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Opt-in DirectComposition flip-model backend (present=dcomp), A/B vs blt+DwmFlush - #25
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…nt=dcomp) (#24) Spike proved WS_EX_LAYERED + DirectComposition flip-model coexist (cross-process click-through AND display both work) - my earlier PR #11 only broke clicks because it dropped WS_EX_LAYERED. Add it as an opt-in A/B backend, default unchanged: - present=blt (default): blt-model swapchain on the layered HWND, paced by DwmFlush. - present=dcomp: flip-model CreateSwapChainForComposition + DComp visual on the SAME WS_EX_LAYERED window (click-through preserved), paced natively by vsync Present(1,0). Per-pixel alpha for show/hide (transparent frame to hide); magnify PS now outputs alpha 1.0 (no-op for blt under LWA_ALPHA). Switching requires a restart (swapchain is created at init). Default behavior is identical, so this is safe to merge; dcomp is for A/B by feel. If it wins we make it the sole path and delete blt. build.bat test: 32 cases / 94 assertions; both backends verified rendering correctly via WIND_SELFTEST (incl. HDR FP16). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This was referenced May 25, 2026
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Closes #24. Adds
present=dcompas an opt-in presentation backend (defaultpresent=bltunchanged), so the DComp flip-model path can be A/B-tested by feel. Keeps WS_EX_LAYERED on both (spike-proven to coexist with DComp). If dcomp wins we make it the only path and delete blt. 32 tests pass; both backends verified rendering (incl. HDR). Default behavior identical → safe to merge.🤖 Generated with Claude Code