On Tue, 10 Mar 2026 15:57:13 GMT, Martin Fox <[email protected]> wrote:
>> This PR enables translucent window backdrops for JavaFX stages on macOS and >> Windows 11. Since we’re reliant on the operating system for these effects >> (they typically require real-time blurring of the desktop) I needed to flesh >> out a fairly complete prototype to sort out the API. I will start a >> discussion about the API on the mailing list. >> >> There’s a crude manual test for trying out the different backdrop materials. >> >> java @build/run.args -Djavafx.enablePreview=true >> tests/manual/stage/BackdropTest.java >> >> You’ll want to drag the windows around to avoid having them overlap each >> other since they’re all created in the center of the screen. For windows >> without title bars you can click anywhere on the background to drag the >> window except for TRANSPARENT stages on Windows which are a bit tricker to >> get a hold of; try to click on a text label. >> >> If you create an UNDECORATED stage on Windows the backdrop won’t be >> translucent initially. This can be corrected by changing the stage’s color >> scheme. This is an OS bug that I haven’t found a workaround for. >> >> The changes on Windows 11 are minimal since we’re just invoking an OS >> feature by calling DwmSetWindowAttribute. I did need to make two small >> changes to the D3D9 Prism code to ensure that the swap chain and back buffer >> support an alpha channel so JavaFX can composite its content on top of the >> backdrop. This is the same way the old UNIFIED stage style worked before it >> became unreliable (see >> [JDK-8154847](https://bugs.openjdk.org/browse/JDK-8154847)). >> >> On macOS I moved the GlassHostView so it’s now a permanent part of the >> NSWindow. For some time the host view has been a remnant left over from an >> older approach to implementing fullscreen. Now it serves as a common parent >> for the NSVisualEffectView that provides the backdrop and the GlassView3D >> that contains the JavaFX content. Making it the permanent contentView of the >> NSWindow simplifies some code. >> >> To validate the API I did prototype this for Windows 10 (thanks @mstr2!). >> Well, I prototyped this using DirectComposition so it should work on Win10 >> but I can't test Win10 myself. Using DirectComposition is much more involved >> so I shelved that implementation for now but it does inform the API. It’s >> the reason the backdrop needs to be specified before the Java window is >> shown and the platform window created. > > Martin Fox has updated the pull request with a new target base due to a merge > or a rebase. The pull request now contains five commits: > > - Merge remote-tracking branch 'upstream/master' into osbackdrop > - Merge remote-tracking branch 'upstream/master' into osbackdrop > - Removed unused import > - Merge remote-tracking branch 'upstream/master' into osbackdrop > - OS supplied translucent window backdrops This PR has been on hold while we figure out how it would work with the D3D12. For legacy technologies like D3D9 the OS performs some magic; invoking the old Aero glass effect by calling ::DwmExtendFrameIntoClientArea automatically allows the D3D9 swap chain to composite over the backdrop. For D3D12 it looks like we need to implement this directly by building a compositing swap chain. We haven't sorted out exactly how this will work. I would like to enable dynamically changing the backdrop after the window is shown (moving the call from Stage.initBackdrop to Stage.setBackdrop or Scene.setBackdrop). But it remains to be seen whether we can get that to work with D3D12 or not. ------------- PR Comment: https://git.openjdk.org/jfx/pull/2048#issuecomment-4032777583
