EXOPlayer居中播放，类似ImageView的CENTER_CROP

1、自定义TextureView

import android.content.Context;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.view.TextureView;

/**
 * 视频自动居中裁剪自定义TextureView
 */
public class TextureVideoView extends TextureView{

    private float mVideoHeight;
    private float mVideoWidth;

    private ScaleType mScaleType;
    public enum ScaleType {
        CENTER_CROP, TOP, BOTTOM
    }

    public void setWH(float mVideoWidth,float mVideoHeight){
        this.mVideoWidth=mVideoWidth;
        this.mVideoHeight=mVideoHeight;
        updateTextureViewSize();
    }

    public TextureVideoView(Context context) {
        super(context);
        initView();
    }

    public TextureVideoView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initView();
    }

    public TextureVideoView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        initView();
    }

    private void initView() {
        setScaleType(ScaleType.CENTER_CROP);
    }

    public void setScaleType(ScaleType scaleType) {
        mScaleType = scaleType;
    }

    private void updateTextureViewSize() {
        float sx = (float) getWidth() / mVideoWidth;
        float sy = (float) getHeight() / mVideoHeight;

        Matrix matrix = new Matrix();
        float maxScale = Math.max(sx, sy);

        //第1步:把视频区移动到View区,使两者中心点重合.
        matrix.preTranslate((getWidth() - mVideoWidth) / 2, (getHeight() - mVideoHeight) / 2);

        //第2步:因为默认视频是fitXY的形式显示的,所以首先要缩放还原回来.
        matrix.preScale(mVideoWidth / (float) getWidth(), mVideoHeight / (float) getHeight());

        //第3步,等比例放大或缩小,直到视频区的一边超过View一边, 另一边与View的另一边相等. 因为超过的部分超出了View的范围,所以是不会显示的,相当于裁剪了.
        matrix.postScale(maxScale, maxScale, getWidth() / 2, getHeight() / 2);//后两个参数坐标是以整个View的坐标系以参考的

        setTransform(matrix);
    }
}

二、设置mTextureVideoView.setScaleType(TextureVideoView.ScaleType.CENTER_CROP);属性

三、当获取到视频的宽高时mTextureVideoView.setWH()

注：Exo获取视频宽高方法：

player.setVideoListener(new SimpleExoPlayer.VideoListener() {
            public void onVideoSizeChanged(int width, int height, int unappliedRotationDegrees, float pixelWidthHeightRatio) {
              //视频宽和高
            }
            @Override
            public void onRenderedFirstFrame() {

            }
        });

    }