Feature request: Public API for setting channel names/labels

[hongquanli]

Summary

Currently, there's no public API to set custom channel names/labels in the ArrayViewer. The only way to customize channel labels is through the private _lut_controllers API, which requires polling with QTimer to wait for initialization.

Use Case

When displaying multi-channel microscopy data (e.g., OME-TIFF with channel metadata), it's desirable to show meaningful channel names like "DAPI", "GFP", "RFP" instead of numeric indices "0", "1", "2".

Current Workaround

# Must poll because _lut_controllers isn't available immediately
def _update_labels():
    controllers = getattr(viewer, "_lut_controllers", None)
    if controllers:
        for i, name in enumerate(channel_names):
            if i in controllers:
                controllers[i].key = name
                controllers[i].synchronize()
    else:
        QTimer.singleShot(100, _update_labels)  # Retry

QTimer.singleShot(100, _update_labels)

This approach:

• Relies on private API (_lut_controllers)
• Requires polling with arbitrary delays
• May break if internal API changes

Proposed Solutions (any of these would help)

Option 1: Constructor parameter

viewer = ndv.ArrayViewer(data, channel_names=["DAPI", "GFP", "RFP"])

Option 2: Public method

viewer = ndv.ArrayViewer(data)
viewer.set_channel_names(["DAPI", "GFP", "RFP"])

Option 3: Signal when ready

viewer = ndv.ArrayViewer(data)
viewer.ready.connect(lambda: update_labels(viewer))

Context

This came up while implementing channel name display in hongquanli/ndviewer_light#6, a lightweight viewer for microscopy data that uses NDV as its backend.

Thank you for considering this enhancement!

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🤖 This issue was generated with Claude Code while working on hongquanli/ndviewer_light#6