Save Image to Android device

[mvuori]

This is a funny issue. People claim that calling scanFile should work, but I have seen no sign that anyone has actually managed to make it work from Qt...

Yes, I am trying the same thing, but currently, on a personal app, just use Android app media.re.Scan: as needed.

[eiriham]

Using an app wont solve my problem, but thanks for the advice.

[Qojote]

I had the same issue to show a picture taken by my app immediatly after saving it. And scanFile works for me.

I wrote a java class extending org.qtproject.qt5.android.bindings.QtActivity and declared it in the manifest file.

public class AndroidAccess extends org.qtproject.qt5.android.bindings.QtActivity
{
  public static MediaScannerConnection s_mMs;

  @Override
  public void onCreate(Bundle savedInstanceState)
  {
     ...
     s_mMs = new MediaScannerConnection(getApplicationContext(), null);
     s_mMs.connect();
  }

  public static void scanForPicture(String name)
  {
     s_mMs.scanFile(name, null);
  }
}

and then in my Qt class i simply call:

QAndroidJniObject::callStaticMethod<void>("org/tud/qpcam/AndroidAccess",
                                           "scanForPicture",
                                           "(Ljava/lang/String;)V",
                                           QAndroidJniObject::fromString(this->getSavePicturesDir().absolutePath()).object<jstring>());

whereas getSavePicturesDir() returns the directory where the pictures were saved to.
Works like charm with Qt 5.6 and android 4.4 - 6.0.

[eiriham]

Thanks! I am trying to get this to work now.
How did you register it in the manifest file?
And how do I know the path? I mean, how did you know you had to put in "org/tud/qpcam/AndroidAccess"?

I try this but the isAvailable returns false:

    qDebug()<< "Is available: " << QAndroidJniObject::isClassAvailable("MediaScanner");

    QAndroidJniObject::callStaticMethod<void>("MediaScanner",
                                               "scanForPicture",
                                               "(Ljava/lang/String;)V",
                                               QAndroidJniObject::fromString(this->getSavePicturesDir().absolutePath()).object<jstring>());

[Devopia53]

@eiriham

You can use the sendBroadcast(). MediaScanner is simple to implement only JNI without JAVA code.

[Qojote]

Well, i tried a lot of ways and sendBroadcast() did not work for me. So maybe my way isnt the shortest one, but it works and thats what matters, doesnt it?

• Create the android files "create Android APK"

• set the package name, e.g. "aha.androscanner" in manifest

• open manifest in text mode and replace android:name="org.qtproject.qt5.android.bindings.QtActivity" with android:name="aha.androscanner.AndroScannerInJava"

• Create a subdirectory below the android folder, e.g. ...android/src/aha/androscanner

• Put in a java file, named exactly like in point 3, e.g. AndroScannerInJava.java and add it to project

• add "android: QT += androidextras" to your .pro file

• Fill in the code

AndroScannerInJava.java

package aha.androscanner;

import android.media.MediaScannerConnection;
import android.os.Bundle;

public class AndroScannerInJava extends org.qtproject.qt5.android.bindings.QtActivity
{
    public static MediaScannerConnection s_mMs;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        System.out.println("in the activity");

        super.onCreate(savedInstanceState);

        s_mMs = new MediaScannerConnection(getApplicationContext(), null);
        s_mMs.connect();

    }

    public static void scanForPicture(String name)
    {
        System.out.print("scan for picture -> ");
        System.out.println(name);

        s_mMs.scanFile(name, null);
    }
}

Within Qt code you call:

void MainWindow::saveThatPicture()
{
    qDebug() << "saveThatPicture!";

    QPixmap pix(700,700);
    pix.fill(Qt::red);

    QDir picDir = QDir(QStandardPaths::writableLocation(QStandardPaths::PicturesLocation));
    QDir saveDir = QDir(picDir.filePath("aha"));
    if(!saveDir.exists())
        picDir.mkdir("aha");

    QString filePath = saveDir.filePath("test.jpg");
    pix.save(filePath);


    QAndroidJniObject::callStaticMethod<void>("aha/androscanner/AndroScannerInJava",
                                               "scanForPicture",
                                               "(Ljava/lang/String;)V",
                                               QAndroidJniObject::fromString(filePath).object<jstring>());
}

