package com.moral.andbrickslib.compresshelper;
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import android.content.res.Resources;
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import android.graphics.Bitmap;
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import android.graphics.BitmapFactory;
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import android.media.ExifInterface;
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import java.io.File;
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import java.io.IOException;
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/**
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* Bitmap 压缩相关操作工具类
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*
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*
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*
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* 原理不明白请查看我博客：http://www.cnblogs.com/liushilin/p/6116759.html
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*
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* Author: nanchen
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* Email: liushilin520@foxmail.com
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* Date: 2017-02-13 15:43
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*/
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public class BitmapUtil {
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/**
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* 计算图片的压缩比率
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*
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* @param options 参数
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* @param reqWidth 目标的宽度
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* @param reqHeight 目标的高度
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* @param pathName 路径
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* @return 计算的SampleSize
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*/
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private static int calculateInSampleSize(BitmapFactory.Options options, String pathName, int reqWidth, int reqHeight) {
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// 源图片的高度和宽度
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int height = options.outHeight;
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int width = options.outWidth;
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if (height == -1 || width == -1) {
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try {
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ExifInterface exifInterface = new ExifInterface(pathName);
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height = exifInterface.getAttributeInt(ExifInterface.TAG_IMAGE_LENGTH, ExifInterface.ORIENTATION_NORMAL);//获取图片的高度
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width = exifInterface.getAttributeInt(ExifInterface.TAG_IMAGE_WIDTH, ExifInterface.ORIENTATION_NORMAL);//获取图片的宽度
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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int inSampleSize = 1;
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if (height > reqHeight || width > reqWidth) {
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final int halfHeight = height / 2;
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final int halfWidth = width / 2;
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// Calculate the largest inSampleSize value that is a power of 2 and keeps both
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// height and width larger than the requested height and width.
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while ((halfHeight / inSampleSize) > reqHeight
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&& (halfWidth / inSampleSize) > reqWidth) {
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inSampleSize *= 2;
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}
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}
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return inSampleSize;
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}
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/**
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* 计算图片的压缩比率
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*
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* @param options 参数
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* @param reqWidth 目标的宽度
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* @param reqHeight 目标的高度
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* @return 计算的SampleSize
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*/
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private static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
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// 源图片的高度和宽度
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int height = options.outHeight;
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int width = options.outWidth;
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int inSampleSize = 1;
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if (height > reqHeight || width > reqWidth) {
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final int halfHeight = height / 2;
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final int halfWidth = width / 2;
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// Calculate the largest inSampleSize value that is a power of 2 and keeps both
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// height and width larger than the requested height and width.
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while ((halfHeight / inSampleSize) > reqHeight
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&& (halfWidth / inSampleSize) > reqWidth) {
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inSampleSize *= 2;
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}
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}
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return inSampleSize;
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}
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/**
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* 从Resources中加载图片
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*
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* @param res Resource
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* @param resId 资源id
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* @param reqWidth 请求宽度
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* @param reqHeight 请求高度
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* @return Bitmap
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*/
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public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId, int reqWidth, int reqHeight) {
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final BitmapFactory.Options options = new BitmapFactory.Options();
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options.inJustDecodeBounds = true; // 设置成了true,不占用内存，只获取bitmap宽高
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BitmapFactory.decodeResource(res, resId, options); // 读取图片长款
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options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight); // 调用上面定义的方法计算inSampleSize值
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// 使用获取到的inSampleSize值再次解析图片
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options.inJustDecodeBounds = false;
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Bitmap src = BitmapFactory.decodeResource(res, resId, options); // 载入一个稍大的缩略图
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return createScaleBitmap(src, reqWidth, reqHeight, options.inSampleSize); // 进一步得到目标大小的缩略图
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}
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/**
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* 通过传入的bitmap，进行压缩，得到符合标准的bitmap
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*
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* @param src Bitmap源图
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* @param dstWidth 宽度
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* @param dstHeight 高度
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* @return 新的Bitmap
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*/
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private static Bitmap createScaleBitmap(Bitmap src, int dstWidth, int dstHeight, int inSampleSize) {
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//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。
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if (inSampleSize % 2 == 0) {
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return src;
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}
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if (src == null){
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return null;
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}
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// 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
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Bitmap dst = Bitmap.createScaledBitmap(src, dstWidth, dstHeight, false);
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if (src != dst) { // 如果没有缩放，那么不回收
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src.recycle(); // 释放Bitmap的native像素数组
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}
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return dst;
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}
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/**
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* 从SD卡上加载图片
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*
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* @param pathName 路径
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* @param reqWidth 请求宽度
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* @param reqHeight 请求高度
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* @return Bitmap
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*/
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public static Bitmap decodeSampledBitmapFromFile(String pathName, int reqWidth, int reqHeight) {
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final BitmapFactory.Options options = new BitmapFactory.Options();
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options.inJustDecodeBounds = true;
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BitmapFactory.decodeFile(pathName, options);
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options.inSampleSize = calculateInSampleSize(options, pathName,reqWidth, reqHeight);
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options.inJustDecodeBounds = false;
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Bitmap src = BitmapFactory.decodeFile(pathName, options);
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return createScaleBitmap(src, reqWidth, reqHeight, options.inSampleSize);
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}
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/**
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* 删除临时图片
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* @param path 图片路径
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*/
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public static void deleteTempFile(String path){
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File file = new File(path);
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if (file.exists()){
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file.delete();
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}
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}
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}
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