You can use type converters to convert data types between the data source and the UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary. This allows you to:
Texture2D
property from an int
value.There are two categories of type converters: global converters and per-binding converters.
Global converters are statically registered and are available to all binding instances, regardless of the binding modes. The binding system provides several pre-registered global converters for convenience, such as converters between style values and their underlying data representation. You can use them to bind a regular float
or a StyleKeyword
to a StyleFloat
property, instead of using StyleFloat
in the data source.
To register a global converter, use the ConverterGroups.RegisterGlobalConverter
method. This method requires a delegate to convert a source type to a destination type. The delegate must be a ref
delegate to enable bidirectional usage. Upon registration, global converters automatically apply to any binding instances requiring that specific type of conversion, without any additional configuration.
The following example registers a global converter that converts between a Texture2D
and a TextureHandle
:
public struct TextureHandle
{
public static Texture2D ResolveTexture(TextureHandle handle)
{
return /* Actual texture */;
}
public static FromTexture(Texture2D texture)
{
return new TextureHandle { handle = /* Compute handle */ };
}
public int handle;
}
// Registers the global converter
ConverterGroups.RegisterGlobalConverter((ref TextureHandle handle) => TextureHandle.ResolveTexture(handle));
ConverterGroups.RegisterGlobalConverter((ref Texture2D texture) => TextureHandle.FromTexture(texture));
Per-binding converters apply to a specific binding instance. You can register an individual or a group of per-binding converters.
To register an individual converter, use the DataBinding.sourceToUiConverters.AddConverter
or DataBinding.uiToSourceConverters.AddConverter
method. These methods require a delegate to convert a source type to a destination type. The delegate must be a ref
delegate to enable bidirectional usage.
The following example registers and applies individual converters to convert between radians and degrees for a binding instance:
var binding = new DataBinding();
binding.sourceToUiConverters.AddConverter((ref float radian) => Mathf.RadToDeg * radian);
binding.uiToSourceConverters.AddConverter((ref float degree) => Mathf.DegToRad * degree);
To register a group of converters and apply them to a DataBinding
instance, use the ConverterGroup
class.
The following example shows how to register a group of converters:
// Create a converter group
var group = new ConverterGroup("Inverters");
// Add converters to the converter group
group.AddConverter((ref int v) => -v);
group.AddConverter((ref float v) => -v);
group.AddConverter((ref double v) => -v);
// Register the converter group
ConverterGroups.RegisterConverterGroup(group);
// Add a converter to an existing converter group
if (ConverterGroups.TryGetConverterGroup("Inverters", out var group))
{
group.AddConverter((ref short v) => -v);
}
After you have registered a converter group, you can apply it to a binding instance. You can apply a converter group to a binding instance in C#, UI Builder, or UXML.
To apply a converter group in C#, use the DataBinding.ApplyConverterGroupToUI
or DataBinding.ApplyConverterGroupToSource
method. These methods take a converter group name as a parameter.
The following example applies the converter group Inverters
to a binding instance in C#:
var binding = new DataBinding();
if (ConverterGroups.TryGetConverterGroup("Inverters", out var group))
{
binding.ApplyConverterGroupToUI(group);
binding.ApplyConverterGroupToSource(group);
}
Note: When you apply a converter group onto another one, it operates in a “fire-and-forget” manner. This means that when you apply the converter group, it independently performs its intended function without additional ongoing monitoring or management from you.
The following example applies the converter group Inverters
to a binding in UXML:
<ui:DataBinding source-to-ui-converters="Inverters" ui-to-source-converters="Inverters" />
For details about how to apply a converter group in UI Builder, refer to Get started with runtime binding.
Follow these tips and best practices to optimize performance:
enum
types. Allocating memory during conversions can introduce unnecessary overhead and impact performance. Instead, opt for efficient and memory-friendly conversion approaches.Source and destination types must match perfectly unless they’re of type UnityEngine.Object
. For example, you can’t convert an int
to a float
, or a float
to an int
. This can be inconvenient, especially with enum
types. This limitation will be addressed in a future release.