Iteration through the Android File System in the phimpme project

Android uses the single file system structure which has a single root. The task involved creating a custom folder chooser to whitelist folders while displaying images in the gallery in the Phimpme Photo App. The challenge arose in iterating over the files in the most efficient way. The best possible way to represent the file structure is in the form of tree data structure as given below.

Current Alternative

Currently, the MediaStore class contains metadata for all available media on both internal and external storage devices. Since it only returns a list of a particular media file format, it refrains the developer from customizing the structure in his way.

Implementation

Create a public class which represents the file tree. Since each subtree of the tree could itself be represented as file tree itself, therefore the parent of a node will be a FileTree object itself. Therefore declare a list of FileTree objects as children of the node, a FileTree object as the parent of the particular node, node’s own File object along with string values filepath and display name associated with it.

public class FileTree {
 public final String filepath;
 public final String displayName;
 public final List<FileTree> childFileTreeList = new ArrayList<>();
 public final FileTree parent;
 public boolean hasMedia = false;

 public FileTree(String filepath, String displayName, FileTree parent) {
    this.filepath = filepath;
    this.displayName = displayName;
    this.parent = parent;
 }
}

For iterating through the file system, we create a recursive function which is called on the root of the Android file system. If the particular file is a directory, with the help of Depth First traversal algorithm, the directory is traversed. Else, the file is added to the list of the file. The below code snippet is the recursive function.

public static void walkDir(FileTree fileTree, List<File> files) {
  File listFile[] = fileTree.file.listFiles();

  if (listFile != null) {
      for (File file : listFile) {
          if (file.isDirectory()) {
              FileTree childFileTree = new FileTree(file, file.getName(), fileTree);
              fileTree.childFileTreeList.add(childFileTree);
              walkDir(childFileTree, files);
          }
          else {
                  files.add(file);

          }
      }
  }
}

Conclusion

The android file system was used to whitelist folders so that the images of the folders could neither be uploaded nor edited.

For the complete guide to whitelisting folders, navigate here

Native Functions for Performing Image Processing in Phimpme Android

In Android, image processing can be performed using Java or RenderScript or Native(C/C++). The performance of native code(C/C++) for image processing is much better than Java and RenderScript. So we used native code for image processing in the photo editor of the Phimpme image application. In this blog, I explain how image processing is performed in Phimpme Android.

Setting up build script for native code.

NDK helps us to develop Android applications using native languages like C and C++ so that heavy tasks can be performed in relatively less time. We can also use libraries built using C/C++ in Android application using this NDK. NDK can be downloaded using the SDK manager of Android Studio and can be set up following instructions in Android developers’ site.

After setting up the NDK, we will create a simple application involving native code and understand the flow of functions from Java to native.

The java files are present in app/src/main/java directory. Similarly, all the native files are present in app/src/main/jni directory.

So now let’s create necessary files in jni directory.

  • main.c – Native functions are added here
  • Android.mk and Application.mk – make files for building native code using ndkbuild.

Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := main.c       // include the files that should be 
                                // built(.c, .cpp, .h)
LOCAL_LDLIBS += -llog
LOCAL_MODULE := modulename      //name of the module (custom)
include $(BUILD_SHARED_LIBRARY)

Application.mk

APP_OPTIM := release
APP_ABI := all                    //architectures for which native lib
                               //has to be built(can be one or many. 
                               //should be separated by comma)
APP_PLATFORM := android-25 

Add these lines to app’s build.gradle for building native code along with the Gradle build.

externalNativeBuild {
   ndkBuild {
       path 'src/main/jni/Android.mk'
   }
}

The above lines in build.gradle will run Android.mk during the Gradle build.

When the Android.mk runs, it compiles all native code and generates modulename.so files in .externalNativeBuild/ndkBuild directory for all the mentioned architectures. This .so file for a particular architecture is a library containing all the native code compatible with that architecture.

So when this library(.so file) is statically imported into Java code, native code gets linked to Java and enables calling native functions directly from Java.

Importing native Library into Java

Static import of this library can be done by writing the below lines in your Java class.

static {
    System.loadLibrary("modulename");
}

Creating a native function and calling it from Java?

Unlike normal java code, where you call a function by its name, here in native Android development, the name of the native function is different from what you call it in java. To understand this clearly, let’s see an example of simple hello world application. Define the native function in Java and call it normally like any other function.

package org.fossasia.phimpme;

import 

public class MainActivity extends Activity {
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);       
       textView = (TextView)findViewById(R.id.textview);
       textView.setText(helloworld());
   }

    static {
        System.loadLibrary(“modulename”);
    }

     Public native String helloworld();
}

Here the definition of the native function is present in org.fossasia.phimpme package and MainActivity class. So the name of the function in the native file should be “Java_org_fossasia_phimpme_MainActivity_helloworld”.

