EdgeDetectionAutoSkewCorrectionView in Android

EdgeDetectionAutoSkewCorrectionView in Android

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class EdgeDetectionAutoSkewCorrectionView extends View implements View.OnTouchListener {

    private Bitmap mBitmap;
    private Paint mPaint;
    private float mLastTouchX, mLastTouchY;
    private Matrix mMatrix;
    private float mSkewAngle;

    public EdgeDetectionAutoSkewCorrectionView(Context context, AttributeSet attrs) {
        super(context, attrs);

        // Load the image from drawable resource
        mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.image);

        // Initialize the paint object
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setFilterBitmap(true);

        // Set the onTouchListener to detect touch events
        setOnTouchListener(this);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        // Apply edge detection algorithm to the bitmap
        Bitmap edgeDetectedBitmap = applyEdgeDetection(mBitmap);

        // Calculate the skew angle of the image using Hough Transform
        mSkewAngle = calculateSkewAngle(edgeDetectedBitmap);

        // Apply skew correction algorithm to rotate the image and correct the skew angle
        Bitmap skewCorrectedBitmap = applySkewCorrection(mBitmap, mSkewAngle);

        // Draw the rotated image on the canvas
        canvas.drawBitmap(skewCorrectedBitmap, mMatrix, mPaint);
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mLastTouchX = event.getX();
                mLastTouchY = event.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                float x = event.getX();
                float y = event.getY();

                // Calculate the distance moved by the user
                float dx = x - mLastTouchX;
                float dy = y - mLastTouchY;

                // Rotate the image by the distance moved by the user
                mMatrix.postRotate(-dx, mBitmap.getWidth() / 2, mBitmap.getHeight() / 2);
                mMatrix.postTranslate(dx, dy);

                // Redraw the view
                invalidate();

                // Update the last touch coordinates
                mLastTouchX = x;
                mLastTouchY = y;
                break;
        }

        return true;
    }

    // Apply edge detection algorithm to the bitmap
    private Bitmap applyEdgeDetection(Bitmap bitmap) {
        // TODO: Implement edge detection algorithm
        return bitmap;
    }

    // Calculate the skew angle of the image using Hough Transform
    private float calculateSkewAngle(Bitmap bitmap) {
        // TODO: Implement Hough Transform algorithm to calculate skew angle
        return 0.0f;
    }

// Apply skew correction algorithm to rotate the image and correct the skew angle
private Bitmap applySkewCorrection(Bitmap bitmap, float skewAngle) {
    // Create a matrix object for skew correction
    mMatrix = new Matrix();

    // Calculate the center point of the image
    int centerX = bitmap.getWidth() / 2;
    int centerY = bitmap.getHeight() / 2;

    // Apply the skew correction matrix
    mMatrix.postTranslate(-centerX, -centerY);
    mMatrix.postRotate(-skewAngle);
    mMatrix.postTranslate(centerX, centerY);

    // Create a new bitmap object with the skew correction matrix
    Bitmap skewCorrectedBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), mMatrix, true);

    return skewCorrectedBitmap;
}