查看/地产转换

Question

当用户向下滚动recyclerview时，我需要进行以下转换，如附图所示。 “标题A”和“描述”位于RelativeLayout内部，将折叠并更改其属性：

1. “标题A”，来自layout_centerHorizo​​ntal = true，layout_centerVertical = true
2. “描述”从layout_centerHorizo​​ntal = true到layout_centerVertical = true，文本化从30sp到16sp
3. 最小化relativelayout，高度从70dp到wrap_content

当用户向上滚动并点击顶部时，更改将恢复为原始展开形式。 （这类似于折叠工具栏的概念）

我已成功实现，当我点击一个按钮时，布局和视图将使用view.requestlayout（）正确更改。但我不确定如何将转换链接到onscrolled函数的deltaY。

这是我尝试过的：

    changeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            animateChanges();
        }
    });

 private void animateChanges() {

    ViewGroup.LayoutParams layout = relativeLayout.getLayoutParams();
    RelativeLayout.LayoutParams header = (RelativeLayout.LayoutParams) titleA.getLayoutParams();
    RelativeLayout.LayoutParams value = (RelativeLayout.LayoutParams) description.getLayoutParams();

    // if current is not expanded, we change to expand view
    if (!isExpanded) {
        relativeLayout.setGravity(Gravity.CENTER);
        layout.height = (int) getResources().getDimension(R.dimen.height_60);
        header.addRule(RelativeLayout.CENTER_HORIZONTAL, RelativeLayout.TRUE);
        header.addRule(RelativeLayout.ALIGN_PARENT_LEFT, 0);
        header.addRule(RelativeLayout.CENTER_VERTICAL, 0);
        value.addRule(RelativeLayout.CENTER_HORIZONTAL, RelativeLayout.TRUE);
        value.addRule(RelativeLayout.BELOW, R.id.title_a);
        value.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, 0);
        value.addRule(RelativeLayout.CENTER_VERTICAL, 0);
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN) {
            value.addRule(RelativeLayout.ALIGN_PARENT_END, 0);
            header.addRule(RelativeLayout.ALIGN_PARENT_START, 0);
        }
        relativeLayout.setLayoutParams(layout);
        titleA.setLayoutParams(header);
        description.setLayoutParams(value);
        description.setTextSize(TypedValue.COMPLEX_UNIT_PX, getResources().getDimension(R.dimen.font_30));

        titleA.requestLayout();
        description.requestLayout();
        relativeLayout.requestLayout();
    } else {

        relativeLayout.setGravity(Gravity.CENTER_VERTICAL);
        layout.height = ViewGroup.LayoutParams.WRAP_CONTENT;
        header.addRule(RelativeLayout.CENTER_HORIZONTAL, 0);
        header.addRule(RelativeLayout.BELOW, 0);
        header.addRule(RelativeLayout.CENTER_VERTICAL, RelativeLayout.TRUE);
        header.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
        value.addRule(RelativeLayout.CENTER_HORIZONTAL, 0);
        value.addRule(RelativeLayout.CENTER_VERTICAL, RelativeLayout.TRUE);
        value.addRule(RelativeLayout.BELOW, 0);
        value.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN) {
            value.addRule(RelativeLayout.ALIGN_PARENT_END, RelativeLayout.TRUE);
            header.addRule(RelativeLayout.ALIGN_PARENT_START, RelativeLayout.TRUE);
        }
        titleA.setLayoutParams(header);
        description.setLayoutParams(value);
        relativeLayout.setLayoutParams(layout);
        description.setTextSize(TypedValue.COMPLEX_UNIT_PX, getResources().getDimension(R.dimen.font_16));

        relativeLayout.requestLayout();
        titleA.requestLayout();
        description.requestLayout();
    }
    isExpanded = !isExpanded;
}

提前致谢！