Tuesday, April 25, 2017

Read Exif tag of JPG using ExifInterface(FileDescriptor)

android.media.ExifInterface is a class for reading and writing Exif tags in a JPEG file or a RAW image file.
Supported formats are: JPEG, DNG, CR2, NEF, NRW, ARW, RW2, ORF, PEF, SRW and RAF.
Attribute mutation is supported for JPEG image files.


This example show how to open image of jpeg using Intent.ACTION_OPEN_DOCUMENT (added in API level 19), then display the image and read the Exif tag using ExifInterface (FileDescriptor)(added in API level 24).

Please notice:
Because ExifInterface (FileDescriptor) is used here, so the min Sdk Version have to be set API 24.
To convert the Uri return by Storage Access Framework to FileDescriptor, refer to the example in the document "Open Files using Storage Access Framework".


MainActivity.java
package com.blogspot.android_er.androidexif;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.media.ExifInterface;
import android.net.Uri;
import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.io.FileDescriptor;
import java.io.FileNotFoundException;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private static final int RQS_OPEN_IMAGE = 1;

    Button buttonOpen;
    TextView textUri;
    ImageView imageView;

    Uri targetUri = null;

    View.OnClickListener buttonOpenOnClickListener =
            new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    Intent intent = new Intent();
                    intent.setAction(Intent.ACTION_OPEN_DOCUMENT);
                    intent.addCategory(Intent.CATEGORY_OPENABLE);
                    intent.setType("image/jpeg");
                    startActivityForResult(intent, RQS_OPEN_IMAGE);
                }

            };
    View.OnClickListener textUriOnClickListener =
            new View.OnClickListener(){

                @Override
                public void onClick(View v) {
                    if (targetUri != null){
                        Bitmap bm;
                        try {
                            bm = BitmapFactory.decodeStream(
                                    getContentResolver()
                                            .openInputStream(targetUri));
                            imageView.setImageBitmap(bm);
                        } catch (FileNotFoundException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                }

            };

    View.OnClickListener imageOnClickListener =
            new View.OnClickListener(){

                @Override
                public void onClick(View view) {
                    showExif(targetUri);
                }
            };

    void showExif(Uri photoUri){
        if(photoUri != null){

            ParcelFileDescriptor parcelFileDescriptor = null;

            /*
            How to convert the Uri to FileDescriptor, refer to the example in the document:
            https://developer.android.com/guide/topics/providers/document-provider.html
             */
            try {
                parcelFileDescriptor = getContentResolver().openFileDescriptor(photoUri, "r");
                FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();

                /*
                ExifInterface (FileDescriptor fileDescriptor) added in API level 24
                 */
                ExifInterface exifInterface = new ExifInterface(fileDescriptor);
                String exif="Exif: " + fileDescriptor.toString();
                exif += "\nIMAGE_LENGTH: " +
                        exifInterface.getAttribute(ExifInterface.TAG_IMAGE_LENGTH);
                exif += "\nIMAGE_WIDTH: " +
                        exifInterface.getAttribute(ExifInterface.TAG_IMAGE_WIDTH);
                exif += "\n DATETIME: " +
                        exifInterface.getAttribute(ExifInterface.TAG_DATETIME);
                exif += "\n TAG_MAKE: " +
                        exifInterface.getAttribute(ExifInterface.TAG_MAKE);
                exif += "\n TAG_MODEL: " +
                        exifInterface.getAttribute(ExifInterface.TAG_MODEL);
                exif += "\n TAG_ORIENTATION: " +
                        exifInterface.getAttribute(ExifInterface.TAG_ORIENTATION);
                exif += "\n TAG_WHITE_BALANCE: " +
                        exifInterface.getAttribute(ExifInterface.TAG_WHITE_BALANCE);
                exif += "\n TAG_FOCAL_LENGTH: " +
                        exifInterface.getAttribute(ExifInterface.TAG_FOCAL_LENGTH);
                exif += "\n TAG_FLASH: " +
                        exifInterface.getAttribute(ExifInterface.TAG_FLASH);
                exif += "\nGPS related:";
                exif += "\n TAG_GPS_DATESTAMP: " +
                        exifInterface.getAttribute(ExifInterface.TAG_GPS_DATESTAMP);
                exif += "\n TAG_GPS_TIMESTAMP: " +
                        exifInterface.getAttribute(ExifInterface.TAG_GPS_TIMESTAMP);
                exif += "\n TAG_GPS_LATITUDE: " +
                        exifInterface.getAttribute(ExifInterface.TAG_GPS_LATITUDE);
                exif += "\n TAG_GPS_LATITUDE_REF: " +
                        exifInterface.getAttribute(ExifInterface.TAG_GPS_LATITUDE_REF);
                exif += "\n TAG_GPS_LONGITUDE: " +
                        exifInterface.getAttribute(ExifInterface.TAG_GPS_LONGITUDE);
                exif += "\n TAG_GPS_LONGITUDE_REF: " +
                        exifInterface.getAttribute(ExifInterface.TAG_GPS_LONGITUDE_REF);
                exif += "\n TAG_GPS_PROCESSING_METHOD: " +
                        exifInterface.getAttribute(ExifInterface.TAG_GPS_PROCESSING_METHOD);

                parcelFileDescriptor.close();

                Toast.makeText(getApplicationContext(),
                        exif,
                        Toast.LENGTH_LONG).show();

            } catch (FileNotFoundException e) {
                e.printStackTrace();
                Toast.makeText(getApplicationContext(),
                        "Something wrong:\n" + e.toString(),
                        Toast.LENGTH_LONG).show();
            } catch (IOException e) {
                e.printStackTrace();
                Toast.makeText(getApplicationContext(),
                        "Something wrong:\n" + e.toString(),
                        Toast.LENGTH_LONG).show();
            }

            String strPhotoPath = photoUri.getPath();

        }else{
            Toast.makeText(getApplicationContext(),
                    "photoUri == null",
                    Toast.LENGTH_LONG).show();
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        buttonOpen = (Button) findViewById(R.id.opendocument);
        buttonOpen.setOnClickListener(buttonOpenOnClickListener);

        textUri = (TextView) findViewById(R.id.texturi);
        textUri.setOnClickListener(textUriOnClickListener);

        imageView = (ImageView)findViewById(R.id.image);
        imageView.setOnClickListener(imageOnClickListener);
    }

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

        if (resultCode == Activity.RESULT_OK) {

            Uri dataUri = data.getData();

            if (requestCode == RQS_OPEN_IMAGE) {
                targetUri = dataUri;
                textUri.setText(dataUri.toString());
                imageView.setImageBitmap(null);
            }
        }

    }
}


Layout:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.blogspot.android_er.androidexif.MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/opendocument"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Open Document of Image" />

    <TextView
        android:id="@+id/texturi"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <ImageView
        android:id="@+id/image"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />

</LinearLayout>

Next:
Read Exif tag of JPG using ExifInterface(InputStream)
Read Exif tag of JPG using ExifInterface(String filename)

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