Implementing the PDF download of Schedule in Open Event Web app

Open Event Web app now provides an option to its users to download the PDF of event schedule. Earlier it supported the download of list-view only, now it provides the support to download calendar-view as well. The problem incurred while downloading the calendar-view was that the view gets cropped due to limitations with the library used for PDF generation, thus only some parts of the calendar remained in the PDF. The problem is resolved by creating an image for every date in the schedule and adding the generated image to the PDF.

Selecting and adding the data for PDF generation

The data to be added to PDF depending on the filters and date-selectors applied is chosen from the DOM. Selection of data is done by looping through all the dates and adding only the ones which do not have ‘hide’ class added to them. The selected dates are first expanded such that their complete view is available while generating the image. The complete data is stored in a variable depending on if the complete schedule is requested for download or some filter is applied, which is later used for generating the image.

let fullScheduler = true;
let mapValue = '';

pdf = new jsPDF('l', 'pt', 'a1');
$('.calendar').each(function() {
 let hidePresent = $(this).attr('class').split(' ').indexOf('hide') <= 0;

 if (hidePresent) {
   $timeline = $(this);

  // Expanding the schedule for current date
  ...
  ...
 }
 fullScheduler = hidePresent && fullScheduler;
});

if(fullScheduler) {
 $timeline = $('.calendar').parent();
 mapValue = $timeline.children();
}

Adding the notification while generating the PDF

A loader with the notification is added to provide better user experience, as the PDF generation takes place at the time of request itself it may take some time depending on the size of the schedule. The notifications are added using ‘sweetalert’ library already added for Add to calendar notifications.

swal("Generating the PDF",{
 icon: "./images/loader.gif",
 buttons: false
});

Downloading the PDF

The selected dates are stored in an array named ‘schedArr’ whose data sequentially is passed for canvas generation. A new page is added to the PDF of size equal to canvas and the generated canvas is added to that page. With every new page added to the calendar a count is increased to keep a track if all the selected dates are added to PDF.

async.eachSeries(schedArr, function (child, callback) {
 html2canvas(child, {
   onrendered: function (canvas) {
     pdf.addPage(canvas.width, canvas.height);
     child.style.width = initialWidth[count] + 'px';
     pdf.addImage(canvas, 'png', 0, 0, canvas.width, canvas.height);
     currDate++;
     if(currDate === schedArr.length){
       pdf.deletePage(1);
       swal.close();
       pdf.save(scheduleDate + '.pdf');
     }
     count++;
     callback();
   }
 });
});

When the last page is added, the notification is closed and user is prompted to download pop-box.

Resources

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Integrating Google Calendar API in Open Event Web app

Open Event Web app allows organizers to add a feature which enables the users to add any session to their google calendar. The organizer is required to generate an API key and client ID on Google developers console and add the generated credentials to web app generator. The credentials are added to the generated application and every session is added with an Add to calendar button, which on click makes the request to add the corresponding session to the calendar.

Creating Client ID and API key

Enable the Google calendar API from Google developers console. Go to `Create Credentials` tab and generate an API key and client ID for your app. While creating the client ID, an input field is present which requires Authorised javascript origins, mention the domains where the generated application would be deployed.

Adding Client ID and API key to the generator

The Client ID and API key obtained from the developer console is added to the web app generator. The event generated uses these credentials to make a request to the server for adding any session to the calendar.

The added credentials are used to initialise the client in the procedure `initClient()` –

function initClient() {
 let id = document.getElementById('gcalendar-id').value;
 let key = document.getElementById('gcalendar-key').value;
 let CLIENT_ID = id;
 let API_KEY = key;
 let DISCOVERY_DOCS = ["https://www.googleapis.com/discovery/v1/apis/calendar/v3/rest"];
 let SCOPES = "https://www.googleapis.com/auth/calendar";

 gapi.client.init({
   apiKey: API_KEY,
   clientId: CLIENT_ID,
   discoveryDocs: DISCOVERY_DOCS,
   scope: SCOPES
 })
}

Adding session to the Google calendar

Every Google calendar enabled event is provided a button with every session, so that corresponding session can be added to the calendar. A procedure named `handleAuthClick` is called with the details of session being passed as parameter when the user clicks on the button. This function handles the authentication required for adding session to the calendar.