Manifest.xml

<?xml version='1.0' encoding='utf-8'?>
<manifest package="aha.androscanner" xmlns:android="http://schemas.android.com/apk/res/android" android:versionName="1.0" android:versionCode="1" android:installLocation="auto">
    <application android:hardwareAccelerated="true" android:name="org.qtproject.qt5.android.bindings.QtApplication" android:label="-- %%INSERT_APP_NAME%% --">
        <activity android:configChanges="orientation|uiMode|screenLayout|screenSize|smallestScreenSize|layoutDirection|locale|fontScale|keyboard|keyboardHidden|navigation"
                  android:name="aha.androscanner.AndroScannerInJava"
                  android:label="-- %%INSERT_APP_NAME%% --"
                  android:screenOrientation="unspecified"
                  android:launchMode="singleTop">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
            <meta-data android:name="android.app.lib_name" android:value="-- %%INSERT_APP_LIB_NAME%% --"/>
            <meta-data android:name="android.app.qt_sources_resource_id" android:resource="@array/qt_sources"/>
            <meta-data android:name="android.app.repository" android:value="default"/>
            <meta-data android:name="android.app.qt_libs_resource_id" android:resource="@array/qt_libs"/>
            <meta-data android:name="android.app.bundled_libs_resource_id" android:resource="@array/bundled_libs"/>
            <!-- Deploy Qt libs as part of package -->
            <meta-data android:name="android.app.bundle_local_qt_libs" android:value="-- %%BUNDLE_LOCAL_QT_LIBS%% --"/>
            <meta-data android:name="android.app.bundled_in_lib_resource_id" android:resource="@array/bundled_in_lib"/>
            <meta-data android:name="android.app.bundled_in_assets_resource_id" android:resource="@array/bundled_in_assets"/>
            <!-- Run with local libs -->
            <meta-data android:name="android.app.use_local_qt_libs" android:value="-- %%USE_LOCAL_QT_LIBS%% --"/>
            <meta-data android:name="android.app.libs_prefix" android:value="/data/local/tmp/qt/"/>
            <meta-data android:name="android.app.load_local_libs" android:value="-- %%INSERT_LOCAL_LIBS%% --"/>
            <meta-data android:name="android.app.load_local_jars" android:value="-- %%INSERT_LOCAL_JARS%% --"/>
            <meta-data android:name="android.app.static_init_classes" android:value="-- %%INSERT_INIT_CLASSES%% --"/>
            <!--  Messages maps -->
            <meta-data android:value="@string/ministro_not_found_msg" android:name="android.app.ministro_not_found_msg"/>
            <meta-data android:value="@string/ministro_needed_msg" android:name="android.app.ministro_needed_msg"/>
            <meta-data android:value="@string/fatal_error_msg" android:name="android.app.fatal_error_msg"/>
            <!--  Messages maps -->

            <!-- Splash screen -->
            <!--
            <meta-data android:name="android.app.splash_screen_drawable" android:resource="@drawable/logo"/>
            -->
            <!-- Splash screen -->

            <!-- Background running -->
            <!-- Warning: changing this value to true may cause unexpected crashes if the
                          application still try to draw after
                          "applicationStateChanged(Qt::ApplicationSuspended)"
                          signal is sent! -->
            <meta-data android:name="android.app.background_running" android:value="false"/>
            <!-- Background running -->

            <!-- auto screen scale factor -->
            <meta-data android:name="android.app.auto_screen_scale_factor" android:value="false"/>
            <!-- auto screen scale factor -->
        </activity>
    </application>
    <uses-sdk android:minSdkVersion="9" android:targetSdkVersion="14"/>
    <supports-screens android:largeScreens="true" android:normalScreens="true" android:anyDensity="true" android:smallScreens="true"/>

    <!-- The following comment will be replaced upon deployment with default permissions based on the dependencies of the application.
         Remove the comment if you do not require these default permissions. -->
    <!-- %%INSERT_PERMISSIONS -->

    <!-- The following comment will be replaced upon deployment with default features based on the dependencies of the application.
         Remove the comment if you do not require these default features. -->
    <!-- %%INSERT_FEATURES -->

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

</manifest>

Works fine.

[eiriham]

Thanks! While following your steps I get an error. In the application output it says; "Unable to start "pdapp.mediascanner"."

Using logcat I get:

I/ActivityManager(  712): START u0 {flg=0x10000000 cmp=pdapp.mediascanner/.MediaScanner} from uid 2000 on display 0
W/ActivityManager(  712): Permission Denial: starting Intent { flg=0x10000000 cmp=pdapp.mediascanner/.MediaScanner } from null (pid=21117, uid=2000) not exported from uid 10104
I/art     (21117): System.exit called, status: 1
I/AndroidRuntime(21117): VM exiting with result code 1.

And also this:

W/PackageManager( 1369): Failure retrieving resources for pdapp.mediascanner: Resource ID #0x0

I followed your steps to the point.

[Qojote]

Please make sure that you set the permissions to read and write external storage. Furthermore check consitent naming of your package and class names.
Which android version ar you targeting? Do you have installed the android sdk?

[eiriham]

Thanks!

I had forgotten permissions for reading externally.
Your solution works perfectly.

[mvuori]

@Qojote Thank you and congratulations for giving all the details for solving this old and apparently common problem! Without the smallest details, this kind of things are never solved.