It follows a general structure of concatenating these strings Java, package name, Class name, function name defined in Java and replacing all full stops(.) with underscores(_).

The first two arguments in native function are JNIEnv* and jobject. These are present always. For a zero argument definition of a function in Java, there will be these two arguments in the native function. If there are two arguments defined in Java, there will be two arguments additional to these two arguments in the native function. These help in passing data in and out of the native part.

Here’s an example of a native function to output a string to Java

main.c :

#include <jni.h>
jstring Java_org_fossasia_phimpme_MainActivity_helloworld  (JNIEnv * env, jobject obj){
    return (*env)->NewStringUTF(env, "Hello World from Native");
}

Now when you run this application, you see “Hello World from Native” displayed on the screen. I hope this post clears about the flow of the native functions and how to link them with Java.

References

https://developer.android.com/ndk/guides/index.html

Implementing UNDO and REDO in Image Editor of Phimpme Android

The main feature in any image editor application like Phimpme Android other than editing the image is the ability to revert the changes (UNDO) that are done and the ability to revert the reversion i.e reperform the changes (REDO).

In Phimpme Application, we implemented this by using an ArrayList of Bitmaps. We stored the copy of the image bitmap whenever the modification is done on it. This helped us to get back to the previous image when required. But there is a problem in this method. They method may produce OutOfMemory Error when storing the bitmap in ArrayList when memory gets full. So for dealing solving this in the Phimpme application, we added a try – catch block and when the out of memory exception is caught, we recycled and removed the initial modified image from list i.e the image of index 1 in ArrayList. Index 0 is the original image on which we are working on. When we recycled that image, it gives space for adding another image, So added the recent image at the end of the list.

addToUndoList() function is shown below.

private void addToUndoList() {
   try{
       recycleBitmapList(++currentShowingIndex);
       bitmapsForUndo.add(mainBitmap.copy(mainBitmap.getConfig(),true));
   }catch (OutOfMemoryError error){
       bitmapsForUndo.get(1).recycle();
       bitmapsForUndo.remove(1);
       bitmapsForUndo.add(mainBitmap.copy(mainBitmap.getConfig(),true));
   }
}

In the above function, bitmapsForUndo is ArrayList in which we added modified bitmaps in the editor of Phimpme application. mainBitmap is the image bitmap on which all modifications are being done in the editor. The sense of integer variable currentShowingIndex is clear from its name that it points to the index of the image that is currently getting shown.

Eg. Consider a case when you perform 5 edits on an image using Phimpme Editor, then 6 image bitmaps get stored in the ArrayList including the original image and currentShowingIndex will be 5. Now if you undo the steps twice the currentShowingIndex becomes 3. The bitmaps of the index 4 and 5 have not been removed from the ArrayList yet. So they will be useful if you want to redo the changes.

  

When you make an another edit, an image bitmap gets added at index 4 and that should be the last element of the ArrayList. But you see that there is a bitmap of index 5 making that the last element of the ArrayList, not the newly added one. So in order to achieve that, the elements present in the ArrayList whose index is greater than currentShowingIndex have to recycled and removed before adding a newly modified image bitmap to the ArrayList. The first line in the try block of the above functions is referring to the function that is going to implement this. That function’s implementation is given below

private void recycleBitmapList(int fromIndex){
   while (fromIndex < bitmapsForUndo.size()){
       bitmapsForUndo.get(fromIndex).recycle();
       bitmapsForUndo.remove(fromIndex);
   }
}

Removing the bitmap from the ArrayList doesn’t clear the memory. That bitmap has to be recycled before getting removed from the ArrayList which is performed in the above function of the Phimpme application’s image editor.  The above recycleBitmapList function recycles and removes the bitmaps which have an index greater than or equal to the index that is passed as an argument to that function.

This function should also be called in onDestroy function of android activity as

recycleBitmapList(0);

This recycles and removes the whole ArrayList.

As now the implementation of the creation and recycling of the ArrayList is done, we can use this ArrayList to create getter functions for the undo and redo bitmaps. When the getUndoBitmap() is called the currentShowingIndex should decrement by one if greater than zero. When getRedoBitmap() is called the currentShowingIndex has to be incremented by one until it gets equal to the index of the last element present in the array list.

