Enhancing Rotation in Phimp.me using Horizontal Wheel View


To implement rotation of an image in Phimp.me,  we have implemented Horizontal Wheel View feature. It is a custom view for user input that models horizontal wheel controller. How did we include this feature using jitpack.io?

Step 1: 

The jitpack.io repository has to be added to the root build.gradle:

allprojects {
repositories {
maven { url "https://jitpack.io" }

Then, add the dependency to your module build.gradle:

compile 'com.github.shchurov:horizontalwheelview:0.9.5'

Sync the Gradle files to complete the installation.

Step 2: Setting Up the Layout

Horizontal Wheel View has to be added to the XML layout file as shown below:


app:normalColor="@color/black" />


It has to be wrapped inside a Frame Layout to give weight to the view.
To display the angle by which the image has been rotated, a simple text view has to be added just above it.

android:textSize="14sp" />

Step 3: Updating the UI

First, declare and initialise objects of HorizontalWheelView and TextView.

HorizontalWheelView horizontalWheelView = (HorizontalWheelView) findViewById(R.id.horizontalWheelView);
TextView tvAngle= (TextView) findViewById(R.id.tvAngle);


Second, set up listener on the HorizontalWheelView and update the UI accordingly.

horizontalWheelView.setListener(new HorizontalWheelView.Listener() {
public void onRotationChanged(double radians) {

updates the angle and updateImage() updates the image to be rotated. The following functions have been defined below:

private void updateText() {
String text = String.format(Locale.US, "%.0f°", horizontalWheelView.getDegreesAngle());

private void updateImage() {
int angle = (int) horizontalWheelView.getDegreesAngle();
//Code to rotate the image using the variable 'angle'

is a method of ‘rotatePanel’ which is an object of RotateImageView, a custom view to rotate the image.

Let us have a look at some part of the code inside RotateImageView.

private int rotateAngle;

‘rotateAngle’ is a global variable to hold the angle by which image has to be rotated.

public void rotateImage(int angle) {
rotateAngle = angle;

The method invalidate() is used to trigger UI refresh and every time UI is refreshed, the draw() method is called.
We have to override the draw() method and write the main code to rotate the image in it.

The draw() method is defined below:

public void draw(Canvas canvas) {
if (bitmap == null)
maxRect.set(0, 0, getWidth(), getHeight());// The maximum bounding rectangle

scale = 1;
if (wrapRect.width() > getWidth()) {
scale = getWidth() / wrapRect.width();

canvas.scale(scale, scale, canvas.getWidth() >> 1,
canvas.getHeight() >> 1);
canvas.drawRect(wrapRect, bottomPaint);
canvas.rotate(rotateAngle, canvas.getWidth() >> 1,
canvas.getHeight() >> 1);
canvas.drawBitmap(bitmap, srcRect, dstRect, null);

private void calculateWrapBox() {
matrix.reset(); // Reset matrix is ​​a unit matrix
int centerX = getWidth() >> 1;
int centerY = getHeight() >> 1;
matrix.postRotate(rotateAngle, centerX, centerY); // After the rotation angle


And here you go:


Refer to Github- Horizontal Wheel View for more functions and for a sample application.

Creating a Notification in Open Event Android App

It is a good practice to show user a notification for alerts and have their attention for important events they want to remember. Open Event Android app shows notifications for the actions like bookmarks, upcoming events etc. In this blog we learn how to create similar kind of alert notification.


Displaying notification after bookmarking a track

NotificationCompat is available as part of the Android Support Library, so the first step is opening your project’s module-level build.gradle file and adding the support library to the dependencies section. First we initialize the notification manager with the context of application so a user can see notification irrespective of where it is in app.

NotificationManager mManager = (NotificationManager) this.getApplicationContext().getSystemService(NOTIFICATION_SERVICE);
int id = intent.getIntExtra(ConstantStrings.SESSION, 0);
String session_date;
Session session = realmRepo.getSessionSync(id);

We then get the info we want to display in the notification from the intent. While adding an action to your notification is optional, the reality is that the vast majority of applications add actions to their notifications. We define a notification action using a PendingIntent. In this instance, we update our basic notification with a PendingIntent.

Intent intent1 = new Intent(this.getApplicationContext(), SessionDetailActivity.class);
intent1.putExtra(ConstantStrings.SESSION, session.getTitle());
intent1.putExtra(ConstantStrings.ID, session.getId());
PendingIntent pendingNotificationIntent = PendingIntent.getActivity(this.getApplicationContext(), 0, intent1, PendingIntent.FLAG_UPDATE_CURRENT);
Bitmap largeIcon = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);

We also test the condition for the OS version to display the marker image, see image 1 for reference. The minimum requirement for a notification are:

  • An icon: Create the image you want to use and then add it to you project’s ‘drawable’ folder. Here notification shows bookmark option
  • Title text. You can set a notification’s title either by referencing a string resource, or by adding the text to your notification directly.
  • Detail text. This is the most important part of your notification, so this text must include everything the user needs to understand exactly what they’re being notified about.
int smallIcon = R.drawable.ic_bookmark_white_24dp;
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) smallIcon = R.drawable.ic_noti_bookmark;

String session_timings = String.format("%s - %s",
       DateConverter.formatDateWithDefault(DateConverter.FORMAT_12H, session.getStartsAt()),
       DateConverter.formatDateWithDefault(DateConverter.FORMAT_12H, session.getEndsAt()));
session_date = DateConverter.formatDateWithDefault(DateConverter.FORMAT_DATE_COMPLETE, session.getStartsAt());

Finally we build notification using notification builder having various options to set text style, small icons, big icon etc., see the complete class here,

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)
       .setContentText(session_date + "\n" + session_timings)
       .setStyle(new NotificationCompat.BigTextStyle().bigText(session_date + "\n" + session_timings))

mManager.notify(session.getId(), mBuilder.build());