Android自定义ViewGroup实现可滚动的横向布局（2）

上一篇文章自定义viewgroup（1）地址：

这里直接代码：

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);
  }
}

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