android ImageView 设定宽度铺满，高度自定义

问题：imageView 宽度铺满，高度自定义，会出现上下留白的现象（一般比例的还好）

解决：

<xxx.xxx.xxx.xxx.FullWidthImageView
    android:id="@+id/iv_image_corp"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:src="@drawable/pic_icon">
</cxxx.xxx.xxx.xxx.FullWidthImageView>

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.support.v7.widget.AppCompatImageView;
public class FullWidthImageView extends AppCompatImageView {
    public FullWidthImageView(Context context) {
        super(context);
    }
 
    public FullWidthImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }
 
    public FullWidthImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }
 
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        Drawable drawable = getDrawable();
        if (drawable != null) {
            int width = MeasureSpec.getSize(widthMeasureSpec);
            int height = Math.round((float) width / (float) drawable.getIntrinsicWidth() * drawable.getIntrinsicHeight());
            setMeasuredDimension(width, height);
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }
}