function handleAuthClick(title, location, calendarStart, calendarEnd, timezone, description) {
 let isSignedIn = gapi.auth2.getAuthInstance().isSignedIn.get();
 if (!isSignedIn) {
   gapi.auth2.getAuthInstance().signIn().then(function() {
     main.listUpcomingEvents(title, location, calendarStart, calendarEnd, timezone, description);
   });
 } else {
   main.listUpcomingEvents(title, location, calendarStart, calendarEnd, timezone, description);
 }
}

A function named `listUpcomingEvents` makes the request to insert the event object with details of the session to the calendar.

function listUpcomingEvents(title, location, calendarStart, calendarEnd, timezone, description) {
 let event = {
  ... // Event details  


  ... // Code for notifications
  ...
  ...
   'colorId': '5'
 };

 let request = gapi.client.calendar.events.insert({
   'calendarId': 'primary',
   'resource': event
 });
 request.execute(function(event) {
  // Success notification
 });
}

When the session with the corresponding data is added to calendar, an alert box notifying successful addition of session is shown up on the screen.

Resources

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Building 64 bit lzma file

Meilix contains the kernel and casper file in image-i386.tar.lzma. This lzma is a compression method for files. It provides a high compression ratio and fast decompression.

Lzma files contains the Meilix file system, we get the same content inside it which we get when when we mount an ISO file. Lzma file is basically an image of the Meilix Operating System.

Solution:

We need to build a lzma file of 64 bit for Meilix. If we extract the lzma file we will find a README file which contains all the information of the ISO used to build this lzma file.

When we search through the files we find a file named README.diskdefines which contains the information of the file system.

#define DISKNAME  Lubuntu 12.10 "Quantal Quetzal" - Release i386
#define TYPE  binary
#define TYPEbinary  1
#define ARCH  i386
#define ARCHi386  1
#define DISKNUM  1
#define DISKNUM1  1
#define TOTALNUM  0
#define TOTALNUM0  1

The first line depicts that name and version of the ISO with the architecture from where this file system has been taken.

So we thought to build the same system with release amd64.

We download the ISO and tried to compress it into lzma.tar.

Decompression of lzma.tar file is easy but to compress a file into lzma.tar is done as follows:

When using tar, the first word after -f is the output filename

tar -c --lzma -f foo.tar.lzma sourcefile(s)

We mounted the lubuntu 12.10 64 bit ISO and copied it into another folder. Then tried to compress it with lzma algorithm. It resulted in a big size file which can’t be pushed to Github.

So we find out that a file name filesystem.casper is largest in size and can also be removed. Therefore we removed that file and build the ISO again and pushed.
We tested the ISO and file that the build is working file.

Changes made:

  • One we need to push the 64 bit lzma
  • We need to edit this line in build.sh of Meilix

# Arch to build ISO for, i386 or amd64
arch=${1:-i386}

Finally we got the file as image-amd64.tar.lzma

So, if we look into the Readme file we can found the version which it used for building the zip.

#define DISKNAME  Ubuntu 12.10 "Quantal Quetzal" - Release amd64
#define TYPE  binary
#define TYPEbinary  1
#define ARCH  amd64
#define ARCHamd64  1
#define DISKNUM  1
#define DISKNUM1  1
#define TOTALNUM  0
#define TOTALNUM0  1

We can see that it is based on the same version but the architecture is different.

Resources

  1. GNU lzma tar: https://www.gnu.org/software/tar/manual/html_node/gzip.html
  2. Python lzma compression: https://docs.python.org/3/library/lzma.html

 

 

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Delete Image Permanently from Trashbin in Phimpme App

In the Phimpme Android application, users can perform various operations on the images including renaming an image, sharing images, deleting images from the storage etc. However, with the implementation of the Trash Bin feature in the app, the user is now provided with the option to restore back the deleted images. Whenever the delete operation is performed, the selected images are moved to the Trash Bin and the user has the option to either delete the photos permanently or restoring back the deleted photos by navigating to the Trash bin section. So in this post, I’d be discussing the implementation of permanently deleting image/images from the Trashbin.

Step 1

Firstly, we need to add permanent delete option in the popup menu provided in the itemview in the TrashView section. Every item in the Trashbin section displays a popup menu with two options-restore and delete permanently. The permanent delete option has been implemented in the itemview by adding the following lines of code.

