CODEWITHSUNDEEP
androidpersistenceandroid-roomstorage-access-framework
ro.nin
ro.nin

Reputation: 121

Managing local images with persistent data

I'm struggling to understand what could be a simple workaround for associating images and persistent data objects in android. In more details, i've put up a simple room persistence architecture and now I need to add a field "image" to the java persisted object. I've tried to work with uri but my knowledge of Android is very poor, and what I get is that the uri I recover when picking an image with the android file manager is only valid until reboot, so if I would save the so obtained uri in the database, it would make no sense when recovered later. How should I manage?

Basically what I need is a simple way to link an object to a local image stored in the phone (or captured on the fly with the camera), no worries about image deletion by the user or anything, just a simple way.

For istance I tried to tinker with the google code example but i clearly failed because I don't know what i'm doing

private Bitmap getBitmapFromUri(Uri uri) throws IOException {
        ParcelFileDescriptor parcelFileDescriptor =
                getContentResolver().takePersistableUriPermission(uri, Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
        FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
        Bitmap image = BitmapFactory.decodeFileDescriptor(fileDescriptor);
        parcelFileDescriptor.close();
        return image;
    }

this code results in compilation error, with required: parcedDescriptor... and VOID found, on the call of takePersistableUriPermission. I don't even know if that is a solution to my problem.

this is the code I use to get the uri from the local image, but I'm planning also to let the Camera snap a photo and pass it to for saving/linking it

// ACTION_OPEN_DOCUMENT is the intent to choose a file via the system's file
                // browser.
                Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);

                // Filter to only show results that can be "opened", such as a
                // file (as opposed to a list of contacts or timezones)
                intent.addCategory(Intent.CATEGORY_OPENABLE);

                // Filter to show only images, using the image MIME data type.
                // If one wanted to search for ogg vorbis files, the type would be "audio/ogg".
                // To search for all documents available via installed storage providers,
                // it would be "*/*".
                intent.setType("image/*");

                startActivityForResult(intent, READ_REQUEST_CODE);

Upvotes: 0

Views: 812

Answers (1)

CommonsWare
CommonsWare

Reputation: 1006944

the uri I recover when picking an image with the android file manager is only valid until reboot, so if I would save the so obtained uri in the database, it would make no sense when recovered later

That's not quite accurate.

A Uri that you pull in via ACTION_OPEN_DOCUMENT will be good for whatever activity gets the Uri via onActivityResult(). If you pass that Uri to another component, you can use FLAG_GRANT_READ_URI_PERMISSION to allow that component to read the content at that Uri. But once your process ends, your access to that content goes away.

Since you used ACTION_OPEN_DOCUMENT, you can use takePersistableUriPermission() request to have long-term access to the content, but that still only works if the content is still there. If the user deletes the content, or perhaps even moves it, you will lose access.

For istance I tried to tinker with the google code example but i clearly failed because I don't know what i'm doing

takePersistableUriPermission() does not return a ParcelFileDescriptor. Otherwise, that particular call seems OK.

With respect to loading the image, please use an existing image-loading library (e.g., Glide, Picasso).

Upvotes: 1

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