These methods are shown below.

private Bitmap getUndoBitmap(){
   if (currentShowingIndex - 1 >= 0)
       currentShowingIndex -= 1;
   else currentShowingIndex = 0;

   return bitmapsForUndo
           .get(currentShowingIndex)
           .copy(bitmapsForUndo.get(currentShowingIndex).getConfig(), true);
}

private Bitmap getRedoBitmap(){
   if (currentShowingIndex + 1 <= bitmapsForUndo.size())
       currentShowingIndex += 1;
   else currentShowingIndex = bitmapsForUndo.size() - 1;

   return bitmapsForUndo
           .get(currentShowingIndex)
           .copy(bitmapsForUndo.get(currentShowingIndex).getConfig(), true);
}

Logic part is done by here. We integrated these getter functions to button click functions of Phimpme Image Editor. setButtonVisibility() is called whenever undo or redo is button is pressed. This function sets the enable state and visibility of the button i.e the undo button is visible and enabled only if undo is possible. So does for the redo button.

setButtonVisibility() is shown below.

private void setButtonsVisibility() {
   if (currentShowingIndex > 0) {
       undo.setColorFilter(Color.BLACK);
       undo.setEnabled(true);
   }else {
       undo.setColorFilter(Color.GRAY);
       undo.setEnabled(false);
   }

   if (currentShowingIndex + 1 < bitmapsForUndo.size()) {
       redo.setColorFilter(Color.BLACK);
       redo.setEnabled(true);
   }else {
       redo.setColorFilter(Color.GRAY);
       redo.setEnabled(false);
   }
}

The above function grays the button if it is in the disabled state and will be black when the enabled state conditions are satisfied.

Finally, the OnClick() function of the editor of Phimpme is shown below.

@Override
public void onClick(View v) {
   switch (v.getId()){
       case R.id.edit_undo:
           onUndoPressed();
           break;
       case R.id.edit_redo:
           onRedoPressed();
           break;
   }
}

private void onUndoPressed() {
   if (mainBitmap != null) {
       if (!mainBitmap.isRecycled()) {
           mainBitmap.recycle();
       }
   }
   mainBitmap = getUndoBitmap();
   mainImage.setImageBitmap(mainBitmap);
   setButtonsVisibility();
}

private void onRedoPressed() {
   if (mainBitmap != null) {
       if (!mainBitmap.isRecycled()) {
           mainBitmap.recycle();
       }
   }
   mainBitmap = getRedoBitmap();
   mainImage.setImageBitmap(mainBitmap);
   setButtonsVisibility();
}

This shows how we implemented undo and redo in Image Editor of Phimpme Image Application.

Implementing a zoomable ImageView by Extending the Default ViewPager in Phimpme Android

When I was trying to give default gallery-like experience to the gallery of Phimpme Image Application, where you can zoom an image with pan and pinch controls along with the ability to navigate to another photo by swipe gestures, I faced a problem in which when the zoomed image is swiped expecting it to get panned, instead of that, the viewpager switched to another page.

This implementation of Viewpager with zoomable image in it might seem straightforward in the beginning but once you start implementing this in most common way i.e using default ViewPager for navigation between images and zooming libraries like TouchImageView, subsampling-scale-image-view or PhotoView for zooming the image with pinch and pan controls, you will notice that when you swipe left or right on the zoomed image, the pager navigates to other images instead of the zoomed image getting panned. The viewpager responds to the swipe event and causes page change and it doesn’t let zoomable view to respond to that event.

In the above screenshot, front image is zoomed and when we swipe left, instead of the image getting panned, it is switching to next page.

How to solve this?

As the problem is caused by the default ViewPager utilizing the swipe event without transferring it to child views, a custom viewpager can be created by extending default viewpager and having a touch intercept method which transfers the event to its child views. A sample implementation of this custom view pager which I used in the app is shown below.


public class CustomViewPager extends ViewPager {
    public CustomViewPager(Context context) {
        super(context);
    }

    public CustomViewPager(Context context, AttributeSet attrs)
    {
        super(context,attrs);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        try {
            return super.onInterceptTouchEvent(ev);
        } catch (IllegalArgumentException e) {
            return false;
        }
    }
}

Now we can replace normal viewpager with this custom view pager in image viewing activity and layout resource for that activity. The normal pager adapter which is used with default view pager can be used with this custom viewpager also. You can get a clear understanding of what I described here by having a look at the below implementation.

