transparency and .gif files

[Al_C]

Hi,
I create a form, then place a picturebox on it.
Then I set the picturebox image to a .gif that I have
edited in GIFConstructionSet to create a transparent
background for. But when I run the code, what should be
transparent is not really transparent. Is there a property in
the picture box I need to tweak? I though the whole idea
was to put the transparency information right in the gif file.
Suggestions, clues, pointers?
Any of the above appreciated.
Thanks,
Al

 

[Guest]

I think you may still need to set the transparency in the picture's properties.
eg
dim b as new bitmap(c:\pic.bmp)
b.maketransparent(b.getpixel(0,0))

 

[Al_C]

Thanks for getting back Andrew.
I've tried the get pixel approach
dim b as new bitmap(c:\pic.bmp)
b.maketransparent(b.getpixel(0,0))
and while it makes it "transparent", I wind up seeing the underlying
form. So it shows up as gray.
Al

 

[Guest]

I've had a lot of problems with transparency of forms, with things such as
transparency key not working for me as I would have expected. The below does
work for me, though, to display a small irregularly shaped form over a base
form containing a picturebox:

In the Form constructor:
....
dim DisplayImage as new bitmap(c:\...)
DisplayImage.MakeTransparent(DisplayImage.GetPixel(0,0))
FormBorderStyle = Windows.Forms.FormBorderStyle.None
Toplevel = False
Parent = BaseForm.PictureBox
....

Protected Overrides Sub OnPaint(ByVal e As
System.Windows.Forms.PaintEventArgs)
Dim bm As New Bitmap(Me.Width, Me.Height)
Dim g As Graphics = Graphics.FromImage(bm)
g.Clear(DisplayImage.GetPixel(0, 0))
bm.MakeTransparent(DisplayImage.GetPixel(0, 0))
g.Dispose()
BackgroundImage = bm
TransparencyKey = DisplayImage.GetPixel(0, 0)
e.Graphics.DrawImage(DisplayImage, 0, 0, ScaleWidth, ScaleHeight)
MyBase.OnPaint(e)
End Sub

 

[Al_C]

Thanks Andrew, Time for me to watch some football, but will try your
code tomorrow.
Will let you know how I make out.
Al

 

[Ken Tucker [MVP]]

Hi,

The transparent background will let the picture boxes background to
show through. I believe you want to see the form background instead. I
would draw the gif on the form in the forms paint event instead of using a
picturebox.

Ken

 

[Al_C]

Hi Ken & Andrew,
My ultimate goal is to have an image moving around the screen.
So I need to be able to change its location based on the timer popping.
I was able to establish the transparencykey in the form constructor and
when then when the timer pops -

Me.PictureBox1.Location = New System.Drawing.Point(x, y)

Problem I have is that the transparency key applies to everything
including the form. And that it actually lets me see right through the
whole application all the way to the desktop All I want is for it to
be transparent to the form.

First I can't make things transparent and now they are too transparent!!

Al

 

[Al_C]

Hi,
I finally have it almost working.
On program startup I read in the image I want from disk and establish the
transparency color. This works fine as long as I have a background color
for the form. But soon as I change from a background color to a background
image I get a picture box with a control color around my image.

Dim DisplayImage As New Bitmap("c:\b1.gif") 'on startup
outside the form construct

DisplayImage.MakeTransparent(DisplayImage.GetPixel(0, 0))
Me.PictureBox1.Image = CType(DisplayImage, System.Drawing.Image)

For now I have the last two lines hard coded in the form construct.

Then I have a timer_tick event that
x = x + 1
tick = tick + tick + x
y = 200 + Sin(tick) * 100 'just to get a rather up and
down y value
Me.PictureBox1.Location = New System.Drawing.Point(x, y) 'redraw the
picture box.

This works great as long as I don;t have an image as a background on the
form.

Any thoughts?