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releasenotes [2018/08/04 16:04]
christian [Release Notes for PDFtalk 2.0]
releasenotes [2020/02/23 15:42] (current)
christian [CMaps]
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-====== Release Notes for PDFtalk 2.0 ======+====== Release Notes ======
  
-This is the release of the second major version of the PDF library in October 2017.+===== PDFtalk 2.3 =====
  
-===== What's new =====+February 2020 
 +==== PostScript ==== 
 + 
 +Added **[[PostScript]]** to the PDFtalk runtime. 
 + 
 +The package **[PostScript]** implements some low level methods which are used by PDFtalk.  
 + 
 +PostScript was implemented after PDFtalk and used some basic methods of it (Number reading and writing, ASCII85 encoding and PostScript character names). These dependencies have been reversed so that PostScript can be used stand-alone while PDFtalk now depends on it. This also reflects the correct historical relationship. 
 + 
 +==== CMaps ==== 
 + 
 +Added **[[CMap]]** to the **{PDFtalk Fonts}** bundle. 
 + 
 +**CMaps** are PostScript programs defining complex code mappings. The mechanism is very general and allows for variable byte length encodings. Because of its generality, CMaps are used by some PDF writers to even encode simple mappings. Hence, it is necessary to fully implement CMaps in order to decode PDF text. 
 + 
 +This is not intended to be used by the user of the library. Rather, it is part of the basic font infrastructure enabling decoding of PDF strings. This will be the base for Text extraction in the next step. 
 + 
 +=== Standard CMaps === 
 + 
 +PDF defines 181 standard CMaps which are to be understood by a conforming reader. These CMaps are available at GitHub(([[https://​github.com/​adobe-type-tools/​cmap-resources]] Standard CMaps from Adobe)). All maps have been imported as methods containing the source of the CMaps. Since they are rather large (16 MB with sources), it might be important to not load them into a runtime image when you don't need them, i.e. do text extraction in your application. 
 + 
 +Therefore, I put them into a seperate package (outside of the runtime, but part of the project bundle): **[PostScript CMap instances]**. The CMaps are constructed from the source methods lazily when needed. If the package is not loaded, the source of a requested CMap is downloaded from GitHub, which is slower. 
 + 
 +=== Known problem === 
 + 
 +The PDF specification allows bfchar-mappings to have a string of UTF-16BE characters as destination. This is not yet implemented. 
 + 
 +==== Typing ==== 
 + 
 +=== Allow narrower types to shadow broader types === 
 + 
 +Example: 
 +<code smalltalk>​ 
 +DecodeParms 
 + <type: #​ZipFilterParameter>​ 
 + <type: #​Dictionary>​ 
 +</​code>​ 
 + 
 +''​ZipFilterParameter''​ is a subtype of ''​Dictionary''​. Because it is declared before, it is tried to match it first. Before, both alternatives were equal and ''​Dictionary''​ might have matched, even when the dictionary was a valid ''​ZipFilterParameter''​. 
 + 
 +=== Generalized ''​Textstring''​ to ''​String''​ === 
 + 
 +Textstring does not need to be differenciated. We can rely on VisualWorks handling of multi byte strings. 
 + 
 +===== PDFtalk 2.2 ===== 
 + 
 +August 2019 
 + 
 +Renamed ''​OrderedDictionary''​ to ''​Valuemap''​ in the **[Values]** package. 
 +This version replaces all references of ''​OrderedDictionary''​. 
 + 
 +PDFtalk now depends on the **[Values]** package with version 3.x and up and is incompatible the earlier versions. 
 + 
 +===== PDFtalk 2.1 ===== 
 + 
 +July 2019 
 + 
 +Flate encoding is using zlib of VW 8.1 now. 
 +This solved problems allocating buffers under heavy load 
 +===== PDFtalk 2.0 ===== 
 + 
 +October 2017 
 + 
 +==== What's new ====
  
