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XCEngine/docs/plan/NewEditor_D3D12_LegacyD2DClosurePlan_2026-04-22.md

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# NewEditor D3D12 Legacy D2D Closure Plan
Date: 2026-04-22
## 1. Problem Statement
`new_editor` main-window realtime presentation has already moved onto the native `D3D12` path, but the codebase still retains a legacy `D2D / D3D11On12` bridge in the host layer.
That residual path is no longer the main realtime hot path, but it is still architecturally serious because it keeps a second rendering/composition implementation alive for the same UI draw model.
Current residual seam:
- `app/Rendering/Native/NativeRenderer.*`
- `app/Rendering/D3D12/D3D12WindowInteropContext.*`
- `app/Rendering/D3D12/D3D12WindowInteropHelpers.h`
- host/build references that still compile and link the old bridge
## 2. Confirmed Current Facts
### 2.1 Main window realtime presentation no longer depends on D2D
Main realtime presentation flows through:
- `D3D12WindowRenderer`
- `D3D12UiRenderer`
- `D3D12WindowRenderLoop`
The active main path does not call `NativeRenderer::Render(...)`.
### 2.2 Residual D2D bridge is concentrated, not scattered
The old bridge is now effectively concentrated in:
- screenshot/export flow
- dead hwnd-native D2D window rendering code that is no longer wired into the main frame loop
### 2.3 NativeRenderer is no longer the main texture host
`TexturePort` for the active editor path is already `D3D12UiTextureHost`.
This means the remaining `NativeRenderer` responsibilities can be removed instead of preserved as an active subsystem.
## 3. Root Architectural Issue
The root issue is not “some D2D symbols still exist”.
The root issue is that `new_editor` still retains two incompatible host-side ways to turn UI output into pixels:
1. Active path: native `D3D12` rendering into the swapchain backbuffer.
2. Residual path: `UIDrawData -> D2D replay`, with optional `D3D11On12` resource interop.
As long as both remain alive:
- draw semantics can drift between live output and capture/export output
- future UI/rendering changes must be kept compatible with two host backends
- dead-window code remains available to be accidentally reused
- build/link dependencies preserve obsolete platform coupling
So the correct goal is full single-path closure, not incremental patching.
## 4. Target End State
After this refactor:
1. Main-window realtime rendering remains native `D3D12`.
2. Main-window screenshot capture also uses native `D3D12` backbuffer capture.
3. `new_editor` no longer contains any host-side `D3D11On12` or `D2D` bridge code for the main window.
4. Old hwnd `D2D` renderer code is deleted, not merely disconnected.
5. `XCUIEditorHost` no longer compiles obsolete interop units.
6. Host link dependencies only retain what is still genuinely required.
## 5. Non-Goals
- Do not roll the editor back to `D2D`.
- Do not reintroduce a fallback composition backend.
- Do not change the active `D3D12UiRenderer` architecture back into draw-data replay through another API.
- Do not remove `DirectWrite` from `D3D12UiTextSystem`; text shaping/raster generation remains valid there.
## 6. Refactor Strategy
### Phase A. Replace screenshot bridge with native D3D12 capture
Introduce a native `D3D12` capture path that reads the final swapchain backbuffer and writes PNG through CPU-side WIC encoding.
This capture path must:
- capture the final composited editor frame
- avoid `UIDrawData` replay
- avoid `D3D11On12`
- avoid `D2D`
- operate on the same swapchain backbuffer the user actually sees
Preferred integration point:
- after UI rendering has finished for the active backbuffer
- after the frame has been submitted to the queue
- before `PresentFrame()`
Reason:
- the frame is already fully rendered
- the current backbuffer is still the one about to be presented
- capture remains aligned with the user-visible final image
### Phase B. Collapse screenshot orchestration around the active D3D12 path
Rework `AutoScreenshotController` so it only:
- tracks pending capture requests
- resolves output/history paths
- finalizes success/error summaries
It must no longer own the rendering backend choice.
### Phase C. Delete obsolete NativeRenderer window-render path
Delete the old hwnd `D2D` window renderer behavior:
- `Initialize(HWND)`
- `Resize(...)`
- `Render(...)`
- hwnd render-target management
- D2D draw command replay entrypoint for window presentation
If a remaining utility is still needed after this phase, it must live in a narrowly-scoped replacement component, not inside a zombie renderer class.
