package com.moral.andbrickslib.compresshelper;

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.media.ExifInterface;

import java.io.File;
import java.io.IOException;

/**
 * Bitmap 压缩相关操作工具类
 *
 *
 *
 * 原理不明白请查看我博客：http://www.cnblogs.com/liushilin/p/6116759.html
 *
 * Author: nanchen
 * Email: liushilin520@foxmail.com
 * Date: 2017-02-13  15:43
 */

public class BitmapUtil {
    /**
     * 计算图片的压缩比率
     *
     * @param options   参数
     * @param reqWidth  目标的宽度
     * @param reqHeight 目标的高度
     * @param pathName  路径
     * @return          计算的SampleSize
     */
    private static int calculateInSampleSize(BitmapFactory.Options options, String pathName, int reqWidth, int reqHeight) {
        // 源图片的高度和宽度
        int height = options.outHeight;
        int width = options.outWidth;
        if (height == -1 || width == -1) {
            try {
                ExifInterface exifInterface = new ExifInterface(pathName);
                height = exifInterface.getAttributeInt(ExifInterface.TAG_IMAGE_LENGTH, ExifInterface.ORIENTATION_NORMAL);//获取图片的高度
                width = exifInterface.getAttributeInt(ExifInterface.TAG_IMAGE_WIDTH, ExifInterface.ORIENTATION_NORMAL);//获取图片的宽度
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        int inSampleSize = 1;
        if (height > reqHeight || width > reqWidth) {
            final int halfHeight = height / 2;
            final int halfWidth = width / 2;
            // Calculate the largest inSampleSize value that is a power of 2 and keeps both
            // height and width larger than the requested height and width.
            while ((halfHeight / inSampleSize) > reqHeight
                    && (halfWidth / inSampleSize) > reqWidth) {
                inSampleSize *= 2;
            }
        }
        return inSampleSize;
    }


    /**
     * 计算图片的压缩比率
     *
     * @param options   参数
     * @param reqWidth  目标的宽度
     * @param reqHeight 目标的高度
     * @return          计算的SampleSize
     */
    private static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        // 源图片的高度和宽度
        int height = options.outHeight;
        int width = options.outWidth;
        int inSampleSize = 1;
        if (height > reqHeight || width > reqWidth) {
            final int halfHeight = height / 2;
            final int halfWidth = width / 2;
            // Calculate the largest inSampleSize value that is a power of 2 and keeps both
            // height and width larger than the requested height and width.
            while ((halfHeight / inSampleSize) > reqHeight
                    && (halfWidth / inSampleSize) > reqWidth) {
                inSampleSize *= 2;
            }
        }
        return inSampleSize;
    }

    /**
     * 从Resources中加载图片
     *
     * @param res       Resource
     * @param resId     资源id
     * @param reqWidth  请求宽度
     * @param reqHeight 请求高度
     * @return          Bitmap
     */
    public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId, int reqWidth, int reqHeight) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true; // 设置成了true,不占用内存，只获取bitmap宽高
        BitmapFactory.decodeResource(res, resId, options); // 读取图片长款
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight); // 调用上面定义的方法计算inSampleSize值
        // 使用获取到的inSampleSize值再次解析图片
        options.inJustDecodeBounds = false;
        Bitmap src = BitmapFactory.decodeResource(res, resId, options); // 载入一个稍大的缩略图
        return createScaleBitmap(src, reqWidth, reqHeight, options.inSampleSize); // 进一步得到目标大小的缩略图
    }

    /**
     * 通过传入的bitmap，进行压缩，得到符合标准的bitmap
     *
     * @param src           Bitmap源图
     * @param dstWidth      宽度
     * @param dstHeight     高度
     * @return              新的Bitmap
     */
    private static Bitmap createScaleBitmap(Bitmap src, int dstWidth, int dstHeight, int inSampleSize) {
        //如果inSampleSize是2的倍数，也就说这个src已经是我们想要的缩略图了，直接返回即可。
        if (inSampleSize % 2 == 0) {
            return src;
        }
        if (src == null){
            return null;
        }
        // 如果是放大图片，filter决定是否平滑，如果是缩小图片，filter无影响，我们这里是缩小图片，所以直接设置为false
        Bitmap dst = Bitmap.createScaledBitmap(src, dstWidth, dstHeight, false);
        if (src != dst) { // 如果没有缩放，那么不回收
            src.recycle(); // 释放Bitmap的native像素数组
        }
        return dst;
    }

    /**
     * 从SD卡上加载图片
     *
     * @param pathName      路径
     * @param reqWidth      请求宽度
     * @param reqHeight     请求高度
     * @return              Bitmap
     */
    public static Bitmap decodeSampledBitmapFromFile(String pathName, int reqWidth, int reqHeight) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(pathName, options);
        options.inSampleSize = calculateInSampleSize(options, pathName,reqWidth, reqHeight);
        options.inJustDecodeBounds = false;
        Bitmap src = BitmapFactory.decodeFile(pathName, options);
        return createScaleBitmap(src, reqWidth, reqHeight, options.inSampleSize);
    }

    /**
     * 删除临时图片
     * @param path  图片路径
     */
    public static void deleteTempFile(String path){
        File file = new File(path);
        if (file.exists()){
            file.delete();
        }
    }
}