|By Amyuni Tech||
|June 1, 2009 12:00 PM EDT||
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
% 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
%end of blue layer
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
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)), (LPCSTR)LayerInfo, 0, NULL ) )
// positive return indicates success
// no error
// error occured, closing a layer when none was open
// memory allocation error (low memory or invalid string)
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.
As more and more data is generated from a variety of connected devices, the need to get insights from this data and predict future behavior and trends is increasingly essential for businesses. Real-time stream processing is needed in a variety of different industries such as Manufacturing, Oil and Gas, Automobile, Finance, Online Retail, Smart Grids, and Healthcare. Azure Stream Analytics is a fully managed distributed stream computation service that provides low latency, scalable processing of streaming data in the cloud with an enterprise grade SLA. It features built-in integration with Azur...
Aug. 28, 2015 07:45 PM EDT Reads: 156
Too often with compelling new technologies market participants become overly enamored with that attractiveness of the technology and neglect underlying business drivers. This tendency, what some call the “newest shiny object syndrome,” is understandable given that virtually all of us are heavily engaged in technology. But it is also mistaken. Without concrete business cases driving its deployment, IoT, like many other technologies before it, will fade into obscurity.
Aug. 28, 2015 06:00 PM EDT Reads: 307
With the proliferation of connected devices underpinning new Internet of Things systems, Brandon Schulz, Director of Luxoft IoT – Retail, will be looking at the transformation of the retail customer experience in brick and mortar stores in his session at @ThingsExpo. Questions he will address include: Will beacons drop to the wayside like QR codes, or be a proximity-based profit driver? How will the customer experience change in stores of all types when everything can be instrumented and analyzed? As an area of investment, how might a retail company move towards an innovation methodolo...
Aug. 28, 2015 05:30 PM EDT Reads: 403
Consumer IoT applications provide data about the user that just doesn’t exist in traditional PC or mobile web applications. This rich data, or “context,” enables the highly personalized consumer experiences that characterize many consumer IoT apps. This same data is also providing brands with unprecedented insight into how their connected products are being used, while, at the same time, powering highly targeted engagement and marketing opportunities. In his session at @ThingsExpo, Nathan Treloar, President and COO of Bebaio, will explore examples of brands transforming their businesses by t...
Aug. 28, 2015 03:45 PM EDT Reads: 167
SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.
Aug. 28, 2015 03:30 PM EDT Reads: 812
A producer of the first smartphones and tablets, presenter Lee M. Williams will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater. In his session at @ThingsExpo, Lee Williams, COO of ETwater, will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater.
Aug. 28, 2015 02:00 PM EDT
SYS-CON Events announced today that Micron Technology, Inc., a global leader in advanced semiconductor systems, will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Micron’s broad portfolio of high-performance memory technologies – including DRAM, NAND and NOR Flash – is the basis for solid state drives, modules, multichip packages and other system solutions. Backed by more than 35 years of technology leadership, Micron's memory solutions enable the world's most innovative computing, consumer,...
Aug. 28, 2015 12:30 PM EDT Reads: 144
SYS-CON Events announced today that Pythian, a global IT services company specializing in helping companies leverage disruptive technologies to optimize revenue-generating systems, has been named “Bronze Sponsor” of SYS-CON's 17th Cloud Expo, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Founded in 1997, Pythian is a global IT services company that helps companies compete by adopting disruptive technologies such as cloud, Big Data, advanced analytics, and DevOps to advance innovation and increase agility. Specializing in designing, imple...
Aug. 28, 2015 12:00 PM EDT Reads: 191
While many app developers are comfortable building apps for the smartphone, there is a whole new world out there. In his session at @ThingsExpo, Narayan Sainaney, Co-founder and CTO of Mojio, will discuss how the business case for connected car apps is growing and, with open platform companies having already done the heavy lifting, there really is no barrier to entry.
