自定义View之HorizontalListView

项目已经上线，中间遇到好多问题，其中一个地方遇到横向展示ListView，其实一开始是可以用RecyclerView来实现，问题是RecyclerView没有现成的Item点击事件,需要从写，以后在研究下。现在先记录下HorizontalListView的代码。

package com.cdcm.view.horizontallistview;import java.util.LinkedList;import java.util.Queue;import android.content.Context;import android.database.DataSetObserver;import android.graphics.Rect;import android.util.AttributeSet;import android.view.GestureDetector;import android.view.GestureDetector.OnGestureListener;import android.view.MotionEvent;import android.view.View;import android.widget.AdapterView;import android.widget.ListAdapter;import android.widget.Scroller;//水平方向的listviewpublic 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(OnItemSelectedListener listener) {      mOnItemSelected = listener;   }      @Override   public void setOnItemClickListener(OnItemClickListener listener){      mOnItemClicked = listener;   }      @Override   public void setOnItemLongClickListener(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());        }   };}

   在xml中

<com.cdcm.view.horizontallistview.HorizontalListView    android:id="@+id/horizontallistview"    android:layout_width="match_parent"    android:layout_height="0dp"    android:layout_weight="0.8"    android:background="@color/actionbar_bg"></com.cdcm.view.horizontallistview.HorizontalListView>

至于数据，跟LiseView一样，写Adapter设置数据。