<?xml version=“1.0” encoding=“utf-8”?>
<menu xmlns:android=“http://schemas.android.com/apk/res/android” xmlns:app=“http://schemas.android.com/apk/res-auto”>

<item
    android:id=“@+id/delete_permanently”
    android:title=“@string/delete_permanently”
    app:showAsAction=“never” />
</menu>

Step 2

Now when the user opts to permanently delete any photo from the bin, a function deletePermanent would be invoked passing-in the trashbin object corresponding to the selected item as the parameter. Inside the deletePermanent method, a check is performed to determine whether the corresponding image file exists or not using the .exists method of the File class and if the result is true the file is deleted permanently using the .delete method of the File class. The method deletePermanent returns a boolean value depending on whether the image file is deleted permanently from the storage or not. The code snippets used to implement the deletePermanent method is provided below.

private boolean deletePermanent(TrashBinRealmModel trashBinRealmModel){
  boolean succ = false;
  String path = trashBinRealmModel.getTrashbinpath();
  File file = new File(Environment.getExternalStorageDirectory() + “/” + “.nomedia”);
  //File file = new File(Environment.getExternalStorageDirectory() + “/” + “TrashBin”);
  if(file.exists()){
      File file1 = new File(path);
      if(file1.exists()){
          succ = file1.delete();
      }
  }
  return succ;
}

Step 3

The function deletePermanent used implemented in the previous step returns a boolean value which will be used in this step. So if the deletePermanent method returns true indicating that the image has been deleted from the trashbin, first a method deleteFromRealm is invoked passing-in the path of the image in the Trashbin to delete the corresponding image’s record from the realm database. Thereafter, that particular trashbin item is removed from the ArrayList<TrashbinRealmModel> populating the TrashBin adapter to display the items in the TrashBin Activity and the adapter is notified of this change by the use of NotifyItemRemoved and NotifyItemRangeChanged methods of the RecyclerView adapter class passing-in the position of the item as parameter to the former and position along with the size of the updated list as parameters to the latter function. After the adapter is updated about the change in the dataset, the adapter re-populates the recyclerview thus displaying the remaining items in the trashbin section. The code snippets implementing the above-mentioned operations are provided below.

if(deletePermanent(trashBinRealmModel)){
  deleteFromRealm(trashItemsList.get(position).getTrashbinpath());
  trashItemsList.remove(position);
  notifyItemRemoved(position);
  notifyItemRangeChanged(position, trashItemsList.size());
}
private void deleteFromRealm(final String path){
  Realm realm = Realm.getDefaultInstance();
  realm.executeTransaction(new Realm.Transaction() {
      @Override public void execute(Realm realm) {
          RealmResults<TrashBinRealmModel> trashBinRealmModels = realm.where(TrashBinRealmModel.class).equalTo
                  (“trashbinpath”, path).findAll();
          trashBinRealmModels.deleteAllFromRealm();
      }
  });
}

This is how we have implemented the functionality to permanently delete an image from the Trashbin section in the Phimpme Android application. To get the full source code, please refer to the Phimpme Android Github repository listed in the resource section below.

Resources

  1. Android Developer documentation –https://developer.android.com/reference/java/io/File
  2. Github-Phimpme Android Repository – https://github.com/fossasia/phimpme-android/
  3. Realm database operations Android – https://www.androidhive.info/2016/05/android-working-with-realm-database-replacing-sqlite-core-data/
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Compressing Images in Resolution in Phimpme Android Application

In the Phimpme Android application, users can perform various operations on images such as editing an image, sharing an image, moving the image to another folder, printing a pdf version of the image and many more. However, another important functionality that has been implemented is the option to compress an image. Two modes of compress operation have been implemented namely compress by size and compress by dimensions. In the previous blog post I discussed the implementation of compress by size operation. So in this blog post, I will be discussing how we achieved the functionality to compress any image by resolution.

Step 1

First, we need to add an option in the bottombar menu(in the SingleMediaActivity) to compress the image being viewed. The option to compress an image has been added by implementing the following lines of code in the  menu_bottom_view_pager.xml file.

<item
      android:id=“@+id/action_compress”
      android:orderInCategory=“2”
      app:showAsAction=“always”
      android:icon=“@drawable/compressicn”
      android:title=“Compress”/>

Step 2

Now on selecting the compress option, the user would be prompted to choose the compress mode i.e compress by size or compress by dimension. Once the user opts for compressing the image by resolution, a dialog containing the various resolutions options to choose from is to be displayed. Code snippets used to implement the dialog along with seekbar is displayed below.

