/**
* decode这个图片并且按比例缩放以减少内存消耗，虚拟机对每张图片的缓存大小也是有限制的
*
* @param f
* @param requiredSize
* @return
*/
private Bitmap decodeFile(File f, int requiredSize) {
try {
// decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(f), null, o);
// 计算合理的缩放指数（2的整幂数）
int width_tmp = o.outWidth, height_tmp = o.outHeight;
int scale = 1;
while (true) {
// if (width_tmp / 2 < requiredSize || height_tmp / 2 <
// requiredSize){
// break;
// }
// width_tmp /= 2;
// height_tmp /= 2;
// scale *= 2;
if (width_tmp <= requiredSize || height_tmp <= requiredSize) {
break;
}
width_tmp /= 2;
height_tmp /= 2;
scale *= 2;
}
// decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
// o2.inSampleSize = (int) scale;
o2.inSampleSize = scale;
o2.inPreferredConfig = config.getBitmapConfig();
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e) {
}
return null;
}
