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sampilasampila
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Merge pull request #292 from 3ace/us-1113-doc-tag
[US-1113] Add document tagging code examples
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‎accessibility/README.md‎

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@@ -4,6 +4,12 @@ The examples in this section are showcasing how to work with accessibility featu
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## Examples
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- [pdf_add_image_alt_text.go](pdf_add_image_alt_text.go) showcases how to constuct a `StructTreeRoot` object and add alternate text for images.
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- [pdf_add_image_alt_text.go](pdf_add_image_alt_text.go) showcases how to construct a `StructTreeRoot` object and add alternate text for images.
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- [pdf_copy_page_with_accessibility.go](pdf_copy_page_with_accessibility.go) demonstrates how to copy pages from an existing PDF file to a new PDF file and preserve the structure tree information.
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- [pdf_set_language_identifier.go](pdf_set_language_identifier.go) demonstrates how to set the language identifier for the document and its content.
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- [pdf_copy_page_with_accessibility.go](pdf_copy_page_with_accessibility.go) demonstrates how to copy pages from an existing PDF file to a new PDF file and preserve the structure tree information.
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- [pdf_tag_annots.go](pdf_tag_annots.go) demonstrates how to create a PDF with text annotations that are properly tagged in the document structure tree for accessibility compliance.
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- [pdf_tag_form.go](pdf_tag_form.go) demonstrates how to create a PDF with form fields (text fields, submit and reset buttons) that are properly tagged in the document structure tree for accessibility compliance.
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- [pdf_tag_grid.go](pdf_tag_grid.go) demonstrates how to create a tagged PDF with a grid (table) that is properly tagged in the document structure tree for accessibility compliance.
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- [pdf_tag_link_annot.go](pdf_tag_link_annot.go) demonstrates how to create accessible links in PDF documents following best practices for PDF/UA compliance.
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- [pdf_tag_list.go](pdf_tag_list.go) demonstrates how to create a tagged PDF document with nested lists using proper accessibility tags and document structure tree.
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- [pdf_tag_table.go](pdf_tag_table.go) demonstrates how to create a tagged PDF with a table that includes proper tagging structure for accessibility compliance.

