Android图片压缩-luban

1.主要算法实现

 private File thirdCompress(@NonNull File file) {
 String thumb = mCacheDir.getAbsolutePath() + File.separator + (TextUtils.isEmpty(filename) ? System.currentTimeMillis() : filename);
 double size;
 String filePath = file.getAbsolutePath();
 int angle = getImageSpinAngle(filePath);
 int width = getImageSize(filePath)[0];
 int height = getImageSize(filePath)[1];
 int thumbW = width % 2 == 1 ? width + 1 : width;
 int thumbH = height % 2 == 1 ? height + 1 : height;
 width = thumbW > thumbH ? thumbH : thumbW;
 height = thumbW > thumbH ? thumbW : thumbH;
 double scale = ((double) width / height);
 if (scale <= 1 && scale > 0.5625) {
 if (height < 1664) {
 if (file.length() / 1024 < 150) return file;
 size = (width * height) / Math.pow(1664, 2) * 150;
 size = size < 60 ? 60 : size;
 } else if (height >= 1664 && height < 4990) {
 thumbW = width / 2;
 thumbH = height / 2;
 size = (thumbW * thumbH) / Math.pow(2495, 2) * 300;
 size = size < 60 ? 60 : size;
 } else if (height >= 4990 && height < 10240) {
 thumbW = width / 4;
 thumbH = height / 4;
 size = (thumbW * thumbH) / Math.pow(2560, 2) * 300;
 size = size < 100 ? 100 : size;
 } else {
 int multiple = height / 1280 == 0 ? 1 : height / 1280;
 thumbW = width / multiple;
 thumbH = height / multiple;
 size = (thumbW * thumbH) / Math.pow(2560, 2) * 300;
 size = size < 100 ? 100 : size;
 }
 } else if (scale <= 0.5625 && scale > 0.5) {
 if (height < 1280 && file.length() / 1024 < 200) return file;
 int multiple = height / 1280 == 0 ? 1 : height / 1280;
 thumbW = width / multiple;
 thumbH = height / multiple;
 size = (thumbW * thumbH) / (1440.0 * 2560.0) * 400;
 size = size < 100 ? 100 : size;
 } else {
 int multiple = (int) Math.ceil(height / (1280.0 / scale));
 thumbW = width / multiple;
 thumbH = height / multiple;
 size = ((thumbW * thumbH) / (1280.0 * (1280 / scale))) * 500;
 size = size < 100 ? 100 : size;
 }
 return compress(filePath, thumb, thumbW, thumbH, angle, (long) size);
 }
 

 /**
 
 
 
  
obtain the thumbnail that specify the size
 
  
 
 
  
@param imagePath the target image path
 
  
@param width the width of thumbnail
 
  
@param height the height of thumbnail
 
  
@return {@link Bitmap}
 */
 
 
 
 
private Bitmap compress(String imagePath, int width, int height) {
 
 
BitmapFactory.Options options = new BitmapFactory.Options();

options.inJustDecodeBounds = true;

BitmapFactory.decodeFile(imagePath, options);

int outH = options.outHeight;

int outW = options.outWidth;

int inSampleSize = 1;

if (outH > height || outW > width) {

    int halfH = outH / 2;

    int halfW = outW / 2;

    while ((halfH / inSampleSize) > height && (halfW / inSampleSize) > width) {

        inSampleSize *= 2;

    }
}

options.inSampleSize = inSampleSize;

options.inJustDecodeBounds = false;

int heightRatio = (int) Math.ceil(options.outHeight / (float) height);

int widthRatio = (int) Math.ceil(options.outWidth / (float) width);

if (heightRatio > 1 || widthRatio > 1) {

    if (heightRatio > widthRatio) {

    options.inSampleSize = heightRatio;

} else {

    options.inSampleSize = widthRatio;

}

options.inJustDecodeBounds = false;

return BitmapFactory.decodeFile(imagePath, options);
 
 
}