Trying to get Image url from Android Gallery App, bbut Path is always empty

[Antonio Ortiz]

Hi, I'm trying to get an image url from the Android Gallery, but the path is always empty.

To open the gallery I make an Intent to the app using the following method:

void DialogoArchivoAndroid::abrir()
{
    QAndroidJniObject ACTION_PICK = QAndroidJniObject::fromString("android.intent.action.GET_CONTENT");
    QAndroidJniObject intent("android/content/Intent");
    if (ACTION_PICK.isValid() && intent.isValid())
    {
        intent.callObjectMethod("setAction", "(Ljava/lang/String;)Landroid/content/Intent;", ACTION_PICK.object<jstring>());
        intent.callObjectMethod("setType", "(Ljava/lang/String;)Landroid/content/Intent;", QAndroidJniObject::fromString("image/*").object<jstring>());
        QtAndroid::startActivity(intent.object<jobject>(), 101, this);
    }
}

Once I pick the image the Gallery close an my app returns to foreground and receive data using the handleActivityResult and store the image url in a class attribute name "archivoSeleccionado":

void DialogoArchivoAndroid::handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data)
{
    jint RESULT_OK = QAndroidJniObject::getStaticField<jint>("android/app/Activity", "RESULT_OK");

    if (receiverRequestCode == 101 && resultCode == RESULT_OK)
    {


        QAndroidJniObject uri = data.callObjectMethod("getData", "()Landroid/net/Uri;");

        QAndroidJniObject datosAndroid = QAndroidJniObject::getStaticObjectField("android/provider/MediaStore$MediaColumns",
                                                                                 "DATA", "Ljava/lang/String;");
        QAndroidJniEnvironment env;
        jobjectArray proyeccion = (jobjectArray)env->NewObjectArray(1, env->FindClass("java/lang/String"), NULL);
        jobject proyeccionDatosAndroid = env->NewStringUTF(datosAndroid.toString().toStdString().c_str());
        env->SetObjectArrayElement(proyeccion, 0, proyeccionDatosAndroid);
        QAndroidJniObject contentResolver = QtAndroid::androidActivity().callObjectMethod("getContentResolver", "()Landroid/content/ContentResolver;");
        QAndroidJniObject cursor = contentResolver.callObjectMethod("query",
                                                                    "(Landroid/net/Uri;[Ljava/lang/String;Ljava/lang/String;[Ljava/lang/String;Ljava/lang/String;)Landroid/database/Cursor;",
                                                                    uri.object<jobject>(), proyeccion, NULL, NULL, NULL);
        jint columnIndex = cursor.callMethod<jint>("getColumnIndex", "(Ljava/lang/String;)I", datosAndroid.object<jstring>());
        cursor.callMethod<jboolean>("moveToFirst", "()Z");
        QAndroidJniObject resultado = cursor.callObjectMethod("getString", "(I)Ljava/lang/String;", columnIndex);

        archivoSeleccionado = "file://" + resultado.toString();
        emit archivoSeleccionadoCambio();
    }

Debugging the app I found that RESULT_OK and result code are always -1, but I don't understand why.
I get the code from this thread in the forum.
This is the first time I use the QAndroidActivityResultReceiver and I'm i little lost.

[Leonardo]

Using JNI for complex operations is hard work. I think it would be better for you to extend Qt's activity and do your thing using only Java. I have a similar code for picking images. Here's my suggestion:

1. Create a "src" folder inside "android" and add a new .java file for your custom activity. From my project:

2. Here's a sample code for the activity:

package my.app;

public class MyActivity extends org.qtproject.qt5.android.bindings.QtActivity {

    private static int REQUEST_IMAGE_PICK = 101;

    public static native void photoResult(String filePath);

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {

        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == REQUEST_IMAGE_PICK && resultCode == MyActivity.RESULT_OK){
            this.handleImagePickResult(data);
        }

    }

    private void handleImagePickResult(Intent data){

        try {

            android.net.Uri photoUri = data.getData();
            java.io.File photoFile = this.createImageFile();
            byte[] buf = new byte[10240];
            int count;

            java.io.InputStream input = this.getContentResolver().openInputStream(photoUri);
            java.io.FileOutputStream output = new java.io.FileOutputStream(photoFile);

            do {

                count = input.read(buf);

                if(count > 0){
                    output.write(buf, 0, count);
                }else{
                    break;
                }

