[US-800] Watermark examples.

go.mod

@@ -13,7 +13,7 @@ require (
 	github.com/unidoc/globalsign-dss v0.0.0-20220330092912-b69d85b63736
 	github.com/unidoc/pkcs7 v0.2.0
 	github.com/unidoc/unichart v0.3.0
-	github.com/unidoc/unipdf/v3 v3.62.0
+	github.com/unidoc/unipdf/v3 v3.65.0
 	golang.org/x/crypto v0.31.0
 	golang.org/x/image v0.18.0
 	golang.org/x/text v0.21.0
@@ -50,7 +50,7 @@ require (
 	github.com/unidoc/timestamp v0.0.0-20200412005513-91597fd3793a // indirect
 	github.com/unidoc/unitype v0.4.0 // indirect
 	go.opencensus.io v0.24.0 // indirect
-	golang.org/x/net v0.24.0 // indirect
+	golang.org/x/net v0.33.0 // indirect
 	golang.org/x/oauth2 v0.7.0 // indirect
 	golang.org/x/sys v0.28.0 // indirect
 	golang.org/x/xerrors v0.0.0-20231012003039-104605ab7028 // indirect

go.sum

@@ -128,8 +128,8 @@ github.com/unidoc/timestamp v0.0.0-20200412005513-91597fd3793a h1:RLtvUhe4DsUDl6
 github.com/unidoc/timestamp v0.0.0-20200412005513-91597fd3793a/go.mod h1:j+qMWZVpZFTvDey3zxUkSgPJZEX33tDgU/QIA0IzCUw=
 github.com/unidoc/unichart v0.3.0 h1:VX1j5yzhjrR3f2flC03Yat6/WF3h7Z+DLEvJLoTGhoc=
 github.com/unidoc/unichart v0.3.0/go.mod h1:8JnLNKSOl8yQt1jXewNgYFHhFm5M6/ZiaydncFDpakA=
-github.com/unidoc/unipdf/v3 v3.62.0 h1:CVsxq6k1SSIrprotlFvq6iBhA+5745dWaApB0LKtGcc=
-github.com/unidoc/unipdf/v3 v3.62.0/go.mod h1:0OIzSHHno23Y8WzaK+852abK8d3AxUZ1GQkMqpyCzu8=
+github.com/unidoc/unipdf/v3 v3.65.0 h1:ye3PP9JuUJnQd4BqRR4wJO/EN9EpHRGusMOruDjCS74=
+github.com/unidoc/unipdf/v3 v3.65.0/go.mod h1:tTbloOTKtGGi6z5doJshesDpQYktePhR+7r+WGCkooU=
 github.com/unidoc/unitype v0.4.0 h1:/TMZ3wgwfWWX64mU5x2O9no9UmoBqYCB089LYYqHyQQ=
 github.com/unidoc/unitype v0.4.0/go.mod h1:HV5zuUeqMKA4QgYQq3KDlJY/P96XF90BQB+6czK6LVA=
 go.opencensus.io v0.24.0 h1:y73uSU6J157QMP2kn2r30vwW1A2W2WFwSCGnAVxeaD0=
@@ -153,8 +153,8 @@ golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn
 golang.org/x/net v0.0.0-20190603091049-60506f45cf65/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
 golang.org/x/net v0.0.0-20201110031124-69a78807bb2b/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
-golang.org/x/net v0.24.0 h1:1PcaxkF854Fu3+lvBIx5SYn9wRlBzzcnHZSiaFFAb0w=
-golang.org/x/net v0.24.0/go.mod h1:2Q7sJY5mzlzWjKtYUEXSlBWCdyaioyXzRB2RtU8KVE8=
+golang.org/x/net v0.33.0 h1:74SYHlV8BIgHIFC/LrYkOGIwL19eTYXQ5wc6TBuO36I=
+golang.org/x/net v0.33.0/go.mod h1:HXLR5J+9DxmrqMwG9qjGCxZ+zKXxBru04zlTvWlWuN4=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.7.0 h1:qe6s0zUXlPX80/dITx3440hWZ7GwMwgDDyrSGTPJG/g=
 golang.org/x/oauth2 v0.7.0/go.mod h1:hPLQkd9LyjfXTiRohC/41GhcFqxisoUQ99sCUOHO9x4=

image/README.md

@@ -9,4 +9,5 @@ Having the ability to play around with images allows for the creation of attract
 - [pdf_images_to_pdf.go](pdf_images_to_pdf.go) explains how to add multiple images in a PDF document, one image per page. 
 - [pdf_list_images.go](pdf_list_images.go) explains how to list images in a PDF file. Passes through each page, goes through the content stream and finds instances of both. XObject Images and inline images. Also handles images referred within XObject Form content streams.
 - [pdf_watermark_image.go](pdf_watermark_image.go) explains how to add watermark image to each page of a PDF file.
+- [pdf_remove_watermark_image.go](pdf_remove_watermark_image.go) explains how to remove watermark image from a PDF file.
 - Image extraction example can be found in [../extract](extract) example subfolder.

