LGUG2Z e2e5dbfcae feat(wm): use ghost windows for movement animations ...

This commit tries to render move/resize animations on a DWM-thumbnail
"ghost" window instead of calling MoveWindow per-frame on the real HWND.

The source is cloaked via IApplicationView::SetCloak, the thumbnail is
animated via DwmUpdateThumbnailProperties on a layered host owned by a
single "ghost owner" thread, the border for the source follows the
lerped rect via a new WM_ANIMATE_RECT message handled on the border's
own WndProc thread (preserving today's per-frame border tracking), and
the real SetWindowPos happens once at the end of the animation.

Apps repaint exactly once per animation instead of N times, which is a
substantial win for heavy renderers (browsers, IDEs, Office). For
non-Chromium sources the source is also pre-positioned to target_rect
before the thumbnail is registered so the captured texture is target-
sized and downscales to native 1:1 at the end of the animation rather
than upscaling to a stretched/blurry final frame.

Chromium-shell sources  skip the pre-paint step: their
NativeWindowOcclusionTrackerWin reads DWMWA_CLOAKED and treats any cloak
value as hidden, suspending the renderer; WM_SIZE while cloaked produces
no new frame and the post-uncloak swap chain shows stale or black
content.

For those apps we keep the source cloaked at start_rect for the whole
animation and do the SetWindowPos in post_render after uncloak, where
the visibility flip is what wakes Viz back up.

A short ease-in opacity crossfade in post_render masks the texture
transition for the Chromium path and gives slow renderers time to
present their first post-resize frame before the overlay is removed.

2026-05-03 16:09:28 -07:00

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