Example Code

use lopdf::dictionary;use lopdf::{Document,Object,Stream};use lopdf::content::{Content,Operation};// `with_version` specifes the PDF version this document complies with.letmut doc =Document::with_version("1.5");// Object IDs are used for cross referencing in PDF documents.// `lopdf` helps keep track of them for us. They are simple integers.// Calls to `doc.new_object_id` and `doc.add_object` return an object ID.// "Pages" is the root node of the page tree.let pages_id = doc.new_object_id();// Fonts are dictionaries. The "Type", "Subtype" and "BaseFont" tags// are straight out of the PDF spec.//// The dictionary macro is a helper that allows complex// key-value relationships to be represented in a simpler// visual manner, similar to a match statement.// A dictionary is implemented as an IndexMap of Vec<u8>, and Objectlet font_id = doc.add_object(dictionary!{// type of dictionary"Type" =>"Font",// type of font, type1 is simple postscript font"Subtype" =>"Type1",// basefont is postscript name of font for type1 font.// See PDF reference document for more details"BaseFont" =>"Courier",});// Font dictionaries need to be added into resource// dictionaries in order to be used.// Resource dictionaries can contain more than just fonts,// but normally just contains fonts.// Only one resource dictionary is allowed per page tree root.let resources_id = doc.add_object(dictionary!{// Fonts are actually triplely nested dictionaries. Fun!"Font" => dictionary!{// F1 is the font name used when writing text.// It must be unique in the document. It does not// have to be F1"F1" => font_id,},});// `Content` is a wrapper struct around an operations struct that contains// a vector of operations. The operations struct contains a vector of// that match up with a particular PDF operator and operands.// Refer to the PDF spec for more details on the operators and operands// Note, the operators and operands are specified in a reverse order// from how they actually appear in the PDF file itself.let content =Content{operations:vec![// BT begins a text element. It takes no operands.Operation::new("BT", vec![]),// Tf specifies the font and font size.// Font scaling is complicated in PDFs.// Refer to the spec for more info.// The `into()` methods convert the types into// an enum that represents the basic object types in PDF documents.Operation::new("Tf", vec!["F1".into(),48.into()]),// Td adjusts the translation components of the text matrix.// When used for the first time after BT, it sets the initial// text position on the page.// Note: PDF documents have Y=0 at the bottom. Thus 600 to print text near the top.Operation::new("Td", vec![100.into(),600.into()]),// Tj prints a string literal to the page. By default, this is black text that is// filled in. There are other operators that can produce various textual effects and// colorsOperation::new("Tj", vec![Object::string_literal("Hello World!")]),// ET ends the text element.Operation::new("ET", vec![]),],};// Streams are a dictionary followed by a (possibly encoded) sequence of bytes.// What that sequence of bytes represents, depends on the context.// The stream dictionary is set internally by lopdf and normally doesn't// need to be manually manipulated. It contains keys such as// Length, Filter, DecodeParams, etc.let content_id = doc.add_object(Stream::new(dictionary!{}, content.encode().unwrap()));// Page is a dictionary that represents one page of a PDF file.// Its required fields are "Type", "Parent" and "Contents".let page_id = doc.add_object(dictionary!{"Type" =>"Page","Parent" => pages_id,"Contents" => content_id,});// Again, "Pages" is the root of the page tree. The ID was already created// at the top of the page, since we needed it to assign to the parent element// of the page dictionary.//// These are just the basic requirements for a page tree root object.// There are also many additional entries that can be added to the dictionary,// if needed. Some of these can also be defined on the page dictionary itself,// and not inherited from the page tree root.let pages =dictionary!