Transparent images in VB.NET Compact Framework

well i've tried transparent gif's and that didn't work.
it's a commonly known thing that .net cf doesn't do transparent images, just some people have found solutions. i just can't implement them.

btw: an updated link to the source:
http://forum.xda-developers.com/attachment.php?attachmentid=49573&d=1189102301

i havefolloed the link and received: "Invalid Attachment specified. If you followed a valid link, please notify the administrator"

Have you tried to use an image with "png" format?

sorry, i'm constantly updating it and i can't edit the question now that comments have been made.
please see this thread: http://forum.xda-developers.com/showthread.php?p=1482348
and download slider_source.zip from the link at the bottom of the post.

@junges: just tried with a transparent png image too. didn't work.
it's not todo with the image type it's todo with the compact framework not having transparency capabilities (well not in an easy way anyway).

Hi,
.NET CF doesn't support transparent images, but you can paint the transparent part of the image with the background color of the parent of the image.

You can use SDF 2.1 community edition, one of the components called PictureBox2 does that.

http://www.opennetcf.com/CompactFramework/Products/SmartDeviceFramework/tabid/65/Default.aspx

thanks hardi, i've seen similar solutions like that which don't use open .net cf but that was the easiest to setup.
it's not a practical solution though as i need it to go through to the background image and not 1 solid color.

i was able to get text to go transparently over the top of another image, why should it be so hard to do it with pictures?
isn't it possible to just not paint the pixels that are set to the transparency color?

I see... yeah that's what I want to know too... hehe.
I'm not really sure, but I think the area (the rectangle) occupied by the PictureBox can only be painted by the PictureBox itself. So you need to make the PictureBox paint the background image to do transparency...
Well I'm not really sure, and I would be very interested if there is a solution for this problem :-)

oh ok, thanks.
well at the moment i'm stuck with a 99% developed app that has a bitmap with an ugly color around it :(
i'd even go to the length of importing a dll that's written in native code to do the work.. if that's possible.

the other idea would be simply updating that solid color to use a pixel from the bitmap behind it, every it is moved.
the main trouble is that the bitmap can be moved (dragged).

if anyone has ANY idea and can implement it in my project please share it.

i found this:
http://www.opennetcf.com/Default.aspx?tabid=130

but it's impossible to get it to work.
and for some reason i can't implement IDisposable in vb.net but i can in c#.net ... :(

i'll add extra points if anyone can solve this problem and show me how i can add it to my project.

ok i've made a new picturebox class that inherits from picturebox, and it does the transparency.
the only problem is that if i don't put a picture behind it, it will just show underneath the form instead of just being transparent to the picture behind it.
so i've put the picture behind it.
now the problem is that the image has to move, so i'd have to make it repaint it every time so the image behind it is right.
i need to use a function similar to what's commented out. (it causes errors though) -

Public Class PictureBoxEX
    Inherits PictureBox

    Protected Overloads Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
        Dim attr As New Imaging.ImageAttributes()
        attr.SetColorKey(Color.FromArgb(255, 0, 255), Color.FromArgb(255, 0, 255))
        e.Graphics.DrawImage(Me.Image, Me.ClientRectangle, 0, 0, Me.Image.Width, Me.Image.Height, GraphicsUnit.Pixel, attr)
    End Sub

    Protected Overloads Overrides Sub OnPaintBackground(ByVal e As System.Windows.Forms.PaintEventArgs)
        Dim attr As New Imaging.ImageAttributes()
        attr.SetColorKey(Color.FromArgb(255, 0, 255), Color.FromArgb(255, 0, 255))
        e.Graphics.DrawImage(Slider.sbgimg, Me.ClientRectangle, 0, 0, Me.Image.Width, Me.Image.Height, GraphicsUnit.Pixel, attr)
    End Sub


    'Public Sub rePaint()
    'Dim attr As New Imaging.ImageAttributes()
    '   attr.SetColorKey(Color.FromArgb(255, 0, 255), Color.FromArgb(255, 0, 255))
    '   Me.CreateGraphics.DrawImage(Slider.sbgimg, Me.ClientRectangle, 0, 0, Me.Image.Width, Me.Image.Height, GraphicsUnit.Pixel, attr)
    '   Me.CreateGraphics.DrawImage(Me.Image, Me.ClientRectangle, 0, 0, Me.Image.Width, Me.Image.Height, GraphicsUnit.Pixel, attr)
    'End Sub

End Class

every time the picture moves i need to be able to redraw the image somehow..
anyone got any ideas?

Wow you did it!

How do you move the image? Perhaps on the MouseUp event handler add Refresh()?

yer i've tried refresh. doesn't do anything for some reason..

chrismalone, have you seen this
http://msdn2.microsoft.com/en-us/library/aa446533.aspx#netcfgaming_topic3

I don't really understand it but hope it can help you.
Find "dirty area"

i solved it.
i had to calculate the relative position of the image ontop of the other one and then draw it, then crop that area behind it, and return it to the image on the onpaintbackground event.
@hardi: in the article you just listed it basically says that's inefficient. and it is.
but it's the only way i could get it to work.
anyways here's the class i created:

Public Class PictureBoxEX
    Inherits PictureBox

    Protected Overloads Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
        Dim attr As New Imaging.ImageAttributes()
        attr.SetColorKey(Color.FromArgb(255, 0, 255), Color.FromArgb(255, 0, 255))
        e.Graphics.DrawImage(Me.Image, Me.ClientRectangle, 0, 0, Me.Image.Width, Me.Image.Height, GraphicsUnit.Pixel, attr)
        e.Graphics.Dispose()
    End Sub

    Protected Overloads Overrides Sub OnPaintBackground(ByVal e As System.Windows.Forms.PaintEventArgs)
        e.Graphics.DrawImage(saveimage(Me.Width, Me.Height, Me.Left - Slider.SliderBG.Left, Me.Top - Slider.SliderBG.Top), 0, 0)
        e.Graphics.Dispose()
    End Sub


    Public Function saveimage(ByVal width As Integer, ByVal height As Integer, ByVal locationx As Integer, ByVal locationy As Integer) As Bitmap
        Dim attr As New Imaging.ImageAttributes

        Dim cropped As New Bitmap(width, height)
        Dim g As Graphics = Graphics.FromImage(cropped)
        g.DrawImage(Slider.sbgimg, New Rectangle(0, 0, cropped.Width, cropped.Height), locationx, locationy, cropped.Width, cropped.Height, GraphicsUnit.Pixel, attr)
        g.Dispose()

        Return cropped
    End Function
End Class

Congratulations! :-D
Thanks for sharing the code