activity_imageview.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
   xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent">

   <package.name.path.to.CustomViewPager
       android:id="@+id/cviewpager"
       android:layout_width="match_parent"
       android:layout_height="match_parent"/>
</RelativeLayout>

ImageViewActivity.java

public class ImageViewActivity extends Activity {
    CustomViewPager cViewPager;
    ArrayList<String> imageList;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_imageview);
        imageList = createList(); //some method for creating a list
        cViewPager = (CustomViewPager)findViewById(R.id.cviewpager);  
        mViewPager.setAdapter(new ImagePagerAdapter(imageList));
    }

    class ImagePagerAdapter extends PagerAdapter {
        ArrayList<String> imageList; 
        
        ImagePagerAdapter(ArrayList<String> imageList){
            this.imageList = imageList;
        }

     [email protected]
        public int getCount() {
            return (null != imageList) ? imageList.size() : 0;
        }

       [email protected]
        public boolean isViewFromObject(View view, Object object) {
            return view == object;
        }

        @Override
        public View instantiateItem(ViewGroup container, int position) {
            PhotoView photoView = new PhotoView(container.getContext());
            Glide.with(getContext())
                .load(UriFromFile(new File(imageList.get(position))))
                .asBitmap()
                .thumbnail(0.2f)
                .into(photoView);
            photoView.setMaximumScale(5.0F);
            photoView.setMediumScale(3.0F);
            container.addView(photoView, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
            return photoView;
        }

        @Override
         public void destroyItem(ViewGroup container, int position, Object object) {
             container.removeView((View) object);
         }
     }
}

In the above pager adapter, the PhotoView library is used for a zoomable view. The image is loaded into photoview using image caching library Glide. The pager adapter here takes a List of paths to images on the device as the input argument. A simple method for creating such list had been discussed in my first post.

Here you can see that the on swiping left the zoomed image got panned.

This method of implementing zoomable view in ViewPager is used many gallery applications. One among those applications is LeafPic. We are now integrating that into Phimpme Image Application.

References:

https://developer.android.com/reference/android/support/v4/view/ViewPager.html

https://developer.android.com/training/gestures/viewgroup.html

https://github.com/MikeOrtiz/TouchImageView

https://github.com/chrisbanes/PhotoView

 

Adding Multiple Themes in Phimpme Android

In Phimpme-Android we decided to add a new feature that is providing multiple themes to the users. We have 3 types of themes in Phimpme Dark Theme, Light Theme and Amoled Theme. In this post, I am explaining how I added multiple themes support in phimpme android.

 Choose Theme in Phimpme Dialog

You need a Helper class that will store the data about the theme and all the colors related to a theme.

Before you begin you need to create a Helper class. In Phimpme I created a Helper class as ThemeHelper

public class ThemeHelper {

 public static final int DARK_THEME = 2;
 public static final int LIGHT_THEME = 1;
 public static final int AMOLED_THEME = 3;

 private PreferenceUtil SP;
 private Context context;

 private int baseTheme;
 private int primaryColor;
 private int accentColor;

 public ThemeHelper(Context context) {
  this.SP = PreferenceUtil.getInstance(context);
  this.context = context;
  updateTheme();
 }
}

Which contains all the basic method to get colors for textview, icon, toolbar, switch, imageview, background and app primary color.

Now you to provide user to select theme and it can be done using dialog box. Once the user selected any of the theme we have to update that theme and it can be done by following code :

 public void updateTheme(){
  this.primaryColor = SP.getInt(context.getString(R.string.preference_primary_color),
        getColor(R.color.md_light_blue_300));
  this.accentColor = SP.getInt(context.getString(R.string.preference_accent_color),
        getColor(R.color.md_light_blue_500));
  baseTheme = SP.getInt(context.getString(R.string.preference_base_theme), LIGHT_THEME);
 }

Now we have updated the our theme in Phimpme now we have to set the color according to a theme.

To get colors of all components we need to add some function in our helper class which will provide us the colors according to the theme.

As I said we are having 3 themes in Phimpme so I used 3 case to compare which theme user has selected.

