Android, select image using Gallery

[meego_man]

Dear all,

I'm trying to port existing application to Android, iOS and Windows platforms. The application needs the user to select an image and on my first trial I discovered that Qt for Android uses some sort of its own dialog. Is there is a way to use the standard Android image selector (Gallery app I guess) in Qt app? If not, can I somehow write a small piece of Android code, execute it from Qt and get the filename of selected image?

Thank you in advance

[lqsa]

Hello,

The gallery doesn't return the filename of the selected image, it returns an URI. This URI is used for a content resolver to retrieve the image.

My solution is to launch the gallery from QT code and pass the result to the Android code to retrieve the image.


QT Code:

class AndroidImagePicker: public QAndroidActivityResultReceiver
{
public:
    AndroidImagePicker() {}
 
    void show() override {
        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);
            }
    }
 
    virtual void handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject & data) override {        
        jint RESULT_OK = QAndroidJniObject::getStaticField<jint>("android/app/Activity", "RESULT_OK");
        if (receiverRequestCode == 101 && resultCode == RESULT_OK) {
            QAndroidJniObject activity = QtAndroid::androidActivity();
            QAndroidJniObject bytes = QAndroidJniObject::callStaticObjectMethod("lqsa/util/ImageFromActivityResult",
                                                      "getImage",
                                                      "(Landroid/content/Intent;Lorg/qtproject/qt5/android/bindings/QtActivity;)[B",
                                                      data.object<jobject>(), activity.object<jobject>());
 
            QAndroidJniEnvironment env;
            jbyteArray imageDataArray = bytes.object<jbyteArray>();
            if (imageDataArray) {
                jsize imageSize = env->GetArrayLength(imageDataArray);
                if (imageSize > 0) {
                    jboolean isCopy;
                    jbyte *imageBytes = env->GetByteArrayElements(imageDataArray, &isCopy);
                    QImage image = QImage(QImage::fromData((uchar*) imageBytes, imageSize,"JPG"));
                    env->ReleaseByteArrayElements(imageDataArray, imageBytes, JNI_ABORT);
                    emit imageSelected(image);
                }
            }
        }
    }
};

class AndroidImagePicker: public QAndroidActivityResultReceiver
{
public:
    AndroidImagePicker() {}

    void show() override {
        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);
            }
    }

    virtual void handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject & data) override {        
        jint RESULT_OK = QAndroidJniObject::getStaticField<jint>("android/app/Activity", "RESULT_OK");
        if (receiverRequestCode == 101 && resultCode == RESULT_OK) {
            QAndroidJniObject activity = QtAndroid::androidActivity();
            QAndroidJniObject bytes = QAndroidJniObject::callStaticObjectMethod("lqsa/util/ImageFromActivityResult",
                                                      "getImage",
                                                      "(Landroid/content/Intent;Lorg/qtproject/qt5/android/bindings/QtActivity;)[B",
                                                      data.object<jobject>(), activity.object<jobject>());

            QAndroidJniEnvironment env;
            jbyteArray imageDataArray = bytes.object<jbyteArray>();
            if (imageDataArray) {
                jsize imageSize = env->GetArrayLength(imageDataArray);
                if (imageSize > 0) {
                    jboolean isCopy;
                    jbyte *imageBytes = env->GetByteArrayElements(imageDataArray, &isCopy);
                    QImage image = QImage(QImage::fromData((uchar*) imageBytes, imageSize,"JPG"));
                    env->ReleaseByteArrayElements(imageDataArray, imageBytes, JNI_ABORT);
                    emit imageSelected(image);
                }
            }
        }
    }
};

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Android code (file ImageFromActivityResult.java):

package lqsa.util;
 
import android.content.Intent;
import org.qtproject.qt5.android.bindings.QtActivity;
import java.io.InputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
 
public class ImageFromActivityResult {
 
	public static byte[] getImage(Intent intent, QtActivity activity) throws IOException {
        InputStream is = activity.getContentResolver().openInputStream(intent.getData());
		ByteArrayOutputStream buffer = new ByteArrayOutputStream();
		int nRead;
		byte[] data = new byte[16384];
 
		while ((nRead = is.read(data, 0, data.length)) != -1) {
		  buffer.write(data, 0, nRead);
		}
		buffer.flush();
		return buffer.toByteArray();
    }
}

package lqsa.util;

import android.content.Intent;
import org.qtproject.qt5.android.bindings.QtActivity;
import java.io.InputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

public class ImageFromActivityResult {
	
	public static byte[] getImage(Intent intent, QtActivity activity) throws IOException {
        InputStream is = activity.getContentResolver().openInputStream(intent.getData());
		ByteArrayOutputStream buffer = new ByteArrayOutputStream();
		int nRead;
		byte[] data = new byte[16384];

		while ((nRead = is.read(data, 0, data.length)) != -1) {
		  buffer.write(data, 0, nRead);
		}
		buffer.flush();
		return buffer.toByteArray();
    }
}

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