Adding Get Printer Type #2

NewtonRocha · 2017-09-12T17:59:51Z

On windows we have printers that only accept XPS, that function identify that

alexbrainman

Some general comments first.

Alex

alexbrainman · 2017-09-13T00:16:07Z

printer.go

+	return GetPrinterType(printerName)
+}
+
+func GetPrinterType(printerName string) (string, error) {


Instead of creating package function, I suggest, you add new method to Printer struct. This way new method will not need printerName parameter. You will also not need GetFeaultPrinterType function, because you could use printer.Default.... instead.

That is a nice a idea !

alexbrainman · 2017-09-13T00:48:03Z

printer.go

+	return GetPrinterType(printerName)
+}
+
+func GetPrinterType(printerName string) (string, error) {


Maybe instead of returning sting, this function should return more info. Maybe create

type DriverInfo struct { ... Attributes uint32 }

, then you could do:

di, err := myprinter.DriverInfo() if err != nil { ... } if di.Attributes&PRINTER_DRIVER_XPS != 0 { ... }

We could start DriverInfo struct just with Attributes field and add more fields later as needed.

Ok, i made the Driver info with driver name, enviroment and driver path

alexbrainman · 2017-09-13T00:50:45Z

printer.go

+}
+
+func GetPrinterType(printerName string) (string, error) {
+	b := make([]byte, 1024*10)


Why 10K? How large this data is (from your own experiment)? Maybe start with that instead.

Yes, is from my experiment, in my experiment the struct has 6k from a thermal printer with generic driver from windows

alexbrainman · 2017-09-13T00:58:01Z

zapi.go

@@ -33,6 +36,25 @@ func GetDefaultPrinter(buf *uint16, bufN *uint32) (err error) {
 	return
 }

+func GetPrinterDriver(name string, buf *byte, bufN uint32) (err error) {


This file is generated by running "go generate" command. Do not change it manually. This file contains all Windows API, so instead of

func GetPrinterDriver(name string, buf *byte, bufN uint32) (err error)

you want

func GetPrinterDriver(h syscall.Handle, env *uint16, level uint32, di *byte, n uint32, needed *uint32) (err error)

So if you add

//sys GetPrinterDriver(h syscall.Handle, env *uint16, level uint32, di *byte, n uint32, needed *uint32) (err error) = winspool.GetPrinterDriver

and then run "go generate" command, you will get what you want.

I dont know that ! i made the change and generate the code know !

alexbrainman

Looking better.

Thank you.

Alex

alexbrainman · 2017-09-13T08:31:17Z

printer.go

@@ -74,6 +75,21 @@ const (
 //sys	StartPagePrinter(h syscall.Handle) (err error) = winspool.StartPagePrinter
 //sys	EndPagePrinter(h syscall.Handle) (err error) = winspool.EndPagePrinter
 //sys	EnumPrinters(flags uint32, name *uint16, level uint32, buf *byte, bufN uint32, needed *uint32, returned *uint32) (err error) = winspool.EnumPrintersW
+//sys   GetPrinterDriver(h syscall.Handle, env *uint16, level uint32, di *byte, n uint32, needed *uint32) (err error) = winspool.GetPrinterDriverW
+
+func convertLPTSTRToString(ptr *uint16) string {


You don't need to implement that function, because it already exists. Search for syscall.UTF16ToString in net package - it will show how to do that.

alexbrainman · 2017-09-13T08:36:31Z

printer.go

+	}
+	di := (*DRIVER_INFO_8)(unsafe.Pointer(&b[0]))
+
+	ndi := newDriverInfo(di)


You can just:

return &DriverInfo{ Name: ..., ... }, nil

and you won't need newDriverInfo function.

alexbrainman · 2017-09-13T08:36:58Z

printer.go

@@ -161,6 +164,42 @@ func Open(name string) (*Printer, error) {
 	return &p, nil
 }

+func (p *Printer) DriverInfo() (*DriverInfo, error) {


New function needs documentation.

