From 89fc9d86c727aa8dc80232b461a7903a3c16d10e Mon Sep 17 00:00:00 2001 From: Přemysl Janouch Date: Fri, 12 Apr 2019 23:10:42 +0200 Subject: Cleanup, improve communication while printing --- ql/ql_linux.go | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 212 insertions(+) create mode 100644 ql/ql_linux.go (limited to 'ql/ql_linux.go') diff --git a/ql/ql_linux.go b/ql/ql_linux.go new file mode 100644 index 0000000..1b1f22c --- /dev/null +++ b/ql/ql_linux.go @@ -0,0 +1,212 @@ +package ql + +import ( + "errors" + "image" + "io" + "os" + "path/filepath" + "syscall" + "time" + "unsafe" +) + +// #include +import "C" + +// ----------------------------------------------------------------------------- + +func _IOC(dir, typ, nr, size int) uintptr { + return (uintptr(dir) << C._IOC_DIRSHIFT) | + (uintptr(typ) << C._IOC_TYPESHIFT) | + (uintptr(nr) << C._IOC_NRSHIFT) | + (uintptr(size) << C._IOC_SIZESHIFT) +} + +const ( + iocnrGetDeviceID = 1 +) + +// lpiocGetDeviceID reads the IEEE-1284 Device ID string of a printer. +func lpiocGetDeviceID(fd uintptr) ([]byte, error) { + var buf [1024]byte + if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, + _IOC(C._IOC_READ, 'P', iocnrGetDeviceID, len(buf)), + uintptr(unsafe.Pointer(&buf))); err != 0 { + return nil, err + } + + // In theory it might get trimmed along the way. + length := int(buf[0])<<8 | int(buf[1]) + if 2+length > len(buf) { + return buf[2:], errors.New("the device ID string got trimmed") + } + + return buf[2 : 2+length], nil +} + +// ----------------------------------------------------------------------------- + +type Printer struct { + File *os.File + Manufacturer string + Model string + + LastStatus *Status + MediaInfo *MediaInfo + + // StatusNotify is called whenever we receive a status packet. + StatusNotify func(*Status) +} + +// Open finds and initializes the first USB printer found supporting +// the appropriate protocol. Returns nil if no printer could be found. +func Open() (*Printer, error) { + // Linux usblp module, located in /drivers/usb/class/usblp.c + paths, err := filepath.Glob("/dev/usb/lp[0-9]*") + if err != nil { + return nil, err + } + for _, candidate := range paths { + f, err := os.OpenFile(candidate, os.O_RDWR, 0) + if err != nil { + continue + } + // Filter out obvious non-printers. + deviceID, err := lpiocGetDeviceID(f.Fd()) + if err != nil { + f.Close() + continue + } + parsedID := parseIEEE1284DeviceID(deviceID) + // Filter out printers that wouldn't understand the protocol. + if !compatible(parsedID) { + f.Close() + continue + } + return &Printer{ + File: f, + Manufacturer: parsedID.FindFirst("MANUFACTURER", "MFG"), + Model: parsedID.FindFirst("MODEL", "MDL"), + }, nil + } + return nil, nil +} + +// Initialize initializes the printer for further operations. +func (p *Printer) Initialize() error { + // Clear the print buffer. + invalidate := make([]byte, 400) + if _, err := p.File.Write(invalidate); err != nil { + return err + } + + // Initialize. + if _, err := p.File.WriteString("\x1b\x40"); err != nil { + return err + } + + // Flush any former responses in the printer's queue. + // + // I'm not sure if this is necessary, or rather whether the kernel driver + // does any buffering that could cause data to be returned at this point. + /* + var dummy [32]byte + for { + if _, err := f.Read(dummy[:]); err == io.EOF { + break + } + } + */ + + return nil +} + +var errTimeout = errors.New("timeout") +var errInvalidRead = errors.New("invalid read") + +func (p *Printer) updateStatus(status Status) { + p.LastStatus = &status + if p.StatusNotify != nil { + p.StatusNotify(p.LastStatus) + } +} + +// pollStatusBytes waits for the printer to send a status packet and returns +// it as raw data. +func (p *Printer) pollStatusBytes( + timeout time.Duration) (*Status, error) { + start, buf := time.Now(), [32]byte{} + for { + if n, err := p.File.Read(buf[:]); err == io.EOF { + time.Sleep(10 * time.Millisecond) + } else if err != nil { + return nil, err + } else if n < 32 { + return nil, errInvalidRead + } else { + p.updateStatus(Status(buf)) + return p.LastStatus, nil + } + if time.Now().Sub(start) > timeout { + return nil, errTimeout + } + } +} + +// Request new status information from the printer. The printer +// must be in an appropriate mode, i.e. on-line and not currently printing. +func (p *Printer) UpdateStatus() error { + // Request status information. + if _, err := p.File.WriteString("\x1b\x69\x53"); err != nil { + return err + } + + // Retrieve status information. + if _, err := p.pollStatusBytes(time.Second); err != nil { + p.LastStatus = nil + return err + } + return nil +} + +var errErrorOccurred = errors.New("error occurred") +var errUnexpectedStatus = errors.New("unexpected status") +var errUnknownMedia = errors.New("unknown media") + +func (p *Printer) Print(image image.Image) error { + data := makePrintData(p.LastStatus, image) + if data == nil { + return errUnknownMedia + } + if _, err := p.File.Write(data); err != nil { + return err + } + + // See diagrams: we may receive an error status instead of the transition + // to the printing state. Or even after it. + // + // Not sure how exactly cooling behaves and I don't want to test it. + for { + status, err := p.pollStatusBytes(10 * time.Second) + if err != nil { + return err + } + + switch status.Type() { + case StatusTypePhaseChange: + // Nothing to do. + case StatusTypePrintingCompleted: + return nil + case StatusTypeErrorOccurred: + return errErrorOccurred + default: + return errUnexpectedStatus + } + } +} + +// Close closes the underlying file. +func (p *Printer) Close() error { + return p.File.Close() +} -- cgit v1.2.3-54-g00ecf