            }while(true);

            output.close();
            input.close();

            photoResult(photoFile.getAbsolutePath());

        }catch(java.lang.Exception ex){
            photoResult("");
        }

    }
        
    private java.io.File createImageFile(){

        java.io.File file;

        try {
            file = java.io.File.createTempFile("MY_", ".jpg", this.getCacheDir());
        }catch(java.lang.Exception ex){
            return null;
        }

        return file;

    }
    
    public void photoFromGallery(){

        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);

        intent.setType("image/*");
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);

        if(intent.resolveActivity(getPackageManager()) != null){
            startActivityForResult(intent, REQUEST_IMAGE_PICK);
        }else{
            photoResult("");
        }

    }
    
}

3. On your manifest, change the "android:name" of your <activity> to "my.app.MyActivity" and add the following inside <application>:

<provider
	 tools:replace="android:authorities"
	 android:name="android.support.v4.content.FileProvider"
	 android:authorities="my.app.files"
	 android:exported="false"
	 android:grantUriPermissions="true">
	 <meta-data
		 android:name="android.support.FILE_PROVIDER_PATHS"
		 android:resource="@xml/file_paths"></meta-data>
 </provider>

4. Create a "res/xml/file_paths.xml" file with this content:

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <cache-path name="photos" path="" />
    <external-path name="dcim" path="DCIM"/>
</paths>

5. Now you just need to implement the "callback" from Java to Qt. When initializing your app, bind it to a C++ function.

JNINativeMethod methods[] = {{"photoResult", "(Ljava/lang/String;)V", reinterpret_cast<void *>(MyPhotoResult)}};
QAndroidJniEnvironment env;

jclass objectClass = env->GetObjectClass(QtAndroid::androidActivity().object());

env->RegisterNatives(objectClass, methods, sizeof(methods) / sizeof(methods[0]));

env->DeleteLocalRef(objectClass);

void MyPhotoResult(JNIEnv *env, jobject obj, jstring jdata){
	QString filePath = QAndroidJniObject(jdata).toString();
	// do your thing
}

I don't remember exactly why, but as you see I had to copy the file to a place where Qt could manipulate it. I couldn't access the file directly. Maybe you can work around that, I don't know, but it works as it is.

[Antonio Ortiz]

Hi, thanks for your quick answer (and sorry for my late one). I use your code as base and still couldn't get the file path. But I investigate a like more and find out that it was a problem with my Android version, for Android >= 5.1 things change a little bit.
I found the answer in the next post:
https://stackoverflow.com/questions/34006608/qt-and-android-get-path-from-image-in-gallery
https://stackoverflow.com/questions/30567217/android-5-1-1-lollipop-return-null-file-path-if-image-chosen-from-gallery
https://forum.qt.io/topic/66324/qt-android-image-picker-issue-with-android-5-5-1/3

And this is my final code:
class.h

#ifndef DIALOGOARCHIVOANDROID_HPP
#define DIALOGOARCHIVOANDROID_HPP

#include <QObject>

#ifdef Q_OS_ANDROID
    #include <QtAndroidExtras>
    #include <QAndroidActivityResultReceiver>
    #include <QAndroidJniObject>
    #include <QAndroidJniEnvironment>
#endif

#ifdef Q_OS_ANDROID
class DialogoArchivoAndroid : public QObject, QAndroidActivityResultReceiver
#else
class DialogoArchivoAndroid : public QObject
#endif
{
    Q_OBJECT

    Q_PROPERTY(QString archivoSeleccionado READ getArchivoSeleccionado WRITE setArchivoSeleccionado NOTIFY archivoSeleccionadoCambio)

    QString archivoSeleccionado;

public:
    explicit DialogoArchivoAndroid(QObject *parent = 0);

    QString getArchivoSeleccionado() const;
    void setArchivoSeleccionado(const QString &value);



#ifdef Q_OS_ANDROID
    Q_INVOKABLE void abrir();
    virtual void handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject & data) override;
#endif
    Q_INVOKABLE bool verificarSO();


signals:

    void archivoSeleccionadoCambio();

public slots:
};

