android - Reusing bitmaps for BitmapFactory.decodeFile and BitmapFactory.Options.inBitmap -

my app decodes lot of bitmaps sd card, want reuse existing bitmaps decrease gc work. see examples android training , this video , works perfect bitmapfactory.decoderesource, not bitmapfactory.decodefile. use next code:

private void testbitmapreusing() {         bitmapfactory.options options = newoptions();         bitmap bitmap = decode(options);          options.inbitmap = bitmap;         bitmap = decode(options);     }      private bitmapfactory.options newoptions() {         bitmapfactory.options options = new bitmapfactory.options();         options.insamplesize = 1;         options.inmutable = true;         return options;     }      private bitmap decode(bitmapfactory.options options) {         return  bitmapfactory.decodefile("/mnt/sdcard/sun.jpg", options);         //  return bitmapfactory.decoderesource(getresources(), r.drawable.sun, options);     } 

commented code (bitmapfactory.decoderesource) works expected, decodes new bitmap using existing bitmap. uncommented code (bitmapfactory.decodefile) doesn't decode new bitmap. writes log message "e/bitmapfactory: unable decode stream: java.lang.illegalargumentexception: problem decoding existing bitmap"

so mistake?

update realize fail. try decode gif images, impossible reuse bitmaps in gif format. docs says:

the source content must in jpeg or png format (whether resource or stream) 

it might not you're looking directly, alternate approach create map (e.g. hashmap) , add resources they're being called. this:

hashmap<string, bitmap> map = new hashmap<string, bitmap>();  public bitmap loadbitmap(string location) {     if (map.containskey(location))         return map.get(location);      bitmap bmp = yourdecodemethod(location);     map.put(location, bmp);      return bmp; } 

this same way use when not want reload resources every time. sorry if not wanted do, tried best understand actual goal :)

good luck!