I have added the functions to get colors for background, text and subtext as follows in phimpme.

public int getBackgroundColor(){
  int color;
  switch (baseTheme){
    case DARK_THEME:color = getColor(R.color.md_dark_background);break;
    case AMOLED_THEME:color = getColor(R.color.md_black_1000);break;
    case LIGHT_THEME:
    default:color = getColor(R.color.md_light_background);
  }
  return color;
 }



 public int getTextColor(){
  int color;
  switch (baseTheme){
    case DARK_THEME:color = getColor(R.color.md_grey_200);break;
    case AMOLED_THEME:color = getColor(R.color.md_grey_200);break;
    case LIGHT_THEME:
    default:color = getColor(R.color.md_grey_800);
  }
  return color;
 }

 public int getSubTextColor(){
  int color;
  switch (baseTheme){
    case DARK_THEME:color = getColor(R.color.md_grey_400);break;
    case AMOLED_THEME:color = getColor(R.color.md_grey_400);break;
    case LIGHT_THEME:
    default:color = getColor(R.color.md_grey_600);
  }
  return color;
 }

In the above functions, I am comparing which theme user has selected and returned the color according to the theme.

Now set the color to text by using above function you don’t need care which theme user has selected because those function will check and return the color according to the theme.

So it can be done simply,

textview.setTextColor(getTextColor());
editText.setTextColor(getTextColor());
editText.setHintTextColor(getSubTextColor());

                                     Light Theme &  Dark Theme (Phimpme)

Resources:

https://github.com/fossasia/phimpme-android/blob/development/app/src/main/java/org/fossasia/phimpme/leafpic/util/ThemeHelper.java

http://www.hidroh.com/2015/02/16/support-multiple-themes-android-app/

Preparing a release for Phimpme Android

Most of the essential features are now in a stable state in our Phimpme Android app. So we decided to release a beta version of the app. In FOSSASIA we follow branch policy where in development all current development will take place and in master branch the stable code resides.

Releasing an app is not just building an apk and submitting to the distribution platform, certain guidelines should follow.

How I prepare a released apk for Phimpme

List down the feature

We discussed on our public channel what features are now in stable state and can be released. Features such as account manager and Share Activity is excluded because it is not complete and in under development mode. We don’t want to show and under development feature. So excluded them. And made a list of available features in different category of Camera, Gallery and Share.

Follow the branch policy.

The releasable and stable codebase should be on master branch. It is good to follow the branch policy because it helps if we encounter any problem with the released apk. We can directly go to our master branch and check there. Development branch have very volatile because of active development going on.

Every Contributor’s contribution is important

When we browse our old branches such as master in case of ours. We see generally it is behind 100s of commits to the development. In case of that when we create a PR for that then it generally contains all the old commits to make the branch up to the latest.

In this case while opening and merging do not squash the commits.

Testing from Developer’s end

Testing is very essential part in development. Before releasing it is a good practice that Developer should test the app from their end. We tested app features in different devices with varying Android OS version and screen size.

  • If there is any compatibility issue, report it right away and there are several tools in Android to fix.
  • Support variety of devices and screen sizes

Changing package name, application ID

Package name, application ID are vitals of an app. Which uniquely identifies them as app in world. Like I changed the package name of Phimpme app to org.fossasia.phimpme. Check all the permission app required.

Create Release build type

Build types are great to way categorize the apps. Debug and Release are two. There are various things in codebase which we want only in Debug modes. So when we create Release mode it neglect that part of the code.

Add build types in you application build.gradle

buildTypes {
   release {
       minifyEnabled false
   }

Rebuild app again and verify from the left tab bar

Generate Signed apk and Create keystore (.jks) file

Navigate to Build → Generate Signed APK

Fill all details and proceed further to generate the signed apk in your home directory.

Adding Signing configurations in build.gradle

Copy the keystore (.jks) file to the root of the project and add signing configurations

signingConfigs {
       config {
           keyAlias 'phimpme'
           keyPassword 'phimpme'
           storeFile file('../org.fossasia.phimpme.jks')
           storePassword 'XXXXXXX'
       }
   }

InstallRelease Gradle task

Navigate to the right sidebar of Android Studio click on Gradle


Click on installRelease to install the released apk. It take all the credentials from the signing configurations.

Resources

Adding Stickers Feature on Phimpme Android App with ViewFlipper and Scrollview

For any image editing application stickers play an important role in editing an image. Phimpme is no different. There can be many different kinds of stickers. As Phimpme is an Open Source application. The user can add their own stickers to be implemented on Phimpme. But this gives a long and non-exhaustive list of stickers that the user has to go through. Sorting the stickers into different categories is one way of doing it. It provides quick access to the desired sticker a user wants to add to her or his photo. In order to achieve this, I am using ViewFlipper and Scrollview.

Categorizing the types of Stickers.

How it is done in Phimpme?

