Templating

1 files changed, 209 insertions, 0 deletions

diff --git a/template.go b/template.go
new file mode 100644
index 0000000..17cea11
--- /dev/null
+++ b/template.go
@@ -0,0 +1,209 @@
+package gofpdf
+
+//
+//  GoFPDI
+//
+//    Copyright 2015 Marcus Downing
+//
+//  FPDI
+//
+//    Copyright 2004-2014 Setasign - Jan Slabon
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+// CreateTemplate defines a new template using the current page size.
+func (f *Fpdf) CreateTemplate(fn func(*Tpl)) Template {
+	return newTpl(PointType{0, 0}, f.curPageSize, f.unitStr, f.fontDirStr, fn, f)
+}
+
+// CreateTemplateCustom starts a template, using the given bounds.
+func (f *Fpdf) CreateTemplateCustom(corner PointType, size SizeType, fn func(*Tpl)) Template {
+	return newTpl(corner, size, f.unitStr, f.fontDirStr, fn, f)
+}
+
+// CreateTemplate creates a template not attached to any document
+func CreateTemplate(corner PointType, size SizeType, unitStr, fontDirStr string, fn func(*Tpl)) Template {
+	return newTpl(corner, size, unitStr, fontDirStr, fn, nil)
+}
+
+// UseTemplate adds a template to the current page or another template,
+// using the size and position at which it was originally written.
+func (f *Fpdf) UseTemplate(t Template) {
+	if t == nil {
+		f.SetErrorf("Template is nil")
+		return
+	}
+	corner, size := t.Size()
+	f.UseTemplateScaled(t, corner, size)
+}
+
+// UseTemplateScaled adds a template to the current page or another template,
+// using the given page coordinates.
+func (f *Fpdf) UseTemplateScaled(t Template, corner PointType, size SizeType) {
+	if t == nil {
+		f.SetErrorf("Template is nil")
+		return
+	}
+
+	// You have to add at least a page first
+	if f.page <= 0 {
+		f.SetErrorf("Cannot use a template without first adding a page")
+		return
+	}
+
+	// make a note of the fact that we actually use this template, as well as any other templates,
+	// images or fonts it uses
+	f.templates[t.ID()] = t
+	for _, tt := range t.Templates() {
+		f.templates[tt.ID()] = tt
+	}
+	for name, ti := range t.Images() {
+		name = sprintf("t%d-%s", t.ID(), name)
+		f.images[name] = ti
+	}
+
+	// template data
+	_, templateSize := t.Size()
+	scaleX := size.Wd / templateSize.Wd
+	scaleY := size.Ht / templateSize.Ht
+	tx := corner.X * f.k
+	ty := (f.curPageSize.Ht - corner.Y - size.Ht) * f.k
+
+	f.outf("q %.4F 0 0 %.4F %.4F %.4F cm", scaleX, scaleY, tx, ty) // Translate
+	f.outf("/TPL%d Do Q", t.ID())
+}
+
+var nextTemplateIDChannel = func() chan int64 {
+	ch := make(chan int64)
+	go func() {
+		var nextID int64 = 1
+		for {
+			ch <- nextID
+			nextID++
+		}
+	}()
+	return ch
+}()
+
+// GenerateTemplateID gives the next template ID. These numbers are global so that they can never clash.
+func GenerateTemplateID() int64 {
+	return <-nextTemplateIDChannel
+}
+
+// Template is an object that can be written to, then used and re-used any number of times within a document.
+type Template interface {
+	ID() int64
+	Size() (PointType, SizeType)
+	Bytes() []byte
+	Images() map[string]*ImageInfoType
+	Templates() []Template
+}
+
+// putTemplates writes the templates to the PDF
+func (f *Fpdf) putTemplates() {
+	filter := ""
+	if f.compress {
+		filter = "/Filter /FlateDecode "
+	}
+
+	templates := sortTemplates(f.templates)
+	var t Template
+	for _, t = range templates {
+		corner, size := t.Size()
+
+		f.newobj()
+		f.templateObjects[t.ID()] = f.n
+		f.outf("<<%s/Type /XObject", filter)
+		f.out("/Subtype /Form")
+		f.out("/Formtype 1")
+		f.outf("/BBox [%.2F %.2F %.2F %.2F]", corner.X*f.k, corner.Y*f.k, (corner.X+size.Wd)*f.k, (corner.Y+size.Ht)*f.k)
+		if corner.X != 0 || corner.Y != 0 {
+			f.outf("/Matrix [1 0 0 1 %.5F %.5F]", -corner.X*f.k*2, corner.Y*f.k*2)
+		}
+
+		// Template's resource dictionary
+		f.out("/Resources ")
+		f.out("<</ProcSet [/PDF /Text /ImageB /ImageC /ImageI]")
+
+		tImages := t.Images()
+		tTemplates := t.Templates()
+		if len(tImages) > 0 || len(tTemplates) > 0 {
+			f.out("/XObject <<")
+			for _, ti := range tImages {
+				f.outf("/I%d %d 0 R", ti.i, ti.n)
+			}
+			for _, tt := range tTemplates {
+				id := tt.ID()
+				if objID, ok := f.templateObjects[id]; ok {
+					f.outf("/TPL%d %d 0 R", id, objID)
+				}
+			}
+			f.out(">>")
+		}
+
+		f.out(">>")
+
+		//  Write the template's byte stream
+		buffer := t.Bytes()
+		// fmt.Println("Put template bytes", string(buffer[:]))
+		if f.compress {
+			buffer = sliceCompress(buffer)
+		}
+		f.outf("/Length %d >>", len(buffer))
+		f.putstream(buffer)
+		f.out("endobj")
+	}
+}
+
+// sortTemplates puts templates in a suitable order based on dependices
+func sortTemplates(templates map[int64]Template) []Template {
+	chain := make([]Template, 0, len(templates)*2)
+
+	// build a full set of dependency chains
+	for _, t := range templates {
+		tlist := templateChainDependencies(t)
+		for _, tt := range tlist {
+			if tt != nil {
+				chain = append(chain, tt)
+			}
+		}
+	}
+
+	// reduce that to make a simple list
+	sorted := make([]Template, 0, len(templates))
+chain:
+	for _, t := range chain {
+		for _, already := range sorted {
+			if t == already {
+				continue chain
+			}
+		}
+		sorted = append(sorted, t)
+	}
+
+	return sorted
+}
+
+//  templateChainDependencies is a recursive function for determining the full chain of template dependencies
+func templateChainDependencies(template Template) []Template {
+	requires := template.Templates()
+	chain := make([]Template, len(requires)*2)
+	for _, req := range requires {
+		for _, sub := range templateChainDependencies(req) {
+			chain = append(chain, sub)
+		}
+	}
+	chain = append(chain, template)
+	return chain
+}