<android.support.v7.widget.CardView
  xmlns:android=“http://schemas.android.com/apk/res/android”
  xmlns:app=“http://schemas.android.com/apk/vn.mbm.phimp.me”
  android:layout_width=“match_parent”
  android:layout_height=“wrap_content”
  app:cardCornerRadius=“2dp”
  android:id=“@+id/dialog_chose_provider_title”>
  <LinearLayout
      android:layout_width=“match_parent”
      android:layout_height=“wrap_content”
      android:orientation=“vertical”>

      <TextView
          android:id=“@+id/compress_title”
          android:layout_width=“match_parent”
          android:layout_height=“wrap_content”
          android:padding=“24dp”
          android:text=“@string/compress_by_dimension”
          android:textColor=“@color/md_dark_primary_text”
          android:textSize=“18sp”
          android:textStyle=“bold” />

      <ListView
          android:id=“@+id/listview”
          android:layout_width=“match_parent”
          android:layout_height=“321dp”
          android:layout_alignParentStart=“true”
          android:layout_centerVertical=“true”/>

  </LinearLayout>
</android.support.v7.widget.CardView>

A screenshot displaying the resolutions option dialog is provided below.

Step 3

Now in this final step as mentioned for the compress by size post, we would use the image compression library Compressor to obtain the compress by resolution functionality. After the user has specified the new resolution required, the Compressor class of the library is instantiated by passing-in the context as the parameter and some of its functions are invoked simaltaneously. The functions invoked are setMaxWidth(), setMaxHeight(),  setCompressFormat(), setDestinationDirectoryPath(), compressToFile().

setMaxWidth() – to set the width of the output image.

setMaxHeight() – to set the height of the output image.

setCompressFormat(Bitmap.CompressFormat) – to determine the format of the output compressed image.

setDestinationDirectoryPath(File) – to specify the path to which the compressed image is to be saved.

compressToFile(File) – to perform the compress operation, passing-in the file object of the corresponding image to be compressed.

The compressToFile() function performs the final compress operation and saves the compressed image to the specified path.

Code snippets to implement the above mentioned operations are given below

private void compressDim() {
  ListCompressAdapter lviewAdapter;
  ArrayList<String> compress_option= new ArrayList<String>();
  MediaDetailsMap<String,String> mediaDetailsMap = SingleMediaActivity.mediacompress.getMainDetails(this);
  //gives in the form like 1632×1224 (2.0 MP) , getting width and height of it
  String dim[]=mediaDetailsMap.get(“Resolution”).split(“x”);
  int  width= Integer.parseInt(dim[0].replaceAll(” “,“”));
  String ht[]=dim[1].split(” “);
  int height= Integer.parseInt(ht[0]);
  LayoutInflater inflater = getLayoutInflater();
  final View dialogLayout = inflater.inflate(R.layout.dialog_compresspixel, null);
  TextView title = (TextView) dialogLayout.findViewById(R.id.compress_title);
  title.setBackgroundColor(getPrimaryColor());
  //create options of compress in dimensions in multiple of 2
  int awidth=width;
  int aheight=height;
  ListView listView = (ListView)dialogLayout.findViewById(R.id.listview);
  while ((width%2==0)&&(height%2==0)) {
      compress_option.add(width + ” X “ + height);
      width=width/2;
      height=height/2;
  }

  lviewAdapter = new ListCompressAdapter(this, compress_option);
  listView.setAdapter(lviewAdapter);
  final int finalWidth = awidth;
  final int finalHeight = aheight;
  listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
      @Override
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
          if (position==0){
              cwidth[0] = finalWidth ;
              cheight[0] = finalHeight;}
          else{
              cwidth[0] = finalWidth /(position*2);
              cheight[0] = finalHeight /(position*2);}
          view.setBackgroundColor(R.color.md_light_blue_A400);
          new SaveCompressedImage().execute(“Resolution”);
          finish();
      }
  });
new Compressor(getApplicationContext())
      .setMaxWidth(cwidth[0])
      .setMaxHeight(cheight[0])
      .setCompressFormat(Bitmap.CompressFormat.JPEG)
      .setDestinationDirectoryPath( FileUtilsCompress.createFolders().getPath())
      .compressToFile(new File(saveFilePath));

This is how we have implemented the functionality to compress an image by size in the Phimpme Android application. To get the full source code, please refer to the Phimpme Android Github repository listed in the resource section below.