### Phase D. Delete D3D11On12 interop bridge
Once native `D3D12` capture is live:
- delete `D3D12WindowInteropContext.*`
- delete `D3D12WindowInteropHelpers.h`
- delete all `NativeRenderer` interop code
### Phase E. Build and link closure
Update host build definitions so obsolete units and libraries are removed.
Expected removals if no remaining consumer exists:
- `app/Rendering/Native/NativeRenderer.cpp`
- `app/Rendering/D3D12/D3D12WindowInteropContext.cpp`
- `d2d1.lib`
- `d3d11.lib`
Expected retained dependencies:
- `d3d12.lib`
- `d3dcompiler.lib`
- `dwrite.lib`
- `dxgi.lib`
- `windowscodecs.lib`
## 7. Concrete File-Level Work
### 7.1 Add new native capture unit
Add new host-side unit(s), likely under `app/Rendering/D3D12/`:
- `D3D12WindowCapture.h`
- `D3D12WindowCapture.cpp`
Responsibilities:
- copy current swapchain backbuffer to readback
- map CPU pixels
- encode PNG via WIC
- return rich error text
### 7.2 Extend window renderer / render loop
Modify:
- `app/Rendering/D3D12/D3D12WindowRenderer.h`
- `app/Rendering/D3D12/D3D12WindowRenderer.cpp`
- `app/Rendering/D3D12/D3D12WindowRenderLoop.h`
- `app/Rendering/D3D12/D3D12WindowRenderLoop.cpp`
Needed changes:
- expose a native capture operation on the active backbuffer
- extend present result with capture outcome
- allow present flow to execute capture before `PresentFrame()`
### 7.3 Rework screenshot controller boundary
Modify:
- `app/Rendering/Native/AutoScreenshot.h`
- `app/Rendering/Native/AutoScreenshot.cpp`
- `app/Platform/Win32/EditorWindowRuntimeController.h`
- `app/Platform/Win32/EditorWindowRuntimeController.cpp`
- `app/Platform/Win32/EditorWindow.cpp`
Needed changes:
- stop passing `UIDrawData` into screenshot rendering
- stop depending on `NativeRenderer`
- move screenshot triggering into the D3D12 present path
### 7.4 Delete obsolete renderer/interop code
Delete if fully unreferenced after the above:
- `app/Rendering/Native/NativeRenderer.h`
- `app/Rendering/Native/NativeRenderer.cpp`
- `app/Rendering/Native/NativeRendererHelpers.h`
- `app/Rendering/D3D12/D3D12WindowInteropContext.h`
- `app/Rendering/D3D12/D3D12WindowInteropContext.cpp`
- `app/Rendering/D3D12/D3D12WindowInteropHelpers.h`
### 7.5 Build-system cleanup
Modify:
- `new_editor/CMakeLists.txt`
Remove:
- old source units
- dead link libraries
## 8. Validation Requirements
### 8.1 Build validation
Must build:
- `XCUIEditorHost`
- `XCUIEditorAppLib`
- `XCUIEditorApp`
### 8.2 Runtime validation
Must validate:
1. editor launches normally
2. main window still presents correctly
3. manual screenshot still succeeds
4. startup auto-capture still succeeds if enabled
5. no screenshot path closes or stalls the main window unexpectedly
### 8.3 Structural validation
Searches after completion must show:
- no `NativeRenderer` references in `new_editor/app`
- no `D3D12WindowInteropContext` references in `new_editor`
- no `D3D11On12` references in `new_editor`
- no `ID2D` / `D2D1` references in `new_editor/app`
Exception:
- `DirectWrite` references inside `D3D12UiTextSystem` remain allowed
## 9. Execution Order
1. Add native `D3D12` backbuffer capture path.
2. Route `AutoScreenshotController` through that new path.
3. Remove runtime-controller dependence on `NativeRenderer`.
4. Delete `NativeRenderer` and `D3D12WindowInteropContext`.
5. Clean CMake/link dependencies.
6. Build and smoke-test.
7. Run structural grep validation.
## 10. Success Criteria
This plan is complete only if all of the following are true:
- screenshots come from the native `D3D12` backbuffer path
- no main-window host rendering code path can fall back to `D2D`
- no `D3D11On12` bridge remains in `new_editor`
- old dead window-render code is physically removed
- build and smoke validation pass