feat: windows image printing for label printer

Author: BigJk

cmd/app/window-direct.go

@@ -12,5 +12,5 @@ import (
 // available printing types. This will only be build
 // and executed on Windows systems.
 func init() {
-	serverOptions = append(serverOptions, server.WithPrinter(&windows.Direct{}))
+	serverOptions = append(serverOptions, server.WithPrinter(&windows.Direct{}), server.WithPrinter(&windows.Image{}))
 }

printing/windows/image.go

@@ -0,0 +1,162 @@
+// Package windows provides printing for Sales & Dungeons
+// via direct printing on windows. The printer commands will
+// be written directly to the printer as raw document.
+package windows
+
+import (
+	"fmt"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/alexbrainman/printer"
+)
+
+type Image struct{}
+
+func (dp *Image) Name() string {
+	return "Windows Image Printing"
+}
+
+func (dp *Image) Description() string {
+	return "Print as image to a attached printer. Use the Name of the printer as endpoint. Can be used for label printing. Make sure to setup the right paper size in the printer driver."
+}
+
+func (dp *Image) AvailableEndpoints() (map[string]string, error) {
+	names, err := printer.ReadNames()
+	if err != nil {
+		return nil, err
+	}
+
+	available := map[string]string{}
+	for i := range names {
+		available[names[i]] = names[i]
+	}
+
+	return available, nil
+}
+
+func printPNGWithPowerShell(imagePath, printerName string) error {
+	imgAbs, err := filepath.Abs(imagePath)
+	if err != nil {
+		return fmt.Errorf("abs image path: %w", err)
+	}
+
+	psScript := `
+param(
+  [Parameter(Mandatory = $true)][string]$ImagePath,
+  [Parameter(Mandatory = $true)][string]$PrinterName
+)
+
+Add-Type -AssemblyName System.Drawing
+
+$img = [System.Drawing.Image]::FromFile($ImagePath)
+$pd = New-Object System.Drawing.Printing.PrintDocument
+$pd.PrinterSettings.PrinterName = $PrinterName
+$pd.OriginAtMargins = $false
+$pd.DefaultPageSettings.Margins = New-Object System.Drawing.Printing.Margins(0,0,0,0)
+$pd.PrintController = New-Object System.Drawing.Printing.StandardPrintController
+
+$pd.add_PrintPage({
+    param($sender, $e)
+
+    $page = $e.PageBounds
+
+    # Image size
+    $iw = [double]$img.Width
+    $ih = [double]$img.Height
+
+    # Page size (device units)
+    $pw = [double]$page.Width
+    $ph = [double]$page.Height
+
+    $scale = $pw / $iw
+    $dw = [int]$pw
+    $dh = [int]([Math]::Round($ih * $scale))
+
+    $dx = $page.X
+    $dy = $page.Y
+
+    $e.Graphics.InterpolationMode = [System.Drawing.Drawing2D.InterpolationMode]::HighQualityBicubic
+    $e.Graphics.PixelOffsetMode   = [System.Drawing.Drawing2D.PixelOffsetMode]::HighQuality
+    $e.Graphics.SmoothingMode     = [System.Drawing.Drawing2D.SmoothingMode]::HighQuality
+    $e.Graphics.CompositingQuality= [System.Drawing.Drawing2D.CompositingQuality]::HighQuality
+
+    $e.Graphics.DrawImage($img, $dx, $dy, $dw, $dh)
+})
+
+try {
+    $pd.Print()
+}
+finally {
+    if ($img) { $img.Dispose() }
+    if ($pd)  { $pd.Dispose() }
+}
+`
+	execPath, err := os.Executable()
+	if err != nil {
+		return fmt.Errorf("get executable path: %w", err)
+	}
+
+	scriptPath := filepath.Join(filepath.Dir(execPath), "print_image.ps1")
+	if err := os.WriteFile(scriptPath, []byte(psScript), 0644); err != nil {
+		return fmt.Errorf("create script file: %w", err)
+	}
+
+	cmd := exec.Command(
+		"powershell.exe",
+		"-NoProfile",
+		"-NonInteractive",
+		"-ExecutionPolicy", "Bypass",
+		"-File", scriptPath,
+		imgAbs,
+		printerName,
+	)
+
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("powershell failed: %v\nOutput:\n%s", err, string(out))
+	}
+
+	return nil
+}
+
+func (dp *Image) Print(printerEndpoint string, img image.Image, data []byte) error {
+	file, err := ioutil.TempFile("", "print_*.png")
+	if err != nil {
+		return err
+	}
+
+	padding := 30
+	bounds := img.Bounds()
+	paddedImg := image.NewRGBA(image.Rect(0, 0, bounds.Dx()+padding*2, bounds.Dy()+padding*2))
+
+	white := color.RGBA{255, 255, 255, 255}
+	for y := 0; y < paddedImg.Bounds().Dy(); y++ {
+		for x := 0; x < paddedImg.Bounds().Dx(); x++ {
+			paddedImg.Set(x, y, white)
+		}
+	}
+
+	draw.Draw(paddedImg, image.Rect(padding, padding, bounds.Dx()+padding, bounds.Dy()+padding), img, bounds.Min, draw.Src)
+
+	defer func() {
+		_ = os.Remove(file.Name())
+	}()
+	defer file.Close()
+
+	if err := png.Encode(file, paddedImg); err != nil {
+		return fmt.Errorf("failed to encode image: %w", err)
+	}
+
+	if err := file.Close(); err != nil {
+		return err
+	}
+
+	return printPNGWithPowerShell(file.Name(), printerEndpoint)
+}