‎accessibility/pdf_tag_annots.go‎

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// This example demonstrates how to create a PDF with text annotations
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// using the UniPDF library. The PDF will contain multiple text annotations
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// with different properties, and the annotations will be properly tagged
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// in the document structure tree for accessibility compliance.
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//
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package main
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import (
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"fmt"
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"os"
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"github.com/unidoc/unipdf/v4/common/license"
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"github.com/unidoc/unipdf/v4/core"
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"github.com/unidoc/unipdf/v4/creator"
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"github.com/unidoc/unipdf/v4/model"
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)
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func init() {
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// Make sure to load your metered License API key prior to using the library.
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// If you need a key, you can sign up and create a free one at https://cloud.unidoc.io
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err := license.SetMeteredKey(os.Getenv(`UNIDOC_LICENSE_API_KEY`))
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if err != nil {
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panic(err)
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}
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}
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func main() {
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outputPath := "pdf_tag_annots.pdf"
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err := createPdfWithTextAnnotations(outputPath)
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if err != nil {
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fmt.Printf("Error: %v\n", err)
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os.Exit(1)
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}
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fmt.Printf("Complete, see output file: %s\n", outputPath)
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}
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// Create a new PDF with text annotations.
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func createPdfWithTextAnnotations(outputPath string) error {
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// Create a new Creator.
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c := creator.New()
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// Construct the StructTreeRoot.
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str := model.NewStructTreeRoot()
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// Construct base K dictionary.
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docK := model.NewKDictionary()
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docK.S = core.MakeName(string(model.StructureTypeDocument))
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str.AddKDict(docK)
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// Create a new page with standard letter size.
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page := model.NewPdfPage()
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mediaBox := core.MakeArrayFromFloats([]float64{0, 0, 612, 792})
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mediaRect, err := model.NewPdfRectangle(*mediaBox)
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if err != nil {
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return fmt.Errorf("failed to create MediaBox rectangle: %w", err)
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}
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page.MediaBox = mediaRect
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// Add first text annotation.
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textAnnotation1 := model.NewPdfAnnotationText()
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textAnnotation1.Contents = core.MakeString("This is a sample text annotation!")
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textAnnotation1.Rect = core.MakeArray(
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core.MakeInteger(100), // x1
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core.MakeInteger(600), // y1 (from bottom of page)
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core.MakeInteger(150), // x2 (x1 + width)
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core.MakeInteger(650), // y2 (y1 + height)
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)
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// Set annotation properties.
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textAnnotation1.Open = core.MakeBool(false) // Closed by default
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textAnnotation1.Name = core.MakeName("Comment")
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docK.AddKChild(textAnnotation1.GenerateKDict())
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// Add second text annotation.
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textAnnotation2 := model.NewPdfAnnotationText()
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textAnnotation2.Contents = core.MakeString("Another annotation with more detailed information about this section.")
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textAnnotation2.Rect = core.MakeArray(
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core.MakeInteger(300), // x1
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core.MakeInteger(550), // y1
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core.MakeInteger(350), // x2
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core.MakeInteger(600), // y2
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)
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textAnnotation2.Open = core.MakeBool(true) // Open by default
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textAnnotation2.Name = core.MakeName("Note")
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docK.AddKChild(textAnnotation2.GenerateKDict())
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// Add third text annotation.
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textAnnotation3 := model.NewPdfAnnotationText()
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textAnnotation3.Contents = core.MakeString("You can click on these yellow icons to view the annotation content.")
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textAnnotation3.Rect = core.MakeArray(
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core.MakeInteger(450), // x1
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core.MakeInteger(400), // y1
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core.MakeInteger(500), // x2
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core.MakeInteger(450), // y2
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)
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textAnnotation3.Open = core.MakeBool(false)
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textAnnotation3.Name = core.MakeName("Help")
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docK.AddKChild(textAnnotation3.GenerateKDict())
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// Add annotations to the page.
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page.AddAnnotation(textAnnotation1.PdfAnnotation)
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page.AddAnnotation(textAnnotation2.PdfAnnotation)
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page.AddAnnotation(textAnnotation3.PdfAnnotation)
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// Add StructTreeRoot to the page.
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c.SetStructTreeRoot(str)
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// Add the page to the writer.
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err = c.AddPage(page)
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if err != nil {
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return err
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}
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// Write the PDF to file.
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err = c.WriteToFile(outputPath)
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if err != nil {
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return err
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}
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return nil
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}

