XNA: Proxyclasses to ‘Serialize’ assets using the IntermediateSerializer
Posted by Roy Triesscheijn on 28th September 2010
As some of you’ve might seen, I’ve been breaking my head over the following problem for the past few days:
How do I serialize the class like the following without creating a special ‘intermediate’ struct for each and ever classes
public class MyData
{
[ContentSerializer(SharedResource = true)]
public Texture2D myTexture;
public int myInt;
public string[] myLines;
public MyData() { } // for deserialization
public MyData(int myInt, Texture2DProxy myTexture, string[] myLines)
{
this.myInt = myInt;
this.myTexture = myTexture;
this.myLines = myLines;
}
}
Even though I’ve marked the Texture2D as a shared resource, I still can’t serialize it using the IntermediateSerializer because a Texture2D always has a reference to a GraphicsDevice object, and the IS can’t serialize that.
Fortunately some helpfull people in #XNA on Efnet (ecosky and flashed, that’s you guys!) told me about proxyclasses, first I was confused and thought they wanted me to write a proxy for every class in my project, but soon they helped me understand that I should write a proxy class for Texture2D. I just had to write a proxy class that can be serialized and that will store the path to texture, so that it can reload itself when deserialized.
I quickly came up with the following class, very simple but it will suffice for now:
public class Texture2DProxy
{
public Texture2DProxy(string path)
{
LoadTexture(path);
}
public Texture2DProxy() { }
private void LoadTexture(string path)
{
ContentManager content = GameServices.GetService<ContentManager>(); //My own class, see my code snippet, you can also reference a static CM here.
texture = content.Load<Texture2D>(path);
this.path = path;
}
[ContentSerializerIgnore()] //make this is not serialized
private Texture2D texture;
[ContentSerializerIgnore()]
public Texture2D Texture
{
get
{
if (texture == null)
{
LoadTexture(path);
}
return texture;
}
}
[ContentSerializer()] //make sure this is, even-though it's a private field.
private string path;
}
Now we just need to replace Texture2D with Texture2DProxy everywhere, and update some code. In the end we can now serialize and deserialize the MyData class like this:
public void DoSerialize(MyData myData)
{
XmlWriterSettings settings = new XmlWriterSettings();
settings.Indent = true;
using (XmlWriter writer = XmlWriter.Create("example.xml", settings))
{
IntermediateSerializer.Serialize(writer, myData, null);
}
}
public MyData DoLoad()
{
MyData tmp;
XmlReaderSettings settings = new XmlReaderSettings();
using(XmlReader reader = XmlReader.Create("example.xml", settings))
{
tmp = IntermediateSerializer.Deserialize<MyData>(reader, null);
}
return tmp;
}
Btw, serializing like this will generate the following XML file:
<?xml version="1.0" encoding="utf-8"?>
<XnaContent>
<Asset Type="XNASerialization.MyData">
<myTexture>#Resource1</myTexture>
<myInt>42</myInt>
<myLines>
<Item>Two households, both alike in dignity,</Item>
<Item>In fair Verona, where we lay our scene,</Item>
<Item>From ancient grudge break to new mutiny,</Item>
<Item>Where civil blood makes civil hands unclean.</Item>
</myLines>
</Asset>
<Resources>
<Resource ID="#Resource1" Type="XNASerialization.Texture2DProxy">
<path>latern</path>
</Resource>
</Resources>
</XnaContent>
With this problem out of the way, I can now finally start working on a way to save and restore levels in Hollandia. Oh btw, you can ofcourse do the same trick with SoundEffects and Models or anything else for that matter.
Tags: C#, Code, Content, Deserialize, IntermediateSerializer, Serialization, XNA
Posted in Blog, General Coding, General Gamedesign, Hollandia, Tips, XNA | 3 Comments »
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