Horrible notes on PDF

[ipdf/sam.git] / chapters / Background.tex

diff --git a/chapters/Background.tex b/chapters/Background.tex
index 87d18ce..f11c1be 100644 (file)
--- a/chapters/Background.tex
+++ b/chapters/Background.tex
@@ -99,6 +99,30 @@ In this section we will consider various approaches and motivations to specifyin
 
 \subsection{The Portable Document Format}
 
+``A PDF file should be thought of as a flattened representation of a data structure
+consisting of a collection of objects that can refer to each other in any arbitrary
+way.''
+
+The PDF 1.7 standard describes a format which is \rephrase{essentially PostScript plus everything in the kitchen sink}.
+\begin{itemize}
+       \item PDF is not just crippled postscript
+       \item Objects - has a type system, like a programming language, not like the DOM where all objects are fundamentally the same - this is similar to PostScript
+       \item File structure - Header, body, reference table (location of objects in file), trailer (location of reference table and special objects)
+       \begin{itemize}
+               \item Read the file from the end
+               \item File can be updated incrementally as long as the trailer is at the end
+       \end{itemize}
+       \item Document structure - This is basically a graph, wheras the DOM is a tree
+       \item Content streams - objects but conceptually different - operators or instructions
+       \item Interactivity --- At this point, PDF suddenly changes from being PostScript to being XML
+       \begin{itemize}
+               \item 
+       \end{itemize}
+\end{itemize}
+
+The biggest difference between the PDF design philosophy and the HTML5 philosophy is the emphasis in PDF on the actual file format.
+This means PDF is more complicated but also more efficient (at least, we would hope so).
+
 
 \subsection{Scientific Computation Packages}