目的:RecyclerView中item有权重加载的图片需要根据手机尺寸转换成正方形,需要获取到ImageView真实的宽度重新设置高度达到正方形的效果

image.png

//注册一个观察者来监听视图树??
        ViewTreeObserver viewTreeObserver = mImgIconA.getViewTreeObserver();
        viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                mImgIconA.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                //获取绘制完之后的宽度
                int width = mImgIconA.getMeasuredWidth();
                //拿到View的LayoutParams
                ViewGroup.LayoutParams layoutParams = mImgIconA.getLayoutParams();
                //将他的宽度赋值给高度,这样就是一个正方形了
                layoutParams.height = width;
                mImgIconA.setLayoutParams(layoutParams);
                mImgIconB.setLayoutParams(layoutParams);
                mImgIconC.setLayoutParams(layoutParams);
            }
        });