我创建了一个pull to refresh listview，当我滚动或拉动一点然后我必须添加标题视图。
这里是我的自定义列表视图类
package com.app.refreshableList;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewConfiguration;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;
import com.app.xxxxxx.R;
import com.google.android.gms.internal.el;
public class RefreshableListView extends ListView {
Boolean isScrool = false;
private View mHeaderContainer = null;
private View mHeaderView = null;
private ImageView mArrow = null;
private ProgressBar mProgress = null;
private TextView mText = null;
private float mY = 0;
private float mHistoricalY = 0;
private int mHistoricalTop = 0;
private int mInitialHeight = 0;
private boolean mFlag = false;
private boolean mArrowUp = false;
private boolean mIsRefreshing = false;
private int mHeaderHeight = 0;
private OnRefreshListener mListener = null;
private static final int REFRESH = 0;
private static final int NORMAL = 1;
private static final int HEADER_HEIGHT_DP = 62;
private static final String TAG = RefreshableListView.class.getSimpleName();
private ListViewObserver mObserver;
private View mTrackedChild;
private int mTrackedChildPrevPosition;
private int mTrackedChildPrevTop;
OnTouchListener touch;
View vHeader;
@Override
protected void onScrollChanged(int l, int t, int oldl, int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (mTrackedChild == null) {
if (getChildCount() > 0) {
mTrackedChild = getChildInTheMiddle();
mTrackedChildPrevTop = mTrackedChild.getTop();
mTrackedChildPrevPosition = getPositionForView(mTrackedChild);
}
} else {
boolean childIsSafeToTrack = mTrackedChild.getParent() == this
&& getPositionForView(mTrackedChild) == mTrackedChildPrevPosition;
if (childIsSafeToTrack) {
int top = mTrackedChild.getTop();
if (mObserver != null) {
float deltaY = top - mTrackedChildPrevTop;
mObserver.onScroll(deltaY);
}
mTrackedChildPrevTop = top;
} else {
mTrackedChild = null;
}
}
}
private View getChildInTheMiddle() {
return getChildAt(getChildCount() / 2);
}
public void setObserver(ListViewObserver observer) {
mObserver = observer;
}
public RefreshableListView(final Context context) {
super(context);
initialize();
}
public RefreshableListView(final Context context, final AttributeSet attrs) {
super(context, attrs);
initialize();
}
public RefreshableListView(final Context context, final AttributeSet attrs,
final int defStyle) {
super(context, attrs, defStyle);
initialize();
}
public void setOnRefreshListener(final OnRefreshListener l) {
mListener = l;
}
@Override
public void setOnTouchListener(OnTouchListener l) {
// TODO Auto-generated method stub
super.setOnTouchListener(l);
}
public void completeRefreshing() {
mProgress.setVisibility(View.INVISIBLE);
mArrow.setVisibility(View.VISIBLE);
mHandler.sendMessage(mHandler.obtainMessage(NORMAL, mHeaderHeight, 0));
mIsRefreshing = false;
invalidateViews();
}
@Override
public boolean onInterceptTouchEvent(final MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mHandler.removeMessages(REFRESH);
mHandler.removeMessages(NORMAL);
mY = mHistoricalY = ev.getY();
if (mHeaderContainer.getLayoutParams() != null) {
mInitialHeight = mHeaderContainer.getLayoutParams().height;
}
break;
}
return super.onInterceptTouchEvent(ev);
}
@Override
public boolean onTouchEvent(final MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_MOVE:
mHistoricalTop = getChildAt(0).getTop();
break;
case MotionEvent.ACTION_UP:
if (!mIsRefreshing) {
if (mArrowUp) {
startRefreshing();
mHandler.sendMessage(mHandler.obtainMessage(REFRESH,
(int) (ev.getY() - mY) / 2 + mInitialHeight, 0));
} else {
if (getChildAt(0).getTop() == 0) {
mHandler.sendMessage(mHandler.obtainMessage(NORMAL,
(int) (ev.getY() - mY) / 2 + mInitialHeight, 0));
}
}
} else {
mHandler.sendMessage(mHandler.obtainMessage(REFRESH,
(int) (ev.getY() - mY) / 2 + mInitialHeight, 0));
}
mFlag = false;
break;
}
return super.onTouchEvent(ev);
}
@Override
public boolean dispatchTouchEvent(final MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_MOVE
&& getFirstVisiblePosition() == 0) {
float direction = ev.getY() - mHistoricalY;
int height = (int) (ev.getY() - mY) / 2 + mInitialHeight;
if (height < 0) {
height = 0;
}
float deltaY = Math.abs(mY - ev.getY());
ViewConfiguration config = ViewConfiguration.get(getContext());
if (deltaY > config.getScaledTouchSlop()) {
// Scrolling downward
if (direction > 0) {
// Refresh bar is extended if top pixel of the first item is
// visible
if (getChildAt(0) != null) {
if (getChildAt(0).getTop() == 0) {
if (mHistoricalTop < 0) {
// mY = ev.getY(); // TODO works without
// this?mHistoricalTop = 0;
}
// if (isScrool == true) {
//
// } else {
// isScrool = true;
// addHeaderView(vHeader);
//
// // Animation anim = AnimationUtils.loadAnimation(
// // getContext(), R.anim.bounce_animation);
// // startAnimation(anim);
//
// smoothScrollToPosition(getChildAt(0).getTop());
// // bottom_layout.setVisibility(View.VISIBLE);
// }
// Extends refresh bar
/*****
* commented by me on 10-09-2014
*/
setHeaderHeight(height);
