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MILEFFECTSERR_ALREADYATTACHEDTOLISTENER
The scope of MILEFFECTSERR_ALREADYATTACHEDTOLISTENER is MIL effect child collections and listeners. A graph or effect object is already attached to the listener the caller is trying to register. Keep 0x88980618 beside the returning method because a wrapper can replace this distinction with a generic subsystem message.
Do not hide the original condition
This is not proof that event delivery is broken; it prevents duplicate attachment to an already associated listener. For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, do not catch the HRESULT and continue rendering with a partially connected graph; later failures can obscure the invariant that was first violated.
Subsystem boundary
When MILEFFECTSERR_ALREADYATTACHEDTOLISTENER is returned, composite effects and graph listeners have collection lifetimes independent of visual appearance. An empty child set can invalidate an operation that expects aggregation, while registering the same listener twice creates duplicate ownership of notifications in the MILEFFECTSERR_ALREADYATTACHEDTOLISTENER path. For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, both cases require inspecting collection membership and subscription state rather than pixel output.
For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, inspect the following boundary: listener registration lifetime and duplicate subscription.
Facts worth preserving
| Record | Why it matters here |
|---|---|
| Effect instance and owning graph or group identity | For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, recording effect instance and owning graph or group identity separates the MIL effect child collections and listeners boundary from a later wrapper symptom. |
| Connector, input, child, listener, property, or transform involved | In MILEFFECTSERR_ALREADYATTACHEDTOLISTENER diagnostics, recording connector, input, child, listener, property, or transform involved ties the HRESULT to the MIL effect child collections and listeners boundary rather than to the final visible failure. |
| Calculated input and output bounds | Comparing calculated input and output bounds shows whether MILEFFECTSERR_ALREADYATTACHEDTOLISTENER follows input, object state, or environment. |
| Construction sequence and first method returning the HRESULT | Preserving construction sequence and first method returning the HRESULT provides the evidence needed to test this distinction: this is not proof that event delivery is broken; it prevents duplicate attachment to an already associated listener. |
What each result would imply
| Test | Interpretation | Hold constant |
|---|---|---|
| Same environment, reduced input | If MILEFFECTSERR_ALREADYATTACHEDTOLISTENER disappears with a smaller faithful case, complexity within MIL effect child collections and listeners is implicated. | For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, keep effect instance and owning graph or group identity fixed while simplifying calculated input and output bounds. |
| Same input, fresh object generation | If MILEFFECTSERR_ALREADYATTACHEDTOLISTENER changes after rebuilding state, examine ownership across the effect instance, connector builder, graph owner, listener, and bounds calculator. | For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, place connector, input, child, listener, property, or transform involved on the timeline of the last successful transition. |
| Same operation on a controlled second path | If MILEFFECTSERR_ALREADYATTACHEDTOLISTENER follows one environment, the failure is not explained by source data alone. | For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, compare visual generation, effect registration, shader profile, rendering tier, and target dimensions while preserving construction sequence and first method returning the HRESULT. |
Isolation procedure
For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, test one child or one listener registration, then add and remove entries while logging object identity. When MILEFFECTSERR_ALREADYATTACHEDTOLISTENER is returned, include an empty collection and a duplicate registration as explicit negative controls.
- When MILEFFECTSERR_ALREADYATTACHEDTOLISTENER is returned, track registration tokens and detach before attaching a different lifetime.
- Rebuild the smallest graph containing only the implicated node and one known input in the MILEFFECTSERR_ALREADYATTACHEDTOLISTENER path.
- For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, log ownership changes and graph generation numbers.
- When MILEFFECTSERR_ALREADYATTACHEDTOLISTENER is returned, validate the graph before allocating large intermediate resources.
Verification after repair
A correction for MILEFFECTSERR_ALREADYATTACHEDTOLISTENER should let the operation at the MIL effect child collections and listeners boundary complete repeatedly under the original supported conditions. Repeat the control that begins with “Track registration tokens and detach before attaching a different lifetime” and confirm that the following lifecycle step also succeeds. For MILEFFECTSERR_ALREADYATTACHEDTOLISTENER, keep the original failing sample and one deliberate negative case so fallback cannot be mistaken for repair.
Technical references
When MILEFFECTSERR_ALREADYATTACHEDTOLISTENER is returned, these references define the public API family, object model, or error list used to interpret this status.
- Microsoft Open Specifications: HRESULT values.
- Microsoft: WPF bitmap effects overview.
- Microsoft: PixelShader class.
- Microsoft: Direct2D custom effects.
- Microsoft: ID2D1TransformGraph.
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