Pixel color at cursor position

[Davve]

In Visual Basic 2010, how do I fetch the color of the pixel on the cursor's position (whether it be outside the program or inside)?

[ForumAccount]

I just Googled your thread name + VB.NET at the end and got this:

Public NotInheritable Class Win32

    '//apis
    <DllImport("user32.dll")> _
    Private Shared Function GetDC(ByVal hwnd As IntPtr) As IntPtr
    End Function

    <DllImport("user32.dll")> _
    Private Shared Function ReleaseDC(ByVal hwnd As IntPtr, _
                                      ByVal hdc As IntPtr) As Int32
    End Function

    <DllImport("gdi32.dll")> _
    Private Shared Function GetPixel(ByVal hdc As IntPtr, _
                                     ByVal nXPos As Integer, _
                                     ByVal nYPos As Integer) As UInteger
    End Function

    '//methods
    Public Shared Function GetPixelColor(ByVal x As Integer, _
                                         ByVal y As Integer) As System.Drawing.Color
        Dim hdc As IntPtr = Win32.GetDC(IntPtr.Zero)
        Dim pixel As UInteger = Win32.GetPixel(hdc, x, y)
        Win32.ReleaseDC(IntPtr.Zero, hdc)
        Return Color.FromArgb(CInt(pixel And &HFF), _
                              CInt(pixel And &HFF00) >> 8, _
                              CInt(pixel And &HFF0000) >> 16)
    End Function

End Class

[Davve]

Well, I am using your code together with this to draw a zoomed in version of the screen on the form (8x8 pixels):

...
Dim xx, yy, ww, hh, mousex, mousey As Integer
ww = 8
hh = 8
mousex = MousePosition.X
mousey = MousePosition.Y
For xx = -4 To 4
    For yy = -4 To 4
        Dim rect As New Rectangle(160 + xx * ww, 72 + yy * hh, ww, hh)
        draw.Color = Win32.GetPixelColor(mousex + xx, mousey + yy)
        preview.FillRectangle(draw, rect)
    Next
Next

I have put this in a timer that updates every 100 milliseconds. However, this is EXTREMELY slow, is there a way to optimize it? Even if I put the timer at 1 second, it still lags like hell.

EDIT: Nevermind, reduced all the lag by only checking the pixels once.

[moti barski]

41 screen capture

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim screenBounds = Screen.PrimaryScreen.Bounds
        Dim screenShot As New Bitmap(screenBounds.Width, screenBounds.Height)
        Using g = Graphics.FromImage(screenShot)
            g.CopyFromScreen(screenBounds.Location, Point.Empty, screenBounds.Size)
        End Using
        PictureBox1.Image = screenShot
        'Dim filePath = IO.Path.Combine(My.Computer.FileSystem.SpecialDirectories.MyPictures, "ScreenShot.bmp")
        'screenShot.Save(filePath, Imaging.ImageFormat.Bmp)
    End Sub
End Class

use the .GetPixelColor(mousex + xx, mousey + yy)
on the image captured

[moti barski]

in the timer tick event :

Dim screenBounds = Screen.PrimaryScreen.Bounds
        Dim screenShot As New Bitmap(screenBounds.Width, screenBounds.Height)
        Using g = Graphics.FromImage(screenShot)
            g.CopyFromScreen(screenBounds.Location, Point.Empty, screenBounds.Size)
        End Using
        me.text = screenShot.GetPixelColor(cursor.position.x, cursor.position.y)

haven't tasted this yet