将位图旋转90度并保存

Question

all! I'm at a total loss here with this question. It may have been answered, but I can't find anyone asking for precisely what I need.

I have a jpeg file saved to the SDCARD, and want to programatically rotate it 90 degrees clockwise, then save it back to the card (either overwriting the original or deleting the original after editing). The jpeg is loaded into

File myFile;

Can anyone advise me as to how to go about this? I imagine it has something to do with BitmapFactory and Matrices, but like I said: I'm a little over my head here!

Thanks!

Answer 1

Try this.

public Bitmap rotate(String file)
{
         Bitmap source = BitmapFactory.decodeFile("/sdcard/ChuckNorris.png");
         Bitmap b = Bitmap.createBitmap(source.getWidth(), source.getHeight(), Config.ARGB_8888);

         Paint p = new Paint();
         p.setColor(Color.BLACK);

         Canvas f = new Canvas(b);
         f.drawBitmap(source, 0, 0, p);

         f.rotate(90);

         return b;
}

Note: Doesn't try on my own

Answer 2

I found the answer!

For JPG files, apparently you can just niftily edit the exif data using the following method:

ExifInterface exif = new ExifInterface(myFile.getAbsolutePath());
exif.setAttribute(ExifInterface.TAG_ORIENTATION, "6");
exif.saveAttributes();

Are there any downsides to using this approach? It seems to work pretty well as far as I can determine..