Android - display image permissions failure(kotlin, android studio).

Question

3.00/5 (2 votes)

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Kotlin, Android Studio... - Loading a JPG file into an imageview
File Permissions problem.

I have a small application which I load an image from storage
INITIALLY using Chooser, but on the subsequent calls directly using
the handle retrieved.

1. Initial load is using the file chooser - and this shows an image.
2. Subsequent loads are OK
3. Exiting the Emulator and then restarting (killing the permissions of course) - means I have to add permissions.
4. Try to add permissions for reading external storage fails.

What I have tried:

1. Added uses-permissions in the AndroidManifest.xml file as follows

<uses-permission android:name="android.permission.ACTION_OPEN_DOCUMENT"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

2. Call to the chooser...

imgSelect.setOnClickListener{displayFileChooser()}

3. Function it called.

private fun displayFileChooser(){
    val chooseFile =  Intent(Intent.ACTION_OPEN_DOCUMENT)
    chooseFile.addCategory(Intent.CATEGORY_OPENABLE)
    chooseFile.type = "*/*"
    startActivityForResult(chooseFile, 1)
}

This all works until I exit the emulator and restart....- killing the permissions.
Saved the Image URI and on load, simply set the image to the URI -
OBVIOUSLY, I will need permissions for this, thus on APPLICATION START, I have the following (in my onCreate() function).

val p = arrayOf("android.permission.ACTION_OPEN_DOCUMENT")
requestPermissions(p, 200)

and of course we override the onRequestPermissions....

<pre>    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        }

When I start the application after exiting the emulator - this onRequestPermissionsResult returns a -1 (permission denied)....
Thus, I cannot reload images unless I use the chooser again - which
really defeats the object here.

Would any kind person have any ideas how I can overcome this
heinous and annoying result and get permission approved.

Thanks

Posted 29-Apr-23 6:32am

Member 10488837

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Comments

Richard MacCutchan 30-Apr-23 4:19am

How do you expect to open the image file without using the file chooser? What reference are you using to access the file in the second attempt?

Member 10488837 30-Apr-23 5:33am

Thanks for your time sir.
Using the URI I previously stored - simply set the imaged to the saved URI.
"imgNode.setImageURI(currentURI)"
When I do this I get a permissions Exception of permission denied.
As I am getting permission denied, I thought I didn't need to actually open
the file as it was permission problem not open problem.

Richard MacCutchan 30-Apr-23 6:39am

What is the actual content of currentURI at that point?

Member 10488837 30-Apr-23 7:48am

content://com.android.externalstorage.documents/document/primary%3APictures%2FSierra%20%26%20Wolfy.jpg

Richard MacCutchan 30-Apr-23 7:50am

Try adding the permissions that you originally used to open the file.

Member 10488837 30-Apr-23 7:56am

Sorry sir, don't understand...
I used the chooser - and permission was set to ACTION_OPEN_DOCUMENT
Obviously that's the permission I need but I thought I set that in
these 2 statements.
"val p = arrayOf("android.permission.ACTION_OPEN_DOCUMENT")"
"requestPermissions(p, 200)"

Is that not correct? - should I do more.

Thanks so much for your time

EDIT: -
Just to clarify

When I do the requestPermissions(p,200) - this obviously goes through
the override "onRequestPermissionsResult()" - and in there I am getting
the PermissionDenied... - This is in the CreateView() of the parent form.
I will try this in the current form.

Further Edit: -
Utilising the requestPermissions call in the current form still has no change,
I am getting the following Exception...
java.lang.SecurityException: Permission Denial: opening provider com.android.externalstorage.ExternalStorageProvider from ProcessRecord{cdb11de 6067:com.example.missioncontroller/u0a153} (pid=6067, uid=10153) requires that you obtain access using ACTION_OPEN_DOCUMENT or related APIs

In Addition, following the call - it goes through the "onRequestPermissionsResult" override.
This gives a -1 in the grantResults field

Just for completeness, here's the function I originally used to call the chooser -
private fun displayFileChooser(){
val chooseFile = Intent(Intent.ACTION_OPEN_DOCUMENT)
chooseFile.addCategory(Intent.CATEGORY_OPENABLE)
chooseFile.type = "*/*"
startActivityForResult(chooseFile, 1)
}
And of course - the onActivityResult

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
if (requestCode == 1 && resultCode == Activity.RESULT_OK){
val content = data!!.data
val src = content!!.path
currImg.setImageURI(content)
currentURI = content
currChk.isChecked = true
checkDataChanged()
}
}

Richard MacCutchan 30-Apr-23 11:53am

The error message is telling you what's wrong. Try the same code that you used originally, but just using the name of the file, instead of the chooser.

