Welcome!

ColdFusion Authors: Yakov Fain, Maureen O'Gara, Nancy Y. Nee, Tad Anderson, Daniel Kaar

Related Topics: Adobe Flex, ColdFusion

Adobe Flex: Tutorial

Creating Layered PDFs with Escape Calls to the PDF Converter Printer

PDF Layers are called Optional Content within the PDF specifications

Background information
PDF Layers are called Optional Content within the PDF specifications. This is a feature that was added as of PDF-1.5 (Acrobat 6.) A layer is identified by an identifier and a title. Only the layer title is visible to the end-user of the PDF document. Layers can be structured as a tree or as a hierarchy of layers.  Here is a sample Optional Content object in a PDF:

9 0 obj <</Type/OCG/Name(Blue Layer) >> endobj

Each page using this layer should add the layer to its list of resources, for example:

6 0 obj <</Type /Page /Parent 3 0 R /MediaBox [0 0 612 792 ] /Contents [7 0 R ]
/Resources << /ProcSet [/PDF /Text] /Font <</F10 10 0 R >>
/Properties <</OC9 9 0 R >>
>> >> endobj


OC9 is the layer ID (Blue Layer) and is the layer title (strings in PDF are surrounded by parenthesis). To indicate that various objects within the page content belong to specific layers, the following syntax is used:

% start the Blue Layer that contains the text: Page 1
/OC /OC9 BDC
BT /F10 5.76  Tf 1 0 0 1 24 745.56 Tm 0.026  Tc -0.067  Tw (Page 1) Tj ET

% start a sub-layer that will contain a filled rectangle
/OC /OC11 BDC
n 1 g 96 326.96 35.76 -6.6 re f*
% end of sub-layer 1
EMC

% start another sub-layer that will contain another filled rectangle
/OC /OC13 BDC
n 1 g 96 526.96 35.76 -6.6 re f*
% end of sub-layer 2
EMC


%end of blue layer
EMC


Although the code shows one parent layer and two nested layers (contained within the parent layer), this is not enough to define the hierarchy of layers. The Order string is used to determine the hierarchy of layers. The Order string is part of the document Catalog. The Order string for the above PDF sample should look like this:

/Order [ 9 0 R [11 0 R 13 0 R] ]

The object IDs are needed to create a proper order string. The order string can also contain a parent node that is not a layer but only a container for other layers. In the example above we could have all the layers below to one parent layer called (Layered PDF) by using:

/Order [ (Layered PDF)  9 0 R [11 0 R 13 0 R]  ]

It is important that the Order string matches the order of layers as they appear in the page content, otherwise the PDF viewer will not be able to properly “show and hide” layers with their sub-layers.

Note: There is an inconsistency in the PDF specifications related to defining nodes that are parents of other layers. To have a Layered PDF as the parent of layer 9, we do not use [(Layered PDF) [9 0 R] ] as one might expect but [(Layered PDF) 9 0 R] as if the 2 nodes were on the same level.

Creating Groups of Layers
The PDF format allows creating groups of mutually exclusive layers where showing one layer will automatically hide the other. These are called radio-button groups and defined using the RBGroups PDF keyword. One can also define which layers are visible by default and which are hidden, for example:

/RBGroups [[ 11 0 R 13 0 R]]  /ON[ 11 0 R] /OFF [13 0 R] indicates that layers 11 and 13 are grouped and that layer 11 is visible by default whereas 13 is invisible.

Dynamically Creating Layers using the Amyuni PDF Converter
External developers need to be aware of layer titles only. The layers IDs and object numbers are not significant to the developer, so the implemented API will only use layer titles to insert layers and define the layer hierarchy.

Layers can be inserted within a PDF file while the document is being printed by calling Escape sequences. Escape sequences are GDI artifacts that enable developers to send custom data to a printer driver.

Checking that the Printer supports PDF Layers
The first step to start adding layers is to check that the printer has support for the escape sequences that are defined by Amyuni. The following calls are needed include:

// check if PDF printer supports layers
#define ESCAPE_SETLAYER        248

CHAR    technology[4];
int escape = ESCAPE_SETLAYER;
ExtEscape( hDC, GETTECHNOLOGY, 0, NULL, sizeof(technology), (LPSTR)technology
);

// the technology should be PDF
if ( lstrcmp(technology, "PDF") )
{
MessageBox( 0, "Not an Amyuni PDF driver", "Error", MB_ICONERROR );
}

// and support the SETLAYER escape
if ( !ExtEscape( hDC, QUERYESCSUPPORT, sizeof(escape), (LPCSTR)&escape, 0,
NULL ) )   
{
MessageBox( 0, "Not an Amyuni PDF driver", "Error", MB_ICONERROR );
}

GETTECHNOLOGY and QUERYESCSUPPORT are escape sequences that are predefined by Windows GDI. ESCAPE_SETLAYER is a custom escape that is processed by the Amyuni printer.

