Windows.UI.Xaml.Controls.Handle.java Source code

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Here is the source code for Windows.UI.Xaml.Controls.Handle.java

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//-------------------------------------------------------------------------------------------------------
// Copyright (C) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
//-------------------------------------------------------------------------------------------------------
package Windows.UI.Xaml.Controls;

import org.json.JSONException;
import org.json.JSONObject;

public class Handle {

    public int value;
    public boolean fromNative;

    //TODO: Lifetime
    // Can't really do weak references without cumbersome client API for keeping things alive.
    // Need to expose reasonable destruction APIs, some automatic with trees of UI objects.
    static java.util.ArrayList<Object> _objectsAssignedOnManagedSide = new java.util.ArrayList<Object>();
    static java.util.ArrayList<Object> _objectsAssignedOnNativeSide = new java.util.ArrayList<Object>();

    static java.util.HashMap<Object, Integer> _managedHandleLookup = new java.util.HashMap<Object, Integer>();
    static java.util.HashMap<Object, Integer> _nativeHandleLookup = new java.util.HashMap<Object, Integer>();

    // Create a handle from the native side
    public Handle() {
        this.value = _objectsAssignedOnNativeSide.size();
        this.fromNative = true;
    }

    // Create a handle from the managed side,
    // using the already-chosen value
    public Handle(int value) {
        this.value = value;
        this.fromNative = false;
    }

    Handle(int value, boolean fromNative) {
        this.value = value;
        this.fromNative = fromNative;
    }

    public static Object toObject(Handle handle) {
        if (handle.fromNative) {
            return _objectsAssignedOnNativeSide.get(handle.value);
        } else {
            return _objectsAssignedOnManagedSide.get(handle.value);
        }
    }

    public static Handle fromObject(Object obj) {
        Integer value = _managedHandleLookup.get(obj);
        if (value != null) {
            return new Handle((int) value, false);
        }
        value = _nativeHandleLookup.get(obj);
        if (value != null) {
            return new Handle((int) value, true);
        }
        return null;
    }

    public static Handle fromJSONObject(JSONObject obj) {
        try {
            int value = obj.getInt("value");
            boolean fromNative = obj.optBoolean("fromNative");
            return new Handle(value, fromNative);
        } catch (JSONException ex) {
            throw new RuntimeException(ex);
        }
    }

    public JSONObject toJSONObject() {
        try {
            JSONObject obj = new JSONObject();
            obj.put("_t", "H");
            obj.put("value", this.value);
            if (this.fromNative) {
                obj.put("fromNative", true);
            }
            return obj;
        } catch (JSONException ex) {
            throw new RuntimeException(ex);
        }
    }

    public static Object deserialize(JSONObject obj) {
        Handle handle = Handle.fromJSONObject(obj);
        return Handle.toObject(handle);
    }

    public void register(Object instance) {
        if (this.fromNative) {
            assign(instance, _objectsAssignedOnNativeSide);
            _nativeHandleLookup.put(instance, this.value);
        } else {
            assign(instance, _objectsAssignedOnManagedSide);
            _managedHandleLookup.put(instance, this.value);
        }
    }

    void assign(Object instance, java.util.ArrayList<Object> list) {
        if (list.size() == this.value) {
            list.add(instance);
        } else if (list.size() > this.value) {
            list.set(this.value, instance);
        } else {
            // Just fill with nulls up to this point.
            // This would have been caused by an earlier instantiation exception,
            // but cascading errors simply from unexpected handles are annoying.
            while (list.size() < this.value) {
                list.add(null);
            }
            list.add(instance);
        }
    }
}