Introduction

Microsoft Windows provides a function used to get a color stored in a pixel. The .NET Framework supports this operation in the Bitmap class, which is equipped with a method named GetPixel. By calling this method, you can retrieve the color of a pixel.

Practical Learning: Creating the Application

1. Copy the following picture and paste it somewhere in your computer

   

2. Start Microsoft Visual Studio
3. On the Visual Studio dialog box, click Create New Project
4. In the Create a New Project dialog box, click Windows Forms App
5. Click Next
6. Set the Name to ColorSelector
7. Click Next
8. In the Framework combo box, select the highest version and click Create
9. In the Solution Explorer, right-click Form1.cs and click Rename
10. Type Exercise (to get Exercise.cs) and press Enter twice
11. Design the form as follows:

    

    Control		Text	Name	Other Properties
    PictureBox			PbxColorSelector	Image: ColorPalette.png
    Label		Number
    Label		HEX
    Label		Red:
    TextBox			TxtNumberRed
    TextBox			TxtHexadecimalRed
    Label		Green:
    TextBox			TxtNumberGreen
    TextBox			TxtHexadecimalGreen
    Label		Blue:
    TextBox			TxtNumberBlue
    TextBox			TxtHexadecimalBlue
    Panel			pnlPreview	BorderStyle: FixedSingle
    Label		Color:
    TextBox			TxtHexadecimalColor
    Button		Close	BtnClose

12. Right-click the form and click View Code
13. Change the document as follows:

    Public Class Exercise
        Dim IsSelecting As Boolean = False
    
        Private Sub PbxColorSelector_MouseDown(sender As Object, e As MouseEventArgs) Handles PbxColorSelector.MouseDown
            IsSelecting = True
        End Sub
    
        Private Sub PbxColorSelector_MouseUp(sender As Object, e As MouseEventArgs) Handles PbxColorSelector.MouseUp
            IsSelecting = False
        End Sub
    
        Private Sub PbxColorSelector_MouseMove(sender As Object, e As MouseEventArgs) Handles PbxColorSelector.MouseMove
            If IsSelecting Then
                Dim Bitmap As Bitmap = CType(PbxColorSelector.Image, Bitmap)
                Dim Color As Color = Bitmap.GetPixel(e.X, e.Y)
    
                TxtHexadecimalRed.Text = Color.R.ToString("X2")
                TxtHexadecimalGreen.Text = Color.G.ToString("X2")
                TxtHexadecimalBlue.Text = Color.B.ToString("X2")
    
                TxtNumberRed.Text = Color.R.ToString()
                TxtNumberGreen.Text = Color.G.ToString()
                TxtNumberBlue.Text = Color.B.ToString()
    
                TxtColor.Text = $"#{Color.R:X2}{Color.G:X2}{Color.B:X2}"
    
                PnlPreview.BackColor = Color
            End If
        End Sub
    
        Private Sub BtnClose_Click(sender As Object, e As EventArgs) Handles BtnClose.Click
            Close()
        End Sub
    End Class

14. To execute the application, on the main menu, click Debug and click Start Without Debugging:

    

15. Click and hold the mouse on the picture boxmouse and drag to produce a color:

    

    

16. Close the form

Color Selector

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