GDI+ and desktop interaction

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This isn't really a coding question, more me trying to understand why the below is happening. Though if someone can provide a solution that would be fantastic.

I've written a screensaver using Winforms and GDI+ that draws shapes to a manually controlled buffer then renders the finished image to the form. Everything works as intended. (stuff flies around the screen)

As an after-thought I decided to add a moving "spy-hole" that uses the forms transparency key to cut through to the desktop below my form.

This also works fine but introduces "choppyness" to the animation. After doing some tests with the Stopwatch function: Its not down to excessive load placed on the on the system. My "spy-hole" takes around 5000 ticks to render. I have also tried various compositing and smoothing options to little or no effect.

The screen saver runs at around 30fps and adjusts itself based on system performance to maintain this.

I'm guessing that the issue is caused by the desktop being repainted independently of my form and causing pauses while it does so? Or could there be another reason?

What I have tried:

Included in the problem description.

Posted 11-Nov-16 7:48am

5everin

Updated 11-Nov-16 8:29am

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Dave Kreskowiak · Accepted Answer · 2016-11-11T08:29:00

Solution 1

Instead of making a hole through the form, take a screen shot of the Desktop and then use that as the first image you paint on your form, then paint your other graphics on top of it. No transparency needed at all.

Posted 11-Nov-16 8:29am

Dave Kreskowiak

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5everin 11-Nov-16 14:53pm

Thanks. That would work, I didn't mention that the program can use multiple monitors. Any idea if that would add complications.

(edit) was worried that a screen grab would only pick up the contents of the primary monitor, it doesn't.

Dave Kreskowiak 11-Nov-16 17:15pm

Nope.