android 折叠效果

学习笔记，代码
自定义LinearLayout:

class ExpandLinearLayout extends LinearLayout {

/**
 * 折叠按钮图标
 */

private ImageView mExpandBtn;

/**
 * 是否折叠的临界高度
 */
private int mLimitHeight = 100;

/**
 * 是否展开了
 */
private boolean mIsExpand = false;

/**
 * 是否支持展开折叠功能
 */
private boolean mSupportExpand = true;

public ExpandLinearLayout(Context context) {
    super(context);
    init();
}

public ExpandLinearLayout(Context context, @Nullable AttributeSet attrs) {
    super(context, attrs);
    init();
}

public ExpandLinearLayout(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
}

/**
 * 初始化
 */
public void init() {
    setOrientation(VERTICAL);
}

/**
 * 重写onMeasure动态控制控件的高度
 *
 * @param widthMeasureSpec
 * @param heightMeasureSpec
 */
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    //获取自身的测量高度
    int measureHeight = getMeasuredHeight();

    //设置折叠按钮是否显示
    setExpandBtnVisiable(measureHeight <= mLimitHeight ? View.GONE : View.VISIBLE);

    //如果不支持折叠或者需要展开或者高度不到折叠高度,就保持默认测量
    if (!mSupportExpand || mIsExpand || measureHeight <= mLimitHeight) {
        return;
    }

    //重新设置高度测量参数
    heightMeasureSpec = MeasureSpec.makeMeasureSpec(mLimitHeight, MeasureSpec.EXACTLY);

    Log.e("aaa", "onMeasure: "+mLimitHeight );
    Log.e("bbb", "onMeasure: "+heightMeasureSpec );

    //重新测量
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

/**
 * 绑定展开折叠按钮图标
 *
 * @param view
 * @param expandRes
 * @param foldRes
 */
public void bindExpandButton(ImageView view, final int expandRes, final int foldRes) {
    mExpandBtn = view;
    if (view == null) {
        return;
    }
    view.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            setIsExpand(!mIsExpand);
            mExpandBtn.setImageResource(mIsExpand ? expandRes : foldRes);
        }
    });
    setExpandBtnVisiable(GONE);
}

/**
 * 获取临界折叠高度
 *
 * @return
 */
public int getLimitHeight() {
    return mLimitHeight;
}

/**
 * 设置临界折叠高度
 *
 * @param limitHeight
 */
public void setLimitHeight(int limitHeight) {
    this.mLimitHeight = limitHeight;
}

/**
 * 获取是否展开了
 *
 * @return
 */
public boolean isIsExpand() {
    return mIsExpand;
}

/**
 * 设置是否展开
 *
 * @param isExpand
 */
public void setIsExpand(boolean isExpand) {
    this.mIsExpand = isExpand;
    requestLayout();

}

/**
 * 获取当前是否支持折叠展开功能
 *
 * @return
 */
public boolean isSupportExpand() {
    return mSupportExpand;
}

/**
 * 设置折叠还是展开
 *
 * @param supportExpand
 */
public void setSupportExpand(boolean supportExpand) {
    this.mSupportExpand = supportExpand;
    setExpandBtnVisiable(GONE);
}

/**
 * 设置折叠图标是否显示
 *
 * @param visiable
 */
private void setExpandBtnVisiable(int visiable) {
    if (mExpandBtn != null) {
        if (!mSupportExpand) {
            mExpandBtn.setVisibility(GONE);
        } else {
            mExpandBtn.setVisibility(visiable);
        }
    }
}
}

用法:在布局中直接使用。