[Android-development] [Interest] Android-6 File Opening Permissions

[Robert Iakobashvili]

Dear Ekke,
It is very good example which is asking not only Camera
by also external storage file permissions.

It is worth to add it to the examples of Android Extras.
jm2c

Thanks.

Kind regards,
Robert


On Thu, Apr 6, 2017 at 12:29 PM, ekke <ekke at ekkes-corner.org> wrote:
> here's also an example app demonstrating HowTo ask for permissions if
> Camera is needed
> https://github.com/ftylitak/qzxing/tree/master/examples/QZXingLive
> haven't tested by myself yet, but will soon integrate into QtWorldSummit
> Conference APP to read QR Codes
>
> ekke
>
> Am 06.04.17 um 10:31 schrieb Robert Iakobashvili:
>> Hi,
>> Replying to my own email hoping it will help somebody
>> not to waist time.
>>
>> The issue was related to Android-6 and above file treatment permissions.
>>
>> It is well covered by the excellent link below:
>> http://www.bytran.org/androidmpermissions.htm
>>
>> IMHO, I would believe that it could be explained in Qt-documentation
>> for Android-Extras - note for the maintainer. Thanks.
>>
>> Kind regards,
>> Robert
>>
>>
>> On Thu, Mar 23, 2017 at 7:23 PM, Robert Iakobashvili
>> <coroberti at gmail.com> wrote:
>>> Hello,
>>>
>>> Qt-5.7, Nexus-7, Android-6, API 25 or 22.
>>>
>>> 1. Running Intent from Qt widget app to ask for a new file rather in a
>>> standard way works properly:
>>>
>>> QAndroidJniObject intent("android/content/Intent");
>>> QAndroidJniObject ACTION_CREATE_DOCUMENT =
>>> QAndroidJniObject::fromString("android.intent.action.CREATE_DOCUMENT");
>>>
>>>         if (ACTION_CREATE_DOCUMENT.isValid() && intent.isValid())
>>>         {
>>>             intent.callObjectMethod("setAction",
>>>
>>> "(Ljava/lang/String;)Landroid/content/Intent;",
>>>                                     ACTION_CREATE_DOCUMENT.object<jstring>());
>>>             intent.callObjectMethod("setType",
>>>
>>> "(Ljava/lang/String;)Landroid/content/Intent;",
>>>
>>> QAndroidJniObject::fromString("text/html").object<jstring>());
>>>             intent.callObjectMethod("putExtra",
>>>
>>> "(Ljava/lang/String;Z)Landroid/content/Intent;",
>>>
>>> QAndroidJniObject::fromString("android.intent.extra.LOCAL_ONLY").object<jstring>(),
>>>                                     jboolean(true));
>>>             QtAndroid::startActivity(intent.object<jobject>(),
>>>
>>> AndroidOpenFileReceiver::NEW_FILE_NAME_REQUEST,
>>>                                      this->android_receiver_);
>>>         }
>>>
>>> 2. File could be selected and seen as immediately created in a
>>> derivative of a QAndroidActivityResultReceiver
>>>
>>> handleActivityResult
>>>
>>> const QString fileURI =
>>> data.callObjectMethod("getData","()Landroid/net/Uri;").toString();
>>>
>>> and that could be translated by calling Java to the absolute file path
>>> for the file selected, i.e. first.htm:
>>>
>>> /storage/emulated/0/Download/first.htm
>>>
>>> 3. The file content could be written or read in Java using Java I/O Streams.
>>> Further the stream and file are closed in Java.
>>>
>>> 4. Unfortunately, returning to C++ the file is found existing, but open fails.
>>> That happens in all cases consistently: whenever dealing with it in
>>> Java before or not.
>>>
>>> if (!QFile::exists(filename)) - it exists
>>>         return false;
>>>
>>> QFile file(filename);
>>> if (!file.open(QFile::ReadWrite)) - fails
>>> {
>>>      if (!file.open(QFile::ReadOnly)) - fails.
>>>             return false;
>>> }
>>>
>>> 5. The C++ code above works fine if the location of the files is in
>>> /data/data/<app-path>
>>>     or any writable standard path returned by Qt.
>>>
>>> 6. My conclusion is that on Nexus-7 the Intent returned path in
>>> /storage/emulated/0/Download/
>>>     is considered to be an External Storage.
>>>
>>>     But the manifest has appropriate Write and Read permissions for
>>> External Storage.
>>>
>>> The question is what I am missing like
>>> permission for that specific thread or running something on the GUI
>>> thread, or etc.
>>>
>>> Thanks in advance for any help or ideas.
>>>
>>> Kind regards,
>>> Robert
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