// Stop list scroll to prevent the list from
// overscrolling
ev.setAction(MotionEvent.ACTION_CANCEL);
mFlag = false;
}
}
} else if (direction < 0) {
// Scrolling upward
// Refresh bar is shortened if top pixel of the first item
// is
// visible
if (getChildAt(0) != null) {
if (getChildAt(0).getTop() == 0) {
setHeaderHeight(height);
// If scroll reaches top of the list, list scroll is
// enabled
if (getChildAt(1) != null
&& getChildAt(1).getTop() <= 1 && !mFlag) {
ev.setAction(MotionEvent.ACTION_DOWN);
mFlag = true;
}
}
}
}
}
mHistoricalY = ev.getY();
}
try {
return super.dispatchTouchEvent(ev);
} catch (Exception e) {
return false;
}
}
@Override
public boolean performItemClick(final View view, final int position,
final long id) {
if (position == 0) {
// This is the refresh header element
return true;
} else {
return super.performItemClick(view, position - 1, id);
}
}
private void initialize() {
LayoutInflater inflator = (LayoutInflater) getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
vHeader = inflator.inflate(R.layout.search_header, null);
LayoutInflater inflater = (LayoutInflater) getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mHeaderContainer = inflater.inflate(R.layout.refreshable_list_header,
null);
mHeaderView = mHeaderContainer
.findViewById(R.id.refreshable_list_header);
mArrow = (ImageView) mHeaderContainer
.findViewById(R.id.refreshable_list_arrow);
mProgress = (ProgressBar) mHeaderContainer
.findViewById(R.id.refreshable_list_progress);
mText = (TextView) mHeaderContainer
.findViewById(R.id.refreshable_list_text);
addHeaderView(mHeaderContainer);
mHeaderHeight = (int) (HEADER_HEIGHT_DP * getContext().getResources()
.getDisplayMetrics().density);
setHeaderHeight(0);
}
private void setHeaderHeight(final int height) {
if (height <= 1) {
mHeaderView.setVisibility(View.GONE);
} else {
mHeaderView.setVisibility(View.VISIBLE);
}
// Extends refresh bar
LayoutParams lp = (LayoutParams) mHeaderContainer.getLayoutParams();
if (lp == null) {
lp = new LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT);
}
lp.height = height;
mHeaderContainer.setLayoutParams(lp);
// Refresh bar shows up from bottom to top
LinearLayout.LayoutParams headerLp = (LinearLayout.LayoutParams) mHeaderView
.getLayoutParams();
if (headerLp == null) {
headerLp = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT);
}
headerLp.topMargin = -mHeaderHeight + height;
mHeaderView.setLayoutParams(headerLp);
if (!mIsRefreshing) {
// If scroll reaches the trigger line, start refreshing
if (height > mHeaderHeight && !mArrowUp) {
mArrow.startAnimation(AnimationUtils.loadAnimation(
getContext(), R.anim.rotate));
mText.setText("Release to update");
rotateArrow();
mArrowUp = true;
} else if (height < mHeaderHeight && mArrowUp) {
mArrow.startAnimation(AnimationUtils.loadAnimation(
getContext(), R.anim.rotate));
mText.setText("Pull down to update");
rotateArrow();
mArrowUp = false;
}else {
if (isScrool == true) {
} else {
isScrool = true;
addHeaderView(vHeader);
// Animation anim = AnimationUtils.loadAnimation(
// getContext(), R.anim.bounce_animation);
// startAnimation(anim);
smoothScrollToPosition(getChildAt(0).getTop());
// bottom_layout.setVisibility(View.VISIBLE);
}
}
}
}
private void rotateArrow() {
Drawable drawable = mArrow.getDrawable();
Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
canvas.save();
canvas.rotate(180.0f, canvas.getWidth() / 2.0f,
canvas.getHeight() / 2.0f);
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight());
drawable.draw(canvas);
canvas.restore();
mArrow.setImageBitmap(bitmap);
}
private void startRefreshing() {
mArrow.setVisibility(View.INVISIBLE);
mProgress.setVisibility(View.VISIBLE);
mText.setText("Loading...");
mIsRefreshing = true;
if (mListener != null) {
mListener.onRefresh(this);
}
}
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(final Message msg) {
super.handleMessage(msg);
int limit = 0;
switch (msg.what) {
case REFRESH:
limit = mHeaderHeight;
break;
case NORMAL:
limit = 0;
break;
}
// Elastic scrolling
if (msg.arg1 >= limit) {
setHeaderHeight(msg.arg1);
int displacement = (msg.arg1 - limit) / 10;
if (displacement == 0) {
mHandler.sendMessage(mHandler.obtainMessage(msg.what,
msg.arg1 - 1, 0));
} else {
mHandler.sendMessage(mHandler.obtainMessage(msg.what,
msg.arg1 - displacement, 0));
}
}
}
};
public interface OnRefreshListener {
public void onRefresh(RefreshableListView listView);
}
public static interface ListViewObserver {
public void onScroll(float deltaY);
}
}
这里的方法dispatchTouchEvent(final MotionEvent ev)我做了一个条件
if (isScrool == true) {
} else {
isScrool = true;
addHeaderView(vHeader);
// Animation anim =
// AnimationUtils.loadAnimation(
// getContext(), R.anim.bounce_animation);
// startAnimation(anim);
smoothScrollToPosition(getChildAt(0).getTop());
// bottom_layout.setVisibility(View.VISIBLE);
}
此处addHeaderView(vHeader);
添加标题，但我的列表视图向下滚动到最后一项任何人都可以告诉我这里发生了什么？
答案 0 :(得分：0)
尝试拨打 listView.setSelectionAfterHeaderView(); 。这会将ListView滚动到顶部。