Resources

  1. Android Developer documentation –https://developer.android.com/reference/java/io/File
  2. Github-Phimpme Android Repository – https://github.com/fossasia/phimpme-android/
  3. Compressor Library – https://github.com/zetbaitsu/Compressor

 

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Compress Images Size in Phimpme Android application

In the Phimpme Android application, users can perform various operations on images such as editing an image, sharing an image, moving the image to another folder, printing a pdf version of the image and many more. However, another important functionality that has been implemented is the option to compress an image. Two modes of compress operation have been implemented namely compress by size and compress by dimensions. So in this blog post, I will be discussing how we achieved the functionality to compress any image by size.

Step 1

First, we need to add an option in the bottom bar menu(in the SingleMediaActivity) to compress the image being viewed. The option to compress an image has been added by implementing the following lines of code in the  menu_bottom_view_pager.xml file.

<item
      android:id=“@+id/action_compress”
      android:orderInCategory=“2”
      app:showAsAction=“always”
      android:icon=“@drawable/compressicn”
      android:title=“Compress”/>

Step 2

Now on selecting the compress option, the user would be prompted to choose the compress mode i.e compress by size or compress by dimension. Once the user has opted for the size mode a dialog with a seekbar to set the compress percentage is to be displayed. Code snippets used to implement the dialog along with seekbar is displayed below.

<RelativeLayout
  android:layout_width=“wrap_content”
  android:layout_height=“wrap_content”
  android:layout_marginTop=“8dp”>

  <SeekBar
      android:id=“@+id/seekBar”
      android:layout_width=“match_parent”
      android:layout_height=“wrap_content”
      android:layout_weight=“0.65”
      android:max=“90”
      android:progressBackgroundTint=“@color/colorPrimary”
      android:thumb=“@drawable/ic_location_on_black_24dp” />

  <TextView
      android:id=“@+id/textview2”
      android:layout_width=“wrap_content”
      android:layout_height=“wrap_content”
      android:layout_alignParentEnd=“true”
      android:layout_below=“@+id/seekBar”
      android:layout_marginBottom=“5dp”
      android:layout_marginEnd=“16dp”
      android:text=“95%”
      android:textAppearance=“@style/TextAppearance.AppCompat.Body1”
      android:textSize=“16sp” />
</RelativeLayout>

A screenshot displaying the dialog to set the compress percentage is provided below

Step 3

Here to obtain the compress functionality we have used an open-sourced custom image compression library Compressor. After the user has set the compress percentage, the Compressor class of the library is instantiated by passing-in the context as the parameter and some of its functions are invoked simultaneously. The functions invoked are setQuality(), setCompressFormat(), setDestinationDirectoryPath(), compressToFile().

setQuality(int) – to set the percentage compressed.

setCompressFormat(Bitmap.CompressFormat) – to determine the format of the output compressed image.

setDestinationDirectoryPath(File) – to specify the path to which the compressed image is to be saved.

compressToFile(File) – to perform the compress operation, passing-in the file object of the corresponding image to be compressed.

The compressToFile() function performs the final compress operation and saves the compressed image to the specified path.

Code snippets to implement the above-mentioned operations are given below

private void compressSize() {

  LayoutInflater inflater = getLayoutInflater();
  View dialogLayout = inflater.inflate(R.layout.dialog_compresssize, null);
  TextView title = (TextView) dialogLayout.findViewById(R.id.compress_title);
  title.setBackgroundColor(getPrimaryColor());
  SeekBar percentsize = (SeekBar) dialogLayout.findViewById(R.id.seekBar);
  percentsize.getThumb().setColorFilter(getAccentColor(), PorterDuff.Mode.SRC_IN);
  percentsize.setProgress(0);
  final TextView percent=(TextView)dialogLayout.findViewById(R.id.textview2);
  percentsize.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
      @Override
      public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
          //options of compress by size from 5% to 9;
          int progress1=95-progress;
          progress1=progress1-progress1%5;
          percent.setText(progress1+“%”);
          percentagecompress=progress1;}

      @Override
      public void onStartTrackingTouch(SeekBar seekBar) {
          //do nothing
      }

      @Override
      public void onStopTrackingTouch(SeekBar seekBar) {
          //do nothing
      }
  });}
new Compressor(getApplicationContext())
.setQuality(percentagecompress)
.setCompressFormat(Bitmap.CompressFormat.JPEG)
.setDestinationDirectoryPath(FileUtilsCompress.createFolders().getPath())
.compressToFile(new File(saveFilePath));

This is how we have implemented the functionality to compress an image by size in the Phimpme Android application. To get the full source code, please refer to the Phimpme Android Github repository.

