Using cputil

Decoding Star ASB Status

Star CloudPRNT devices will report their status in Star ASB format, as a string of 7 or more hexadecimal values. For Example:

"23 86 00 00 00 00 00 00 00 00 00"

This is not easy to decode in all languages, so cputil provides a method to convert this into JSON format data, e.g.:

cputil jsonstatus "23 86 00 00 00 00 00 00 00 00 00"

will generate the output:

{
  "Online": true,
  "CoverOpen": false,
  "CompulsionSwitch": false,
  "OverTemperature": false,
  "Recoverable": true,
  "CutterError": false,
  "MechanicalError": false,
  "ReceiveBufferOverflow": false,
  "BlackMarkError": false,
  "PresenterPaperJam": false,
  "VoltageError": false,
  "PaperEmpty": false,
  "PaperLow": false
}

Handling Print Job media formats

Cputil can help with key parts of the CloudPRNT printing process. A server can prepare a print job in a single input format, which may not be natively supported by the CloudPRNT client device. The server can then use cputil to convert the job, as needed to a format that the CloudPRNT client does support.

Supported input print job media formats are:

Images
- PNG - image/png
- JPEG - image/jpeg
- BMP - image/bmp
- GIF - image/gif
Plain Text - text/plain
Star Document Markup - text/vnd.star.markup

A JSON formatted list of supported input data formats can also be requested from cputil directly, using the supportedinputs option:

cputil supportedinputs

would generate output:

[
  "text/plain",
  "text/vnd.star.markup",
  "image/png",
  "image/jpeg",
  "image/bmp",
  "image/gif"
]

Discovering the possible output formats

Each input document can be converted to various output formats. The exact list of possible outputs will vary from one input type to another. Each input format can be converted to at least one output that is supported by each current Star CloudPRNT device. This guarantees that your server will be able to print to any target device when using cputil, regardless of the printer.

When a CloudPRNT compatible server has a print job ready for a particular client (typically a Star mC-Print2, mC-Print3 or printer with HI0x interface card), the it must:

wait for a poll request from the client (a JSON request sent by HTTP POST)
reply to the client with a suitable JSON response, with at least the fields:
- jobReady set to true.
- mediaTypes an array of media type names in which the job can be provided to the client.

For example:

{
  "jobReady": true,
  "mediaTypes": ["image/jpeg", "image/png"]
}

At this point in the job printing negotiation, cputil can be used to prepare the mediaTypes list, based on the input format that the server plans to use.

For example, for a server that will use a PNG image as the initial print job source, use (where sourceimage.png is the name of the input file):

cputil mediatypes sourceimage.png

which will generate the JSON ready output:

["application/vnd.star.raster","application/vnd.star.line","application/vnd.star.starprnt","application/vnd.star.starprntcore", "image/png","image/jpeg"]

Alternatively, if the server has not yet prepared the print job data, or does not store it as a local file, then the mediatypes-mime option can be used instead, to generate a list of possible outputs, based on the input type (instead of the actual input file).

cputil mediatypes-mime image/png

will generate the JSON ready output:

["application/vnd.star.raster","application/vnd.star.line","application/vnd.star.starprnt","application/vnd.star.starprntcore", "image/png","image/jpeg"]

Converting a job for printing

After a server has provided a JSON response to the CloudPRNT poll with the jobReady field set to true, and a valid mediaTypes list, the client will recognize that it is there is a job for it to print. it will perform the following steps:

select its preferred mediaType, from those available in the list. This is typically selected based on the first format in the list which is supported by the client. However, the exact decision can be client specific.
perform an HTTP GET to the CloudPRNT server to retrieve the job, specifying the chosen mediaType through a query string parameter.

When the server receives the HTTP GET, it should return the job to be printer encoded with the requested media type.

Servers can prepare the job in a single, internally preferred format and then use cputil to convert it to the requested format.

For example, if a server has prepared a print job as PNG data, and the client requests it as StarPRNT printer command data (application/vnd.star.starprnt) then cputil can be used:

cputil decode application/vnd.star.starprnt sourceimage.png outputdata.bin

Which will convert the PNG input file into printer command data stored in "outputdata.bin". If it is more convenient to write the output data to standard output, then use either "-" or "[stdout]" as the output file name.

Conversion options

Conversion can include image scaling, cropping and dithering. For scaling and cropping to work, it is necessary to inform cputil of the printer print width. CloudPRNT servers can obtain this information through the CloudPRNT clientAction "PageInfo" request. Conversion options should be specified on the command line before the convert option.

To specify the print area size, use one of the following options:

thermal2 or thermal58 - set the print area to that of a 2inch/58mm printer, such as the mC-Print2.
thermal3 or thermal80 - set the print area to that of a 3inch/80mm printer, such as a TSP650II or mC-Print3.
thermal4 or thermal112 - set the print area to that of a 4inch/112mm printer, such as the Star TSP800II.

To specify dithering, use the dither option. To specify that the image should be scaled to fit the print area, use the scale-to-fit option. Otherwise the image will not be scaled, but cropped if it is wider than the print area.

For example, to prepare print data as StarPRNT commands for a 2inch printer from a PNG source, with dithering and the image scaled to fit the page:

cputil thermal2 dither scale-to-fit decode application/vnd.star.starprnt sourceimage.png outputdata.bin