2 files changed, 219 insertions, 0 deletions
diff --git a/contrib/gofpdi/gofpdi.go b/contrib/gofpdi/gofpdi.go
new file mode 100644
index 0000000..7b9c822
--- /dev/null
+++ b/contrib/gofpdi/gofpdi.go
@@ -0,0 +1,143 @@
+/*
+Package gofpdi wraps the gofpdi PDF library to import existing PDFs as templates. See github.com/phpdave11/gofpdi
+for further information and examples.
+
+Users should call NewImporter() to obtain their own Importer instance to work with.
+To retain backwards compatibility, the package offers a default Importer that may be used via global functions. Note
+however that use of the default Importer is not thread safe.
+*/
+package gofpdi
+
+import (
+	realgofpdi "github.com/phpdave11/gofpdi"
+	"io"
+)
+
+// gofpdiPdf is a partial interface that only implements the functions we need
+// from the PDF generator to put the imported PDF templates on the PDF.
+type gofpdiPdf interface {
+	ImportObjects(objs map[string][]byte)
+	ImportObjPos(objs map[string]map[int]string)
+	ImportTemplates(tpls map[string]string)
+	UseImportedTemplate(tplName string, x float64, y float64, w float64, h float64)
+	SetError(err error)
+}
+
+// Importer wraps an Importer from the gofpdi library.
+type Importer struct {
+	fpdi *realgofpdi.Importer
+}
+
+// NewImporter creates a new Importer wrapping functionality from the gofpdi library.
+func NewImporter() *Importer {
+	return &Importer{
+		fpdi: realgofpdi.NewImporter(),
+	}
+}
+
+// ImportPage imports a page of a PDF file with the specified box (/MediaBox,
+// /TrimBox, /ArtBox, /CropBox, or /BleedBox). Returns a template id that can
+// be used with UseImportedTemplate to draw the template onto the page.
+func (i *Importer) ImportPage(f gofpdiPdf, sourceFile string, pageno int, box string) int {
+	// Set source file for fpdi
+	i.fpdi.SetSourceFile(sourceFile)
+	// return template id
+	return i.getTemplateID(f, pageno, box)
+}
+
+// ImportPageFromStream imports a page of a PDF with the specified box
+// (/MediaBox, TrimBox, /ArtBox, /CropBox, or /BleedBox). Returns a template id
+// that can be used with UseImportedTemplate to draw the template onto the
+// page.
+func (i *Importer) ImportPageFromStream(f gofpdiPdf, rs *io.ReadSeeker, pageno int, box string) int {
+	// Set source stream for fpdi
+	i.fpdi.SetSourceStream(rs)
+	// return template id
+	return i.getTemplateID(f, pageno, box)
+}
+
+func (i *Importer) getTemplateID(f gofpdiPdf, pageno int, box string) int {
+	// Import page
+	tpl := i.fpdi.ImportPage(pageno, box)
+
+	// Import objects into current pdf document
+	// Unordered means that the objects will be returned with a sha1 hash instead of an integer
+	// The objects themselves may have references to other hashes which will be replaced in ImportObjects()
+	tplObjIDs := i.fpdi.PutFormXobjectsUnordered()
+
+	// Set template names and ids (hashes) in gofpdf
+	f.ImportTemplates(tplObjIDs)
+
+	// Get a map[string]string of the imported objects.
+	// The map keys will be the ID of each object.
+	imported := i.fpdi.GetImportedObjectsUnordered()
+
+	// Import gofpdi objects into gofpdf
+	f.ImportObjects(imported)
+
+	// Get a map[string]map[int]string of the object hashes and their positions within each object,
+	// to be replaced with object ids (integers).
+	importedObjPos := i.fpdi.GetImportedObjHashPos()
+
+	// Import gofpdi object hashes and their positions into gopdf
+	f.ImportObjPos(importedObjPos)
+
+	return tpl
+}
+
+// UseImportedTemplate draws the template onto the page at x,y. If w is 0, the
+// template will be scaled to fit based on h. If h is 0, the template will be
+// scaled to fit based on w.
+func (i *Importer) UseImportedTemplate(f gofpdiPdf, tplid int, x float64, y float64, w float64, h float64) {
+	// Get values from fpdi
+	tplName, scaleX, scaleY, tX, tY := i.fpdi.UseTemplate(tplid, x, y, w, h)
+
+	f.UseImportedTemplate(tplName, scaleX, scaleY, tX, tY)
+}
+
+// GetPageSizes returns page dimensions for all pages of the imported pdf.
+// Result consists of map[<page number>]map[<box>]map[<dimension>]<value>.
+// <page number>: page number, note that page numbers start at 1
+// <box>: box identifier, e.g. "/MediaBox"
+// <dimension>: dimension string, either "w" or "h"
+func (i *Importer) GetPageSizes() map[int]map[string]map[string]float64 {
+	return i.fpdi.GetPageSizes()
+}
+
+// Default Importer used by global functions
+var fpdi = NewImporter()
+
+// ImportPage imports a page of a PDF file with the specified box (/MediaBox,
+// /TrimBox, /ArtBox, /CropBox, or /BleedBox). Returns a template id that can
+// be used with UseImportedTemplate to draw the template onto the page.
