How do I use OnPropertyChanged()

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- Colludium
- - Joined 26 Aug, 2013
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- 23 Oct, 2019
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I'd like to use the OnPropertyChanged() function in instance.js to then clamp the properties values in the editor - how can I do this? Thanks.
- Ashley Construct Team Founder
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- - Joined 21 May, 2007
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- 23 Oct, 2019
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Just call SetPropertyValue inside that method if the value is invalid.
- Colludium
- - Joined 26 Aug, 2013
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- 23 Oct, 2019
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Great, thanks Ashley .
- Colludium
- - Joined 26 Aug, 2013
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- 23 Oct, 2019
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Ashley - maybe I am misunderstanding this. If I enter the following:
OnPropertyChanged(id, value) { this.SetPropertyValue(id, 2); }

Then nothing changes in the editor. In this example I was expecting the value to be clamped to "2". What am I missing? Thanks.
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- Ashley Construct Team Founder
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- - Joined 21 May, 2007
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- 23 Oct, 2019
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Did you check the console? That will be crashing because the method does not exist there. It's on IObjectInstance, which you normally access from your IInstanceBase-derived instance class with this._inst.
- Colludium
- - Joined 26 Aug, 2013
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- 23 Oct, 2019
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Ashley - yes, of course, there's nothing in the console. Neither of the following do anything when called inside OnPropertyChanged():
this.SetPropertyValue(id, 2);

this._inst.SetPropertyValue(id, 2);

If I add an undeclared variable inside the OnPropertyChanged(){} then that doesn't highlight an error in the console either - it's as if OnPropertyChanged is not being called. This is a behavior rather than a plugin - could that make a difference (no reason to think so, I expect)? The undeclared variable with no console error makes me suspect that this might be an editor bug, but I could be missing something hugely obvious...
- Ashley Construct Team Founder
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- 23 Oct, 2019
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I'm sure it works - several official features use it. E.g. try setting the text object's font size to -1 and it clamps it to 0.1. I can't tell why it's not working for you, I guess I'd need to see real running code.

Mikal
- Joined 22 Apr, 2016
- 111 topics • 1,182 posts
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24 Oct, 2019
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I was wondering about this too and tried it, I can get it to work with a plugin, but not with a behavior (it looks the the OnPropertyChanged function is not called when changing the property of the behaior on an instance.

Here's the code from the top-level instance.js (using the SDK behavior example to test from here: construct.net/en/make-games/manuals/addon-sdk )

"use strict";

{
	const BEHAVIOR_CLASS = SDK.Behaviors.MyCompany_MyBehavior;
	
	BEHAVIOR_CLASS.Instance = class MyCustomBehaviorInstance extends SDK.IBehaviorInstanceBase
	{
		constructor(sdkBehType, behInst)
		{
			super(sdkBehType, behInst);
		}
		
		Release()
		{
		}
		
		OnCreate()
		{
		}
		
		OnPropertyChanged(id, value)
		{
			console.log("***INFO*** id:"+id+" value:"+value);
			debugger
		}
		
		LoadC2Property(name, valueString)
		{
			return false;		// not handled
		}
	};
}