Android RecyclerView ListView 需要

原有思路:

• View.Post() 方式

  说明:将处理添加到主线程队列中,等待处理,会有显示慢的问题,由于View的复用,当列表滑动后,就不能正确返回相关值了.

• getViewTreeObserver().addOnGlobalLayoutListener()

  说明:添加全局View 变化监听,会被多次调用,并且在列表滑动过程中,跟View.Post() 有相同的问题.

新思路

• onDraw()
• onLayout()
• onMeasure() 中进行获取对应TextView 的getLineCount()

View 的绘制过程为 onMeasure()->onLayout()->onDraw()

所以将处理逻辑放置到 onMeasure()中.

说明:

• 封装 容器 CommendContainerView,继承 RelativeLayout
• 重写 onMeasure()方法,当 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 执行完后, 容器已经知道了所有子View 的相关尺寸, 这个时候 可以去进行判断了.并且不会有延时问题.
• 进行逻辑判断后,调用 super.onMeasure(widthMeasureSpec, heightMeasureSpec); 对子View 再进行一次测量.保证显示逻辑.
• 针对于 用户操作过的 View, 将状态进行缓存.

下面直接上代码:

public class CommendContainerView extends RelativeLayout {

    private TextView mCommendTextView;
    private TextView mCommendFun;
    private CommendShowFunListener mListener;

    private boolean mFlag = true;
    private int mLinesLimit = 1;
    private Boolean mShowAll;
    private int mPos;

    public CommendContainerView(Context context) {
        this(context, null);
    }

    public CommendContainerView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

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

    //初始化布局~
    private void initView(Context context, AttributeSet attrs, int defStyleAttr) {
        inflate(context, R.layout.view_commend_container, this);
        mCommendTextView = findViewById(R.id.commend_ctv_commend);
        mCommendFun = findViewById(R.id.commend_tv_fun);
        mCommendFun.setOnClickListener(onClickListener);
    }

    public void setCommendInfo(CharSequence text, Boolean showAll, int pos) {
        mShowAll = showAll;
        mPos = pos;
        if (null != mShowAll) {
            mFlag = true;
            mCommendFun.setVisibility(VISIBLE);
            if (mShowAll) {
                mCommendFun.setText(R.string.desc_shrinkup);
                mCommendTextView.setMaxLines(Integer.MAX_VALUE);
            } else {
                mCommendFun.setText(R.string.desc_spread);
                mCommendTextView.setMaxLines(mLinesLimit);
            }
            mCommendTextView.setText(text);
        } else {
            mFlag = false;
            mCommendFun.setVisibility(GONE);
            mCommendTextView.setMaxLines(Integer.MAX_VALUE);
            mCommendTextView.setText(text);
        }
    }

    private OnClickListener onClickListener = new OnClickListener() {
        @Override
        public void onClick(View v) {
            mCommendFun.setVisibility(VISIBLE);
            mFlag = true;
            if (null == mShowAll || !mShowAll) {
                mCommendTextView.setMaxLines(Integer.MAX_VALUE);
                mCommendFun.setText(R.string.desc_shrinkup);
                mShowAll = true;
            } else {
                mCommendTextView.setMaxLines(mLinesLimit);
                mCommendFun.setText(R.string.desc_spread);
                mShowAll = false;
            }
            if (null != mListener) {
                mListener.onShowStatusChange(mPos, mShowAll);
            }
        }
    };

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (!mFlag) {
            mFlag = true;
            if (mCommendTextView.getLineCount() > mLinesLimit) {
                //超过行数~
                mCommendFun.setVisibility(VISIBLE);
                mCommendFun.setText(R.string.desc_spread);
                mCommendTextView.setMaxLines(mLinesLimit);
            } else {
                mCommendFun.setVisibility(GONE);
                mCommendTextView.setMaxLines(Integer.MAX_VALUE);
            }
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }

    public void setCommendShowFunListener(CommendShowFunListener listener) {
        this.mListener = listener;
    }

    public void setLinesLimit(int limit) {
        this.mLinesLimit = limit;
    }

    interface CommendShowFunListener {
        void onShowStatusChange(int pos, boolean showAll);
    }

}