工作日记第一篇（图片处理《压缩》）

原本已经在度娘上搜出了各种压缩图片的处理方式，有暴力的失真的也有温柔的。

但是今天由于需求问题需要将图片压缩。

接下里就是压缩的代码

InputStream inputStream =null;

Bitmap bitmap =null;

try{

inputStream = context.getContentResolver().openInputStream(uri);

BitmapFactory.Options options =newBitmapFactory.Options();

options.inJustDecodeBounds=true;

BitmapFactory.decodeStream(inputStream, null,options);

// int imageHeight = options.outHeight;

// int imageWidth = options.outWidth;

options.inJustDecodeBounds=false;

options.inSampleSize= GlobalTool.computeSampleSize(options,-1,

512*512);

bitmap = BitmapFactory.decodeStream(inputStream, null,options);

}catch(FileNotFoundException e) {

//TODO Auto-generated catch block

}

以下就是压缩的计算代码

获取inSampleSize ： intcomputeSampleSize

public static intcomputeSampleSize(BitmapFactory.Options options,

intminSideLength, intmaxNumOfPixels) {

intinitialSize =computeInitialSampleSize(options,minSideLength,

maxNumOfPixels);

introundedSize;

if(initialSize <=8) {

roundedSize=1;

while(roundedSize< initialSize) {

roundedSize<<=1;

}

}else{

roundedSize= (initialSize +7) /8*8;

}

return roundedSize;

}

获取intinitialSize

private static intcomputeInitialSampleSize(BitmapFactory.Options options,

int minSideLength, intmaxNumOfPixels) {

doublew = options.outWidth;

doubleh = options.outHeight;

int lowerBound = (maxNumOfPixels == -1) ?1:

(int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));

int upperBound = (minSideLength == -1) ?128:

(int) Math.min(Math.floor(w / minSideLength),

Math.floor(h / minSideLength));

if(upperBound < lowerBound) {

return lowerBound;

}

if((maxNumOfPixels == -1) &&

(minSideLength == -1)) {

return1;

}else if(minSideLength == -1) {

return lowerBound;

}else{

return upperBound;

}

}

outW=2448.0/outH=3264.0

outW*outH=7990272.0

outW*outH/maxNumOfPixels=30.48046875

initialSize=6

roundedSize=8

scaleSize=1/8

byte=499392/rowCount=1224

height=408/width=306

上面还有一些打印的计算结果便于理解