Resources

  1. Android Developer documentation –https://developer.android.com/reference/java/io/File
  2. Compressor Library – https://github.com/zetbaitsu/Compressor
  3. Seekbar Tutorial – https://abhiandroid.com/ui/seekbar
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Implementing Undo Operation in Phimpme Android application

In the Phimpme Android application, users can perform various operations on the images available including renaming an image, sharing images, deleting images from the storage etc. However, there might occur a scenario where the user accidentally or in a rush performs some action and would want to undo it the very next second, so in such cases the undo action feature comes in pretty handy. So in this blog post, I will be discussing the undo operation option implemented for the delete image feature in Phimpme Android app.

Step 1

Firstly, we need to add an “Undo” action button in the Snackbar that displays the success operation message. With this addition, the user would have time to undo an operation until the snackbar message is being displayed on the screen. The undo action button can be added to the Snackbar by the use of the setAction method of the Snackbar class. The code snippets used to implement the button is provided below

Snackbar snackbar = SnackBarHandler.showWithBottomMargin2(mDrawerLayout, String.valueOf(no) + ” “ + getString(R.string
              .trashbin_move_onefile),
      navigationView.getHeight
              (), Snackbar.LENGTH_SHORT);
snackbar.setAction(“UNDO”, new View.OnClickListener() {
  @Override
  public void onClick(View view) {
      getAlbum().moveAllMedia(getApplicationContext(), getAlbum().getPath(), media1);
      refreshListener.onRefresh();
  }
});
snackbar.show();

Step 2

When the user performs the delete operation, first the photos are moved to the trashbin and the user have the option to delete them from there. Now, if the user opts for undo operation, on clicking the undo button the function moveallMedia will be invoked passing-in context, the path of the current album and an ArrayList<Media> containing the deleted media on which the undo operation is to be performed upon, as parameters. Here the ArrayList<Media> passed as a parameter contains the trashbin paths of the images deleted by the previous action. A method storeDeletedFilesTemporarily has been used that returns the list containing the deleted images trashbin paths. The implementation of the method storeDeletedFilesTemporarily has been provided below.

private ArrayList<Media> storeDeletedFilesTemporarily(){
ArrayList<Media> deletedImages = new ArrayList<>();
if(!all_photos && !fav_photos && editMode){
for(Media m: getAlbum().getSelectedMedia()){
String name = m.getPath().substring(m.getPath().lastIndexOf(“/”) + 1);
deletedImages.add(new Media(Environment.getExternalStorageDirectory() + “/” + “.nomedia” + “/” + name));
}
} else if(all_photos && !fav_photos && editMode){
for(Media m: selectedMedias){
String name = m.getPath().substring(m.getPath().lastIndexOf(“/”) + 1);
deletedImages.add(new Media(Environment.getExternalStorageDirectory() + “/” + “.nomedia” + “/” + name));
}
}
return deletedImages;
}

Step 3

Now in the final step, I’d discuss the implementation of the moveAllMedia method that actually completes the undo operation. As I mentioned earlier that on performing the delete operation the images are moved to the bin folder(which is hidden from the other applications), so the moveAllMedia method here will again move the images from the trashbin folder to the current folder. With this operation deleted images would be stored back to their original folder and their trashbin record would be simultaneously deleted from the Realm database. The code implementation of the moveAllMedia method is provided below.

public int moveAllMedia(Context context, String targetDir, ArrayList<Media> albummedia){
 int n = 0;
 try
 {
    int index=-1;
    for(int i =0;i<albummedia.size(); i++)
    {
       String s = albummedia.get(i).getPath();
       int indexOfLastSlash = s.lastIndexOf(“/”);
       String fileName = s.substring(indexOfLastSlash + 1);

       if(!albummedia.get(i).getPath().equals(targetDir+“/”+fileName)){
          index=-1;
       }else{
          index=i;
          break;

       }
    }
    if(index!=-1)
    {
       n = –1;
    }else{
       for (int i = 0; i < albummedia.size(); i++) {

          if (moveMedia(context, albummedia.get(i).getPath(), targetDir)) {
             String from = albummedia.get(i).getPath();
             scanFile(context, new String[]{ from, StringUtils.getPhotoPathMoved(albummedia.get(i).getPath(),
                   targetDir) },
                   new MediaScannerConnection.OnScanCompletedListener() {
                      @Override
                      public void onScanCompleted(String s, Uri uri) {
                         Log.d(“scanFile”, “onScanCompleted: “ + s);
                      }
                   });
             media.remove(albummedia.get(i));
             n++;
          }
       }
       setCount(media.size());
    }
 } catch (Exception e) { e.printStackTrace(); }
 return n;

}

This is how we have implemented the functionality to perform Undo operation in the Phimpme Android application. To get the full source code, please refer to the Phimpme Android Github repository.

