This project is a rewiring and expansion of the pdf viewer library 
for android.

License:
========
LGPL-2.1 

Forked from:
============
The primary source of this project comes from JBlough's 
Android-Pdf-Viewer-Library 
(https://github.com/jblough/Android-Pdf-Viewer-Library)

The secondary source used to expand on this library is Katjas' fork
of the sun pdfrenderer (https://github.com/katjas/PDFrenderer) which
provides improved support for Alternate Colorspace, Function Type4 
(Postscript) and CID font type 0. 


Improvement made:
=================
In this project, the library has been patched primarily to handle 
a subset of small-sized, black-and-white documents with some PS-type 
drawings and some CJK languages. No investigation has been made on its 
performance on color and image documents.

The Function Type4 has been improved to handle postscript commands with
one level of nesting (such as in the case of an IF statement). 

The CID-to-Unicode maps for Japan1, Korea1, CNS1 and GB1 have been added
to the CIDFontType0 support. 

The DroidSansJapanese.ttf is added as a backup font set in cases where 
the pdf document does not provide embedded true fonts for the CJK 
languages. This font set is chosen instead of its improved descendent 
(the DroidSansFallback.ttf) because of memory constraint. 

The CMap Format12 has been added to the library to handle the cmap of
DroidSansJapanese.ttf. 


Other changes made:
===================
As the original library has many areas still incomplete, developers who 
want to use this library may have to modify and debug the source along 
their own project. Some rewiring has been done to make that convenient.

The original pdfviewer library is relocated to the directory "src-pdf".
All supporting library packages including bouncycastle have been 
relocated to this directory.

Two classes in the "src-pdf/pdf/main" directory provide the main access to 
this library: 
- The class Renderer.java is the wrapper class of the whole pdf renderer 
  engine (not to be confused with the PDFRenderer.java inside the library).
- The class SavelogPDF.java allows the logs of this library to be managed 
  collectively with the developer's own project.

Password locking of pdf document has been dropped in the Renderer class. 
Please refer to the primary source to see how to re-enact it if desired.

This pdf viewer library is known to hold up memory and easily causes OOM 
errors on android, because the original sun library was not designed for 
embedded systems. To handle this, hard-references are enforced instead of 
soft-references when setting up the parameters (DEFAULTKEEPCACHES) in 
Renderer.java. However, this means memory needs to be consciously released 
once rendering is done.

Example Application:
====================

An example application is found under com.android.example.pdfRenderer. Its
source code is in the "src" directory and its resources in the "res" directory.
In this sample application, the FileLoader.java class provides a template
on how to call the renderer engine. 

The example application accesses documents in the default Downloads directory
and display the pages as rendered images in a ListView. Lazy loading is 
applied. When a page, P, is called for by the ListView object, the cache is
checked to see if a previously rendered image is available for page P.
If not, the pages in the range P-r to P+r are all rendered and cached,
where r is the number of neighboring pages that can be rendered in the same
batch using the same renderer object. On older machines with less memory, 
set r=0.(OOM errors may still occur if user flings the list).
A cleanup call must be made after a renderer finishes its job.

Every rendered page is cached as a bitmap file before display. In this 
example application, caching is done by simply saving the bitmap in the 
internal directory. A better managed cache (such as the LRU disk cache) 
should be used for real applications.

How to:
=======
To incorporate this library as part of a project under development in Eclipse:
1. Copy only the “src-pdf” directory into project.
2. In Project Properties, add “src-pdf” to the source of Java Build Path.
3. If you want to handle all logs collectively, provide your version of
   Savelog.java in your own project, and make calls to it from 
   “src-pdf/pdf/main/SavelogPDF.java”. A sample of Savelog.java is found in 
   the sample application.
   If you want to use the default Log messages instead, then uncomment them in
   SavelogPDF.java.
4. Use “src-pdf/pdf/main/Renderer.java” as needed.


Known bugs:
===========

1. The PDFParser in the library. is incomplete.
2. Colorspace needs work. Most colored objects are not properly handled.