Currently, there are six different categories for stickers. Namely: Facial, Hearts, Objects, Comments, Wishes, Animals. The following code is used to store the category name:

public static final String[] stickerPath = {"stickers/type1", "stickers/type2", "stickers/type3", "stickers/type4", "stickers/type5", "stickers/type6"};
public static final String[] stickerPathName = {"Facial", "Hearts", "Objects", "Comments", "Wishes", "Animals"};

 

We need to populate the sticker fragment with the different categories. This is done by overriding onBinderHolder() function and using ImageHolder to handle onClickListener.

private ImageClick mImageClick = new ImageClick();

Getting the position of the stickerPathName and setting it in stickerFragment.

@Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        ImageHolder imageHoler = (ImageHolder) holder;
        String name = stickerPathName[position];
        imageHoler.text.setText(name);
        imageHoler.text.setTag(stickerPath[position]);
        imageHoler.text.setOnClickListener(mImageClick);
    }

 

Adding Stickers to the different categories.

Now that we have different categories, we can assign different types of stickers to specific categories.

We are using RecyclerView.Adapter<ViewHolder>, which implements onCreateViewHolder() method. onCreateViewHolder method is created every time we need a new view, hence RecyclerView comes handy in such situation rather than a normal list.

First, we need to define the xml file where each sticker will be displayed in the form of ImageView. This ImageView has specific maxHeight and maxWidth for a uniform view.

The xml file name is: view_sticker_item.xml

<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/img"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:maxHeight="50dp"
    android:maxWidth="50dp"
    android:paddingLeft="5dp"
    android:paddingRight="5dp"
    android:scaleType="centerInside" />


After we set up view_sticker_item.xml, we have to inflate it.

@Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewtype) {
        View v = null;
        v = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.view_sticker_item, parent, false);
        ImageHolder holder = new ImageHolder(v);
        return holder;
    }

 

I have saved all the images in the assets folder and distributed it among type1, type2, type3, type4, type5 and type6.

One thing is to be kept in mind that the images should be in png format. PNG format images are only pixelated on the required areas. So that it does not hamper the background of the image.

Displaying stickers

Displaying sticker are done by overriding onBindViewHolder again. It accepts two parameters: ViewHolder holder and int position. ImageHolder is used to set the image of the sticker and then handling it by onClickListner().

@Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        ImageHolder imageHoler = (ImageHolder) holder;
        String path = pathList.get(position);
        ImageLoader.getInstance().displayImage("assets://" + path,
                imageHoler.image, imageOption);
        imageHoler.image.setTag(path);
        imageHoler.image.setOnClickListener(mImageClick);
    }

 

public void addStickerImages(String folderPath) {
        pathList.clear();
        try {
            String[] files = mStirckerFragment.getActivity().getAssets()
                    .list(folderPath);
            for (String name : files) {
                pathList.add(folderPath + File.separator + name);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        this.notifyDataSetChanged();
    }

 

So sticker fragment on Phimpme looks like this:  

                                        

Link:

https://github.com/fossasia/phimpme-android

Resources

 

Adding Twitter Integration with MVP Architecture in Phimpme Android

The Account manager layout part of Phimpme is set. Now we need to start adding different account to make it functional. We first start with twitter. Twitter functionality is integrated with the help of Twitter Kit provided by Twitter itself. We followed the steps provided on the installation guide.

Note: Before Starting this first go to apps.twitter.com and create new app, add the relevant information such as name, description, URL etc.

How twitter works in Phimpme

A dialog box appear when user selected the add account option in Account manager. Select Twitter option from it.

Twitter guides to use custom TwitterLoginButton for sign in. But as we are using a common dialog box. How to initiate login from there?

Using TwitterAuthClient

Twitter Auth Client invoke the Twitter callback and popup the login window. On authorized the correct user it goes inside the onSuccess method and start a Twitter session which helps us to get the information which we want to store in database such as username, access token.

client.authorize(getActivity(), new Callback<TwitterSession>() {
 [email protected]
   public void success(Result<TwitterSession> result) {

       // Creating twitter session, after user authenticate
       // in twitter popup
       TwitterSession session = TwitterCore.getInstance()
               .getSessionManager().getActiveSession();
       TwitterAuthToken authToken = session.getAuthToken();


       // Writing values in Realm database
       account.setUsername(session.getUserName());
       account.setToken(String.valueOf(session.getAuthToken()));

   }

Working with MVP architecture to show Twitter data to User in a recyclerView

Finally after successful login from Twitter, we also need to show user that you are successfully logged in Phimpme app and also provide a sign out feature so that user can logout from Twitter anytime.