Resources

  1. Android Developer documentation –https://developer.android.com/reference/java/io/File
  2. MediaScanner Tutorial – https://stackoverflow.com/questions/9414955/trigger-mediascanner-on-specific-path-folder-how-to/25086535

 

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Option to Restore Deleted Images in Phimpme Android Application

In the Phimpme Android application, users can perform various operations on the images including renaming an image, sharing images, deleting images from the storage etc. However with the implementation of Trash Bin feature in the app, the user is now provided with the option to restore back the deleted images. Whenever the delete operation is performed, the selected images are moved to the Trash Bin and the user has the option to either delete the photos permanently or restoring back the deleted photos by navigating to the Trash bin section. So, in this post I’d be discussing the implementation of restore image/images functionality.

Step 1

Firstly, we need to add restore option in the popup menu provided in the itemview in the TrashView section. Every item in the Trashbin section displays a popup menu with two options-restore and delete permanently. The popup menu along with the two options have been implemented by adding the following lines of code.

<?xml version=“1.0” encoding=“utf-8”?>
<menu xmlns:android=“http://schemas.android.com/apk/res/android” xmlns:app=“http://schemas.android.com/apk/res-auto”>

<item
    android:id=“@+id/restore_option”
    android:title=“@string/restore_photo”
    app:showAsAction=“never” />

<item
    android:id=“@+id/delete_permanently”
    android:title=“@string/delete_permanently”
    app:showAsAction=“never” />
</menu>

Step 2

Now after the user opts to restore a particular image, the corresponding realm object for the image would be retrieved from the Realm database. This realm object would contain attributes namely trashbinpath, oldpath, datetime, timeperiod. Here the oldpath attribute contains the path where it  was stored in the device storage before the delete operation was performed on the image. Thereafter to restore the image to its old path, a move operation would be performed which would move the image from the TrashBin section to the album it was stored in before deletion. With this move operation, the image is restored to its old path and is visible in the respective album resulting in the removal/deletion of the image from the TrashBin section. The method implemented to perform the above mentioned operations is provided below.

private boolean restoreImage(TrashBinRealmModel trashBinRealmModel){
  String oldpath = trashBinRealmModel.getOldpath();
  boolean success = false;
  try {
      String from = trashBinRealmModel.getTrashbinpath();
      if (success = moveMedia(context, from, targetDir)) {
          scanFile(context, new String[]{ from, StringUtils.getPhotoPathMoved(pathofmed, targetDir) });
      }
  } catch (Exception e) { e.printStackTrace(); }
  return success;
}

Step 3

In the previous step, the move operation for the restore feature was performed by the restoreImage method which inturn uses method moveMedia() to get the job done. So in this step, I’d be discussing about the implementation of the moveMedia() method. Inside the moveMedia() method, moveFile method of ContentHelper class is invoked passing-in context, sourcefile, and the destination folder as the parameters. Thereafter a normal rename operation is performed by the use of the renameTo method to move the file to destination folder. Now if the rename operation is performed successfully, the file is moved to its old path whereas if the rename operation fails to get the job done, a copy operation is initiated to copy the file to the destination folder and the image  the is deleted from the trashbin section if the copy operation is successful. The code snippets used to implement the moveMedia and moveFile are provided below.

private boolean moveMedia(Context context, String source, String targetDir) {
 File from = new File(source);
 File to = new File(targetDir);
 return ContentHelper.moveFile(context, from, to);
}
public static boolean moveFile(Context context, @NonNull final File source, @NonNull final File targetDir) {
 // First try the normal rename.
 File target = new File(targetDir, source.getName());

 boolean success = source.renameTo(target);

 if (!success) {
    success = copyFile(context, source, targetDir);
    if (success) {
       success = deleteFile(context, source);
    }
 }
 //if (success) scanFile(context, new String[]{ source.getPath(), target.getPath() });
 return success;

}

This is how we have implemented the functionality to restore a deleted image in the Phimpme Android application. To get the full source code, please refer to the Phimpme Android Github repository listed in the resource section below.

