<TableRow
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="10dp"
            android:layout_marginRight="10dp"
            android:layout_marginTop="10dp">

            <Button
                android:id="@+id/button4"
                android:layout_width="match_parent"
                android:text="@string/r1960"
                android:textColor="#ffffff"
                android:textSize="@dimen/loptatext"
                android:shadowColor="#000000"
                android:shadowRadius="7"
                android:layout_weight="1"
                android:background="@drawable/tlacitko_stav" />

            <Button
                android:id="@+id/button5"
                android:layout_width="match_parent"
                android:text="@string/r1964"
                android:textColor="#ffffff"
                android:textSize="@dimen/loptatext"
                android:shadowColor="#000000"
                android:shadowRadius="7"
                android:layout_weight="1"
                android:background="@drawable/tlacitko_stav" />

            <Button
                android:id="@+id/button6"
                android:layout_width="match_parent"
                android:text="@string/r1968"
                android:textColor="#ffffff"
                android:textSize="@dimen/loptatext"
                android:shadowColor="#000000"
                android:shadowRadius="7"
                android:layout_weight="1"
                android:background="@drawable/tlacitko_stav" />

            <Button
                android:id="@+id/button7"
                android:layout_width="match_parent"
                android:text="@string/r1972"
                android:textColor="#ffffff"
                android:textSize="@dimen/loptatext"
                android:shadowColor="#000000"
                android:shadowRadius="7"
                android:layout_weight="1"
                android:background="@drawable/tlacitko_stav" />
        </TableRow>

public class SquareButton extends Button {
    public SquareButton(Context context) {
        super(context);
    }

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

    public SquareButton(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public SquareButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int size = Math.min(widthMeasureSpec, heightMeasureSpec);
        super.onMeasure(size, size);
    }
}