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public interface VisualTagConnection
This interface provides contactless connection to a visual tag (bar code) target. It can be used to retrieve data from visual tags and to generate visual tag images.
VisualTagConnection
is built on top of Generic Connection
Framework GCF. The URL needed to open a VisualTagConnection
is
provided in the
TargetProperties
received in the
TargetListener
callback when target is discovered. The connection may
also be opened manually without
DiscoveryManager
functionality. Below is the definition for the URL in the EBNF format. As the
connection is opened before any target is available, the URL only contains the
scheme definition.
<visual tag url> ::= "vtag:"
Method Summary | |
---|---|
java.lang.Object |
generateVisualTag(byte[] data,
java.lang.Class imageClass,
ImageProperties properties)
Generates a visual tag image containing specified data. |
byte[] |
readVisualTag(java.lang.Object tagImage,
java.lang.Class imageClass,
java.lang.String symbologyName)
Reads a visual tag. |
Methods inherited from interface javax.microedition.io.Connection |
---|
close |
Method Detail |
---|
byte[] readVisualTag(java.lang.Object tagImage, java.lang.Class imageClass, java.lang.String symbologyName) throws VisualTagCodingException, java.io.IOException
Reads a visual tag. The application has access to the visual tag image and
the used image class is provided as parameter. The symbology to be used in
decoding the data is also specified. Names of the standardized symbologies
are defined in SymbologyManager
class. If decoding
of the data fails, a VisualTagCodingException
is thrown.
tagImage
- visual tag image to be decodedimageClass
- the class identifying the type of the tagImage
,
null
if platform default image class is usedsymbologyName
- name of the symbology to be used in the data decoding
java.lang.NullPointerException
- if tagImage
or
symbology
is null
java.lang.IllegalArgumentException
- if symbology
or
imageClass
is not supported by the API implementation
VisualTagCodingException
- if decoding visual tag fails
java.io.IOException
- if connection has been closedjava.lang.Object generateVisualTag(byte[] data, java.lang.Class imageClass, ImageProperties properties) throws VisualTagCodingException, java.io.IOException
Generates a visual tag image containing specified data. The visual tag
image is generated according to the properties defined in the properties
parameter and it is an instance of the specified image class. The application
developer retrieves the image properties are with method
SymbologyManager.getImageProperties
.
method. It is also recommended that the size
of the screen is checked before generating the visual tag image to make sure
that the generated image fits completely on the screen. If encoding of
the data fails, a VisualTagCodingException
is thrown.
The implementation of this method must produce
the best quality image that fits into the given image dimensions. This
must be done with as little anti-aliasing as
possible, and the returned image must still
be readable. If the implementation can not generate the image without
heavy zooming or anti-aliasing, an IllegalArgumentException
must be thrown.
data
- data to be encoded into the visual tag imageimageClass
- the instance of the Class
object that
must be used in the generated image,
null
if platform default image class is usedproperties
- properties of visual tag image to be generated
java.lang.NullPointerException
- if data
or
properties
is null
java.lang.IllegalArgumentException
- if imageClass
is
not supported by the API implementation or the image according the
properties cannot be generated
VisualTagCodingException
- if encoding of the data fails
java.io.IOException
- if connection has been closed
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