{// Type of dictionary"Type" =>"Pages",// Vector of page IDs in document. Normally would contain more than one ID// and be produced using a loop of some kind."Kids" => vec![page_id.into()],// Page count"Count" =>1,// ID of resources dictionary, defined earlier"Resources" => resources_id,// A rectangle that defines the boundaries of the physical or digital media.// This is the "page size"."MediaBox" => vec![0.into(),0.into(),595.into(),842.into()],};// Using `insert()` here, instead of `add_object()` since the ID is already known.doc.objects.insert(pages_id,Object::Dictionary(pages));// Creating document catalog.// There are many more entries allowed in the catalog dictionary.let catalog_id = doc.add_object(dictionary!{"Type" =>"Catalog","Pages" => pages_id,});// The "Root" key in trailer is set to the ID of the document catalog,// the remainder of the trailer is set during `doc.save()`.doc.trailer.set("Root", catalog_id);doc.compress();// Store file in current working directory.// Note: Line is excluded when running testsiffalse{    doc.save("example.pdf").unwrap();}

use lopdf::dictionary;use std::collections::BTreeMap;use lopdf::content::{Content,Operation};use lopdf::{Document,Object,ObjectId,Stream,Bookmark};pubfngenerate_fake_document() ->Document{letmut doc =Document::with_version("1.5");let pages_id = doc.new_object_id();let font_id = doc.add_object(dictionary!{"Type" =>"Font","Subtype" =>"Type1","BaseFont" =>"Courier",});let resources_id = doc.add_object(dictionary!{"Font" => dictionary!{"F1" => font_id,},});let content =Content{operations:vec![Operation::new("BT", vec![]),Operation::new("Tf", vec!["F1".into(),48.into()]),Operation::new("Td", vec![100.into(),600.into()]),Operation::new("Tj", vec![Object::string_literal("Hello World!")]),Operation::new("ET", vec![]),],};let content_id = doc.add_object(Stream::new(dictionary!{}, content.encode().unwrap()));let page_id = doc.add_object(dictionary!{"Type" =>"Page","Parent" => pages_id,"Contents" => content_id,"Resources" => resources_id,"MediaBox" => vec![0.into(),0.into(),595.into(),842.into()],});let pages =dictionary!{"Type" =>"Pages","Kids" => vec![page_id.into()],"Count" =>1,};    doc.objects.insert(pages_id,Object::Dictionary(pages));let catalog_id = doc.add_object(dictionary!{"Type" =>"Catalog","Pages" => pages_id,});    doc.trailer.set("Root", catalog_id);    doc}fnmain() -> std::io::Result<()>{// Generate a stack of Documents to merge.let documents =vec![        generate_fake_document(),        generate_fake_document(),        generate_fake_document(),        generate_fake_document(),];// Define a starting `max_id` (will be used as start index for object_ids).letmut max_id =1;letmut pagenum =1;// Collect all Documents Objects grouped by a mapletmut documents_pages =BTreeMap::new();letmut documents_objects =BTreeMap::new();letmut document =Document::with_version("1.5");formut docin documents{letmut first =false;        doc.renumber_objects_with(max_id);        max_id = doc.max_id +1;        documents_pages.extend(            doc.get_pages().into_iter().map(|(_, object_id)|{if !first{let bookmark =Bookmark::new(String::from(format!("Page_{}", pagenum)),[0.0,0.0,1.0],0, object_id);                            document.add_bookmark(bookmark,None);                            first =true;                            pagenum +=1;}(                            object_id,                            doc.get_object(object_id).unwrap().to_owned(),)}).collect::<BTreeMap<ObjectId,Object>>(),);        documents_objects.extend(doc.objects);}// "Catalog" and "Pages" are mandatory.letmut catalog_object:Option<(ObjectId,Object)> =None;letmut pages_object:Option<(ObjectId,Object)> =None;// Process all objects except "Page" typefor(object_id, object)in documents_objects.iter(){// We have to ignore "Page" (as are processed later), "Outlines" and "Outline" objects.// All other objects should be collected and inserted into the main Document.match object.type_name().unwrap_or(b""){b"Catalog" =>{// Collect a first "Catalog" object and use it for the future "Pages".                