Merge pull request #265 from kellemNegasi/us-833-text-watermark-example

[US-856] Example for Text Watermark

Author: anovik

text/Roboto-Regular.ttf

@@ -0,0 +1,82 @@
+/*
+ * An example of adding text watermark to pdf pages.
+ *
+ * Run as: go run pdf_add_text_watermark.go <input.pdf> <watermark text> <output.pdf>
+ */
+package main
+
+import (
+	"fmt"
+	"image/color"
+	"os"
+
+	"github.com/unidoc/unipdf/v3/common/license"
+	"github.com/unidoc/unipdf/v3/creator"
+	"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) < 4 {
+		fmt.Printf("Usage: go run pdf_add_text_watermark.go input.pdf watermark output.pdf\n")
+		os.Exit(1)
+	}
+
+	inputPath := os.Args[1]
+	watermark := os.Args[2]
+	outputPath := os.Args[3]
+
+	file, err := os.Open(inputPath)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+	defer file.Close()
+
+	pdfReader, err := model.NewPdfReader(file)
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	c := creator.New()
+
+	totalPageNumb, err := pdfReader.GetNumPages()
+	if err != nil {
+		fmt.Printf("Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	for i := 1; i <= totalPageNumb; i++ {
+		page, err := pdfReader.GetPage(i)
+		if err != nil {
+			fmt.Printf("Error: failed to get page %d. %v\n", i, err)
+			os.Exit(1)
+		}
+		options := model.WatermarkTextOptions{
+			Alpha:     0.3,
+			FontSize:  40,
+			FontPath:  "Roboto-Regular.ttf",
+			FontColor: color.RGBA{R: 255, G: 0, B: 0, A: 1},
+			Angle:     30,
+		}
+
+		err = page.AddWatermarkText(watermark, options)
+		if err != nil {
+			fmt.Printf("Error: failed to add watermark on page %d. %v\n", i, err)
+		}
+
+		c.AddPage(page)
+	}
+
+	c.WriteToFile(outputPath)
+	fmt.Print("Watermark added successfully.\n")
+}