OnOpenAssetAttribute

Description

Callback attribute for opening an asset in Unity (e.g the callback is fired when double clicking an asset in the Project Browser).

Adding this attribute to a static method will make the method be called when Unity is about to open an asset. The method should have the following signature:
static bool OnOpenAsset(int instanceID, int line)
Return true if you handled the opening of the asset or false if an external tool should open it.

no example available in JavaScript

// C# example:
using UnityEngine;
using UnityEditor;
using UnityEditor.Callbacks;

public class MyAssetHandler
{
    [OnOpenAssetAttribute(1)]
    public static bool step1(int instanceID, int line)
    {
        string name = EditorUtility.InstanceIDToObject(instanceID).name;
        Debug.Log("Open Asset step: 1 (" + name + ")");
        return false; // we did not handle the open
    }

    // step2 has an attribute with index 2, so will be called after step1
    [OnOpenAssetAttribute(2)]
    public static bool step2(int instanceID, int line)
    {
        Debug.Log("Open Asset step: 2 (" + instanceID + ")");
        return false; // we did not handle the open
    }
}

OnOpenAssetAttribute has an option to provide an order index in the callback, starting at 0. This is useful if you have more than one OnOpenAssetAttribute callback, and you would like them to be called in a certain order. Callbacks are called in order, starting at zero.

Inherited members