There is no such thing as spinning a window, but you can relatively easily spin some content. And if this content mimics the appearance of a standard window, you can create an impression of a spinning window.
That was the idea, but how to achieve that?
The problem consists of at least two parts, how to show your pseudo-window at an angle, and how animate this view by changing this angle with time. You can use two approaches, 2D and 3D. With 3D, you can use WPF 3D model shaped as a rectangular parallelepiped with a window on one side. (Please see
3-D Graphics Overview[
^].) It will be not to hard to show it on a background of a window, but showing it "in the air" would be much harder. I would try to just use a transparent background.
But with 2D approach, you can pretty easily achieve a non-rectangular shape of a background window perfectly matching your current pseudo-window object. You can allow transparency and make this window's
Background transparent.
Of course, first you would need to get rid of all the
non-client areas of your "real" background window, which is achieved by using the special window style,
None:
Window.WindowStyle Property (System.Windows)[
^],
https://msdn.microsoft.com/en-us/library/system.windows.windowstyle%28v=vs.110%29.aspx[
^].
Also, remove the window's borders (border style).
To show the rectangular UI element at an angle, let me assume that you don't want to show it in space perspective. Oddly enough, this is not a transform supported by standard WPF transforms (and not by
System.Drawing transforms). Such transform is not affine (which also sounds a bit surprising) and cannot be created, but it's tricky enough; you would have to do all yourself, up to the pixel level with all the interpolation problems. But if you agree to limit the view with a simple parallel projection, which can also create fair rotation impression, you can use the transform.
To transform your image, you can use
Transform Class (System.Windows.Media)[
^],
Transforms Overview[
^].
The transform you need to show rotation is
scale transform in X direction (if you "rotate" around the vertical axes):
ScaleTransform Class (System.Windows.Media)[
^].
Now, animation. First of all, forget "Window.Loaded event" and never remember it. I don't even want to discuss it now. You just have to keep the view animated all the time, or during some predefined period of time. Now, due to two factors, you cannot use standard WPF animation. These factors are: you really want to show uniform rotation speed, your transform factor should be a sinusoidal function of time, because the change of angle is a linear function; the second factor is: you have to recalculate and adjust the region as you rotate.
So, you have to animate the rotation from scratch. This is how: create a separate thread and calculate all the geometry for every phase of rotation. Then, in a pretty short cycle, you have to calculate the real time in the moment (use
System.Diagnostics.Stopwatch,
Stopwatch Class (System.Diagnostics)[
^]). On each phase, you have to notify the rendering subsystem to re-render your window. You cannot call anything related to UI from non-UI thread. Instead, you need to use the method
Invoke or
BeginInvoke of
System.Windows.Threading.Dispatcher (for both Forms or WPF) or
System.Windows.Forms.Control (Forms only).
[EDIT #1]
You should not assign different value of
ScaleTransform to
UIElement.RenderTransform in a loop; this is impossible. Instead, do it only once (one normal place for it, as well as for creation of a thread, in overridden
OnContentRendered), and then, in the thread loop, change the scale factor
Transform.ScaleX.
You need to pass an instance of
Dispatcher and
ScaleTransform to a thread. I explained a good way to do it based on the
ThreadWrapper I proposed here:
How to pass ref parameter to the thread[
^].
[END EDIT #1]
You will find detailed explanation of how it works and code samples in my past answers:
Control.Invoke() vs. Control.BeginInvoke(),
Problem with Treeview Scanner And MD5.
See also more references on threading:
.NET event on main thread,
How to get a keydown event to operate on a different thread in vb.net,
Control events not firing after enable disable + multithreading.
If you do all that properly, your show may really impress people.
It's possible that someone could give you other solutions or give more detail on, say, 3D model approach…
[EDIT #2]
Answered in detail in my new short (Tips & Tricks) article
How to "Rotate" a WPF Window?
This article covers only more interesting "2D" approach with "pseudo-rotation" of a "pseudo-window" which produced a spinning impression, which I think is pleasing enough. The WPF 3D API approach will take a lot more effort and would be more trivial at the same time…
[END EDIT #2]
—SA
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