+// Note: This uses the default Importer. Call NewImporter() to obtain a custom Importer.
+func ImportPage(f gofpdiPdf, sourceFile string, pageno int, box string) int {
+	return fpdi.ImportPage(f, sourceFile, pageno, box)
+}
+
+// ImportPageFromStream imports a page of a PDF with the specified box
+// (/MediaBox, TrimBox, /ArtBox, /CropBox, or /BleedBox). Returns a template id
+// that can be used with UseImportedTemplate to draw the template onto the
+// page.
+// Note: This uses the default Importer. Call NewImporter() to obtain a custom Importer.
+func ImportPageFromStream(f gofpdiPdf, rs *io.ReadSeeker, pageno int, box string) int {
+	return fpdi.ImportPageFromStream(f, rs, pageno, box)
+}
+
+// UseImportedTemplate draws the template onto the page at x,y. If w is 0, the
+// template will be scaled to fit based on h. If h is 0, the template will be
+// scaled to fit based on w.
+// Note: This uses the default Importer. Call NewImporter() to obtain a custom Importer.
+func UseImportedTemplate(f gofpdiPdf, tplid int, x float64, y float64, w float64, h float64) {
+	fpdi.UseImportedTemplate(f, tplid, x, y, w, h)
+}
+
+// GetPageSizes returns page dimensions for all pages of the imported pdf.
+// Result consists of map[<page number>]map[<box>]map[<dimension>]<value>.
+// <page number>: page number, note that page numbers start at 1
+// <box>: box identifier, e.g. "/MediaBox"
+// <dimension>: dimension string, either "w" or "h"
+// Note: This uses the default Importer. Call NewImporter() to obtain a custom Importer.
+func GetPageSizes() map[int]map[string]map[string]float64 {
+	return fpdi.GetPageSizes()
+}
diff --git a/contrib/gofpdi/gofpdi_test.go b/contrib/gofpdi/gofpdi_test.go
new file mode 100644
index 0000000..70ef6cc
--- /dev/null
+++ b/contrib/gofpdi/gofpdi_test.go
@@ -0,0 +1,76 @@
+package gofpdi
+
+import (
+	"bytes"
+	"github.com/jung-kurt/gofpdf"
+	"github.com/jung-kurt/gofpdf/internal/example"
+	"io"
+	"sync"
+	"testing"
+)
+
+func ExampleNewImporter() {
+	// create new pdf
+	pdf := gofpdf.New("P", "pt", "A4", "")
+
+	// for testing purposes, get an arbitrary template pdf as stream
+	rs, _ := getTemplatePdf()
+
+	// create a new Importer instance
+	imp := NewImporter()
+
+	// import first page and determine page sizes
+	tpl := imp.ImportPageFromStream(pdf, &rs, 1, "/MediaBox")
+	pageSizes := imp.GetPageSizes()
+	nrPages := len(imp.GetPageSizes())
+
+	// add all pages from template pdf
+	for i := 1; i <= nrPages; i++ {
+		pdf.AddPage()
+		if i > 1 {
+			tpl = imp.ImportPageFromStream(pdf, &rs, i, "/MediaBox")
+		}
+		imp.UseImportedTemplate(pdf, tpl, 0, 0, pageSizes[i]["/MediaBox"]["w"], pageSizes[i]["/MediaBox"]["h"])
+	}
+
+	// output
+	fileStr := example.Filename("contrib_gofpdi_Importer")
+	err := pdf.OutputFileAndClose(fileStr)
+	example.Summary(err, fileStr)
+	// Output:
+	// Successfully generated ../../pdf/contrib_gofpdi_Importer.pdf
+}
+
+func TestGofpdiConcurrent(t *testing.T) {
+	wg := sync.WaitGroup{}
+	for i := 0; i < 100; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			pdf := gofpdf.New("P", "mm", "A4", "")
+			pdf.AddPage()
+			rs, _ := getTemplatePdf()
+			imp := NewImporter()
+			tpl := imp.ImportPageFromStream(pdf, &rs, 1, "/MediaBox")
+			imp.UseImportedTemplate(pdf, tpl, 0, 0, 210.0, 297.0)
+			// write to bytes buffer
+			buf := bytes.Buffer{}
+			if err := pdf.Output(&buf); err != nil {
+				t.Fail()
+			}
+		}()
+	}
+	wg.Wait()
+}
+
+func getTemplatePdf() (io.ReadSeeker, error) {
+	tpdf := gofpdf.New("P", "pt", "A4", "")
+	tpdf.AddPage()
+	tpdf.SetFont("Arial", "", 12)
+	tpdf.Text(20, 20, "Example Page 1")
+	tpdf.AddPage()
+	tpdf.Text(20, 20, "Example Page 2")
+	tbuf := bytes.Buffer{}
+	err := tpdf.Output(&tbuf)
+	return bytes.NewReader(tbuf.Bytes()), err
+}