CNA-GAP-006: GraphicsDeviceManager never calls its FindBestDevice, RankDevices or CanResetDevice virtuals

CNA snapshot 009d40f5  ·  Known Issues › Functional gaps  ·  source links pinned to 009d40f5

The three XNA selection hooks are implemented (as a default GDI, a no-op and 'device exists') but CreateDevice and ApplyChanges do not consult them, so overriding them has no effect on device selection or reset.

Identifier

CNA-GAP-006

Category

Functional gap

Subsystem

Core & runtime

Status

Open

Verified against

CNA 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

None

Affected contract

Microsoft::Xna::Framework::GraphicsDeviceManager::FindBestDevice(bool), RankDevices(std::vector<GraphicsDeviceInformation>&), CanResetDevice(const GraphicsDeviceInformation&)

Expected behaviour

In XNA 4.0 (IL of GraphicsDeviceManager.ChangeDevice) device changes call FindBestDevice (which ranks through RankDevices) and CanResetDevice to decide between reset and re-creation; subclasses override them to choose adapters or modes.

Actual behaviour at TARGET

In GraphicsDeviceManager.cpp the three methods exist, but CreateDevice and ApplyChanges build their GraphicsDeviceInformation directly and always reset the Game-owned device in place; nothing calls the virtuals.

Source locations

• modules/runtime/src/GraphicsDeviceManager.cpp — FindBestDevice, RankDevices, CanResetDevice, CreateDevice, ApplyChanges

Evidence

Checked by reading the named sources at 009d40f5; nothing was built or executed for this entry. CNA supports a single adapter and never re-creates the Game's device, so the hooks have little to decide; the gap is that overrides are silently ignored.

Focused reproduction

No focused reproduction is known. Nothing has been invented here; the evidence above is what exists.

Current tests

GraphicsDeviceManagerTests.cpp does not override the hooks.

Regression test

Either call the hooks from CreateDevice/ApplyChanges or document them as inert; a test override that records calls would pin whichever is chosen.

Blast radius

Ported XNA games that override these hooks to filter modes or adapters.

Workaround

Adjust PresentationParameters in a PreparingDeviceSettings handler instead.