alexbrainman · 2017-09-13T08:40:24Z

printer.go

+	return ndi, nil
+}
+
+func (p *Printer) PrintDataType() (string, error) {


Please, remove this function. The name does not explain what it does, and it is simple enough to be implemented in couple of lines of code.

alexbrainman · 2017-09-13T08:45:09Z

printer.go

+	n := uint32(len(b))
+	var needed uint32
+	var env uint16 = 0
+	err := GetPrinterDriver(p.h, &env, 8, &b[0], n, &needed)


Why are you using &env and not nil here? &end points to empty environment, while nil is default for "the current environment of the calling application and client machine". Which do we want here?

alexbrainman · 2017-09-13T09:17:42Z

cmd/print/print.go

+		return err
+	}
+
+	err = p.StartDocument(documentName, dataType)


I suspect you had some problem with this code always passing "RAW" to StartDocument. What is the problem? How can I reproduce it? Can you create an issue about this problem and make this PR fix the problem?

The problem is: i had a printer that doesnt accept RAW datatype, the problem is that print only accepts XPS documents.

But what is the data that you need to write to the printer when you pass "XPS_PASS" to it? Can I send text data? Will it print properly? Does every printer that reports PRINTER_DRIVER_XPS will work with "XPS_PASS"? Are there any references to all of this somewhere on the Internet?

Maybe we could just introduce another flag for the program that describes data type, and default it to "RAW" instead?

Normal string data, you can send normal text, its print properly, the driver do the work, and Yes every printer with PRINTER_DRIVER_XPS will work with XPS_PASS

And yes, we can do other flag for program to describe data type and set RAW as default

Thank you for explaining. I will wait for you to address my other comments now.

Alex

alexbrainman · 2017-09-13T09:18:50Z

cmd/print/print.go

@@ -41,6 +41,7 @@ func listPrinters() error {
 	if err != nil {
 		return err
 	}
+


Remove blank line. Unrelated to your change.

alexbrainman · 2017-09-13T09:20:19Z

printer.go

 	"unsafe"
 )

+const (
+	PRINTER_DRIVER_XPS uint32 = 0x00000002


s/PRINTER_DRIVER_XPS uint32/PRINTER_DRIVER_XPS/

make PRINTER_DRIVER_XPS untyped. Untyped consts fit anything.

alexbrainman · 2017-09-13T09:21:54Z

printer.go

 	"unsafe"
 )

+const (
+	PRINTER_DRIVER_XPS uint32 = 0x00000002


Maybe add PRINTER_DRIVER_PACKAGE_AWARE and others.

alexbrainman · 2017-09-13T09:23:19Z

printer.go

+const (
+	PRINTER_DRIVER_XPS uint32 = 0x00000002
+	RAW                       = "RAW"
+	XPS_PASS                  = "XPS_PASS"


Delete both RAW and XPS_PASS. Users won't need them.

NewtonRocha · 2017-10-16T12:55:39Z

Sorry for delay, i was very busy with my work those days, i will respond yours comments late today @alexbrainman

alexbrainman · 2017-10-18T00:08:51Z

Sorry for delay, i was very busy with my work those days, i will respond yours comments late today

No worries. Take as long as you like.

Alex

alexbrainman · 2018-04-21T08:04:07Z

@NewtonRocha I could not wait for you to make your changes, so copied and adjusted your code. Feel free to comment here https://github.com/alexbrainman/printer/tree/fix1

Thank you.

Alex

Adding Get Printer Type

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alexbrainman reviewed Sep 13, 2017

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alexbrainman mentioned this pull request Jan 20, 2018

any "hello world" for it? #3

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Adding Get Printer Type #2

Adding Get Printer Type #2

NewtonRocha commented Sep 12, 2017 •

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Adding Get Printer Type #2

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Adding Get Printer Type #2

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NewtonRocha commented Oct 16, 2017

alexbrainman commented Oct 18, 2017

alexbrainman commented Apr 21, 2018

NewtonRocha commented Sep 12, 2017 •

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