[LKasianAnsys]

Issue

Resolves #30

Context

Until now, a mouse drag in server mode moved the server's camera or cross-section widget, but the save_state API would keep the last synced camera, and dragging the cross-section plane did not actually move the clipping plane.

In this PR, the server now detects the end of a gesture from the forwarded release or wheel event, and records the camera through the same code path used by the CLIENT mode sync_camera.

Manual check: start VISOR in SERVER mode.

• Camera: Drag the camera to new position. Save the state, and load it in a new session. The loaded session should reflect the new camera position (not the default camera).
• Cross-section plane: Turn on the cross-section widget, and move the clipping plane through a part of the dataset; you should see the part clipped by the plane as expected. Save state. Load the state in a new remote session. The clipping plane and clipped dataset should both be present.

Copilot summary

This pull request introduces a robust mechanism for recording and publishing camera and cross-section plane states at the end of user gestures (such as mouse drags and wheel events) in SERVER mode, ensuring accurate state synchronization after interactive changes. The changes span the renderer, window, widget, and test layers, with new hooks and logic to capture and publish state only when gestures complete, and comprehensive tests to verify the behavior.

Key changes grouped by theme:

Recording and Publishing State at Gesture End:

• Added logic in server_window.py to detect the end of user gestures (mouse button release or wheel event) and trigger recording and publishing of the pipeline camera and cross-section plane states in a single, locked section. ([[1]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-a39360576881e234c010ed98e5367fb7a7d1b387da52f55a42d1efcf30ba092aR13-R16), [[2]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-a39360576881e234c010ed98e5367fb7a7d1b387da52f55a42d1efcf30ba092aR29-R37), [[3]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-a39360576881e234c010ed98e5367fb7a7d1b387da52f55a42d1efcf30ba092aL91-R117))
• Implemented record_pipeline_camera and record_cross_section_plane methods in ServerRenderer to handle state recording and publishing, ensuring no redundant frame requests and correct state capture only when necessary. ([src/ansys/visor/viewer/renderer/server_renderer.pyR93-R117](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-f2ab9442d7526c6bc406de355e3ce5fc287e09ff8c49b5d1efec698a93ab723dR93-R117))
• Modified _publish_camera to separate camera record publishing from frame requests, introducing _publish_camera_record for clarity and correct sequencing. ([src/ansys/visor/viewer/renderer/server_renderer.pyL154-R185](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-f2ab9442d7526c6bc406de355e3ce5fc287e09ff8c49b5d1efec698a93ab723dL154-R185))

Widget Enhancements for Cross-Section Plane Tracking:

• Added link_plane_to_handle and take_handle_moved methods to VisorCrossSectionWidget, enabling the widget to mark when the handle has been moved and to synchronize the clip plane with the handle at every drag step. ([[1]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-b0fef21f1bcc21331db361eecdc8bb7fbe52d8da6c4e9f64556f890030dcacfcR37-R38), [[2]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-b0fef21f1bcc21331db361eecdc8bb7fbe52d8da6c4e9f64556f890030dcacfcR67), [[3]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-b0fef21f1bcc21331db361eecdc8bb7fbe52d8da6c4e9f64556f890030dcacfcR183-R198))
• Ensured the cross-section widget links the plane to the handle upon initialization in ServerRenderer. ([src/ansys/visor/viewer/renderer/server_renderer.pyR66](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-f2ab9442d7526c6bc406de355e3ce5fc287e09ff8c49b5d1efec698a93ab723dR66))

Renderer Refactoring for State Recording:

• Refactored sync_camera and sync_cross_section_plane in PipelineRenderer to delegate state recording and projection to new _write_camera and _write_cross_section helpers, clarifying responsibilities and supporting the new gesture-end recording logic. ([[1]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-9199ec1a3522d373bbefbf5a83b3eff4045fda5f22969be86aaac1a946c694f5L292-L299), [[2]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-9199ec1a3522d373bbefbf5a83b3eff4045fda5f22969be86aaac1a946c694f5L374-L386))

Testing and Validation:

• Added comprehensive integration tests to verify that camera and cross-section plane states are recorded and published only at gesture end, and that no redundant frame requests are made. Tests cover wheel events, drags, orientation ball clicks, and cross-section handle movements. ([[1]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-232814e2a82defe690b9c786f507c4d72bf3ff26707ef1adcc1c3da3b204213eR12-R19), [[2]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-232814e2a82defe690b9c786f507c4d72bf3ff26707ef1adcc1c3da3b204213eR34-R43), [[3]](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-232814e2a82defe690b9c786f507c4d72bf3ff26707ef1adcc1c3da3b204213eR54-R204))
• Introduced a unit test to ensure gesture-end recording only occurs under the correct lock, preventing race conditions. ([tests/unit/renderer/test_server_window.pyR202-R211](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-1d3469247a2b4faf2316bde832548716aa2a75bc1998ee07d58fec284f48bae3R202-R211))

Documentation and Changelog:

• Updated the changelog to describe the new behavior for recording camera and cross-section drags in SERVER mode. ([doc/changelog.d/190.added.mdR1](https://github.com/ansys/Visual-Interactive-Simulation-Object-Renderer/pull/190/files#diff-83ff440840cf81f5cca748d99436963d52c68219d0d9d61057861937c8a45569R1))

These changes collectively ensure that interactive camera and cross-section manipulations are reliably and efficiently captured and published, improving the accuracy of remote rendering state synchronization.

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References: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]