get Pixel color

[marvinklein]

how do i get the color of a specific point in a picture box?

[Volvere]

perhaps, get the image object and convert it bitmap. Then u can use GetPixel and SetPixel function

[marvinklein]

that works if it is an actual image, but what if i have been drawing lines on a form using the pen object and then i want to find if a point on the for has a line going through it?

[PT Exorcist]

IMO in that way you could do some maths instad of using gdi

[marvinklein]

no, maths won't cut it. do you know of a way toa ctually get the pixel color?

[MrPolite]

if you want to get the pixel color then you better draw on the actual image in the picturebox. the you can easily do what Volvere said.

want help with that?

[Danny J]

'First we get the picturebox's picture
        Dim img As New Bitmap(PictureBox1.Image)
 
        'To get the color of a pixel, use this. 
        'Replace X and Y with the point of the pixel you want to get.
        img.GetPixel(x, y)
 
        'To set the color of a pixel, do this.
        'Again, replace X and Y with the pixel you want to set, and the color to set it to.
        img.SetPixel(x, y, Color)

[marvinklein]

ok, this is the code i am using to draw the line:

myPictureBox.DrawLine(New Pen(Color.Black), x1 , y1, x2, y2)

now this is what i want to do:
Dim my Color as Color = myPictureBox.GetPixel(x, y)
'EXCEPT GetPixel DOSN'T EXIST!

the problem with drawing onto a bitmap contained in the picturebox is that functions like DrawLine don't exist. All you have then is GetPixel and SetPixel!

So, can somebody please try and come up with a function that returns the color of a pixel in an object that is not a bitmap? (Like you can in 6.0 using the Point function)

thanks...

[nemaroller]

Dim x As Bitmap = PictureBox1.Image
        MessageBox.Show(x.GetPixel(10, 10).ToString)

You can still draw on the picturebox itself. And reset your bitmap to the image when you need to get a pixel. IF you need to do this 1000 times a second, this isn't a good solution obviously.

In which case, this article may help you (in C#):
http://msdn.microsoft.com/library/de...rp11152001.asp

[marvinklein]

that article is perfect for c#, but i'm using vb.net and there are a lot of useful functions that i simply don't have. maybe i should somehow use the image gdi more directly. i've never used gdi, so i don't really know what i'm talking about, so if you know where i can read something about the image gdi that would be really helpful i think.

[Sheppe]

To draw lines, etc., you need to use a Graphics object. The following example shows you how to draw a line using the Graphics object, and how to use a Bitmap object to call GetPixel. The message boxes are only used to indicate that GetPixel does indeed work. To use this code, place it in the Load event of a form. The form must have a picturebox on it named PictureBox1. This is a crude example, but it's good as a demo:

Dim bmp As New Bitmap(PictureBox1.Size.Width, PictureBox1.Size.Height)
        Dim grph As Graphics
        grph = Graphics.FromImage(bmp)
 
        grph.DrawLine(New Pen(Color.Red), 0, 0, PictureBox1.Size.Width, PictureBox1.Size.Height)
 
        PictureBox1.Image = bmp
 
        MessageBox.Show("Color at point 0,0 is " & bmp.GetPixel(0, 0).ToString)
 
        MessageBox.Show("Color at point 10,10 is " & bmp.GetPixel(10, 10).ToString)

[marvinklein]

thanks a lot eveybody. that last post made everything work.
this issue is now resolved.