The SETLAYER escape takes one parameter which is a Unicode string, The escape can be wrapped into a helper function such as:

void SetLayer( HDC hDC, LPWSTR LayerInfo )
{
switch ( ExtEscape( hDC, ESCAPE_SETLAYER, (int)((wcslen(LayerInfo) + 1)
* sizeof(LayerInfo[0])), (LPCSTR)LayerInfo, 0, NULL ) )
{
default:
// positive return indicates success
case 0:
// no error
return;

case -1:
// error occured, closing a layer when none was open
break;

case -2:
// memory allocation error (low memory or invalid string)
break;
}
}

The same escape call is used to start a layer or sub-layer, end a layer or define the hierarchy of layers.

Setting the Hierarchy of Layers
The order or hierarchy of layers is sent to the PDF printer using the SETLAYER escape before the call to StartDoc. It can actually be called anytime during the printing as long as the call is made outside of a StartPage/EndPage block but before the EndDoc is called. The advantage of setting the hierarchy before StartDoc is that it allows the PDF printer to expect layer support and switch the file header to PDF-1.5.

If the hierarchy of layers is not known before the call the StartDoc, the developer can call SetLayer( L"" ) with an empty string before the call to StartDoc simply to instruct the PDF printer to output PDF-1.5 header. The order string should contain the titles of all the layers and their hierarchy, all in Unicode format. E.g.:

// set the order and hierrachy of layers
SetLayer( hDC, L"/Order[(Blue Layer)[(Blue Layer - 1)(Blue Layer - 2)](Red
Layer)(Green Layer)]"
);

This will produce a layer structure like this:



To group layers within radio-button groups, the /RBGroups, /ON and /OFF entries should be added to the call above. This code for e.g. will make the red and green layers as part of a group:

// set the order and radio/button groups of layers
SetLayer( hDC, L"/Order[(Blue Layer)[(Blue Layer - 1)(Blue Layer - 2)](Red
Layer)(Green Layer)]" \
L"/RBGroups[[(Red Layer)(Green Layer)]]/OFF[(Red Layer)]/ON[(Green Layer)]"

);

Drawing Objects within Layers
Within a StartPage/EndPage sequence of calls, calling SetLayer with a valid layer title will start a new layer and place all subsequent drawing instructions within that layer. Calling SetLayer with an empty string will end the last layer. If multiple layers are nested, multiple calls to SetLayer with an empty string are needed to close all layers.

If all layers are not closed at the call to EndPage, the PDF printer will automatically close all open layers, for example:


// start parent layer
SetLayer( hDC, L"Blue Layer" );
SetTextColor( hDC, RGB(0, 0, 255) );
TextOut( hDC, 200, yPos, buf, lstrlen(buf) );
yPos += 200;

// start blue sub-layer 1
SetLayer( hDC, L"Blue Layer - 1" );
SetTextColor( hDC, RGB(0, 0, 128) );
TextOut( hDC, 800, yPos, "Blue Layer - 1", lstrlen("Blue Layer - 1") );
yPos += 200;
SetLayer( hDC, L"" );    // close blue sub-layer 1
SetLayer( hDC, L"" );    // close blue parent layer

The sequence of opening and closing layers should be consistent with the order string for the PDF viewer to show or hide layers with their sub-layers in a consistent way.

The contents for this post were provided by Dany Amiouny using the Amyuni PDF Converter developer tool.

Please visit us at www.amyuni.com to learn more about Amyuni Developer Pro tools or our Professional Services page to contact one of our qualified PDF experts.

More Stories By Amyuni Tech

Franc Gagnon is a technical copywriter for Amyuni Technologies–a PDF solution provider. Amyuni products are integrated into applications used worldwide. The company's software tools are the PDF engines behind several leading business applications created by large software companies such as Intuit, Sage, CaseWare and many more.