catalog_object =Some((ifletSome((id, _)) = catalog_object{                        id}else{*object_id},                    object.clone(),));}b"Pages" =>{// Collect and update a first "Pages" object and use it for the future "Catalog"// We have also to merge all dictionaries of the old and the new "Pages" objectifletOk(dictionary) = object.as_dict(){letmut dictionary = dictionary.clone();ifletSome((_,ref object)) = pages_object{ifletOk(old_dictionary) = object.as_dict(){                            dictionary.extend(old_dictionary);}}                    pages_object =Some((ifletSome((id, _)) = pages_object{                            id}else{*object_id},Object::Dictionary(dictionary),));}}b"Page" =>{}// Ignored, processed later and separatelyb"Outlines" =>{}// Ignored, not supported yetb"Outline" =>{}// Ignored, not supported yet            _ =>{                document.objects.insert(*object_id, object.clone());}}}// If no "Pages" object found, abort.if pages_object.is_none(){println!("Pages root not found.");returnOk(());}// Iterate over all "Page" objects and collect into the parent "Pages" created beforefor(object_id, object)in documents_pages.iter(){ifletOk(dictionary) = object.as_dict(){letmut dictionary = dictionary.clone();            dictionary.set("Parent", pages_object.as_ref().unwrap().0);            document.objects.insert(*object_id,Object::Dictionary(dictionary));}}// If no "Catalog" found, abort.if catalog_object.is_none(){println!("Catalog root not found.");returnOk(());}let catalog_object = catalog_object.unwrap();let pages_object = pages_object.unwrap();// Build a new "Pages" with updated fieldsifletOk(dictionary) = pages_object.1.as_dict(){letmut dictionary = dictionary.clone();// Set new pages count        dictionary.set("Count", documents_pages.len()asu32);// Set new "Kids" list (collected from documents pages) for "Pages"        dictionary.set("Kids",            documents_pages.into_iter().map(|(object_id, _)|Object::Reference(object_id)).collect::<Vec<_>>(),);        document.objects.insert(pages_object.0,Object::Dictionary(dictionary));}// Build a new "Catalog" with updated fieldsifletOk(dictionary) = catalog_object.1.as_dict(){letmut dictionary = dictionary.clone();        dictionary.set("Pages", pages_object.0);        dictionary.remove(b"Outlines");// Outlines not supported in merged PDFs        document.objects.insert(catalog_object.0,Object::Dictionary(dictionary));}    document.trailer.set("Root", catalog_object.0);// Update the max internal ID as wasn't updated before due to direct objects insertion    document.max_id = document.objects.len()asu32;// Reorder all new Document objects    document.renumber_objects();// Set any Bookmarks to the First child if they are not set to a page    document.adjust_zero_pages();// Set all bookmarks to the PDF Object tree then set the Outlines to the Bookmark content map.ifletSome(n) = document.build_outline(){ifletOk(Object::Dictionary(dict)) = document.get_object_mut(catalog_object.0){            dict.set("Outlines",Object::Reference(n));}}    document.compress();// Save the merged PDF.// Store file in current working directory.// Note: Line is excluded when running doc testsiffalse{        document.save("merged.pdf").unwrap();}Ok(())}

use lopdf::Document;// For this example to work a parser feature needs to be enabled#[cfg(not(feature ="async"))]#[cfg(feature ="nom_parser")]{letmut doc =Document::load("assets/example.pdf").unwrap();    doc.version ="1.4".to_string();    doc.replace_text(1,"Hello World!","Modified text!",None);// Store file in current working directory.// Note: Line is excluded when running testsiffalse{        doc.save("modified.pdf").unwrap();}}#[cfg(feature ="async")]#[cfg(feature ="nom_parser")]{    tokio::runtime::Builder::new_current_thread().build().expect("Failed to create runtime").block_on(asyncmove{letmut doc =Document::load("assets/example.pdf").await.unwrap();                        doc.version ="1.4".to_string();            doc.replace_text(1,"Hello World!","Modified text!",None);// Store file in current working directory.// Note: Line is excluded when running testsiffalse{                doc.save("modified.pdf").unwrap();}});}

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