examples: add PDF export and TOC generation examples

This only works on Windows as it uses OLE to drive MS Word, but
it allows offloading complex functionality to the actual MS Word
instead of implementing a Word renderer.

Fixes unidoc#185

_examples/document/pdf-export-ole/main.go

@@ -0,0 +1,61 @@
+// Copyright 2017 Baliance. All rights reserved.
+package main
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+
+	"baliance.com/gooxml/document"
+	"github.com/go-ole/go-ole/oleutil"
+)
+
+// NOTE: This example can only run on Windows and requires that Word be installed.
+
+func main() {
+	doc := document.New()
+
+	para := doc.AddParagraph()
+	run := para.AddRun()
+	para.SetStyle("Title")
+	run.AddText("Simple Document Formatting")
+
+	para = doc.AddParagraph()
+	para.SetStyle("Heading1")
+	run = para.AddRun()
+	run.AddText("Some Heading Text")
+
+	para = doc.AddParagraph()
+	para.SetStyle("Heading2")
+	run = para.AddRun()
+	run.AddText("Some Heading Text")
+	doc.SaveToFile("simple.docx")
+
+	cwd, _ := os.Getwd()
+	ConvertToPDF(filepath.Join(cwd, "simple.docx"), filepath.Join(cwd, "simple.pdf"))
+}
+
+// ConvertToPDF uses go-ole to convert a docx to a PDF using the Word application
+func ConvertToPDF(source, destination string) {
+	ole.CoInitialize(0)
+	defer ole.CoUninitialize()
+
+	iunk, err := oleutil.CreateObject("Word.Application")
+	if err != nil {
+		log.Fatalf("error creating Word object: %s", err)
+	}
+
+	word := iunk.MustQueryInterface(ole.IID_IDispatch)
+	defer word.Release()
+
+	// opening then saving works due to the call to doc.Settings.SetUpdateFieldsOnOpen(true) above
+
+	docs := oleutil.MustGetProperty(word, "Documents").ToIDispatch()
+	wordDoc := oleutil.MustCallMethod(docs, "Open", source).ToIDispatch()
+
+	// file format constant comes from https://msdn.microsoft.com/en-us/vba/word-vba/articles/wdsaveformat-enumeration-word
+	const wdFormatPDF = 17
+	oleutil.MustCallMethod(wordDoc, "SaveAs2", destination, wdFormatPDF)
+	oleutil.MustCallMethod(wordDoc, "Close")
+	oleutil.MustCallMethod(word, "Quit")
+}

_examples/document/toc-generation-ole/main.go

@@ -0,0 +1,95 @@
+// Copyright 2017 Baliance. All rights reserved.
+package main
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+
+	"baliance.com/gooxml/document"
+	"baliance.com/gooxml/measurement"
+	"baliance.com/gooxml/schema/soo/wml"
+
+	"github.com/go-ole/go-ole/oleutil"
+)
+
+// NOTE: This example can only run on Windows and requires that Word be installed.
+
+var lorem = `Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin lobortis, lectus dictum feugiat tempus, sem neque finibus enim, sed eleifend sem nunc ac diam. Vestibulum tempus sagittis elementum`
+
+func main() {
+	doc := document.New()
+
+	// Force the TOC to update upon opening the document
+	doc.Settings.SetUpdateFieldsOnOpen(true)
+
+	// Add a TOC
+	doc.AddParagraph().AddRun().AddField(document.FieldTOC)
+	// followed by a page break
+	doc.AddParagraph().Properties().AddSection(wml.ST_SectionMarkNextPage)
+
+	nd := doc.Numbering.AddDefinition()
+	for i := 0; i < 9; i++ {
+		lvl := nd.AddLevel()
+		lvl.SetFormat(wml.ST_NumberFormatNone)
+		lvl.SetAlignment(wml.ST_JcLeft)
+		if i%2 == 0 {
+			lvl.SetFormat(wml.ST_NumberFormatBullet)
+			lvl.RunProperties().SetFontFamily("Symbol")
+			lvl.SetText("")
+		}
+		lvl.Properties().SetLeftIndent(0.5 * measurement.Distance(i) * measurement.Inch)
+	}
+
+	// and finally paragraphs at different heading levels
+	for i := 0; i < 4; i++ {
+		para := doc.AddParagraph()
+		para.SetNumberingDefinition(nd)
+		para.Properties().SetHeadingLevel(1)
+		para.AddRun().AddText("First Level")
+
+		doc.AddParagraph().AddRun().AddText(lorem)
+		for i := 0; i < 3; i++ {
+			para := doc.AddParagraph()
+			para.SetNumberingDefinition(nd)
+			para.Properties().SetHeadingLevel(2)
+			para.AddRun().AddText("Second Level")
+			doc.AddParagraph().AddRun().AddText(lorem)
+
+			para = doc.AddParagraph()
+			para.SetNumberingDefinition(nd)
+			para.Properties().SetHeadingLevel(3)
+			para.AddRun().AddText("Third Level")
+			doc.AddParagraph().AddRun().AddText(lorem)
+		}
+	}
+	doc.SaveToFile("toc.docx")
+
+	cwd, _ := os.Getwd()
+	UpdateFields(filepath.Join(cwd, "toc.docx"))
+}
+
+// UpdateFields uses go-ole to convert a docx to a PDF using the Word application
+func UpdateFields(source string) {
+	ole.CoInitialize(0)
+	defer ole.CoUninitialize()
+
+	iunk, err := oleutil.CreateObject("Word.Application")
+	if err != nil {
+		log.Fatalf("error creating Word object: %s", err)
+	}
+	defer iunk.Release()
+
+	word := iunk.MustQueryInterface(ole.IID_IDispatch)
+	defer word.Release()
+
+	docs := oleutil.MustGetProperty(word, "Documents").ToIDispatch()
+	defer docs.Release()
+	wordDoc := oleutil.MustCallMethod(docs, "Open", source).ToIDispatch()
+	defer wordDoc.Release()
+
+	const wdFormatXMLDocument = 12
+	oleutil.MustCallMethod(wordDoc, "SaveAs2", source, wdFormatXMLDocument)
+	oleutil.MustCallMethod(wordDoc, "Close")
+	oleutil.MustCallMethod(word, "Quit")
+}