''' This class represents one of the balls in the game grid.

''' </summary>

''' <remarks></remarks>

Public Class Block

Public Const BlockSize As Integer = 25

Private colorValue As Color

Private deletionValue As Boolean = False

Private Shared rand As New Random

Public Property Color As Color

Get

Return colorValue

End Get

Set(ByVal Value As Color)

colorValue = Value

End Set

End Property

Public Property MarkedForDeletion As Boolean

Get

Return deletionValue

End Get

Set(ByVal Value As Boolean)

deletionValue = Value

End Set

End Property

Public Sub New(ByVal newColor As Color)

colorValue = newColor

End Sub

Public Sub New(ByVal colors As Color)

Dim ncolors As Integer = colors.Length

Dim pickedColor As Integer

pickedColor = rand.Next(0, ncolors)

colorValue = colors(pickedColor)

End Sub

Public Sub Draw(ByVal graphics As Graphics, ByVal point As Point)

Dim brush As System.Drawing.Drawing2D.LinearGradientBrush = _

CreateTheBrush(point)

DrawTheCircle(graphics, brush, point)

End Sub

Private Sub DrawTheCircle(ByVal graphics As Graphics, _

ByVal brush As LinearGradientBrush, ByVal location As Point)

Dim topleft As Point = location

Dim bottomright As Point = New Point(location.X + _

BlockSize, location.Y + BlockSize)

Dim transTopLeft As Point = PointTranslator.TranslateToBL( _

topleft)

Dim transBottomRight As Point = _

PointTranslator.TranslateToBL(bottomright)

Dim transwidth As Integer = transBottomRight.X – transTopLeft.X

Dim transheight As Integer = _

transBottomRight.Y – transTopLeft.Y

graphics.FillEllipse(brush, New Rectangle(transTopLeft, _

New Size(transwidth, transheight)))

End Sub

Private Function CreateTheBrush(ByVal location As Point) As _

LinearGradientBrush

Dim transLocation As Point = _

PointTranslator.TranslateToBL(location)

Dim brushpt1 As Point = transLocation

Dim brushpt2 As New Point(transLocation.X + Block.BlockSize _

+ 4, transLocation.Y – BlockSize – 4)

Dim brush As New LinearGradientBrush(brushpt1, _

brushpt2, Me.Color, System.Drawing.Color.White)

Return brush

End Function

End Class

По второму варианту, в панели Solution Explorer выполняем правый щелчок по имени проекта и в контекстном меню выбираем Add, New Item, в панели Add New Item выделяем шаблон Code File, в окне Name записываем имя Grid.vb и щёлкаем кнопку Add. В проект (и в панель Solution Explorer) добавляется этот файл, открывается пустое окно редактирования кода, в которое записываем код со следующего листинга.

Листинг 20.17. Новый файл.

''' <summary>

''' This class represents the grid of blocks. It handles most of

''' the game play.

''' </summary>

''' <remarks></remarks>

Public Class Grid

' The grids is 12 columns and 15 rows of Block objects.

Dim matrix(11, 14) As Block

''' <summary>

''' Creates a few rows of blocks to start the game.

''' Game starts with Red, Blue, and Green blocks.

''' </summary>

''' <param name="nrows">Number of rows of blocks to create

''' to start the game.</param>

''' <remarks></remarks>

Public Sub New(ByVal nrows As Integer)

If nrows > matrix.GetLength(0) Then

Throw New Exception("Must start with " & _

matrix.GetLength(0) & " or fewer rows.")

End If

Dim row As Integer

Dim column As Integer

For row = 0 To nrows – 1

For column = 0 To matrix.GetLength(1) – 1

matrix(row, column) = New Block( _

New Color {Color.Red, Color.Blue, Color.Green})

Next

Next

For row = nrows To matrix.GetLength(0) – 1

For column = 0 To matrix.GetLength(1) – 1

matrix(row, column) = Nothing

Next

Next

End Sub

''' <summary>

''' A new row may be added at any time. New rows have Gray

''' blocks in addition

''' to Red, Blue, and Green. This makes the game more difficult.

''' </summary>