CODEWITHSUNDEEP
c#winforms
ChJ16
ChJ16

Reputation: 61

How to have different opacity for multiple controls?

I have a problem with the opacity of some controls.

So I set the form opacity to 0.3, when the form is loaded, and the problem is that it makes the other controls as tranparent as the form. Here is the code.

private void Form1_Load(object sender, EventArgs e)
{
      this.Opacity = 0.3;
}

By doing this, all my controls are as transparent as the form. Is there any way to have different opacity for the controls inside the form ? I don't want the other to be transparent at all.

Upvotes: 0

Views: 385

Answers (1)

Phil1970
Phil1970

Reputation: 2624

My first recommandation would be to avoid that. Having a semi-transparent background with opaque controls will look somewhat weird. Instead, consider changing the opacity when the form is active say from 0.3 to 0.7 so that it is easier to read.

Also another problem if some controls are opaque and the background is almost transparent, then your UI might not work well on some background. For example, if the background is really dark, then dark text (control) will be hard to see. If the background is white, then white controls like edit box would be the same color as the background.

You can get a few idea from other people comments. Even though some comment are for WPF, you might be able to take some idea for WinForms. And if you don't get the expected result, you might also consider using WPF for that part of the UI.

Having said that, a possible workaround to get what you want is to create two top-level windows at the same position (and move/resize them as appropriate). That way, you can have one window with a transparency key and the desired background for opaque area that will be used to have opaque and semi-transparent area. The other window will use the opacity so that it would be semi-transparent. This is the window that will contain your UI controls (and the one that would be on the top).

I have used that technic in the past to have a semi-transparent client area with a fully opaque frame in one application where I want to be able to see through client area (adjustable opacity) so that I could "draw" in my window using the image in another application as a reference.

Another comment is that you might need actual control with windows handle and direct Win32 API access for some customization that are not available in WinForms and/or WPF. In my application, I was handling activation in a way that if I click on the bottom level windows, the top-level window still appears as the active one (caption bar color). If one has no standard caption bar (either the frame is custom or no frame at all), then you would not have that problem.

As suggested by some links in the comment section, it might also be possible to get what you want using a single top-level windows. I have not tried that. In fact, when I try the above solution, I think that my application was still supported on Windows XP and as such you are more limited in options and the behavior is somewhat different essentially because XP more or less write directly to screen while Vista and later use bitmaps (buffers) for each windows.

I have also used combined transparency key and opacity for splash screen (on a single window) and it works on most system but sometime I got black background instead of desired background on some system (probably some XP machine with specific configuration).

Upvotes: 1

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