Updating printers while application is running?

[Philip Race]

On 6/8/22 11:34 AM, Tobias Oelgarte wrote:
>
> I don't know if there is an common event available in the Java2D 
> backend to detect added/removed printers directly. So far i could not 
> see anything like that.
>

I am referring to windows native code we have in Java 2D.
It is completely invisible at the API level of Java 2D.

> Every PrintService instance should implement the equals() [1] method 
> to determine uniqueness. This could be used to compare/intersect the 
> observable set of printers hold by 
> javafx.print.Printer#getAllPrinters() against the array of 
> PrintService instances exposed by 
> PrintServiceLookup.getPrintServices(...). That way it should be 
> possible to detect if a printer was removed or added. It could also be 
> used to update the default printer property (on access and/or 
> periodically).
>

Well yes, there's got to be a comparison.  No one said "I don't know 
what to do here" ..


-phil.

> [1] 
> https://docs.oracle.com/en/java/javase/18/docs/api/java.desktop/javax/print/PrintService.html#equals(java.lang.Object)
>
> On 07.06.22 21:44, Philip Race wrote:
>> Ahem .. well .. I guess we (I) forgot to get back to that.
>>
>> Since the current implementation on Windows wraps the Java 2D 
>> printing code
>> and it registers with windows to be told about changes in printers 
>> then the
>> calls being made in the method with that comment would (well, should) 
>> provide
>> the updated printers ..
>>
>> The comment was (I think) referring to the need to know when there 
>> was actually
>> a change there to avoid perpetual re-creation.
>>
>> If the 2D side is working as expected I'll see if there's something I 
>> can do along the lines
>> of a quick check every time that the number of underlying printers is 
>> the same and then if not it is worthwhile,
>> coupled with a refresh every 2 minutes so it should never get too stale.
>>
>> -phil.
>>
>> On 6/7/22 11:39 AM, Tobias Oelgarte wrote:
>>> Is there some way to update the ObservableSet of Printers once the 
>>> Application is running? Calling Printer.getAllPrinters() always 
>>> returns the same OberservableSet and it does not change - ever. [1]
>>>
>>> We have an JavaFx based application running under Windows 10/11 that 
>>> is used to print on wireless printers, that are not always 
>>> available. Having to restart the the application every time a 
>>> printer goes away or comes available is a serious pain for the users.
>>>
>>> Is there any kind of workaround?
>>>
>>> I doubt it will be fixed in the near future, since this comment is 
>>> from 6 years ago [2]:
>>>
>>>     // This is static. Eventually I want it to be dynamic, but first
>>>     // it needs to be enhanced to only create new instances where
>>>     // there really has been a change, which will be rare.
>>>
>>> [1] 
>>> https://stackoverflow.com/questions/38470568/javafx-doesnt-detect-changes-of-available-printers
>>>
>>> [2] 
>>> https://github.com/openjdk/jfx/blob/master/modules/javafx.graphics/src/main/java/com/sun/prism/j2d/PrismPrintPipeline.java#L99
>>