LayoutParams和onMeasure的效率（自定义16:9图片）

-- SetLayoutParams和onMeasure的差别
setLayoutParams：设置view的宽度和高度。
onMeasure: 设置view的可见宽度和高度。

1） LayoutParams

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
params.width = CommonUtils.getScreenWidth(mContext);
params.height = CommonUtils.getScreenWidth(mContext) * 9 / 16;
point.iv_news.setLayoutParams(params);

2）重写View的onMeasure()方法

android自定义正方形的imageview和textview- https://blog.csdn.net/hy_programmer/article/details/48137807

* 自定义16:9的图片显示

public class CustomRatioImageView extends ColorImageView {
    public CustomRatioImageView(Context context) {
        super(context);
    }
    public CustomRatioImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
    public CustomRatioImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(getDefaultSize(0, widthMeasureSpec), getDefaultSize(0, heightMeasureSpec));
        int childWidthSize = getMeasuredWidth();
        int childHeighSize = childWidthSize * 9 / 16;
        //高度和宽度9:16
        heightMeasureSpec = MeasureSpec.makeMeasureSpec(childHeighSize, MeasureSpec.EXACTLY);
        widthMeasureSpec = MeasureSpec.makeMeasureSpec(childWidthSize, MeasureSpec.EXACTLY);
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}