#endif // DIALOGOARCHIVOANDROID_HPP

Class.cpp

#include "dialogoarchivoandroid.hpp"

DialogoArchivoAndroid::DialogoArchivoAndroid(QObject *parent) : QObject(parent)
{

}

QString DialogoArchivoAndroid::getArchivoSeleccionado() const
{
    return archivoSeleccionado;
}

bool DialogoArchivoAndroid::verificarSO()
{
#ifdef Q_OS_ANDROID
    return true;
#endif
    return false;
}

void DialogoArchivoAndroid::setArchivoSeleccionado(const QString &value)
{
    archivoSeleccionado = value;
}


#ifdef Q_OS_ANDROID


void DialogoArchivoAndroid::abrir()
{
    QAndroidJniObject Intent__ACTION_PICK = QAndroidJniObject::getStaticObjectField("android/content/Intent", "ACTION_PICK", "Ljava/lang/String;");

    QAndroidJniObject EXTERNAL_CONTENT_URI= QAndroidJniObject::getStaticObjectField("android/provider/MediaStore$Images$Media", "EXTERNAL_CONTENT_URI", "Landroid/net/Uri;");

    QAndroidJniObject intent=QAndroidJniObject("android/content/Intent",
                                               "(Ljava/lang/String;Landroid/net/Uri;)V",
                                               Intent__ACTION_PICK.object<jstring>(),
                                               EXTERNAL_CONTENT_URI.object<jobject>()
                                               );

    QtAndroid::startActivity(intent, 101, this);
}

void DialogoArchivoAndroid::handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data)
{
    jint RESULT_OK = QAndroidJniObject::getStaticField<jint>("android/app/Activity", "RESULT_OK");

    if (receiverRequestCode == 101 && resultCode == RESULT_OK)
    {

        QAndroidJniObject uri = data.callObjectMethod("getData", "()Landroid/net/Uri;");

        QAndroidJniObject datosAndroid = QAndroidJniObject::getStaticObjectField("android/provider/MediaStore$MediaColumns", "DATA", "Ljava/lang/String;");
        QAndroidJniEnvironment env;
        jobjectArray proyeccion = (jobjectArray)env->NewObjectArray(1, env->FindClass("java/lang/String"), NULL);
        jobject proyeccionDatosAndroid = env->NewStringUTF(datosAndroid.toString().toStdString().c_str());
        env->SetObjectArrayElement(proyeccion, 0, proyeccionDatosAndroid);

        QAndroidJniObject contentResolver = QtAndroid::androidActivity().callObjectMethod("getContentResolver", "()Landroid/content/ContentResolver;");
        QAndroidJniObject nullObj;

        QAndroidJniObject cursor = contentResolver.callObjectMethod("query", "(Landroid/net/Uri;[Ljava/lang/String;Ljava/lang/String;[Ljava/lang/String;Ljava/lang/String;)Landroid/database/Cursor;", uri.object<jobject>(), proyeccion, nullObj.object<jstring>(), nullObj.object<jobjectArray>(), nullObj.object<jstring>());
       
        jint columnIndex = cursor.callMethod<jint>("getColumnIndexOrThrow","(Ljava/lang/String;)I", datosAndroid.object<jstring>());
      
        cursor.callMethod<jboolean>("moveToFirst");

        QAndroidJniObject path = cursor.callObjectMethod("getString", "(I)Ljava/lang/String;", columnIndex);
        
        archivoSeleccionado = "file://" +  path.toString();

        cursor.callMethod<jboolean>("close");
        emit archivoSeleccionadoCambio();
    }
}

#endif

[ekkescorner]

@Antonio-Ortiz Hi Antonio,
you can also take a look at my Share Example App where I'm also dealing with Android content pathes and to see HowTo use JAVA instead of JNI - much easier to write.
see my blog at Qt: http://blog.qt.io/blog/2018/01/16/sharing-files-android-ios-qt-app-part-2/
and esp this JAVA class to get the FilePath from ContentProvider: https://github.com/ekke/ekkesSHAREexample/blob/master/android/src/org/ekkescorner/utils/QSharePathResolver.java