#PDF STACKS AND BOX PDF#

I have some debug code in the test build of our PDF library to show such an event and it finally found me a file last week with a stack underflow. Chapter 6: Stacks 1 Chapter 6: Stacks You are familiar with the concept of a stack from many everyday examples. If we cannot get the old value from the stack we could reset the value to the original default settings. We just carry on and use the current value rather than replacing it with the value from the stack.ģ. The software stops and does not display the PDF file.Ģ. Which is one reason why it is the name adopted by the excellent programming question site stackoverflow.īut it does happen so what do you do if you try to get a value from an empty queue – there is nothing in the pile and you try to retrieve a value? There are THREE possible options and I have been looking for examples to see which approach to use:-ġ. This is generally due to software bugs or poor coding – it should not happen. It works perfectly with recursive structures where you can keep pushing and then pulling.īut if you put more values onto the pile than it can hold this is stack overflow, while trying to pull items from an empty stack in stack underflow. It is the opposite of a queue where you join the end and have to wait your turn to reach the front of the queue.Ī common use of a stack in the PDF file format is to save values – you can push a value like the GraphicsState onto the stack, make changes and then retrieve the original by pulling the saved value back off the stack. If you add an item it goes on the top of the pile and it will be the first item retrieved. The PDF format makes extensive use of stacks.Ī stack is like a pile of books. He has an MA in Medieval History and a passion for reading. Mark Stephens Mark has been working with Java and PDF since 1999 and is a big NetBeans fan.

Pdf stacks and box