Account manager has a recyclerView which takes data from the database and show it to the User.

Steps:

class AccountContract {
   internal interface View : MvpView{

       /**
        * Setting up the recyclerView. The layout manager, decorator etc.
        */
       fun setUpRecyclerView()

       /**
        * Account Presenter calls this function after taking data from Database Helper Class
        */
       fun setUpAdapter(accountDetails: RealmResults<AccountDatabase>)

       /**
        * Shows the error log
        */
       fun showError()
   }

   internal interface Presenter {

       /**
        * function to load data from database, using Database Helper class
        */
       fun loadFromDatabase()

       /**
        * setting up the recyclerView adapter from here
        */
       fun handleResults(accountDetails: RealmResults<AccountDatabase>)
   }
}

This class clearly show what functions are in View and what are in Presenter. The View interface extended to MvpView which actually holds some common functions such as onComplete()

  • Implement View interface in AccountActivity

class AccountActivity : ThemedActivity(), AccountContract.View

And perform all the action which are happening on the View such as setting up the RecyclerView

override fun setUpRecyclerView() {
   val layoutManager = LinearLayoutManager(this)
   accountsRecyclerView!!.setLayoutManager(layoutManager)
   accountsRecyclerView!!.setAdapter(accountAdapter)
}
  • Main Business Logic should not be in Activity class

That’s why using MVP we have very less number of lines of code in our Main Activity because it separate the work on different zones which help developer to easily work, maintain and other user to contribute.

So like in our case I need to update the RecyclerView adapter by taking data from database. That work should not be in activity that’s why I create a class AccountPresenter and extend this to our Presenter interface in contract class

class AccountPresenter extends BasePresenter<AccountContract.View>
       implements AccountContract.Presenter

I added the function which take care of loading data from database

@Override
public void loadFromDatabase() {
   handleResults(databaseHelper.fetchAccountDetails());
}
  • Always consider the future and keep an eye for future development

Right now I not need to do alot on Database, I just need to pick the whole data and show it on View. But I need to take case of future development in this part as well. There might be more complex operation on Database in future, then it will create complexity in the codebase, if it is not architectured well.

So, I created a DatabaseHelper class which takes care of all the database operations, the advantage of this is, anyone who have to contribute in Database part or debugging the databse need not to search for every activity and scroll lines of code, the work will be in DatabaseHelper for sure.

Added DatabaseHelper in data package

public class DatabaseHelper {

   private Realm realm;

   public DatabaseHelper(Realm realm) {
       this.realm = realm;
   }

   public RealmResults<AccountDatabase> fetchAccountDetails(){
       return realm.where(AccountDatabase.class).findAll();
   }

   public void deleteSignedOutAccount(String accountName){
       final RealmResults<AccountDatabase> deletionQueryResult =  realm.where(AccountDatabase.class)
               .equalTo("name", accountName).findAll();

       realm.executeTransaction(new Realm.Transaction() {
 [email protected]
           public void execute(Realm realm) {
               deletionQueryResult.deleteAllFromRealm();
           }
       });
   }
}

Flow Diagram:

Browse the Phimpme GitHub Repository for complete illustration.

Resources

  1. Twitter KIt overview : https://dev.twitter.com/twitterkit/android/overview
  2. Login with Twitter: https://dev.twitter.com/twitterkit/android/log-in-with-twitter
  3. MVP Architecture by Ribot: https://github.com/ribot/android-boilerplate

 

Adding Image Editor in Phimpme Android app

Image editing is a core feature of our Phimpme Android Application. We are using this already existing components Image Editor. Currently our app flow is Gallery → Open images. Now we add an option menu in the top named “Edit” which redirect to the edit Image Activity with that image path. Perform the edit operations there and apply the changed and finally updated the album with new file.

The task is to first get the image path pass to the EditImageActivity and then save the edited image in different folder after user finish with editing.

Below are the high level architecture of how it is achieved with help of ImageEditor.

Steps to integrate Editor:

  • Get the selected Image URI

Firstly, add the permission in manifest file

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Get the local images in your internal or SD Card using Media Store content provider.

Uri uri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI; 

String[] projection = { MediaStore.Images.Media._ID, MediaStore.Images.Media.BUCKET_ID,MediaStore.Images.Media.BUCKET_DISPLAY_NAME }; 

Cursor cursor = getContentResolver().query(uri, projection, null, null, null);

After that you can iterate the cursor to end and get details.