image/pdf_remove_watermark_image.go

@@ -0,0 +1,81 @@
+/*
+ * Remove watermark image to each page of a PDF file.
+ *
+ * Run as: go run pdf_remove_watermark_image.go input.pdf output.pdf
+ */
+
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/unidoc/unipdf/v3/common/license"
+	"github.com/unidoc/unipdf/v3/model"
+)
+
+func init() {
+	// Make sure to load your metered License API key prior to using the library.
+	// If you need a key, you can sign up and create a free one at https://cloud.unidoc.io
+	err := license.SetMeteredKey(os.Getenv(`UNIDOC_LICENSE_API_KEY`))
+	if err != nil {
+		panic(err)
+	}
+}
+
+func main() {
+	if len(os.Args) < 3 {
+		fmt.Printf("go run pdf_remove_watermark_image.go input.pdf output.pdf\n")
+		os.Exit(1)
+	}
+
+	inputPath := os.Args[1]
+	outputPath := os.Args[2]
+
+	pdfReader, f, err := model.NewPdfReaderFromFile(inputPath, nil)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+	defer f.Close()
+
+	numPages, err := pdfReader.GetNumPages()
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	for i := 0; i < numPages; i++ {
+		pageNum := i + 1
+
+		// Read the page.
+		page, err := pdfReader.GetPage(pageNum)
+		if err != nil {
+			fmt.Printf("Error: %v\n", err)
+			os.Exit(1)
+		}
+
+		// For watermarks applied by Adobe, just pass nil as argument.
+		// For custom watermarks use pdf_list_images.go to figure out the name of watermark object.
+		err = page.RemoveWatermarkImage("Img1")
+		if err != nil {
+			fmt.Printf("Error: %v\n", err)
+			os.Exit(1)
+		}
+	}
+
+	// Generate a PDFWriter from PDFReader.
+	pdfWriter, err := pdfReader.ToWriter(nil)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	err = pdfWriter.WriteToFile(outputPath)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Printf("Complete, see output file: %s\n", outputPath)
+}

image/pdf_watermark_image.go

@@ -8,11 +8,11 @@ package main
 
 import (
 	"fmt"
+	"image"
 	"os"
 
 	"github.com/unidoc/unipdf/v3/common"
 	"github.com/unidoc/unipdf/v3/common/license"
-	"github.com/unidoc/unipdf/v3/creator"
 	"github.com/unidoc/unipdf/v3/model"
 )
 
@@ -49,13 +49,25 @@ func addWatermarkImage(inputPath string, outputPath string, watermarkPath string
 	common.Log.Debug("Input PDF: %v", inputPath)
 	common.Log.Debug("Watermark image: %s", watermarkPath)
 
-	c := creator.New()
+	// Create the watermark image from file.
+	wImgFile, err := os.Open(watermarkPath)
+	if err != nil {
+		return err
+	}
+	defer wImgFile.Close()
+
+	watermarkImg, _, err := image.Decode(wImgFile)
+	if err != nil {
+		return err
+	}
 
-	watermarkImg, err := c.NewImageFromFile(watermarkPath)
+	image, err := model.DefaultImageHandler{}.NewImageFromGoImage(watermarkImg)
 	if err != nil {
 		return err
 	}
 
+	xImage, err := model.NewXObjectImageFromImage(image, nil, nil)
+
 	// Read the input pdf file.
 	f, err := os.Open(inputPath)
 	if err != nil {
@@ -82,21 +94,19 @@ func addWatermarkImage(inputPath string, outputPath string, watermarkPath string
 			return err
 		}
 
-		// Add to creator.
-		c.AddPage(page)
-
-		watermarkImg.ScaleToWidth(c.Context().PageWidth)
-		watermarkImg.SetPos(0, (c.Context().PageHeight-watermarkImg.Height())/2)
-		watermarkImg.SetOpacity(0.5)
-		_ = c.Draw(watermarkImg)
+		// Add watermark with options.
+		page.AddWatermarkImage(xImage, model.WatermarkImageOptions{Alpha: 0.5, FitToWidth: true})
 	}
 
-	// Add reader outline tree to the creator.
-	c.SetOutlineTree(pdfReader.GetOutlineTree())
-
-	// Add reader AcroForm to the creator.
-	c.SetForms(pdfReader.AcroForm)
+	// Generate a PDFWriter from PDFReader.
+	pdfWriter, err := pdfReader.ToWriter(nil)
+	if err != nil {
+		return err
+	}
 
-	err = c.WriteToFile(outputPath)
-	return err
+	err = pdfWriter.WriteToFile(outputPath)
+	if err != nil {
+		return err
+	}
+	return nil
 }