CommandHandler scrollToPartPause

GoJS
1

Hello,

while investigating a perceived performance problem when selecting the next similar node to the current selected one, I found a setter without documentation.
CommandHandler.scrollToPartPause. Setting this number didn’t have any visible impact as far as I could see. What does this do or is this a leftover?

I am also still wondering why scrollToPart() is very fast but delays diagram.select() that happens 1 line before that by around 100ms. This also only occurs when the scrollToPart() function needs to scroll the diagram.

3

That’s an undocumented property that controls how long the pause is between each time that the CommandHandler.scrollToPart command has to expand a tree or group. If the Part that you want to scroll to is already visible, then no such expansion automations are needed, so the property is not used.

I don’t know what you mean by “but delays diagram.select()”. You should be able to call Diagram.select at any time, assuming you have a reference to a Part.

However I can see why one would want to delay the automatic starting of text editing until after the scrolling is finished – it would be disconcerting if it tried to immediately start editing or whatever modal operation you want to conduct.

4

Thank you for explaining the undocumented setter. 👍

Our code does something like this: (pseudo code)

const similarItem= searchSimilarItem(diagram.selection);
if (similarItem) {
    diagram.select(similarItem);
    diagram.commandHandler.scrollToPart(similarItem);
}

You can always see the effect of the last line instantaneously but the selection sometimes takes around 100-200ms to actually change.
So far I seem to be able to reproduce it more often if scrollToPart() only wants to scroll less than 20px on the y axis only.

Edit: Changing the order of diagram.select and scrollToPart seems to fix the issue.