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<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());
    }
  };

}

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<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;
  }
}