  • Create a separate folder where edited images will be saved.

Now after editing we have to place the edited image into a seperate folder with a new name. You can create folder like this:

File aviaryFolder = new File(baseDir, FOLDER_NAME);

Generating new file which will be saved as edited image

public static File getEmptyFile(String name) {

  File folder = FileUtils.createFolders();

  if (folder != null) {

     if (folder.exists()) {

        File file = new File(folder, name);

        return file;

     }

  }

  return null;

}
FileUtils.getEmptyFile("edited"

     + System.currentTimeMillis() + ".png");

 

It will save new image as named edited<timeinmillis> so it will be unique.

  • StartActivityforResult with the image URI and edit activity

So firstly, when user open image and click on edit. We create an empty file using the above method. Getting the image uri and pass it into the editImageActivity. Other than Uri, also pass the output file path.

And startActivityForResult with intent and request code.

You can track the editing done by user and finally save if there is some edit done, like in Phimpme we keep a counter which increased on change of Bitmap.

Update the Album by putting the image Media Store

ContentValues values = new ContentValues(2);

String extensionName = getExtensionName(dstPath);

values.put(MediaStore.Images.Media.MIME_TYPE, "image/" + (TextUtils.isEmpty(extensionName) ? "jpeg" : extensionName));

values.put(MediaStore.Images.Media.DATA, dstPath);

context.getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);

Please visit the whole code here: github.com/fossasia/phimpme-android

Resources

Using Activities with Bottom navigation view in Phimpme Android

Can we use Bottom Navigation View with activities? In the FOSSASIA Phimpme Project we integrated two big projects such as Open Camera and Leafpic. Both are activity based projects and not developed over fragment. The bottom navigation we use will work with fragment.

In Leafpic as well as in Open Camera, there are a lot of Multi level inheritance which runs the app components. The problem faced to continue to work on activities. For theme management using base activity is necessary. The base activity extend to AppcompatActivity. The leafpic code hierarchy is very complex and depend on various activities. Better way is to shift to activities for using Bottom navigation view and  work with activity similar like fragments.

Image source: https://storage.googleapis.com/material-design/

Solution:

This is possible if we copy the bottom navigation item in each of the activity and setting the clicked state of it as per the menu item ID.

Steps to Implement (How I did in Phimpme)

  • Add a Base Activity which takes care of two thing

    • Taking the layout element and setting in the activity.
    • Set up the correct navigation menu item clicked

Function selectBottomNavigationBarItem(int itemId) will take care of what item is currently active. Called this function in onStart(), getNavigationMenuItemId() function will return the menu id and selectBottomNavigagionBarItem update the bottom navigation view.

public abstract class BaseActivity extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener

private void updateNavigationBarState() {
   int actionId = getNavigationMenuItemId();
   selectBottomNavigationBarItem(actionId);
}

void selectBottomNavigationBarItem(int itemId) {
   Menu menu = navigationView.getMenu();
   for (int i = 0, size = menu.size(); i < size; i++) {
       MenuItem item = menu.getItem(i);
       boolean shouldBeChecked = item.getItemId() == itemId;
       if (shouldBeChecked) {
           item.setChecked(true);
           break;
       }
   }
}
  • Add two abstract functions in the BaseActivity for above task
public abstract int getContentViewId();

public abstract int getNavigationMenuItemId();
  • Extend every activity to the Base Activity

For example I created a blank Activity: AccountsActivity and extend to BaseActivity

public class AccountsActivity extends BaseActivity
  • Implement the abstract function in the every activity and set the correct layout and menu item id.

@Override
public int getContentViewId() {
 return R.layout.content_accounts;
}

@Override
public int getNavigationMenuItemId() {
   return R.id.navigation_accounts;
}
  • Remove the setContentView(R.layout.activity_main);
  • Add the onNavigationItemSelected in BaseActivity

@Override
public boolean onNavigationItemSelected(@NonNull final MenuItem item) {
   switch (item.getItemId()) {
       case R.id.navigation_home:
    startActivity(new Intent(this, LFMainActivity.class));
           Break;
       case R.id.navigation_camera:
           startActivity(new Intent(this, CameraActivity.class));
           Break;
       case R.id.navigation_accounts:
           startActivity(new Intent(this, AccountsActivity.class));
           Break;
   }
   finish();
   return true;
}

Output:

The transition is as smooth as we use bottom navigation views with Fragment. The bottom navigation also appear on above of the activity.

Source: https://stackoverflow.com/a/42811144/2902518

Resources: