Did You Know That... Type Converters allow you to use property attributes in Complex Types
There are two ways to add attributes to any element in Silverlight:
- property attribute syntax, which takes a string
- Property elements
Silverlight provides a number of built-in type converters to allow you to use the simpler property attribute syntax, where you might otherwise need to use a property element. The most familiar example of this is that you can write
<Rectangle Name="myRect0"
Width="100"
Height="44"
Canvas.Left="0"
Canvas.Top="10"
StrokeThickness="2"
Stroke="Black"
Fill="Red"
/>
A naïve view of this code, might lead you to think that the stroke and fill colors are both strings.
You can quickly disabuse yourself of this notion by adding a little bit of code to your handleLoad event handler
handleLoad: function(plugIn, userContext, rootElement)
{
this.plugIn = plugIn;
var myRect = plugIn.content.FindName("myRect0");
alert("myRect.stroke = " + myRect.Stroke);
alert("myRect.fill = " + myRect.Fill);
}
You might expect the first alert box to say "myRect.stroke = Black" and the second alert box to say "myRect.fill= Red"
But on reflection, you realize that what is in the stroke and in the fill is not a string, but rather is a solidColorBrush object that has been placed there using the typeConverter, as shown in figure 1
All of this makes a great deal more sense when you realize that the type converters are simply acting as shorthand, allowing you to avoid the more verbose but more explicit code, shown here
<Rectangle Name="myRect0"
Width="100"
Height="44"
Canvas.Left="120"
Canvas.Top="10"
StrokeThickness="2"
>
<Rectangle.Stroke>
<SolidColorBrush Color="Black" />
</Rectangle.Stroke>
<Rectangle.Fill>
<SolidColorBrush Color="Red" />
</Rectangle.Fill>
</Rectangle>