برنامج للتلوين فيه بعض الدوال

السلام عليكم ورحمة الله وبركاته

الكود التالي لعمل برنامج تلوين صور بالتعبئه .. ارجو مساعدتي في فهمها وشرحها لي .. :(

Private Declare Function SelectObject Lib "gdi32" (ByVal hdc As Long, ByVal hObject As Long) As Long
Private Declare Function CreateSolidBrush Lib "gdi32" (ByVal crColor As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function GetPixel Lib "gdi32" (ByVal hdc As Long, ByVal X As Long, ByVal Y As Long) As Long
Private Declare Function ExtFloodFill Lib "gdi32" (ByVal hdc As Long, ByVal X As Long, ByVal Y As Long, ByVal crColor As Long, ByVal wFillType As Long) As Long
Const FLOODFILLBORDER = 0 ' Fill until crColor& color encountered.
Const FLOODFILLSURFACE = 1 ' Fill surface until crColor& color not encountered.
Const crNewColor = &HFFFF80
Dim mBrush As Long
Private Sub Form_Load()
    'KPD-Team 1999
    'URL: http://www.allapi.net/
    'E-Mail: KPDTeam@Allapi.net
    'Create a solid brush
    
    'Select the brush into the PictureBox' device context
    SelectObject Picture1.hdc, mBrush
    'API uses pixels
    Picture1.ScaleMode = vbPixels
End Sub
Private Sub Form_Unload(Cancel As Integer)
    'Delete our new brush
    DeleteObject mBrush
End Sub
Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
    'Floodfill...
    
    ExtFloodFill Picture1.hdc, X, Y, GetPixel(Picture1.hdc, X, Y), FLOODFILLSURFACE
End Sub


Private Sub Picture2_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 1 Then
mBrush = CreateSolidBrush(Picture2.Point(X, Y))
'mBrush = Picture2.Point(X, Y)
Label1.BackColor = Picture2.Point(X, Y)

  SelectObject Picture1.hdc, mBrush
End If

End Sub