android HorizontalScrollView

public class MyHorizontalScrollView extends HorizontalScrollView implements
OnClickListener {
/**
* 图片滚动时的回调接口
*
* @author zhy
*
*/
public interface CurrentImageChangeListener {
void onCurrentImgChanged(int position, View viewIndicator);
}

/**
* 条目点击时的回调
*
* @author zhy
*
*/
public interface OnItemClickListener {
void onClick(View view, int pos);
}

private CurrentImageChangeListener mListener;

private OnItemClickListener mOnClickListener;

private static final String TAG = "MyHorizontalScrollView";

/**
* HorizontalListView中的LinearLayout
*/
private LinearLayout mContainer;

/**
* 子元素的宽度
*/
private int mChildWidth;
/**
* 子元素的高度
*/
private int mChildHeight;
/**
* 当前最后一张图片的index
*/
private int mCurrentIndex;
/**
* 当前第一张图片的下标
*/
private int mFristIndex;
/**
* 当前第一个View
*/
private View mFirstView;
/**
* 数据适配器
*/
private HorizontalScrollViewAdapter mAdapter;
/**
* 每屏幕最多显示的个数
*/
private int mCountOneScreen;
/**
* 屏幕的宽度
*/
private int mScreenWitdh;

/**
* 保存View与位置的键值对
*/
private Map<View, Integer> mViewPos = new HashMap<View, Integer>();

public MyHorizontalScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
// 获得屏幕宽度
WindowManager wm = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
mScreenWitdh = outMetrics.widthPixels;
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mContainer = (LinearLayout) getChildAt(0);
}

/**
* 加载下一张图片
*/
protected void loadNextImg() {
// 数组边界值计算
if (mCurrentIndex == mAdapter.getCount() - 1) {
return;
}
// 移除第一张图片，且将水平滚动位置置0
scrollTo(0, 0);
mViewPos.remove(mContainer.getChildAt(0));
mContainer.removeViewAt(0);

// 获取下一张图片，并且设置onclick事件，且加入容器中
View view = mAdapter.getView(++mCurrentIndex, null, mContainer);
view.setOnClickListener(this);
mContainer.addView(view);
mViewPos.put(view, mCurrentIndex);

// 当前第一张图片小标
mFristIndex++;
// 如果设置了滚动监听则触发
if (mListener != null) {
notifyCurrentImgChanged();
}

}

/**
* 加载前一张图片
*/
protected void loadPreImg() {
// 如果当前已经是第一张，则返回
if (mFristIndex == 0)
return;
// 获得当前应该显示为第一张图片的下标
int index = mCurrentIndex - mCountOneScreen;
if (index >= 0) {
// mContainer = (LinearLayout) getChildAt(0);
// 移除最后一张
int oldViewPos = mContainer.getChildCount() - 1;
mViewPos.remove(mContainer.getChildAt(oldViewPos));
mContainer.removeViewAt(oldViewPos);

// 将此View放入第一个位置
View view = mAdapter.getView(index, null, mContainer);
mViewPos.put(view, index);
mContainer.addView(view, 0);
view.setOnClickListener(this);
// 水平滚动位置向左移动view的宽度个像素
scrollTo(mChildWidth, 0);
// 当前位置--，当前第一个显示的下标--
mCurrentIndex--;
mFristIndex--;
// 回调
if (mListener != null) {
notifyCurrentImgChanged();

}
}
}

/**
* 滑动时的回调
*/
public void notifyCurrentImgChanged() {
// 先清除所有的背景色，点击时会设置为蓝色
for (int i = 0; i < mContainer.getChildCount(); i++) {
mContainer.getChildAt(i).setBackgroundColor(Color.WHITE);
}

mListener.onCurrentImgChanged(mFristIndex, mContainer.getChildAt(0));

}

/**
* 初始化数据，设置数据适配器
*
* @param mAdapter
*/
public void initDatas(HorizontalScrollViewAdapter mAdapter) {
this.mAdapter = mAdapter;
mContainer = (LinearLayout) getChildAt(0);
// 获得适配器中第一个View
final View view = mAdapter.getView(0, null, mContainer);
mContainer.addView(view);

// 强制计算当前View的宽和高
if (mChildWidth == 0 && mChildHeight == 0) {
int w = View.MeasureSpec.makeMeasureSpec(0,
View.MeasureSpec.UNSPECIFIED);
int h = View.MeasureSpec.makeMeasureSpec(0,
View.MeasureSpec.UNSPECIFIED);
view.measure(w, h);
mChildHeight = view.getMeasuredHeight();
mChildWidth = view.getMeasuredWidth();
Log.e(TAG, view.getMeasuredWidth() + "," + view.getMeasuredHeight());
mChildHeight = view.getMeasuredHeight();
// 计算每次加载多少个View
mCountOneScreen = mScreenWitdh / mChildWidth + 2;

Log.e(TAG, "mCountOneScreen = " + mCountOneScreen
+ " ,mChildWidth = " + mChildWidth);

}
// 初始化第一屏幕的元素
//        initFirstScreenChildren(mCountOneScreen);
initFirstScreenChildren(mAdapter.getCount());
}

/**
* 加载第一屏的View
*
* @param mCountOneScreen
*/
public void initFirstScreenChildren(int mCountOneScreen) {
mContainer = (LinearLayout) getChildAt(0);
mContainer.removeAllViews();
mViewPos.clear();

for (int i = 0; i < mCountOneScreen; i++) {
View view = mAdapter.getView(i, null, mContainer);
view.setOnClickListener(this);
mContainer.addView(view);
mViewPos.put(view, i);
mCurrentIndex = i;
}

if (mListener != null) {
notifyCurrentImgChanged();
}

}

@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_MOVE:
// Log.e(TAG, getScrollX() + "");

int scrollX = getScrollX();
// 如果当前scrollX为view的宽度，加载下一张，移除第一张
if (scrollX >= mChildWidth) {
loadNextImg();
}
// 如果当前scrollX = 0， 往前设置一张，移除最后一张
if (scrollX == 0) {
loadPreImg();
}
break;
}
return super.onTouchEvent(ev);
}

@Override
public void onClick(View v) {
if (mOnClickListener != null) {
for (int i = 0; i < mContainer.getChildCount(); i++) {
mContainer.getChildAt(i).setBackgroundColor(Color.WHITE);
}
mOnClickListener.onClick(v, mViewPos.get(v));
}
}

public void setOnItemClickListener(OnItemClickListener mOnClickListener) {
this.mOnClickListener = mOnClickListener;
}

public void setCurrentImageChangeListener(
CurrentImageChangeListener mListener) {
this.mListener = mListener;
}

}