Transparency in windows forms - doesn't work on some pcs - C# Discussion Boards

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 21:59

Hi I have created an application with transparent main window that displays some text. To initially display and change the text, I use the following code:

if (behavior.IsVisible)
{
                Show();
                mImage = new Bitmap(Width, Height);
                Graphics dc = Graphics.FromHwnd(Handle);
                dc.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SingleBitPerPixelGridFit;
                SizeF size = dc.MeasureString(behavior.DisplayText, behavior.Font);
                dc.Dispose();

                Height = (int)size.Height + 1;
                Width = (int)size.Width + 1;
                mImage = new Bitmap(Width, Height);
                dc = Graphics.FromImage(mImage);
                dc.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SingleBitPerPixelGridFit;

                Color background = (behavior.Color.ToArgb() == Color.White.ToArgb()) ? Color.Black : Color.White;
                dc.Clear(background);

                dc.DrawString(behavior.DisplayText, behavior.Font, new SolidBrush(behavior.Color), 0, 0);
                mTextColor = behavior.Color.ToArgb();

                dc.Dispose();

                BackgroundImage = mImage;
                TransparencyKey = background;
}
else
{
                Hide();
                BackgroundImage = null;
}

For some reason the window shows transparent on my PC and at least one other, while on most I still get a white background (i.e. no transparency). The only difference I can think of is that on the PCs where the transparency displays correctly, VS2005 is installed, while it's VS2003 or none on the others (I'm using latest video drivers etc).
Does anyone know of this issue and how to fix it?

Thanks,
Dmitry

blackjack215010-Apr-07 22:07

blackjack2150

10-Apr-07 22:07

I'm not 100% sure, but I think that transparent windows can only be rendered in Windows XP.

Re: Transparency in windows forms - doesn't work on some pcs

Delta-Z10-Apr-07 22:09

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 22:09

You are correct, but I am talking all XP SP2 PCs here, its 2007 Wink | ;)

I think it is probably different DLL versions, like different common controls DLL, but I don't know where to start and what to look for.

Martin#10-Apr-07 22:14

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 22:14

Hello,

Had the same problem and if you search in google or msdn you will find a lot of other people sharing it.
What I found out is, that it has something todo with the graphic card and the Color quality (16bit or 32 bit).

I use the MakeTransparent method of the Bitmap class instead.
This works fine for me!

Color transparentcolor = bkgrnd.GetPixel(0,0); //If you know the pixel where the TransparentColor should be
BackgroundImage.MakeTransparent(transparentcolor);

Hope it helps!

All the best,

Martin

Delta-Z10-Apr-07 22:28

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 22:28

I have seen the postings of other people, however those that do have a solution are for C or Java. One of them talks about disabling DirectDraw acceleration for the application. It would be fine with me, but I could not find a way to do it in C# (no search results whatsoever).
I have tried MakeTransparent, but it doesn't work at all - now I see a background painted grey ("transparent" color) on all computers. Frown | :(

Can you explain more how you are using it so it works?

Thanks,
Dmitry

Martin#10-Apr-07 22:39

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 22:39

Hello,

I'm using it for Forms with a BackgroundImage.
This Image has rounded edges with a special color, which is not used in other regions of the Image.
I don't use the TransparencyKey property at all!

//I'm getting my Image from a file during runtime
Bitmap bkgrnd = new Bitmap(myimagepath);
Color transparentcolor = bkgrnd.GetPixel(0,0);
bkgrnd.MakeTransparent(transparentcolor );
this.BackgroundImage = bkgrnd;

Hope it helps!

All the best,

Martin

Stevo Z10-Apr-07 22:42

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 22:42

This didn't help me.... Frown | :(

Martin#10-Apr-07 22:58

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 22:58

Zilo(svk) wrote:
This didn't help me....

Why?

Show me the code you are using!

All the best,

Martin

Stevo Z10-Apr-07 23:10

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 23:10

I don't know why, it just doesn't work. Myabe I'm doing something wrong...

Resources.StartUpPicture.MakeTransparent(Color.FromArgb(80, 80, 80));

//or

//Color transparentColor = Resources.StartUpPicture.GetPixel(0, 0);
//Resources.StartUpPicture.MakeTransparent(transparentColor);

//doesn't matter, I know the color values

this.BackgroundImage = Resources.StartUpPicture;
this.BackgroundImageLayout = ImageLayout.Stretch;

Martin#10-Apr-07 23:38

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 23:38

Zilo(svk) wrote:
I don't know why, it just doesn't work. Myabe I'm doing something wrong...

