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Option Explicit
 
Dim mode    As Long
Dim down    As Boolean
Dim fx      As Single
Dim fy      As Single
 
Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
    Static pal As Long
    Select Case KeyCode
    Case vbKeyUp:       pal = pal + 1 And &HF
    Case vbKeyDown:     pal = pal - 1 And &HF
    Case vbKeySpace:    mode = (mode + 1) Mod 3
    End Select
    ForeColor = QBColor(pal)
    Caption = Choose(mode + 1, "Ëèíèÿ", "Ïðÿìîóãîëüíèê", "Îêðóæíîñòü") & ": " & pal
End Sub
Private Sub Form_Load()
    DrawWidth = 3: Form_KeyDown 0, 0
End Sub
Private Sub Form_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)
    AutoRedraw = False: fx = x: fy = y: Circle (x, y), 100, vbRed: down = True
End Sub
Private Sub Form_MouseMove(Button As Integer, Shift As Integer, x As Single, y As Single)
    If down Then Me.Refresh: Circle (fx, fy), 100, vbRed: Draw x, y
End Sub
Private Sub Form_MouseUp(Button As Integer, Shift As Integer, x As Single, y As Single)
    AutoRedraw = True: Draw x, y: down = False
End Sub
Private Sub Draw(ByVal x As Single, ByVal y As Single)
    Select Case mode
    Case 0: Line (fx, fy)-(x, y)
    Case 1: Line (fx, fy)-(x, y), , B
    Case 2: Circle (fx, fy), Sqr((fx - x) ^ 2 + (fy - y) ^ 2)
    End Select
End Sub