Detect Pixel color change

[BashMan]

I'm trying to figure out some simple code to detect when a single pixel changes color at a location I choose -anywhere- on the screen. Maybe with just a msgbox popup when it changes.

The visual basic program will just be hidden and running in the background.

I should be able program the rest of the program around it, I just need the detection part. That is where I am stumped.

Any help would be greatly appreciated!!!

I'm using Visual Basic 2008

Thanks in advance!!!!!!!

[dePoPo]

Here is some code to toy with for you. The form's background color takes the color of whatever pixel on the screen you point at. It is based on code to tyake a snapshot of the entire screen, and adopted a bit more to your question.

Public Class Form1

    Public Declare Function GetPixel Lib "gdi32.dll" (ByVal hdc As IntPtr, _
                                                      ByVal nXPos As Int32, _
                                                      ByVal nYPos As Int32 _
                                                     ) As Int32

    Private Declare Function GetDC Lib "user32.dll" (ByVal hWnd As IntPtr) As IntPtr

    Private Declare Function ReleaseDC Lib "user32.dll" (ByVal hWnd As IntPtr, _
                                                         ByVal hdc As IntPtr _
                                                        ) As Int32

    Private mainhdc = New IntPtr()

    Private Sub Form1_Shown(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Shown

        mainhdc = GetDC(IntPtr.Zero)

        While True ' --- endless loop
            BackColor = ColorTranslator.FromWin32(GetPixel(mainhdc, Cursor.Position.X, Cursor.Position.Y))
            Application.DoEvents()
        End While

    End Sub
End Class

[minitech]

No need for all those API functions!! Here's a method to detect the color in a specific area:

Private Function GetScreenColor(ByVal location As Point)
     Dim bmp As New Bitmap(1, 1)
     Using g As Graphics = Graphics.FromImage(bmp)
          g.CopyFromScreen(location, Point.Empty, New Size(1, 1))
     End Using
     Return bmp.GetPixel(0, 0)
End Function

[dark87]

sorry. how to use it if the color changes in the specific area and i want the mouse to move to other cor

[therehere3]

How would i use the "GetScreenColor()" function?

GetScreenColor(What do i put here?)


I tried stuff like: GetScreenColor(100,200) for the x and y axis but not working:/

[formlesstree4]

Of course it won't. The function is expecting a Point, not two values. A point is an X and Y coordinate, but in a single structure.

[therehere3]

Im new but how would i make a point = 2 integers as x and y?

Dim MyPoint As Point = 100, 200

Would that work?

[formlesstree4]

Read the documentation that I linked to; it explains everything you need to know.