[FIXED] Draw from a view is not drawing in exact location in Android

Issue

I am drawing a view in canvas with existing views. But it draw below the view. Not exactly on the view.

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public class MyView extends View {

    Paint paint;
    ViewGroup viewGroup;
    Context context;

    public MyView(Context context, ViewGroup viewGroup) {
        super(context);
        this.viewGroup = viewGroup;
        this.context = context;
        init();

    }

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

    public MyView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    private void init() {
        paint = new Paint();
        paint.setColor(context.getResources().getColor(R.color.gray));
        paint.setStrokeWidth(10);
        paint.setStyle(Paint.Style.FILL);

    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        for (int i = 0; i < viewGroup.getChildCount() - 1; ++i) {
            View child = viewGroup.getChildAt(i);

            Point point = getLocationOnScreen(child);
            Rect rect = new Rect();
            int x = point.x;
            int y = point.y;
            rect.left = x;
            rect.top = y;
            rect.right = x + child.getWidth();
            rect.bottom = y + child.getHeight();
            canvas.drawRect(rect, paint);
        }

        /*for (int i = 0; i < viewGroup.getChildCount() - 1; ++i) {
            View child = viewGroup.getChildAt(i);
            Rect rect = new Rect();
            rect.left = child.getLeft();
            rect.top = child.getTop();
            rect.bottom = child.getBottom();
            rect.right = child.getRight();
            canvas.drawRect(rect, paint);
        }*/
    }
    public static Point getLocationOnScreen(View view) {
        int[] location = new int[2];
        view.getLocationOnScreen(location);
        return new Point(location[0], location[1]);
    }

}

My MainActivity:

public class MainActivity extends AppCompatActivity {

    ConstraintLayout constraintLayout;
    ImageView imageView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        constraintLayout = findViewById(R.id.parent_view);
        imageView = findViewById(R.id.item_profile_img);
        imageView.post(() -> {
            ViewGroup viewGroup = (ViewGroup) constraintLayout;
            constraintLayout.addView(new MyView(MainActivity.this,viewGroup));
        });

    }
}

activity_main.xml:

<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:ignore="HardcodedText,MissingConstraints"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <androidx.constraintlayout.widget.ConstraintLayout
        tools:ignore="HardcodedText,MissingConstraints"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="20dp"
        android:id="@+id/parent_view">

        <ImageView
            android:id="@+id/item_profile_img"
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:src="@drawable/ic_launcher_background"
            app:layout_constraintTop_toTopOf="parent"
            tools:ignore="ContentDescription,MissingConstraints" />

        <TextView
            android:id="@+id/item_student_name_title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="15dp"
            android:text="Student name"
            android:textStyle="bold"
            app:layout_constraintStart_toEndOf="@+id/item_profile_img" />

        <TextView
            android:id="@+id/item_student_college"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="15dp"
            android:layout_marginTop="8dp"
            android:text="Student college"
            app:layout_constraintStart_toEndOf="@+id/item_profile_img"
            app:layout_constraintTop_toBottomOf="@+id/item_student_name_title" />

        <TextView
            android:id="@+id/item_student_specialization"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="15dp"
            android:layout_marginTop="8dp"
            android:text="Student specialization"
            app:layout_constraintStart_toEndOf="@+id/item_profile_img"
            app:layout_constraintTop_toBottomOf="@+id/item_student_college" />

        <TextView
            android:id="@+id/item_student_description"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="15dp"
            android:layout_marginTop="8dp"
            android:text="Student description"
            app:layout_constraintTop_toBottomOf="@+id/item_profile_img"
            tools:ignore="MissingConstraints" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

Please review my code and let me know where I did mistake.

Solution

Try This

change you're for loop inside onDraw() like this

for (int i = 0; i < viewGroup.getChildCount() - 1; ++i) {
            View child = viewGroup.getChildAt(i);

            Rect rect = new Rect();
//            int x = point.x;
//            int x = point.x;
            int x = (int) child.getX() - dpToPx(20);
            int y = (int) child.getY() - dpToPx(20);
            rect.left = x;
            rect.top = y;
            rect.right = x + child.getWidth();
            rect.bottom = y + child.getHeight();
            canvas.drawRect(rect, paint);
        }

use a view.getX() and view.getY() it returns proper x and y position of view minus value 20 is the padding of your parent view

public static int dpToPx(int dp) {
        return (int) (dp * Resources.getSystem().getDisplayMetrics().density);
    }

Answered By - Mayur
Answer Checked By - Mary Flores (JavaFixing Volunteer)