20.TextView，Button 等设置 setCompoundDrawables 无效

场景

在实现设置TextView上方显示图片的时候遇到不显示的现象。代码如下

private void clickShowOrHiddenFlightDetail(View view) {
        
       Drawable rightDrawable = (mRvFlightSegment.getVisibility() == View.VISIBLE ) ? ContextCompat.getDrawable(this, R.drawable.ic_top_jiantou) : ContextCompat.getDrawable(this, R.drawable.ic_down_jiantou);
        mTvFlightDetail.setCompoundDrawables(null, null, rightDrawable, null);
               
    }

API 解释

Sets the Drawables (if any) to appear to the left of, above, to the right of, and below the text. Use null if you do not want a Drawable there. The Drawables must already have had setBounds(Rect) called.

即对 Drawable 进行宽高设置即可

解决方案1：

根据官方api解释，对 drawable.setBounds(Rect) ；

解决方案2：

不用setCompoundDrawables(left, top, right, bottom)，而调用setCompoundDrawablesWithIntrinsicBounds(left, top, right, bottom)。意思是设置Drawable显示在text的左、上、右、下位置。

private void clickShowOrHiddenFlightDetail(View view) {
        
       Drawable rightDrawable = (mRvFlightSegment.getVisibility() == View.VISIBLE ) ? ContextCompat.getDrawable(this, R.drawable.ic_top_jiantou) : ContextCompat.getDrawable(this, R.drawable.ic_down_jiantou);
        mTvFlightDetail.setCompoundDrawablesWithIntrinsicBounds(null, null, rightDrawable, null);
               
    }

两者有些区别详解：

setCompoundDrawables(left, top, right, bottom)和setCompoundDrawablesWithIntrinsicBounds(left, top, right, bottom)：

setCompoundDrawables 画的drawable的宽高是按drawable.setBound()设置的宽高，
所以才有The Drawables must already have had setBounds(Rect) called.即使用之前必须使用Drawable.setBounds设置Drawable的长宽。

setCompoundDrawablesWithIntrinsicBounds是画的drawable的宽高是按drawable固定的宽高，所以才有The Drawables' bounds will be set to their intrinsic bounds.即通过getIntrinsicWidth()与getIntrinsicHeight()获得。