android水平滚动条,Android_Android中实现水平滑动（横向滑动）ListView示例，水平的ListView-HorizontalListView的 - phpStudy...

Android中实现水平滑动(横向滑动)ListView示例

水平的ListView-HorizontalListView的使用

Android中ListView默认的是竖直方向的滑动，由于项目的需求，需要ListView是水平滑动的。有很多的方式可以实现，但是比较好的一种方式就是自己封装一个控件，使用方式和ListView的使用方式是一样的。需要完善的地方：获取到的图片大小没有处理。在界面上展示的是图片的原大小。为了更好的展示效果，应该压缩成统一的尺寸。

HorizontalListView.java 代码如下：

/**

* 横向的ListView

*

* * @author scd

*

*/

public class HorizontalListView extends AdapterView {

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 mRemovedViewQueue = new LinkedList();

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());

}

};

}

适配器 HorizontalListViewAdapter .java如下：

public class HorizontalListViewAdapter extends BaseAdapter {

/** 上下文 */

private Context mContext;

/** 图像数据源 */

private ArrayList> mImageList;

/** 数据源 */

private ArrayList> mTextList;

/** Image */

private static String IMAGE = "ic_";

private Map 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>();

/*

* 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();

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 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;

}

}

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