import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.media.ExifInterface;

import java.io.IOException;

/**
 * Created by pengkv on 15/12/2.
 * 图片旋转工具类
 */
public class ImageRotateUtil {

    /**
     * 读取图片的旋转的角度
     *
     * @param path 图片绝对路径
     * @return 图片的旋转角度
     */
    public static int getBitmapDegree(String path) {
        int degree = 0;
        try {
            // 从指定路径下读取图片，并获取其EXIF信息
            ExifInterface exifInterface = new ExifInterface(path);
            // 获取图片的旋转信息
            int orientation = exifInterface.getAttributeInt(ExifInterface.TAG_ORIENTATION,
                    ExifInterface.ORIENTATION_NORMAL);
            switch (orientation) {
                case ExifInterface.ORIENTATION_ROTATE_90:
                    degree = 90;
                    break;
                case ExifInterface.ORIENTATION_ROTATE_180:
                    degree = 180;
                    break;
                case ExifInterface.ORIENTATION_ROTATE_270:
                    degree = 270;
                    break;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        return degree;
    }

    /**
     * 将图片按照某个角度进行旋转
     *
     * @param bm     需要旋转的图片
     * @param degree 旋转角度
     * @return 旋转后的图片
     */
    public static Bitmap rotateBitmapByDegree(Bitmap bm, int degree) {
        Bitmap returnBm = null;

        // 根据旋转角度，生成旋转矩阵
        Matrix matrix = new Matrix();
        matrix.postRotate(degree);
        try {
            // 将原始图片按照旋转矩阵进行旋转，并得到新的图片
            returnBm = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(), bm.getHeight(), matrix, true);
        } catch (OutOfMemoryError e) {
            e.printStackTrace();
            //当内存溢出时，利用递归进行重新旋转
            while (returnBm == null) {
                System.gc();
                System.runFinalization();
                returnBm = rotateBitmapByDegree(bm, degree);
            }
        }
        if (returnBm == null) {
            returnBm = bm;
        }
        if (bm != returnBm) {
            bm.recycle();
        }
        return returnBm;
    }
}