横向滑动的listview效果的实现方法，scrollview嵌套水平滑动的listview卡顿的解决方法

15-06-13 来源：[db:作者]

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很多时候，界面需要实现横向滑动的listview效果。网络上有一种方法，自定义了HorizontalListView，用法同正常的listview，可实现水平滑动效果。

但是如果一个界面为垂直滑动的scrollview嵌套水平滑动的listview的时候，滑动水平listview的时候，会很卡。我最近就遇到了这样的问题，一直把思路放在监听水平和垂直滑动手势，想实现滑动角度小于45的时候垂直的scrollview 滑动效果被禁止。但是一直没有研究出来。

于是一个偶然的机会，灵光一闪，想到用HorizontalScrollView嵌套gridview，实现水平滑动的效果。果真效果很棒哦。没有卡顿的现象出现。

方法如下：

布局：

<>
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:scrollbars="none" >
<>
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<>
android:id="@+id/server_details_content_view_product_gv"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >

代码中要设置gridview的属性，否则没有滑动效果

/** 设置GirdView参数，length一般为100到230不等，自己设置适配吧。size为列表的大小*/
private void setGridView(GridView gv, int length, int size) {

DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
float density = dm.density;
int gridviewWidth = (int) (size * (length + 4) * density);
int itemWidth = (int) (length * density);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
gridviewWidth, LinearLayout.LayoutParams.FILL_PARENT);
gv.setLayoutParams(params); // 设置GirdView布局参数,横向布局的关键
gv.setColumnWidth(itemWidth); // 设置列表项宽
gv.setHorizontalSpacing(5); // 设置列表项水平间距
gv.setStretchMode(GridView.NO_STRETCH);
gv.setNumColumns(size); // 设置列数量=列表集合数

}

设置适配器的时候。适配器的写法同正常的gridview的适配器，再次不再附代码。如有疑问可以留言哦。

setGridView(vStepsGv, 230,serviceContentList.size());
stepsAdapter = new ServerStepsListAdapter(this, serviceContentList);
vStepsGv.setAdapter(stepsAdapter);

另外如果不需要外层嵌套垂直滑动的scrollview，这个自定义的listview还是不错的啦！附代码：（用法同正常的listview，如有疑问可以留言哦）

/**
* 左右滑动的listview
*
* @author lunizhu
*
*/
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) {
int positionX = position * this.getWidth();
int maxWidth = this.getChildCount() * this.getWidth();
if (positionX <= 0) {
positionX = 0;
}
if (positionX > maxWidth) {
positionX = maxWidth;
}
scrollTo(positionX);
}

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());
}
};

}

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