Android自定义ViewGroup实现可滚动的横向布局（2）

package com.example.libingyuan.horizontallistview.ScrollViewGroup;import android.content.Context;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.widget.Scroller;/** * 自定义ViewGroup * 在横向布局的基础上，增加啦滚动效果，但是没有边界限制 */public class ScrollViewGroup extends ViewGroup {  private Scroller mScroller;  private float mLastMotionX = 0;  public ScrollViewGroup(Context context) {    this(context, null);  }  public ScrollViewGroup(Context context, AttributeSet attrs) {    this(context, attrs, 0);  }  public ScrollViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    init(context);  }  private void init(Context context) {    mScroller = new Scroller(context);  }  @Override  public void computeScroll() {    if (mScroller.computeScrollOffset()) {      scrollTo(mScroller.getCurrX(), mScroller.getCurrY());      postInvalidate();    }  }  @Override  public boolean onTouchEvent(MotionEvent event) {    // TODO Auto-generated method stub    int action = event.getAction();    float x = event.getX();    switch (action) {      case MotionEvent.ACTION_DOWN:        if (!mScroller.isFinished()) {          mScroller.abortAnimation();        }        mLastMotionX = event.getX();        break;      case MotionEvent.ACTION_MOVE:        float delt = mLastMotionX - x;        mLastMotionX = x;        scrollBy((int) delt, 0);        break;      case MotionEvent.ACTION_UP:        invalidate();        break;      default:        break;    }    return true;  }  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    //重新设置宽高    this.setMeasuredDimension(measureWidth(widthMeasureSpec, heightMeasureSpec), measureHeight(widthMeasureSpec, heightMeasureSpec));  }  /**   * 测量宽度   */  private int measureWidth(int widthMeasureSpec, int heightMeasureSpec) {    // 宽度    int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);    int modeWidth = MeasureSpec.getMode(widthMeasureSpec);    //父控件的宽（wrap_content）    int width = 0;    int childCount = getChildCount();    //重新测量子view的宽度，以及最大高度    for (int i = 0; i < childCount; i++) {      View child = getChildAt(i);      measureChild(child, widthMeasureSpec, heightMeasureSpec);      MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();      int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;      width += childWidth;    }    return modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width;  }  /**   * 测量高度   */  private int measureHeight(int widthMeasureSpec, int heightMeasureSpec) {    //高度    int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);    int modeHeight = MeasureSpec.getMode(heightMeasureSpec);    //父控件的高（wrap_content）    int height = 0;    int childCount = getChildCount();    //重新测量子view的宽度，以及最大高度    for (int i = 0; i < childCount; i++) {      View child = getChildAt(i);      measureChild(child, widthMeasureSpec, heightMeasureSpec);      MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();      int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;      height += childHeight;    }    height = height / childCount;    return modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height;  }  @Override  protected void onLayout(boolean changed, int l, int t, int r, int b) {    int childLeft = 0;    int childWidth;    int height = getHeight();    int childCount = getChildCount();    for (int i = 0; i < childCount; i++) {      View child = getChildAt(i);      MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();      childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;      child.layout(childLeft, 0, childLeft + childWidth, height);      childLeft += childWidth;    }  }  @Override  public LayoutParams generateLayoutParams(AttributeSet attrs) {    return new MarginLayoutParams(getContext(), attrs);  }}