void Screen::DrawRectangle(int row, int col, int height, int width)
// precondition: screen is blank/all white,
//               0 <= row < Size() and 0 <= col < Size(),
//               0 < height, and 0 < width
{
    int lastCol = col + width - 1;
    int lastRow = row + height - 1;
    int k;
    
    if (lastCol >= Size())
    {
	lastCol = Size() - 1;
    }
    if (lastRow >= Size())
    {
	lastRow = Size() - 1;
    }

    for(k=col; k <= lastCol; k++)      // top row
    {
	myPixels[row][k] = black;
    }

    if (row + height - 1 < Size())     // is bottom row on screen?
    {
	for(k=col; k <= lastCol; k++)  // bottom row
	{
	    myPixels[lastRow][k] = black;
	}
    }

    for(k=row; k <= lastRow; k++)      // left column
    {
	myPixels[k][col] = black;
    }

    if (col + width - 1 < Size())      // is right col on screen?
    {
	for(k=row; k <= lastRow; k++)  // right column
	{
	    myPixels[k][lastCol] = black;
	}
    }
}