windows feature WS_EX_NOREDIRECTIONBITMAP

[ekicyou]

• Tested on all platforms changed
• Added an entry to CHANGELOG.md if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created an example program if it would help users understand this functionality

Windows additionally has WindowBuilderExt::with_no_redirection_bitmap.
In order to use Direct Composition API, implemented the function to set WS_EX_NOREDIRECTIONBITMAP extended attribute.

ref: MSDN Windows with C++ - High-Performance Window Layering Using the Windows Composition Engine

[francesca64]

It's conventional for builder methods to take a bool, for more flexibility.

[francesca64]

Well, I don't really know how to test this, since it just makes my OpenGL app transparent.

My only question is if this is mutually exclusive with with_transparency. Having both made the client area black.

[ekicyou]

My only question is if this is mutually exclusive with with_transparency. Having both made the client area black.

Excuse my translation.

It becomes exclusive designation.

Both can be used as a means to realize a transparent window, but the realization method is different.

WS_EX_NOREDIRECTIONBITMAP specifies not to display the GDI bitmap.
The GDI bitmap is the old rendering API, not GPU optimized.
By using only composition surfaces directly managed by DWM for screen display, you can intercept maximum GPU optimization of Windows.

As a composition surface, you can specify a swap chain.

I am sorry, I can not prepare a small sample now.
The trial at hand is in trial with the modification of [servo/webrender].

[francesca64]

It would be good if enabling this caused the call to DwmEnableBlurBehindWindow to be skipped, since then there wouldn't be any bad interactions. Other than that, looks good.

[ekicyou]

Thank you. Check the source and fix it.

[francesca64]

Alright, looks great.