Aug. 28, 2015 11:30 AM EDT
As more intelligent IoT applications shift into gear, they’re merging into the ever-increasing traffic flow of the Internet. It won’t be long before we experience bottlenecks, as IoT traffic peaks during rush hours. Organizations that are unprepared will find themselves by the side of the road unable to cross back into the fast lane. As billions of new devices begin to communicate and exchange data – will your infrastructure be scalable enough to handle this new interconnected world?
Aug. 28, 2015 10:00 AM EDT
WebRTC has had a real tough three or four years, and so have those working with it. Only a few short years ago, the development world were excited about WebRTC and proclaiming how awesome it was. You might have played with the technology a couple of years ago, only to find the extra infrastructure requirements were painful to implement and poorly documented. This probably left a bitter taste in your mouth, especially when things went wrong.
Aug. 28, 2015 07:45 AM EDT Reads: 390
Through WebRTC, audio and video communications are being embedded more easily than ever into applications, helping carriers, enterprises and independent software vendors deliver greater functionality to their end users. With today’s business world increasingly focused on outcomes, users’ growing calls for ease of use, and businesses craving smarter, tighter integration, what’s the next step in delivering a richer, more immersive experience? That richer, more fully integrated experience comes about through a Communications Platform as a Service which allows for messaging, screen sharing, video...
Aug. 28, 2015 07:30 AM EDT Reads: 553
SYS-CON Events announced today that IceWarp will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. IceWarp, the leader of cloud and on-premise messaging, delivers secured email, chat, documents, conferencing and collaboration to today's mobile workforce, all in one unified interface
Aug. 28, 2015 03:00 AM EDT Reads: 354
The Internet of Things (IoT) is about the digitization of physical assets including sensors, devices, machines, gateways, and the network. It creates possibilities for significant value creation and new revenue generating business models via data democratization and ubiquitous analytics across IoT networks. The explosion of data in all forms in IoT requires a more robust and broader lens in order to enable smarter timely actions and better outcomes. Business operations become the key driver of IoT applications and projects. Business operations, IT, and data scientists need advanced analytics t...
Aug. 28, 2015 12:30 AM EDT Reads: 345
Akana has announced the availability of the new Akana Healthcare Solution. The API-driven solution helps healthcare organizations accelerate their transition to being secure, digitally interoperable businesses. It leverages the Health Level Seven International Fast Healthcare Interoperability Resources (HL7 FHIR) standard to enable broader business use of medical data. Akana developed the Healthcare Solution in response to healthcare businesses that want to increase electronic, multi-device access to health records while reducing operating costs and complying with government regulations.
Aug. 26, 2015 07:00 AM EDT Reads: 105
For IoT to grow as quickly as analyst firms’ project, a lot is going to fall on developers to quickly bring applications to market. But the lack of a standard development platform threatens to slow growth and make application development more time consuming and costly, much like we’ve seen in the mobile space. In his session at @ThingsExpo, Mike Weiner, Product Manager of the Omega DevCloud with KORE Telematics Inc., discussed the evolving requirements for developers as IoT matures and conducted a live demonstration of how quickly application development can happen when the need to comply wit...
Aug. 2, 2015 11:15 AM EDT Reads: 542
The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.
Aug. 1, 2015 10:00 AM EDT Reads: 472
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Architect for the Internet of Things and Intelligent Systems, described how to revolutionize your archit...
Jul. 30, 2015 07:30 PM EDT Reads: 1,559
MuleSoft has announced the findings of its 2015 Connectivity Benchmark Report on the adoption and business impact of APIs. The findings suggest traditional businesses are quickly evolving into "composable enterprises" built out of hundreds of connected software services, applications and devices. Most are embracing the Internet of Things (IoT) and microservices technologies like Docker. A majority are integrating wearables, like smart watches, and more than half plan to generate revenue with APIs within the next year.
Jul. 30, 2015 02:30 PM EDT Reads: 272
Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Opening Keynote at 16th Cloud Expo, Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, d...
Jul. 30, 2015 12:00 PM EDT Reads: 2,218