@ThingsExpo Stories
Software AG helps organizations transform into Digital Enterprises, so they can differentiate from competitors and better engage customers, partners and employees. Using the Software AG Suite, companies can close the gap between business and IT to create digital systems of differentiation that drive front-line agility. We offer four on-ramps to the Digital Enterprise: alignment through collaborative process analysis; transformation through portfolio management; agility through process automation and integration; and visibility through intelligent business operations and big data.
There will be 50 billion Internet connected devices by 2020. Today, every manufacturer has a propriety protocol and an app. How do we securely integrate these "things" into our lives and businesses in a way that we can easily control and manage? Even better, how do we integrate these "things" so that they control and manage each other so our lives become more convenient or our businesses become more profitable and/or safe? We have heard that the best interface is no interface. In his session at Internet of @ThingsExpo, Chris Matthieu, Co-Founder & CTO at Octoblu, Inc., will discuss how these devices generate enough data to learn our behaviors and simplify/improve our lives. What if we could connect everything to everything? I'm not only talking about connecting things to things but also systems, cloud services, and people. Add in a little machine learning and artificial intelligence and now we have something interesting...
Last week, while in San Francisco, I used the Uber app and service four times. All four experiences were great, although one of the drivers stopped for 30 seconds and then left as I was walking up to the car. He must have realized I was a blogger. None the less, the next car was just a minute away and I suffered no pain. In this article, my colleague, Ved Sen, Global Head, Advisory Services Social, Mobile and Sensors at Cognizant shares his experiences and insights.
We are reaching the end of the beginning with WebRTC and real systems using this technology have begun to appear. One challenge that faces every WebRTC deployment (in some form or another) is identity management. For example, if you have an existing service – possibly built on a variety of different PaaS/SaaS offerings – and you want to add real-time communications you are faced with a challenge relating to user management, authentication, authorization, and validation. Service providers will want to use their existing identities, but these will have credentials already that are (hopefully) irreversibly encoded. In his session at Internet of @ThingsExpo, Peter Dunkley, Technical Director at Acision, will look at how this identity problem can be solved and discuss ways to use existing web identities for real-time communication.
Can call centers hang up the phones for good? Intuitive Solutions did. WebRTC enabled this contact center provider to eliminate antiquated telephony and desktop phone infrastructure with a pure web-based solution, allowing them to expand beyond brick-and-mortar confines to a home-based agent model. It also ensured scalability and better service for customers, including MUY! Companies, one of the country's largest franchise restaurant companies with 232 Pizza Hut locations. This is one example of WebRTC adoption today, but the potential is limitless when powered by IoT. Attendees will learn real-world benefits of WebRTC and explore future possibilities, as WebRTC and IoT intersect to improve customer service.
From telemedicine to smart cars, digital homes and industrial monitoring, the explosive growth of IoT has created exciting new business opportunities for real time calls and messaging. In his session at Internet of @ThingsExpo, Ivelin Ivanov, CEO and Co-Founder of Telestax, will share some of the new revenue sources that IoT created for Restcomm – the open source telephony platform from Telestax. Ivelin Ivanov is a technology entrepreneur who founded Mobicents, an Open Source VoIP Platform, to help create, deploy, and manage applications integrating voice, video and data. He is the co-founder of TeleStax, an Open Source Cloud Communications company that helps the shift from legacy IN/SS7 telco networks to IP-based cloud comms. An early investor in multiple start-ups, he still finds time to code for his companies and contribute to open source projects.
The Internet of Things (IoT) promises to create new business models as significant as those that were inspired by the Internet and the smartphone 20 and 10 years ago. What business, social and practical implications will this phenomenon bring? That's the subject of "Monetizing the Internet of Things: Perspectives from the Front Lines," an e-book released today and available free of charge from Aria Systems, the leading innovator in recurring revenue management.
The Internet of Things will put IT to its ultimate test by creating infinite new opportunities to digitize products and services, generate and analyze new data to improve customer satisfaction, and discover new ways to gain a competitive advantage across nearly every industry. In order to help corporate business units to capitalize on the rapidly evolving IoT opportunities, IT must stand up to a new set of challenges.
There’s Big Data, then there’s really Big Data from the Internet of Things. IoT is evolving to include many data possibilities like new types of event, log and network data. The volumes are enormous, generating tens of billions of logs per day, which raise data challenges. Early IoT deployments are relying heavily on both the cloud and managed service providers to navigate these challenges. In her session at 6th Big Data Expo®, Hannah Smalltree, Director at Treasure Data, to discuss how IoT, Big Data and deployments are processing massive data volumes from wearables, utilities and other machines.
All major researchers estimate there will be tens of billions devices – computers, smartphones, tablets, and sensors – connected to the Internet by 2020. This number will continue to grow at a rapid pace for the next several decades. With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo in Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be!
