图像 */
private ImageView mImage;
}
}