Undo group problem

[Yoan Boisjoli]

Hi Edward! I’m not a pro with scripts but I think that instead of starting an undo group on onChanging and closing it on onChange, you can use the app.beginUndoGroup() and app.endUndoGroup() methods to manually start and end an undo group at the appropriate times.

Here’s an example implementation:

var undoGroupInProgress = false;
slider1.onChanging = function() {
    if (!undoGroupInProgress) {
        app.beginUndoGroup("Preview Slider Change");
        undoGroupInProgress = true;
    }
    // create shape layer to preview (adjust outPoint on the shape layer)
}
slider1.onChange = function() {
    // apply the effect
    if (undoGroupInProgress) {
        app.endUndoGroup();
        undoGroupInProgress = false;
    }
}

With this implementation, the undo group is only started once when the slider is first changed, and is ended once when the slider is released. The undoGroupInProgress variable is used to ensure that the undo group is only closed if it was actually opened in the first place.

This should avoid the “undo mismatch” warning and provide a clean undo history for your users.

Hope this helps/work for you.

[Edward Clayton]

Thanks for the response, Yoan!

I actually tried this exact same thing and it still doesn’t work properly. There are no mismatch errors, but unfortunately it still treats each tiny change during onChanging as its own event.

[Yoan Boisjoli]

Hmm.. Looks like we think alike!

Maybe a better approach is to create a temporary layer on the first onChanging event and then update it during the subsequent onChanging events. This way, you only need to create one undo group when applying the effect in the onChange event.

var previewLayer = null;
function createPreviewLayer() {
    // Create your temporary shape layer here and set its outPoint
    // based on the slider value.
    // Return the created layer.
}
function updatePreviewLayer() {
    // Update the outPoint of the previewLayer based on the slider value.
}
slider1.onChanging = function() {
    if (!previewLayer) {
        previewLayer = createPreviewLayer();
    } else {
        updatePreviewLayer();
    }
}
slider1.onChange = function() {
    // Clean up the preview layer before applying the effect.
    previewLayer.remove();
    app.beginUndoGroup("Apply Effect");
    // Adjust the selection and apply the effect based on the final slider value.
    app.endUndoGroup();
    // Reset the preview layer.
    previewLayer = null;
}

This creates a temporary preview layer and updates it during slider adjustments. When the user releases the slider, the temporary layer is removed, and the effect is applied within a clean undo group. Hope this will give you the desired undo behavior without any warning pop-ups.