Pick Color

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Introduction

This is an amusing way in order to select a color from a page web.

Using the code

As it is knows that the coordinates of a color comes from Red Blue Green (RGB), in order to create the intentional shadings we must convert to Luninosità tone Saturation (HLS). The function is as follows :-

Private Sub Paletta(ByVal TargetForm As String, _
  ByVal PalettaRow As Long, _
  ByVal Saturation As Long)
     Dim RGBColor As String
     Dim Gray As Double
     Dim lum As Double
     Dim sat As Double
     Dim hue As Double
     Dim row As HtmlTableRow
     Dim cell As HtmlTableCell
     Dim RBGcolor As String

     sat = Saturation / 100
     For hue = 0 To 359 Step (360 / PalettaRow)
         row = New HtmlTableRow()
         For lum = 0.1 To 1 Step 0.02
             cell = New HtmlTableCell()
             HlsToRgb(hue, lum, sat, RGBColor)
             cell.BgColor = RGBColor
             cell.Controls.Add(New HyperLink())
             DirectCast(cell.Controls(0), HyperLink).Text = "_"
             DirectCast(cell.Controls(0), HyperLink).ForeColor = _
                 Color.FromArgb(Val("&h" & Mid(RGBColor, 1, 2)), _
                 Val("&h" & Mid(RGBColor, 3, 2)), _
                 Val("&h" & Mid(RGBColor, 5, 2)))
             DirectCast(cell.Controls(0), HyperLink).NavigateUrl = _
                 TargetForm & "?&C=" & RGBColor
             row.Cells.Add(cell)
         Next lum
         Table1.Rows.Add(row)
     Next hue
     row = New HtmlTableRow()
     For Gray = 0 To 255 Step 5.7
         cell = New HtmlTableCell()
         cell.BgColor = Right("00" & Hex(Gray), 2) & _
            Right("00" & Hex(Gray), 2) & Right("00" & Hex(Gray), 2)
         cell.Controls.Add(New HyperLink())
         DirectCast(cell.Controls(0), HyperLink).Text = "_"
         DirectCast(cell.Controls(0), HyperLink).ForeColor = _
            Color.FromArgb(Gray, Gray, Gray)
         DirectCast(cell.Controls(0), HyperLink).NavigateUrl = _
            TargetForm & "?&C=" & Right("00" & Hex(Gray), 2) & _
            Right("00" & Hex(Gray), 2) & Right("00" & Hex(Gray), 2)
         row.Cells.Add(cell)
     Next Gray
     Table1.Rows.Add(row)
 End Sub

 ' Converte HLS in RGB
 Private Sub HlsToRgb(ByVal H As Double, ByVal L As Double, _
       ByVal S As Double, ByRef RGBColor As String)
     Dim p1 As Double
     Dim p2 As Double
     Dim r As Double
     Dim g As Double
     Dim b As Double

     If L <= 0.5 Then
         p2 = L * (1 + S)
     Else
         p2 = L + S - L * S
     End If
     p1 = 2 * L - p2
     If S = 0 Then
         r = Int(L * 255)
         g = Int(L * 255)
         b = Int(L * 255)
     Else
         r = Int(QqhToRgb(p1, p2, H + 120) * 255)
         g = Int(QqhToRgb(p1, p2, H) * 255)
         b = Int(QqhToRgb(p1, p2, H - 120) * 255)
     End If
     RGBColor = Right("00" & Hex(r), 2) & Right("00" & Hex(g), 2) & _
         Right("00" & Hex(b), 2)
 End Sub

The function Paletta previews the page where we give back the result, given the number of lines that composes the table and the brightness (that translates to "full" color or complete gray). After we have printed the table, and have selected the proposed color, the result is collected through :

Request.QueryString("C")

Points of Interest

This code has been translated from my site Web originally in ASP, and served to modify all the elements of the page web (Links, tables, etc.)

History

This is the first version of the Pick Color, but I have some changes already in mind for even more fun... Bye bye :)