Layer Control from an installed plugin doesn't react to selecting new layers added between first and later activations

[Overruler]

To reproduce:

1. Create an effect with a Layer Control UI element, build it as a DLL and install the built DLL.
2. Run the installed plugin effect with 3 layers, each containing a different image.
3. Observe that changing the layer to any of the 3 effects a change in the resulting image.
4. Add 5 more layers, again with unique images.
5. Run the installed plugin effect a second time, now with 8 layers.
6. Observe that changing the layer to any of the 8 appears to work, but only selecting one of the first 3 layers effects a change in the variable containing the index of the selected layer.

Example effect code:

        #region UICode
        LayerControl UserLayer = 0; // Source
        #endregion
        protected override IDeviceImage OnCreateOutput(IDeviceContext dc)
        {
            return Environment.Document.Layers[UserLayer.Clamp(0,Environment.Document.Layers.Count-1)].Image;
        }

[toehead2001]

Can confirm the issue, but it's not a CodeLab issue, as far as I can tell.

Even though the dropdown contains the correct Layer Index values, it looks like ValueChoices in the Token retained the 3 values from the first run.

@rickbrew thoughts?

[rickbrew]

Looks like another corner case of "it wasn't designed for this" :) That is, IndirectUI was always meant to have a static, unchanging property schema. File a bug for me over in the PDN repo and I'll try to look at getting something fixed for the v5.1 release. I can't make promises though.

[BoltBait]

File a bug for me over in the PDN repo and I'll try to look at getting something fixed for the v5.1 release.

@rickbrew I have already filed a request for this functionality here:

https://github.com/paintdotnet/paint.net/issues/3466

[Overruler]

A temporary workaround might be to fill ValueChoices at initialization with indices for up to 512 layers. There is probably no layer limit in PDN itself, but after 512 layers, adding a new layer was taking about 1 second on a very high-end desktop PC, so 512 or 1024 layers seems to be a practical limit.

Perhaps something like this:

        protected override PropertyCollection OnCreatePropertyCollection()
        {
            int defaultLayerIndex = 0;
            List<Property> props = new List<Property>();

            props.Add(new StaticListChoiceProperty(PropertyNames.UserLayer, Enumerable.Range(0, 512).Reverse().Cast<object>().ToArray(), defaultLayerIndex, false, ValueValidationFailureResult.Ignore));
            // ....
        }

        protected override ControlInfo OnCreateConfigUI(PropertyCollection props)
        {
            ControlInfo configUI = CreateDefaultConfigUI(props);
            PropertyControlInfo UserLayerLayerControl = configUI.FindControlForPropertyName(PropertyNames.UserLayer);
            for (int i = 0, n = Math.Min(Environment.Document.Layers.Count, 512); i < n; i++)
            {
                UserLayerLayerControl.SetValueDisplayName(i, Environment.Document.Layers[i].Name);
            }
            // ....
        }