go-catprinter/lib.go

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2024-09-10 20:45:30 +00:00
package catprinter
import (
"github.com/disintegration/imaging"
"github.com/go-ble/ble"
"github.com/go-ble/ble/examples/lib/dev"
"github.com/pkg/errors"
"image"
"log"
"os"
"time"
)
var (
ErrPrinterNotFound = errors.New("unable to find printer, make sure it is turned on and in range")
ErrMissingCharacteristic = errors.New("missing characteristic, make sure the MAC is correct and the printer is supported")
ErrNotBlackWhite = errors.New("image must be black and white (NOT only grayscale)")
ErrInvalidImageSize = errors.New("image must be 384px wide")
)
// Client contains information for the connection to the printer and debugging options.
type Client struct {
device ble.Device
printer ble.Client
characteristic *ble.Characteristic
chunkSize int
Timeout time.Duration
Debug struct {
Log bool // print logs to terminal
DumpRequest bool // saves last data sent to printer to ./request.bin
DumpImage bool // saves formatted image to ./image.png
DontPrint bool // if true, the image is not actually printed. saves paper during testing.
}
}
// NewClient initiates a new client with sane defaults
func NewClient() (*Client, error) {
d, err := dev.DefaultDevice()
if err != nil {
return nil, errors.Wrap(err, "can't create device, superuser permissions might be needed")
}
return NewClientFromDevice(d)
}
// NewClientFromDevice initiates a new client with a custom ble.Device and sane defaults
func NewClientFromDevice(d ble.Device) (*Client, error) {
var c = &Client{}
ble.SetDefaultDevice(d)
c.device = d
c.Timeout = scanTimeout
return c, nil
}
// Stop closes any active connection to a printer and detaches the GATT server
func (c *Client) Stop() error {
if err := c.Disconnect(); err != nil {
return errors.Wrap(err, "can't disconnect printer")
}
return c.device.Stop()
}
// Disconnect closes any active connection to a printer
func (c *Client) Disconnect() error {
if c.printer != nil {
if err := c.printer.CancelConnection(); err != nil {
return err
}
c.printer = nil
}
return nil
}
// Print prints an image to the connected printer. It also formats it and dithers if specified by opts and isAlreadyFormatted.
// Only set isAlreadyFormatted to true if the image is in black and white (NOT ONLY grayscale) and 384px wide.
func (c *Client) Print(img image.Image, opts *PrinterOptions, isAlreadyFormatted bool) error {
if !isAlreadyFormatted {
img = c.FormatImage(img, opts)
}
fmtImg, err := convertImageToBytes(img)
if err != nil {
return err
}
if opts.bestQuality {
fmtImg = commandsPrintImg(fmtImg)
} else {
fmtImg = weakCommandsPrintImg(fmtImg)
}
if c.Debug.DumpRequest {
err = os.WriteFile("./request.bin", fmtImg, 0644)
if err != nil {
log.Println("failed to save debugging request dump", err.Error())
}
}
if c.Debug.DontPrint {
log.Println("image will not be printed as Client.Debug.DontPrint is true")
return nil
}
return c.writeData(fmtImg)
}
// PrintFile dithers, formats and prints an image by path to the connected printer
func (c *Client) PrintFile(path string, opts *PrinterOptions) error {
img, err := imaging.Open(path)
if err != nil {
return err
}
return c.Print(img, opts, false)
}
func (c *Client) log(format string, a ...any) {
if !c.Debug.Log {
return
}
log.Printf(format, a...)
}