Resources

  1. Android Developer documentation –https://developer.android.com/reference/java/io/File
  2. Github-Phimpme Android Repository – https://github.com/fossasia/phimpme-android/
  3. Renaming a file in java – http://stacktips.com/tutorials/java/how-to-delete-and-rename-a-file-in-java
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Working with Shared Preferences in PSLab App

This blog demonstrates how to work with Shared Preferences in an Android app. The blog includes a detailed explanation about what are the methods available to store data in Android and where to use Shared Preferences (a type of data storage method) to save extra memory usage and work efficiently. After the detailed explanation is a step by step guide on how to use Shared Preferences in any Android app by taking an example of one used in PSLab Android app under PR #1236

What are methods available in Android for data storage ?

Android provides a variety of methods to store data some of which are

  1. Shared Preferences
  2. Internal Storage
  3. External Storage
  4. SQLite Database

A very brief description of the above four data storage method would be

  • Shared Preference – Used to store key-data pair for a given app
  • Internal Storage – Used to store any type of data such as pictures, videos, etc. which can be used only within the app
  • External Storage – Used to store any type of data such as audio, video, etc. which can be shared between different apps or different systems
  • SQLite database – It is also a type of Internal Storage method but with a different programming language in use which is SQL

Where to use different data storage methods?

Following are some of the  distinct cases where the above-mentioned data storing methods can be differentiated

  • Shared Preference – Shared Preference should be used when a very small amount of data i.e. key-value pair data is to be stored. An example of it would be storing the state of a widget when an app is closed and restoring the state when the app is opened again.
  • Internal Storage – Internal storage should be used while storing data such as text files, audio, video, photographs, etc. but occupying a very less device memory space. So, internal storage should be used when a limited amount of data needs to be stored for app execution.
  • External Storage – External storage should be used when data to be stored is very large and as a result, Internal storage can’t be used. External Storage can also write data on external memories like SD Card, etc.

How to use Shared Preferences in an Android app?

Following is a step by step guide on how Shared Preferences were used in PSLab Android app

  • First, declare a variable using final and static keyword so as to make its value permanent because it will be used to differentiate current activity/fragment data from other activity/fragment data in a common folder of Shared Preference.
private static final String FRAG_CONFIG = "LuxMeterConfig";
  • Now, we can make Shared Preferences for current activity/fragment by using the code:

When in Activity:

final SharedPreferences settings = getSharedPreferences(FRAG_CONFIG, Context.MODE_PRIVATE);

When in fragment:

final SharedPreferences settings = getActivity().getSharedPreferences(FRAG_CONFIG, Context.MODE_PRIVATE);

Here Context.MODE_PRIVATE is a context through which we define our Shared Preference i.e. for the current context it means that the above made Shared Preference can only be used inside the current activity/fragment. A detailed description of other modes available can be found in [1].

  • Now, Shared Preference for current activity/fragment is ready for use and so now, we can add as many numbers of the key-value pair as we want by using the following code
settings.getInt("HighValue", 2000);

Here, “HighValue” is the key whereas 2000 is the value. The above method is used to give a default value when a pair is created.

  • Now to edit the value of any before-made pair, we can use the Editor method available in the Shared Preference class to edit the default value.
SharedPreferences.Editor editor = settings.edit();
editor.putInt("HighValue", 5000);
editor.apply();

Here, the editor is an instance of edit() method available in Shared Preference class. After changing the default value of the key, we can use apply() method to apply the changes to the default key-value pair.

Where to find the Shared Preference folder on the target device?

To find the Shared Preference folder for any Android application, do the following steps:

  • Connect the target device (device on which app is installed) to the system running Android Studio.
  • Now click on the “Device File Explorer” button in Android Studio as shown in figure 1.

Figure 1. Device File Explorer button in Android Studio

  • Now after clicking the button, a list of folders would pop up as shown in figure 2.

Figure 2. Screenshot of Android Studio showing list of folders on the device

  • Now follow the given path, and you can see the desired folder
/data/data/YOUR_PACKAGE_NAME/shared_prefs/YOUR_PACKAGE_NAME_preferences.xml

So, in this way, the Shared Preferences can be used for data storage in any Android application.

Resources

  1. https://www.androidauthority.com/how-to-store-data-locally-in-android-app-717190/ – Documentation on different modes available to define the context of Shared Preference
  2. https://stackoverflow.com/questions/6146106/where-are-shared-preferences-stored – StackOverflow Q/A for where the Shared Preferences are stored on the target device
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