How to implement Drag Distortion Image filter in android?

Implementing Drag Distortion Image Filter in Android

Drag distortion is a visually captivating image filter that allows users to manipulate images by dragging their fingers across the screen, creating unique distortions and artistic effects. In this article, we will explore the process of implementing a Drag Distortion Image filter in Android.

1. Project Setup

Begin by creating a new Android Studio project. Ensure you have the necessary dependencies for image manipulation and touch handling:

dependencies {
    implementation "androidx.core:core-ktx:1.9.0"
    implementation "androidx.appcompat:appcompat:1.6.1"
    implementation "com.google.android.material:material:1.10.0"
    implementation "androidx.constraintlayout:constraintlayout:2.1.4"
    implementation "androidx.recyclerview:recyclerview:1.3.2"
    implementation "androidx.navigation:navigation-fragment-ktx:2.7.5"
    implementation "androidx.navigation:navigation-ui-ktx:2.7.5"
    implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.6.2"
    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.6.2"
    implementation "androidx.test.ext:junit:1.1.5"
    androidTestImplementation "androidx.test.espresso:espresso-core:3.5.1"
}

2. Layout Design

Create your layout XML file. It should contain an ImageView to display the image and potentially additional UI elements for filter settings.

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

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:scaleType="fitCenter"
        android:src="@drawable/your_image" />

</LinearLayout>

3. Image Processing with OpenCV

Implement the core logic for the drag distortion filter. OpenCV provides powerful image manipulation capabilities. Include OpenCV in your project:

dependencies {
    implementation 'org.opencv:opencv-android:4.8.0'
}

In your activity, use OpenCV to apply the distortion effect on touch events.

import org.opencv.android.Utils
import org.opencv.core.*
import org.opencv.imgproc.Imgproc

// ...

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    // Get ImageView from layout
    imageView = findViewById(R.id.imageView)

    // Load image
    val bitmap = BitmapFactory.decodeResource(resources, R.drawable.your_image)

    // Convert Bitmap to Mat
    val mat = Mat()
    Utils.bitmapToMat(bitmap, mat)

    // Add touch listener to ImageView
    imageView.setOnTouchListener { _, event ->
        val x = event.x
        val y = event.y

        when (event.action) {
            MotionEvent.ACTION_DOWN -> {
                // Handle touch down
                touchDownPoint = Point(x, y)
            }

            MotionEvent.ACTION_MOVE -> {
                // Handle touch move
                val touchMovePoint = Point(x, y)

                // Calculate the distortion effect
                val distortion = touchMovePoint - touchDownPoint

                // Apply distortion using OpenCV
                // ...
            }

            MotionEvent.ACTION_UP -> {
                // Handle touch up
                touchDownPoint = null
            }
        }
        true
    }
}

4. Applying the Distortion Effect

The distortion effect can be achieved by various methods. One approach is to use a combination of OpenCV functions to manipulate the image pixels:

// Apply distortion using OpenCV
fun applyDistortion(mat: Mat, touchDownPoint: Point, touchMovePoint: Point) {
    // Calculate distortion amount
    val distortionX = touchMovePoint.x - touchDownPoint.x
    val distortionY = touchMovePoint.y - touchDownPoint.y

    // Create a perspective transform matrix
    val src = MatOfPoint2f(touchDownPoint, Point(touchDownPoint.x + 1, touchDownPoint.y),
                           Point(touchDownPoint.x, touchDownPoint.y + 1),
                           Point(touchDownPoint.x + 1, touchDownPoint.y + 1))
    val dst = MatOfPoint2f(touchMovePoint, Point(touchMovePoint.x + 1, touchMovePoint.y),
                           Point(touchMovePoint.x, touchMovePoint.y + 1),
                           Point(touchMovePoint.x + 1, touchMovePoint.y + 1))
    val perspectiveMatrix = Imgproc.getPerspectiveTransform(src, dst)

    // Apply perspective transform to the image
    Imgproc.warpPerspective(mat, mat, perspectiveMatrix, mat.size())
}

5. Updating the ImageView

After applying the distortion effect, update the ImageView with the modified image:

// Convert Mat back to Bitmap and update ImageView
val outputBitmap = Bitmap.createBitmap(mat.cols(), mat.rows(), Bitmap.Config.ARGB_8888)
Utils.matToBitmap(mat, outputBitmap)
imageView.setImageBitmap(outputBitmap)

6. Optimizations

For smoother performance and user experience, consider the following optimizations:

• Caching: Cache the image in memory to avoid unnecessary loading and processing.
• Threading: Execute the image processing tasks in a background thread to avoid blocking the UI thread.
• Scaling: Reduce the image size if it is too large for efficient processing.

Conclusion

By following these steps, you can successfully implement a Drag Distortion Image filter in Android. This effect provides a unique and engaging way for users to interact with and transform images, creating artistic and visually captivating experiences.