Member 10488837 30-Apr-23 12:04pm

Agreed, thanks -
I thought that was what I was doing - I don't use the chooser second time,
Just simply call for permission using the same intent
The call for permissions is this
"val p = arrayOf("android.permission.ACTION_OPEN_DOCUMENT")"
"requestPermissions(p, 200)"

Then using the stored URI, I simply put that in my setting of the Image URI
like this -> "imgNode.setImageURI(currentURI)"

I am sorry perhaps I didn't make that clear.

Richard MacCutchan 30-Apr-23 12:07pm

Well you use Intent.CATEGORY_OPENABLE in the original so maybe that is also required here.

Member 10488837 30-Apr-23 12:16pm

Thanks Sir, tried a couple of things...

1. Added CATEGORY_OPENABLE to the permissions so it looks like this...
var p = arrayOf("android.permission.ACTION_OPEN_DOCUMENT", "android.permission.CATEGORY_OPENABLE")

Also - I noticed that the request code for the chooser was 1 and
in the open I used 200 - so I changed this to 1 too to match the chooser
requestPermissions(p, 1)

Interestingly, now I get an array of int from the permissonsresult
Which is [-1], [-1] - both seem to fail!!

Thanks for the good leads thus far though

Richard MacCutchan 30-Apr-23 12:29pm

Sorry, but I have no more suggestions. The changes to the permissions system in Android seems nuch more difficult than it was a few years ago.

Member 10488837 30-Apr-23 12:31pm

Heyy, no worries,
Thanks for your ideas -
it has made me think in different directions
and that's teamwork - I am very grateful and
will post here if I manage to find a solution

It's very kind of you to take the time

Richard MacCutchan 30-Apr-23 12:40pm

Thank you, I appreciate your kind comments.

Member 10488837 30-Apr-23 14:55pm

Sorted: - here's the thing....

From the Kotlin Android Documentation -
When your app opens a file for reading or writing, the system gives your app a URI permission grant for that file, which lasts until the user's device restarts. Suppose, however, that your app is an image-editing app, and you want users to be able to access the 5 images that they most recently edited, directly from your app. If the user's device has restarted, you'd have to send the user back to the system picker to find the files.

To preserve access to files across device restarts and create a better user experience, your app can "take" the persistable URI permission grant that the system offers.

Thus, before I set the image URI -> currImg.SetImageURI(currentURI)

I have inserted the following... Here you can see I have the SetImage as the last line.

val rPermPersist = Intent.FLAG_GRANT_READ_URI_PERMISSION
this.context!!.contentResolver.takePersistableUriPermission(currentURI, rPermPersist)
currImg.setImageURI(currentURI)

This has thus far worked over emulator restarts..

My grateful thanks for your excellent assistance which
gave me the inspiration and ideas upon where to look and
without this, I would have taken an eternity to solve.

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Member 10488837 · Accepted Answer · 2023-04-30T08:59:00

From the Android documentation:-

Persist permissions
When your app opens a file for reading or writing, the system gives your app a URI permission grant for that file, which lasts until the users device restarts. Suppose, however, that your app is an image-editing app, and you want users to be able to access the 5 images that they most recently edited, directly from your app. If the users device has restarted, you would have to send the user back to the system picker to find the files.
To preserve access to files across device restarts and create a better user experience, your app can "take" the persistable URI permission grant that the system offers.

The following code is inserted just before the currImg.SetImageURI(currentURI)

val rPermPersist = Intent.FLAG_GRANT_READ_URI_PERMISSION
this.context!!.contentResolver.takePersistableUriPermission(currentURI, rPermPersist)
currImg.setImageURI(currentURI)

This allows me to restart the emulator and then have persistent permission to that particular file.