P2P RTC will impact the landscape of communications, shifting from traditional telephony style communications models to OTT (Over-The-Top) cloud assisted & PaaS (Platform as a Service) communication services. The P2P shift will impact many areas of our lives, from mobile communication, human interactive web services, RTC and telephony infrastructure, user federation, security and privacy implications, business costs, and scalability. In his session at Internet of @ThingsExpo, Erik Lagerway, Co-founder of Hookflash, will walk through the shifting landscape of traditional telephone and voice services to the modern P2P RTC era of OTT cloud assisted services.
While great strides have been made relative to the video aspects of remote collaboration, audio technology has basically stagnated. Typically all audio is mixed to a single monaural stream and emanates from a single point, such as a speakerphone or a speaker associated with a video monitor. This leads to confusion and lack of understanding among participants especially regarding who is actually speaking. Spatial teleconferencing introduces the concept of acoustic spatial separation between conference participants in three dimensional space. This has been shown to significantly improve comprehension and conference efficiency.
The Internet of Things is tied together with a thin strand that is known as time. Coincidentally, at the core of nearly all data analytics is a timestamp. When working with time series data there are a few core principles that everyone should consider, especially across datasets where time is the common boundary. In his session at Internet of @ThingsExpo, Jim Scott, Director of Enterprise Strategy & Architecture at MapR Technologies, will discuss single-value, geo-spatial, and log time series data. By focusing on enterprise applications and the data center, he will use OpenTSDB as an example to explain some of these concepts including when to use different storage models.
SYS-CON Events announced today that Gridstore™, the leader in software-defined storage (SDS) purpose-built for Windows Servers and Hyper-V, will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Gridstore™ is the leader in software-defined storage purpose built for virtualization that is designed to accelerate applications in virtualized environments. Using its patented Server-Side Virtual Controller™ Technology (SVCT) to eliminate the I/O blender effect and accelerate applications Gridstore delivers vmOptimized™ Storage that self-optimizes to each application or VM across both virtual and physical environments. Leveraging a grid architecture, Gridstore delivers the first end-to-end storage QoS to ensure the most important App or VM performance is never compromised. The storage grid, that uses Gridstore’s performance optimized nodes or capacity optimized nodes, starts with as few a...
The Transparent Cloud-computing Consortium (abbreviation: T-Cloud Consortium) will conduct research activities into changes in the computing model as a result of collaboration between "device" and "cloud" and the creation of new value and markets through organic data processing High speed and high quality networks, and dramatic improvements in computer processing capabilities, have greatly changed the nature of applications and made the storing and processing of data on the network commonplace. These technological reforms have not only changed computers and smartphones, but are also changing the data processing model for all information devices. In particular, in the area known as M2M (Machine-To-Machine), there are great expectations that information with a new type of value can be produced using a variety of devices and sensors saving/sharing data via the network and through large-scale cloud-type data processing. This consortium believes that attaching a huge number of devic...
Innodisk is a service-driven provider of industrial embedded flash and DRAM storage products and technologies, with a focus on the enterprise, industrial, aerospace, and defense industries. Innodisk is dedicated to serving their customers and business partners. Quality is vitally important when it comes to industrial embedded flash and DRAM storage products. That’s why Innodisk manufactures all of their products in their own purpose-built memory production facility. In fact, they designed and built their production center to maximize manufacturing efficiency and guarantee the highest quality of our products.
All major researchers estimate there will be tens of billions devices - computers, smartphones, tablets, and sensors - connected to the Internet by 2020. This number will continue to grow at a rapid pace for the next several decades. Over the summer Gartner released its much anticipated annual Hype Cycle report and the big news is that Internet of Things has now replaced Big Data as the most hyped technology. Indeed, we're hearing more and more about this fascinating new technological paradigm. Every other IT news item seems to be about IoT and its implications on the future of digital business.
Can call centers hang up the phones for good? Intuitive Solutions did. WebRTC enabled this contact center provider to eliminate antiquated telephony and desktop phone infrastructure with a pure web-based solution, allowing them to expand beyond brick-and-mortar confines to a home-based agent model. Download Slide Deck: ▸ Here
BSQUARE is a global leader of embedded software solutions. We enable smart connected systems at the device level and beyond that millions use every day and provide actionable data solutions for the growing Internet of Things (IoT) market. We empower our world-class customers with our products, services and solutions to achieve innovation and success. For more information, visit www.bsquare.com.
With the iCloud scandal seemingly in its past, Apple announced new iPhones, updates to iPad and MacBook as well as news on OSX Yosemite. Although consumers will have to wait to get their hands on some of that new stuff, what they can get is the latest release of iOS 8 that Apple made available for most in-market iPhones and iPads. Originally announced at WWDC (Apple’s annual developers conference) in June, iOS 8 seems to spearhead Apple’s newfound focus upon greater integration of their products into everyday tasks, cross-platform mobility and self-monitoring. Before you update your device, here is a look at some of the new features and things you may want to consider from a mobile security perspective.