一个好用的android图片压缩工具类
发表时间：2020-10-19
发布人：葵宇科技
浏览次数：37
<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">用了良久图片紧缩，之前人们一向应用google的官方图片紧缩办法</span>
final BitmapFactory.Options options = new BitmapFactory.Options(); options.inJustDecodeBounds = true; BitmapFactory.decodeResource(res, resId, options); options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight); options.inJustDecodeBounds = false; return BitmapFactory.decodeResource(res, resId, options);
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final 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;
}代率攀来自google
http://developer.android.com/training/displaying-bitmaps/load-bitmap.html
细心看calucelateInSamplesize办法，该算法返回的是一种紧缩比例，细心一看他的计算过程，你会发明，inSampleSize的变更过程是2-4-8,，而真正进入wile轮回时，宽高就已经被算作是小了一笆攀来计算的了，所以，膳绫擎那个网站说12M能紧缩到0.75M,就是因为差距太大年夜，如不雅安卓手机内部紧缩本身的图片(大年夜概是2M紧缩到100K)，所以此时，这个办法就实用于android编码紧缩了。
所以不才针对于android编码时紧缩，在此对它进行了优化，优化后代码如下：
运行: culculateInSampleSize(bm,200,300)效不雅:
<pre name="code" class="java"><span style="font-family: Arial, Helvetica, sans-serif;">/**</span>* 盘似揭捉缩比例值(改进版 by touch_ping)
*
* 原版2>4>8...倍紧缩
* 当前2>3>4...倍紧缩
*
* @param options
* 解析图片的设备信息
* @param reqWidth
* 所需图片紧缩尺寸最小宽度
* @param reqHeight
* 所需图片紧缩尺寸最小高度
* @return
*/
public static int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
final int picheight = options.outHeight;
final int picwidth = options.outWidth;
Log.i("test", "原尺寸:" + picwidth + "*" +picheight);
int targetheight = picheight;
int targetwidth = picwidth;
int inSampleSize = 1;
if (targetheight > reqHeight || targetwidth > reqWidth) {
while (targetheight >= reqHeight
&& targetwidth>= reqWidth) {
Log.i("test","紧缩:" +inSampleSize + "倍");
inSampleSize += 1;
targetheight = picheight/inSampleSize;
targetwidth = picwidth/inSampleSize;
}
}
Log.i("test","最终紧缩比例:" +inSampleSize + "倍");
Log.i("test", "新尺寸:" + targetwidth + "*" +targetheight);
return inSampleSize;
}
紧缩效不雅如下：
[img]
文件大年夜小大年夜1.12M变成81.75k
最终附上完全紧缩对象类:
package com.example.mqtest;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;
/**
* 图片紧缩对象类
* @author touch_ping
* 2015-1-5 下昼1:29:59
*/
public class BitmapCompressor {
/**
* 质量紧缩
* @author ping 2015-1-5 下昼1:29:58
* @param image
* @param maxkb
* @return
*/
public static Bitmap compressBitmap(Bitmap image,int maxkb) {
//L.showlog("紧缩图片");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
image.compress(Bitmap.CompressFormat.JPEG, 50, baos);// 质量紧缩办法，这里100表示不紧缩，把紧缩后的数据存放到baos中
int options = 100;
// Log.i("test","原始大年夜小" + baos.toByteArray().length);
while (baos.toByteArray().length / 1024 > maxkb) { // 轮回断定如不雅紧缩后图片是否大年夜于(maxkb)50kb,大年夜于持续紧缩
// Log.i("test","紧缩一次!");
baos.reset();// 重置baos即清空baos
options -= 10;// 每次都削减10
image.compress(Bitmap.CompressFormat.JPEG, options, baos);// 这里紧缩options%，把紧缩后的数据存放到baos中
}
// Log.i("test","紧缩后大年夜小" + baos.toByteArray().length);
ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());// 把紧缩后的数据baos存放到ByteArrayInputStream中
Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);// 把ByteArrayInputStream数据生成图片
return bitmap;
}
/**
* http://developer.android.com/training/displaying-bitmaps/load-bitmap.html
* 官网：获取紧缩后的图片
*
* @param res
* @param resId
* @param reqWidth
* 所需图片紧缩尺寸最小宽度
* @param reqHeight
* 所需图片紧缩尺寸最小高度
* @return
*/
public static Bitmap decodeSampledBitmapFromResource(Resources res,
int resId, int reqWidth, int reqHeight) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
options.inSampleSize = calculateInSampleSize(options, reqWidth,
reqHeight);
options.inJustDecodeBounds = false;
return BitmapFactory.decodeResource(res, resId, options);
}
/**
* 官网：获取紧缩后的图片
*
* @param res
* @param resId
* @param reqWidth
* 所需图片紧缩尺寸最小宽度
* @param reqHeight
* 所需图片紧缩尺寸最小高度
* @return
*/
public static Bitmap decodeSampledBitmapFromFile(String filepath,
int reqWidth, int reqHeight) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(filepath, options);
options.inSampleSize = calculateInSampleSize(options, reqWidth,
reqHeight);
options.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(filepath, options);
}
public static Bitmap decodeSampledBitmapFromBitmap(Bitmap bitmap,
int reqWidth, int reqHeight) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 90, baos);
byte[] data = http://www.sjsjw.com/100/000202MYM011683/baos.toByteArray();
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeByteArray(data, 0, data.length, options);
options.inSampleSize = calculateInSampleSize(options, reqWidth,
reqHeight);
options.inJustDecodeBounds = false;
return BitmapFactory.decodeByteArray(data, 0, data.length, options);
}
/**
* 盘似揭捉缩比例值(改进版 by touch_ping)
*
* 原版2>4>8...倍紧缩
* 当前2>3>4...倍紧缩
*
* @param options
* 解析图片的设备信息
* @param reqWidth
* 所需图片紧缩尺寸最小宽度O
* @param reqHeight
* 所需图片紧缩尺寸最小高度
* @return
*/
public static int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
final int picheight = options.outHeight;
final int picwidth = options.outWidth;
Log.i("test", "原尺寸:" + picwidth + "*" +picheight);
int targetheight = picheight;
int targetwidth = picwidth;
int inSampleSize = 1;
if (targetheight > reqHeight || targetwidth > reqWidth) {
while (targetheight >= reqHeight
&& targetwidth>= reqWidth) {
Log.i("test","紧缩:" +inSampleSize + "倍");
inSampleSize += 1;
targetheight = picheight/inSampleSize;
targetwidth = picwidth/inSampleSize;
}
}
Log.i("test","最终紧缩比例:" +inSampleSize + "倍");
Log.i("test", "新尺寸:" + targetwidth + "*" +targetheight);
return inSampleSize;
}
}
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final 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;
}
