Sunday, May 24, 2009

Generating and Printing Surface IdentityTag

Tags support is the most important feature in Microsoft Surface.Tags enable our application to recognize objects through surface.As you know there are 2 types of tags.Byte tag and identity tag.So before placing objects on the surface to recognize we have to print the tag and stick on the bottom part of the object.Then only surface can identify the tag value through its infrared sensing mechanism.There are 3 ways to visualize the tags.One is using the command line tool GenTag.exe and another using it’s visual tool GenTagUI.exe and last using our own programs which make use of the class IdentityTagGenerator

Using IdentityTag Image Generator
Tool is located at

[Install drive]:\Program Files\Microsoft SDKs\Surface\v1.0\Tools\GenTag\GenTag.exe

Syntax :
GenTag.exe <Series> <Value> <FileName.png> [/dpi:number]

Value and Series are in Hex.This tool outputs the tag as png image.Later we can print that image.Dots Per Inch (dpi) is optional.

Using IdentityTag printing tool
Surface now includes a tool in it’s sdk which helps us to generate and print IdentityTags.You can locate the program in start menu itself

Programs->Microsoft Surface sdk 1.0 sp1->Tools->Identity Tag Printing Tool

or in the location

[Install drive]:\Program Files\Microsoft SDKs\Surface\v1.0\Tools\GenTag\GenTagUI.exe

There is nothing to explain about using the tool I think.Try yourself.

Using IdentityTagGenerator class
Microsoft has provided API to visualize the tags and later we can save or print them.The entry to tag visualization API is IdentityTagGenerator.That class contains 2 static methods for getting tag in it’s actual form.

  • Image GenerateTag(long series,long value) : As its signature implies, it returns the tag image according to parameters series and value.There is an overload available which takes dpi as parameter and returns image according to that.
  • RenderTag(long series,long value,Point point,Graphics g) :Draws identity tag on the Graphics object.Mainly targeted to be used in Windows forms applications.Also this helps in distributing tags through applications.
In the first method we can set the returned Image object as source of image control in our application.The second method uses Graphics object and that is available in OnPaint methods or we can create it using the Graphics class.

The usage is straight forward.Seems there is no need to post a sample.

NB: Printed tag should be exactly 1.125 inches square in order to get detected by Surface.

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