System color name error - VB .net

Question

Friends.

I'm making a program where the user enters the RGB values of the colors, and I show the color and the color name. The program is not showing the name but the hexa code. I've tried and I can't find where the error is. See the code.

If Integer.TryParse(txtRed.Text, red) AndAlso Integer.TryParse(txtGreen.Text, green) AndAlso    Integer.TryParse(txtBlue.Text, blue) Then             
            
	Dim cor As Color = Color.FromArgb(red, green, blue)              
             
	lblNomeCor.Text = cor.Name             
	picCor.BackColor = cor         
Else             
	MessageBox.Show("Enter valid values for R, G e B.", "Erro", MessageBoxButtons.OK, 				 MessageBoxIcon.Error)         
End If

Answer 1

Hi

As Dwayne says, this is not an error, just that there are more RGB values that don't have a given name than those that do. If you want, you could offer the User a List of Colours which do have a name and prevent them from using a random RGB unnamed colour.

If that is an option you want to pursue then here is some sample code to show one way to do it.

This is a test example and you should try it out first. All it needs is a new Project with a Default Foem1 and a ComboBox1 and Labels 1 & 2 added via the Designer, then copy/replace the default code with this code.

' Form1 with a ComboBox1 and a Label1
' and a Label2
Option Strict On
Option Explicit On
Public Class Form1
	Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

		' from your post
		Dim c As Color = Color.Red
		Dim s As String = c.Name  ' gives RED

		c = Color.FromArgb(255, 222, 111, 200)
		s = c.Name 'gives "ffde6fc8" which is
		' the RGB values in Hex (as you said)


		' Possible alternative
		' set up a ComboBox to allow User to
		' select only a KnowBolor
		ComboBox1.DataSource = [Enum].GetValues(GetType(KnownColor))

	End Sub

	Private Sub ComboBox4_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged

		Dim cb As ComboBox = DirectCast(sender, ComboBox)

		Dim c As Color = Color.FromKnownColor(DirectCast(cb.SelectedItem, KnownColor))

		Label1.BackColor = c

		Label2.Text = CInt(c.A).ToString & ", " & CInt(c.R).ToString & ", " & CInt(c.G).ToString & ", " & CInt(c.B).ToString
	End Sub
End Class

Answer 2

Let's create a dictionary for KnownColor

Private _NamedColors As Dictionary(Of Color, String)

Private ReadOnly Property NamedColors As IReadOnlyDictionary(Of Color, String)
    Get
        If _NamedColors Is Nothing Then
            _NamedColors = New Dictionary(Of Color, String)()
            For Each kColor As KnownColor In [Enum].GetValues(GetType(KnownColor))
                Dim color As Color = 
                         Color.FromArgb(Color.FromKnownColor(kColor).ToArgb())
                _NamedColors(color) = kColor.ToString()
            Next
        End If
        Return _NamedColors
    End Get
End Property

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim red, green, blue As Integer
    If Integer.TryParse(txtRed.Text, red) AndAlso Integer.TryParse(txtGreen.Text, green) AndAlso Integer.TryParse(txtBlue.Text, blue) Then
        Try
            Dim cor As Color = Color.FromArgb(red, green, blue)
            Dim nameStr As String = Nothing
            If NamedColors.TryGetValue(cor, nameStr) Then
                lblNomeCor.Text = nameStr
            Else
                lblNomeCor.Text = cor.Name
            End If
            picCor.BackColor = cor
        Catch ex As ArgumentException
            MessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error)
        End Try
    Else
        MessageBox.Show("Enter valid values for R, G e B.", "Erro", MessageBoxButtons.OK, MessageBoxIcon.Error)
    End If
End Sub

TextBox is fine, but try NumericUpDown as well.:)