Colin's Journal

It took me two days of digging around to finally figure out why ExpenseClam was not working properly on the HTC One X. The symptoms were straightforward enough: taking a picture would show a blank result, and the expense record showed a warning icon saying that the image file could not be loaded.

By adding some debug cpde, and with the help of a friend who owns the device, I was able to confirm that the camera code was creating an image file and that it was successfully saved. By signing up to testdroid.com I could get access to the logcat output of a real device on the cloud, which gave me the next breakthrough. My call to BitmapFactory.decodeFile was failing to return a bitmap, in turn caused by SkImageDecoder returning null.

Searching online sent me chasing a few red herrings, but eventually I had the idea of removing the code which sets the thumbnail size before taking the photo. Suddenly it worked, the bitmap correctly loads. So what went wrong?

The API documentation for setJpegThumbnailSize is fairly unambiguous “If applications set both width and height to 0, EXIF will not contain thumbnail.” Further to this the method getSupportedJpegThumbnailSizes states “This method will always return a list with at least two elements. Size 0,0 (no thumbnail) is always supported.” Based on this I had chosen to disable thumbnails in order to reduce image file sizes.

It turns out that only most devices support this. The HTC One X accepts setting the thumbnail size to 0, but then produces a file that the BitmapFactory cannot read. Leaving the thumbnail settings to the device defaults works.

Hopefully this post will save someone else a couple of days investigation.

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