VB provides an easy RGB function to convert three colours into a RGB colour code. However, it provides no way of converting it back to the three colours. It also provides no support for HTML colour codes used on web pages. We decided to write some functions to convert HTML colour codes to and from RGB codes, and also functions to break them back down into their constituent colours.
Public Const RedPart = 0
Public Const GreenPart = 1
Public Const BluePart = 2
Public Function HTML(Red As Integer, Green As Integer, Blue As Integer) As String
HTML = ""
If Len(Hex$(Red)) = 1 Then
HTML = HTML & "0" & Hex$(Red)
Else
HTML = HTML & Hex$(Red)
End If
If Len(Hex$(Green)) = 1 Then
HTML = HTML & "0" & Hex$(Green)
Else
HTML = HTML & Hex$(Green)
End If
If Len(Hex$(Blue)) = 1 Then
HTML = HTML & "0" & Hex$(Blue)
Else
HTML = HTML & Hex$(Blue)
End If
End Function
Public Function UnRGB(RGBCol As Long, Part As Integer) As Integer
注释：Part: 0=Red, 1=Green, 2=Blue
Select Case Part
Case 0
UnRGB = RGBCol And &HFF
注释：mask 000000000000000011111111 and shift bits right
Case 1
UnRGB = (RGBCol And &HFF00) / &HFF
注释：mask 000000001111111100000000 and shift bits right
Case 2
UnRGB = (RGBCol And &HFF0000) / &HFFFF
注释：mask 111111110000000000000000 and shift bits right
End Select
End Function
Public Function UnHTML(HTMLCol As String, Part As Integer) As Integer
注释：Part: 0=Red, 1=Green, 2=Blue
Select Case Part
Case 0
UnHTML = (CLng("&H" & HTMLCol) And &HFF0000) / &HFFFF
注释：mask 111111110000000000000000 and shift bits right
Case 1
UnHTML = (CLng("&H" & HTMLCol) And &HFF00) / &HFF
注释：mask 000000001111111100000000 and shift bits right
Case 2
UnHTML = CLng("&H" & HTMLCol) And &HFF
注释：mask 000000000000000011111111 and shift bits right
End Select
End Function
Public Function RGB2HTML(RGBCol As Long) As String
RGB2HTML = HTML(UnRGB(RGBCol, RedPart),
UnRGB(RGBCol, GreenPart), UnRGB(RGBCol, BluePart))
End Function
Public Function HTML2RGB(HTMLCol As String) As Long
HTML2RGB = RGB(UnHTML(HTMLCol, RedPart), UnHTML(HTMLCol, _
GreenPart), UnHTML(HTMLCol, BluePart))
End Function
