Use the drawBitmapMesh to distort the image in Android

Hôm nay mĩnh sẽ hướng dẫn cho các bạn drawBitmapMesh in android là môt phương thức xử lý ảnh với bitmap thật dễ dàng.
DrawBitmap on android is a method of handling images in a gentle and simple way.

Step 1:
Create class MyView extend View.

private class MyView extends View
    {
     
        private final int WIDTH = 20;
        private final int HEIGHT = 20;
     
        private final int COUNT = (WIDTH + 1) * (HEIGHT + 1);

        private final float[] verts = new float[COUNT * 2];

        private final float[] orig = new float[COUNT * 2];
        public MyView(Context context, int drawableId)
        {
            super(context);
            setFocusable(true);
        
            bitmap = BitmapFactory.decodeResource(getResources()
                    , drawableId);
            
            float bitmapWidth = bitmap.getWidth();
            float bitmapHeight = bitmap.getHeight();
            int index = 0;
            for (int y = 0; y <= HEIGHT; y++)
            {
                float fy = bitmapHeight * y / HEIGHT;
                for (int x = 0; x <= WIDTH; x++)
                {
                    float fx = bitmapWidth * x / WIDTH;
   
                    orig[index * 2 + 0] = verts[index * 2 + 0] = fx;
                    orig[index * 2 + 1] = verts[index * 2 + 1] = fy;
                    index += 1;
                }
            }
           
            setBackgroundColor(Color.WHITE);
        }
        @Override
        protected void onDraw(Canvas canvas)
        {
           
            canvas.drawBitmapMesh(bitmap, WIDTH, HEIGHT, verts
                    , 0, null, 0,null);
        }
    
        private void warp(float cx, float cy)
        {
            for (int i = 0; i < COUNT * 2; i += 2)
            {
                float dx = cx - orig[i + 0];
                float dy = cy - orig[i + 1];
                float dd = dx * dx + dy * dy;
     
                float d = (float) Math.sqrt(dd);
               
                float pull = 100000 / ((float) (dd * d));
             
                if (pull >= 1)
                {
                    verts[i + 0] = cx;
                    verts[i + 1] = cy;
                }
                else
                {
                 
                    verts[i + 0] = orig[i + 0] + dx * pull;
                    verts[i + 1] = orig[i + 1] + dy * pull;
                }
            }
         
            invalidate();
        }
        @Override
        public boolean onTouchEvent(MotionEvent event)
        {
         
            warp(event.getX(), event.getY());
            return true;
        }
    }

Step 2: Create class MainActivity extends Activity.

public class MainActivity extends Activity
{
    private Bitmap bitmap;
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(new MyView(this, R.drawable.jinta));
    }
}

All code coppy on android studio below.

public class MainActivity extends Activity
{
    private Bitmap bitmap;
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(new MyView(this, R.drawable.jinta));
    }

private class MyView extends View
    {
     
        private final int WIDTH = 20;
        private final int HEIGHT = 20;
     
        private final int COUNT = (WIDTH + 1) * (HEIGHT + 1);

        private final float[] verts = new float[COUNT * 2];

        private final float[] orig = new float[COUNT * 2];
        public MyView(Context context, int drawableId)
        {
            super(context);
            setFocusable(true);
        
            bitmap = BitmapFactory.decodeResource(getResources()
                    , drawableId);
            
            float bitmapWidth = bitmap.getWidth();
            float bitmapHeight = bitmap.getHeight();
            int index = 0;
            for (int y = 0; y <= HEIGHT; y++)
            {
                float fy = bitmapHeight * y / HEIGHT;
                for (int x = 0; x <= WIDTH; x++)
                {
                    float fx = bitmapWidth * x / WIDTH;
   
                    orig[index * 2 + 0] = verts[index * 2 + 0] = fx;
                    orig[index * 2 + 1] = verts[index * 2 + 1] = fy;
                    index += 1;
                }
            }
           
            setBackgroundColor(Color.WHITE);
        }
        @Override
        protected void onDraw(Canvas canvas)
        {
           
            canvas.drawBitmapMesh(bitmap, WIDTH, HEIGHT, verts
                    , 0, null, 0,null);
        }
    
        private void warp(float cx, float cy)
        {
            for (int i = 0; i < COUNT * 2; i += 2)
            {
                float dx = cx - orig[i + 0];
                float dy = cy - orig[i + 1];
                float dd = dx * dx + dy * dy;
     
                float d = (float) Math.sqrt(dd);
               
                float pull = 100000 / ((float) (dd * d));
             
                if (pull >= 1)
                {
                    verts[i + 0] = cx;
                    verts[i + 1] = cy;
                }
                else
                {
                 
                    verts[i + 0] = orig[i + 0] + dx * pull;
                    verts[i + 1] = orig[i + 1] + dy * pull;
                }
            }
         
            invalidate();
        }
        @Override
        public boolean onTouchEvent(MotionEvent event)
        {
         
            warp(event.getX(), event.getY());
            return true;
        }
    }
}

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