Sorry, I meant what's the effect you see right now?

I don't know if working with the Resources is ok.

Martin

Stevo Z10-Apr-07 23:51

Re: Transparency in windows forms - doesn't work on some pcs

10-Apr-07 23:51

Allright, it works this way

Bitmap bmp = (Bitmap)Resources.StartUpPicture.Clone();

bmp.MakeTransparent(Color.FromArgb(80,80,80));
this.BackgroundImage = bmp;// Resources.StartUpPicture;
this.BackgroundImageLayout = ImageLayout.Stretch;

But behind the transparent image, there is still gray form background... And I need to make it transparent too, thats why I used the TransparencyKey.

Anyway thanx for help

Martin#11-Apr-07 0:08

Re: Transparency in windows forms - doesn't work on some pcs

11-Apr-07 0:08

Zilo(svk) wrote:
But behind the transparent image, there is still gray form background... And I need to make it transparent too, thats why I used the TransparencyKey.

I have the same thing at my form!
Don't use the TransparencyKey!

Zilo(svk) wrote:
this.BackgroundImageLayout = ImageLayout.Stretch;

I don't know what this does, maybe just for test reason, leave it out.

All the best,

Martin

Stevo Z11-Apr-07 0:26

Re: Transparency in windows forms - doesn't work on some pcs

11-Apr-07 0:26

That's for stretching the image to form's size. I can't leave it out (tried and didn't help)

Anyway, why do you think Bitmap.MakeTransparent() will changed form's background to transparent? Imagine that you have black image with red triangle within, and you want to use it as triangle startup Form(with no borders, buttons etc..) . Just setting the black color on image as transparent will cause to display square Form with default background and red triangle within (instead black form with red triangle). In my point of view you have two options. You can changed the Form.Region value to display only triangle (which is not so difficult in this case), or use TransparencyKey. Image I use is almost impossible to describe in Region (many diffrent shapes) , so I have only one option left -> TransparencyKey.

Or do you know any other ways to do that?

Martin#11-Apr-07 1:05

Re: Transparency in windows forms - doesn't work on some pcs

11-Apr-07 1:05

What I'm having is a image which fills completely the Form.
The Form also has a gray Bockground.
Then I "MakeTransparent" with a special color, and at the reagon (at the rounded edge) on the bitmap, where the special color was, my Form also shows the things which are under the Form (not my gray Background).
Maybe there is a propblem because you are doing the stretching after the MakeTransparent.
Try the stretching before.

All the best,

Martin

Stevo Z11-Apr-07 1:33

Re: Transparency in windows forms - doesn't work on some pcs

11-Apr-07 1:33

I tried to put it before or remove it. No change. I'll probobly stick with TransparencyKey, which by the way I use on one more place-> Trasparent Flash player. So I need to make it work Smile | :)

Delta-Z11-Apr-07 1:37

Re: Transparency in windows forms - doesn't work on some pcs

11-Apr-07 1:37

Strange, here it doesn't work at all... I think maybe what I am seeing is actually form's BackColor. What did you set it to be (Color.Transparent throws exception)?
UPDATE: Regarding the bit depth/resulution, on some PCs the transparency only works in 16 bit color (on the old Intel onboard graphics). Blasted graphics drivers Frown | :(

Martin#11-Apr-07 2:12

Re: Transparency in windows forms - doesn't work on some pcs

11-Apr-07 2:12

Hello,

I'm really confused!

Just made a test project.

)MainForm has a Backgroundimage during DesignTime.
)BackgroundImage is a bmp File designed in Paint (All Black only a Red Line in the middle)
)BackgoundColor is Default "Control".
)No TransparencyKey set
)Following code in the Forms constructor (After InitializeComponents)

Bitmap b = this.BackgroundImage as Bitmap;
b.MakeTransparent(Color.Black);
this.BackgroundImage = b;

)When I start now, I see just the Red line and the Desktop.
)If I move the Form then off corse the Desktop is not refreshing in the Forms region.

All the best,

Martin

Stevo Z11-Apr-07 2:21