Source: https://carsnewstoday.com/programming/data-engineering/unlock-android-app-image-mastery-expert-guide-to-uploading-caching-saving-and-sharing-visuals-seamlessly/

Safeguarding Visual Content

After retrieving an image from the internet, you can archive it on an SD card for later use.

Example Implementation

1. Register with the
   
   App42 platform
   
   .
2. Create a new application on the quick-start page following registration.
3. If you’re already registered, log in to the
   
   AppHQ
   
   console and create an application via the App Manager Create App link.
4. Download the project from
   
   here
   
   and import it into Eclipse.
5. Open the MainActivity.java file and provide the necessary details in the
   
onCreate

   method as shown below (application keys for AppHQ console).

app42api.initialize(this,"app42 api key","app42 secret key");

change the application name with your application name in res/strings (useful to save image in sd card), then build and run the application

design details

get an image for your app from an android sd card with the code written in the mainactivity.java file.

/*     * call when user clicks on browse photo     */    private void browsephoto(string imagename) {        if (this.imagename != null  !this.imagename.equals(""))            this.imagename = imagename;        intent i = new intent(intent.action_pick,                android.provider.mediastore.images.media.external_content_uri);        startactivityforresult(i, result_load_image);    }    /*     * callback when user select image from gallery for upload     * get a callback     * @see android.app.activity#onactivityresult(int, int,     * android.content.intent)     */    @override    protected void onactivityresult(int requestcode, int resultcode, intent data) {        super.onactivityresult(requestcode, resultcode, data);        if (requestcode == result_load_image  resultcode == result_ok                 null != data) {            uri selectedimage = data.getdata();            string[] filepathcolumn = { mediastore.images.media.data };            cursor cursor = getcontentresolver().query(selectedimage,                    filepathcolumn, null, null, null);            cursor.movetofirst();            int columnindex = cursor.getcolumnindex(filepathcolumn[0]);            string picturepath = cursor.getstring(columnindex);            cursor.close();            progressdialog.setmessage("uploading image");            progressdialog.show();            uploadimage(picturepath);        }    }

To transfer an image from your Android device's SD card gallery to a remote server, simply adhere to the code outlined in the MainActivity.java file.

private void uploadImage(String imagePath) {        app42api.buildUploadService().uploadFile(imageName, imagePath,                UploadFileType.IMAGE, description, new App42Callback() {                    public void onSuccess(Object uploadObj) {                        // todo auto-generated method stub                        onUploadResult(uploadObj);                    }                    public void onException(Exception ex) {                        // todo auto-generated method stub                        System.out.println(ex);                        onUploadError(ex);                    }                });    }

If you wish to disseminate an image to your friends using multiple apps installed on your device, follow the code in the MainActivity.java file.

Intent intent = new Intent(Intent.ACTION_SEND);intent.setType("text/plain");intent.putExtra(Intent.EXTRA_TEXT, "Hey friends, checkout this image" + "\" + imageUrl);intent.putExtra(android.content.Intent.EXTRA_SUBJECT, "Check my image");startActivity(Intent.createChooser(intent, "Share"));

The ImageCacher.java file encompasses all the necessary code to disseminate an image from the web or cache accordingly.

To load an image without downsampling in your Android activity class file, utilize the following code:

ImageView imgLogo = (ImageView) findViewById(R.id.my_image);ImageCacher imageCacher = new ImageCacher(this, -1);imageCacher.loadImage(imageUrl, imgLogo);

If you wish to load an image with downsampling in your Android activity class, please adhere to the code below:

ImageView imgLogo = (ImageView) findViewById(R.id.my_image);ImageCacher imageCacher = new ImageCacher(this, samplingImageSize);imageCacher.loadImage(imageUrl, imgLogo);

To retrieve an image from the web or cache, follow the code snippet below:

public Bitmap fetchBitmap(String url) {    String filename = String.valueOf(url.hashCode());    File file = new File(cacheDir, filename);    // from SD cache    Bitmap bitmap;    if (isSamplingReq) {        bitmap = decodeWithoutResampling(file);    } else {        bitmap = decodeWithResampling(file);    }    if (bitmap != null)        return bitmap;    // from web    try {        Bitmap image = null;        InputStream inputStream = new URL(url).openStream();        OutputStream outputStream = new FileOutputStream(file);        Utility.copyStream(inputStream, outputStream);        outputStream.close();        if (isSamplingReq) {            image = decodeWithoutResampling(file);        } else {            image = decodeWithResampling(file);        }        return image;    } catch (Throwable ex) {        ex.printStackTrace();        if (ex instanceof OutOfMemoryError)            clearCache();        return null;    }}

Code for Image Resampling:

private bitmap decodeWithResampling(File file) {        try {            // Retrieve image dimensions            BitmapFactory.Options options = new BitmapFactory.Options();            options.inJustDecodeBounds = true;            BitmapFactory.decodeStream(new FileInputStream(file), null, options);            int widthTemp = options.outWidth, heightTemp = options.outHeight;            int scalingFactor = 1;            while (true) {                if (widthTemp / 2  requiredSize                        || heightTemp / 2  requiredSize)                    break;                widthTemp /= 2;                heightTemp /= 2;                scalingFactor *= 2;            }            BitmapFactory.Options options2 = new BitmapFactory.Options();            options2.inSampleSize = scalingFactor;            return BitmapFactory.decodeStream(new FileInputStream(file), null, options2);        } catch (FileNotFoundException e) {        }        return null;    }

Code without Downsampling:

private bitmap decodeWithoutDownsampling(File file) {        try {            return BitmapFactory.decodeStream(new FileInputStream(file));        } catch (Exception e) {        }        return null;    }

Store Image in SD Card Gallery:

If you desire to store an image in the Android SD card gallery,

you can follow the code outlined in the MainActivity.java file.

void savemyimage() {        bitmap bmimg = imagecacher.getbitmap(imageurl);        file filename;        try {            string path1 = android.os.environment.getexternalstoragedirectory()                    .tostring();            log.i("in save()", "after mkdir");            file file = new file(path1 + "/" + appname);            if (!file.exists())                file.mkdirs();            filename = new file(file.getabsolutepath() + "/" + imagename                    + ".jpg");            log.i("in save()", "after file");            fileoutputstream out = new fileoutputstream(filename);            log.i("in save()", "after outputstream");            bmimg.compress(bitmap.compressformat.jpeg, 90, out);            out.flush();            out.close();            log.i("in save()", "after outputstream closed");            //file parent = filename.getparentfile();            contentvalues image = getimagecontent(filename);            uri result = getcontentresolver().insert(                    mediastore.images.media.external_content_uri, image);            toast.maketext(getapplicationcontext(),                    "file is saved in  " + filename, toast.length_short).show();        } catch (exception e) {            e.printstacktrace();        }    }    public contentvalues getimagecontent(file parent) {        contentvalues image = new contentvalues();        image.put(images.media.title, appname);        image.put(images.media.display_name, imagename);        image.put(images.media.description, "app image");        image.put(images.media.date_added, system.currenttimemillis());        image.put(images.media.mime_type, "image/jpg");        image.put(images.media.orientation, 0);        image.put(images.imagecolumns.bucket_id, parent.tostring()                .tolowercase().hashcode());        image.put(images.imagecolumns.bucket_display_name, parent.getname()                .tolowercase());        image.put(images.media.size, parent.length());        image.put(images.media.data, parent.getabsolutepath());        return image;    }