一个好用的android图片压缩工具类
16lz
2021-01-23
用了很久图片压缩，之前人们一直使用google的官方图片压缩方法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;}代码来自google
http://developer.android.com/training/displaying-bitmaps/load-bitmap.html
仔细看calucelateInSamplesize方法，该算法返回的是一种压缩比例，仔细一看他的计算过程，你会发现，inSampleSize的变化过程是2-4-8,，而真正进入wile循环时，宽高就已经被看成是小了一半来计算的了，所以，上面那个网站说12M能压缩到0.75M,就是因为差距太大，如果安卓手机内部压缩自己的图片(大概是2M压缩到100K)，所以此时，这个方法就适用于android编码压缩了。
所以鄙人针对于android编码时压缩，在此对它进行了优化，优化后代码如下：
运行: culculateInSampleSize(bm,200,300)效果:
/***
* 原版2>4>8...倍压缩
* 当前2>3>4...倍压缩
*
* @param options
* 解析图片的配置信息
* @param reqWidth
* 所需图片压缩尺寸最小宽度
* @param reqHeight
* 所需图片压缩尺寸最小高度
* @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","压缩:" +inSampleSize + "倍");
inSampleSize += 1;
targetheight = picheight/inSampleSize;
targetwidth = picwidth/inSampleSize;
}
}
Log.i("test","最终压缩比例:" +inSampleSize + "倍");
Log.i("test", "新尺寸:" + targetwidth + "*" +targetheight);
return inSampleSize;
}
压缩效果如下：
文件大小从1.12M变成81.75k
最终附上完整压缩工具类:
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;/** * 图片压缩工具类 * @author touch_ping * 2015-1-5 下午1:29:59 */public class BitmapCompressor {/** * 质量压缩 * @author ping 2015-1-5 下午1:29:58 * @param image * @param maxkb * @return */public static Bitmap compressBitmap(Bitmap image,int maxkb) {//L.showlog("压缩图片");ByteArrayOutputStream baos = new ByteArrayOutputStream();image.compress(Bitmap.CompressFormat.JPEG, 50, baos);// 质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中int options = 100;//Log.i("test","原始大小" + baos.toByteArray().length);while (baos.toByteArray().length / 1024 > maxkb) { // 循环判断如果压缩后图片是否大于(maxkb)50kb,大于继续压缩//Log.i("test","压缩一次!");baos.reset();// 重置baos即清空baosoptions -= 10;// 每次都减少10image.compress(Bitmap.CompressFormat.JPEG, options, baos);// 这里压缩options%，把压缩后的数据存放到baos中}//Log.i("test","压缩后大小" + baos.toByteArray().length);ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());// 把压缩后的数据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：获取压缩后的图片 * * @param res * @param resId * @param reqWidth * 所需图片压缩尺寸最小宽度 * @param reqHeight * 所需图片压缩尺寸最小高度 * @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：获取压缩后的图片 * * @param res * @param resId * @param reqWidth * 所需图片压缩尺寸最小宽度 * @param reqHeight * 所需图片压缩尺寸最小高度 * @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 = 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);}/** * 计算压缩比例值(改进版 by touch_ping) * * 原版2>4>8...倍压缩 * 当前2>3>4...倍压缩 * * @param options * 解析图片的配置信息 * @param reqWidth * 所需图片压缩尺寸最小宽度O * @param reqHeight * 所需图片压缩尺寸最小高度 * @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","压缩:" +inSampleSize + "倍");inSampleSize += 1;targetheight = picheight/inSampleSize;targetwidth = picwidth/inSampleSize;}}Log.i("test","最终压缩比例:" +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;}更多相关文章
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