wrap contrib/gofpdi:realgofpdi.Importer

* allow for multiple independent Importer instances
* keep a default Importer for backwards compatibility
* add package level comment

1 files changed, 71 insertions, 16 deletions

diff --git a/contrib/gofpdi/gofpdi.go b/contrib/gofpdi/gofpdi.go
index e600fb1..7b9c822 100644
--- a/contrib/gofpdi/gofpdi.go
+++ b/contrib/gofpdi/gofpdi.go
@@ -1,3 +1,11 @@
+/*
+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 (
@@ -5,9 +13,6 @@ import (
 	"io"
 )
 
-// Create new gofpdi instance
-var fpdi = realgofpdi.NewImporter()
-
 // 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 {
@@ -18,49 +23,61 @@ type gofpdiPdf interface {
 	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 ImportPage(f gofpdiPdf, sourceFile string, pageno int, box string) int {
+func (i *Importer) ImportPage(f gofpdiPdf, sourceFile string, pageno int, box string) int {
 	// Set source file for fpdi
-	fpdi.SetSourceFile(sourceFile)
+	i.fpdi.SetSourceFile(sourceFile)
 	// return template id
-	return getTemplateID(f, pageno, box)
+	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 ImportPageFromStream(f gofpdiPdf, rs *io.ReadSeeker, pageno int, box string) int {
+func (i *Importer) ImportPageFromStream(f gofpdiPdf, rs *io.ReadSeeker, pageno int, box string) int {
 	// Set source stream for fpdi
-	fpdi.SetSourceStream(rs)
+	i.fpdi.SetSourceStream(rs)
 	// return template id
-	return getTemplateID(f, pageno, box)
+	return i.getTemplateID(f, pageno, box)
 }
 
-func getTemplateID(f gofpdiPdf, pageno int, box string) int {
+func (i *Importer) getTemplateID(f gofpdiPdf, pageno int, box string) int {
 	// Import page
-	tpl := fpdi.ImportPage(pageno, box)
+	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 := fpdi.PutFormXobjectsUnordered()
+	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 := fpdi.GetImportedObjectsUnordered()
+	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 := fpdi.GetImportedObjHashPos()
+	importedObjPos := i.fpdi.GetImportedObjHashPos()
 
 	// Import gofpdi object hashes and their positions into gopdf
 	f.ImportObjPos(importedObjPos)
@@ -71,9 +88,9 @@ func getTemplateID(f gofpdiPdf, pageno int, box string) int {
 // 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 UseImportedTemplate(f gofpdiPdf, tplid int, x float64, y float64, w float64, h float64) {
+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 := fpdi.UseTemplate(tplid, x, y, w, h)
+	tplName, scaleX, scaleY, tX, tY := i.fpdi.UseTemplate(tplid, x, y, w, h)
 
 	f.UseImportedTemplate(tplName, scaleX, scaleY, tX, tY)
 }
@@ -83,6 +100,44 @@ func UseImportedTemplate(f gofpdiPdf, tplid int, x float64, y float64, w float64
 // <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()
 }