‎accessibility/pdf_tag_form.go‎

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// This example demonstrates how to create a PDF with form fields
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// using the UniPDF library. The PDF will contain multiple text fields
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// along with submit and reset buttons, and the form fields will be
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// properly tagged in the document structure tree for accessibility compliance.
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//
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// The example covers best practices for PDF/UA compliance:
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// 1. Each form field has an associated label with a tooltip.
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// 2. The document structure tree is constructed with K dictionaries
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// to represent the hierarchical structure of the form elements.
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// 3. Each label is associated with its corresponding form field using
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// marked content IDs (MCID).
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// 4. The submit button is configured to submit the form data to a specified URL.
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// 5. The reset button is configured to reset the specified fields to their default values.
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package main
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import (
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"log"
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"os"
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"github.com/unidoc/unipdf/v4/annotator"
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"github.com/unidoc/unipdf/v4/common/license"
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"github.com/unidoc/unipdf/v4/contentstream/draw"
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"github.com/unidoc/unipdf/v4/core"
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"github.com/unidoc/unipdf/v4/creator"
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"github.com/unidoc/unipdf/v4/model"
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)
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func init() {
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// Make sure to load your metered License API key prior to using the library.
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// If you need a key, you can sign up and create a free one at https://cloud.unidoc.io
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err := license.SetMeteredKey(os.Getenv(`UNIDOC_LICENSE_API_KEY`))
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if err != nil {
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panic(err)
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}
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}
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func main() {
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textFieldsDef := []struct {
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Label string
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Name string
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Rect []float64
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Tooltip string
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}{
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{Label: "Full Name", Name: "full_name", Rect: []float64{123.97, 619.02, 343.99, 633.6}, Tooltip: "Enter your full name"},
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{Label: "Address 1", Name: "address_line_1", Rect: []float64{123.97, 596.82, 343.99, 611.4}, Tooltip: "Enter your primary address"},
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{Label: "Address 2", Name: "address_line_2", Rect: []float64{123.97, 574.28, 343.99, 588.86}, Tooltip: "Enter your secondary address (optional)"},
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}
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c := creator.New()
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page := c.NewPage()
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_, pageHeight, err := page.Size()
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if err != nil {
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log.Fatal(err)
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}
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// Construct the StructTreeRoot.
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str := model.NewStructTreeRoot()
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// Construct base K dictionary.
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docK := model.NewKDictionary()
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docK.S = core.MakeName(string(model.StructureTypeDocument))
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str.AddKDict(docK)
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form := model.NewPdfAcroForm()
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fields := core.MakeArray()
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// Create text fields and its label
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for idx, fdef := range textFieldsDef {
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opt := annotator.TextFieldOptions{}
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textf, err := annotator.NewTextField(page, fdef.Name, fdef.Rect, opt)
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if err != nil {
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log.Fatal(err)
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}
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textf.DV = core.MakeString("") // Set default value for the field.
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textf.V = core.MakeString("") // Set current value for the field.
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textf.TU = core.MakeString(fdef.Tooltip) // Set tooltip for the field.
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*form.Fields = append(*form.Fields, textf.PdfField)
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page.AddAnnotation(textf.Annotations[0].PdfAnnotation)
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y := pageHeight - fdef.Rect[1]
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p := c.NewStyledParagraph()
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p.SetText(fdef.Label)
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p.SetPos(fdef.Rect[0]-80, y-10)
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// Tag the label paragraph and generate its K dictionary.
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// This will be used to associate the label with the form field.
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p.SetStructureType(model.StructureTypeForm)
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// Set unique ID for each field label.
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p.SetMarkedContentID(int64(idx))
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k, err := p.GenerateKDict()
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if err != nil {
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log.Fatalf("Error: %v", err)
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}
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k.Alt = core.MakeString(fdef.Tooltip) // Set alternative text for the label.
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docK.AddKChild(k)
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err = c.Draw(p)
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if err != nil {
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log.Fatal(err)
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}
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line := c.NewLine(fdef.Rect[0], y, fdef.Rect[2], y)
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err = c.Draw(line)
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if err != nil {
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log.Fatal(err)
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}
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fields.Append(textf.ToPdfObject())
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}
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err = addSubmitButton(page, form)
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if err != nil {
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log.Fatal(err)
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}
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err = addResetButton(page, form, fields)
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if err != nil {
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log.Fatal(err)
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}
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c.SetForms(form)
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c.SetStructTreeRoot(str)
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err = c.WriteToFile("pdf_tag_form.pdf")
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if err != nil {
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log.Fatal(err)
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}
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}
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// Add Submit button that will submit all field values.
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func addSubmitButton(page *model.PdfPage, form *model.PdfAcroForm) error {
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optSubmit := annotator.FormSubmitActionOptions{
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Url: "https://unidoc.io",
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Rectangle: draw.Rectangle{
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X: 400.0,
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Y: 400.0,
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Width: 50.0,
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Height: 20.0,
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FillColor: model.NewPdfColorDeviceRGB(0.0, 1.0, 0.0),
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},
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Label: "Submit",
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LabelColor: model.NewPdfColorDeviceRGB(1.0, 0.0, 0.0),
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}
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btnSubmitField, err := annotator.NewFormSubmitButtonField(page, optSubmit)
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if err != nil {
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return err
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}
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*form.Fields = append(*form.Fields, btnSubmitField.PdfField)
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page.AddAnnotation(btnSubmitField.Annotations[0].PdfAnnotation)
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return nil
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}
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// Add Reset button that would reset the specified fields to its default value.
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func addResetButton(page *model.PdfPage, form *model.PdfAcroForm, fields *core.PdfObjectArray) error {
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optReset := annotator.FormResetActionOptions{
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Rectangle: draw.Rectangle{
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X: 100.0,
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Y: 400.0,
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Width: 50.0,
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Height: 20.0,
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FillColor: model.NewPdfColorDeviceGray(0.5),
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},
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Label: "Reset",
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LabelColor: model.NewPdfColorDeviceGray(1.0),
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Fields: fields,
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}
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btnResetField, err := annotator.NewFormResetButtonField(page, optReset)
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if err != nil {
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return err
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}
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// Add widget to existing form.
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*form.Fields = append(*form.Fields, btnResetField.PdfField)
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page.AddAnnotation(btnResetField.Annotations[0].PdfAnnotation)
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return nil
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}

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