 **Name** The new name is //​**PDFtalk**//​. The first version was called //​PDF4Smalltalk//​. The namespace changed from ''​PDF''​ to ''​PDFtalk''​ and the domain "​pdftalk.de"​ provides a home with a wiki dedicated to the library: [[https://​wiki.pdftalk.de|wiki.pdftalk.de]]. **Name** The new name is //​**PDFtalk**//​. The first version was called //​PDF4Smalltalk//​. The namespace changed from ''​PDF''​ to ''​PDFtalk''​ and the domain "​pdftalk.de"​ provides a home with a wiki dedicated to the library: [[https://​wiki.pdftalk.de|wiki.pdftalk.de]].
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 Both new projects are open source with MIT licence. Both new projects are open source with MIT licence.
-===== Changes for users of the library ​=====+==== Changes for users of the library ====
  
 Some changes are incompatible with the previous version, which are described here. Some changes are incompatible with the previous version, which are described here.
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 It is not recommended to load the new version into an image with the old version of the library. It is not recommended to load the new version into an image with the old version of the library.
  
-==== Namespace and bundle structure ​====+=== Namespace and bundle structure ===
  
 The former namespace //PDF// is renamed to **''​PDFtalk''​**. The former namespace //PDF// is renamed to **''​PDFtalk''​**.
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 to see if they are running. You may need to edit the file path to the PDF specification and to your demo directory. to see if they are running. You may need to edit the file path to the PDF specification and to your demo directory.
  
-==== Referencing PDF classes ​====+=== Referencing PDF classes ===
  
 Smalltalk classes representing a PDF type should not be referenced directly anymore. Instead an expression like Smalltalk classes representing a PDF type should not be referenced directly anymore. Instead an expression like
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   - The Smalltalk class name may differ in different ports of the library.   - The Smalltalk class name may differ in different ports of the library.
  
-==== New shared Smalltalk.PDF ​====+=== New shared Smalltalk.PDF ===
  
 The shared variable **''​PDF''​** was added to the Smalltalk namespace. The variable holds the class **''​PDFtalk.PDF''​** which serves as general entry point for the library. The shared variable **''​PDF''​** was added to the Smalltalk namespace. The variable holds the class **''​PDFtalk.PDF''​** which serves as general entry point for the library.
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 Unless you extend the library, there should be no need to add the PDFtalk namespace to the imports of your project. Instead most functionality should be accessed through **''​PDF''​** in the Smalltalk namespace. Unless you extend the library, there should be no need to add the PDFtalk namespace to the imports of your project. Instead most functionality should be accessed through **''​PDF''​** in the Smalltalk namespace.
  
-==== Aligned types ====+=== Aligned types ===
  
 The new typing system allowed to remove the PDF classes **''​Null''​** and **''​Boolean''​**. Instead, they are now implemented by the system classes **''​UndefinedObject''​** and **''​Boolean''​**. The new typing system allowed to remove the PDF classes **''​Null''​** and **''​Boolean''​**. Instead, they are now implemented by the system classes **''​UndefinedObject''​** and **''​Boolean''​**.
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 The work is not finished yet. **''​Number''​** and maybe **''​String''​** and **''​Date''​** could be aligned as well. The work is not finished yet. **''​Number''​** and maybe **''​String''​** and **''​Date''​** could be aligned as well.
-===== Typing redesign ​=====+==== Typing redesign ====
  
 The major change is the redesign of the [[newtyping|PDF typing system]]. Initially, I represented the types of PDF objects by Smalltalk classes with the same name. This turned out to be not sufficient. ​ The major change is the redesign of the [[newtyping|PDF typing system]]. Initially, I represented the types of PDF objects by Smalltalk classes with the same name. This turned out to be not sufficient. ​
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 Therefore, PDF types are now modeled independently. Therefore, PDF types are now modeled independently.
-==== Notes ====+=== Notes ===
  
-=== Specialization only on assignment ​===+== Specialization only on assignment ==
  
 When PDF objects were created, all classes were searched for possible specializations:​ for example, a Dictionary with a #Type entry was automatically converted to its corresponding class. When PDF objects were created, all classes were searched for possible specializations:​ for example, a Dictionary with a #Type entry was automatically converted to its corresponding class.
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 In the new version, objects are only typed and specialized when they are assigned to an attribute of a Dictionary or Array. In the new version, objects are only typed and specialized when they are assigned to an attribute of a Dictionary or Array.
  
-=== System classes as PDF classes===+== System classes as PDF classes ==
  
 The first version had wrappers for all basic types of PDF, such as null, booleans, numbers etc.. This is similar to boxing of primitive types in other programming languages. The first version had wrappers for all basic types of PDF, such as null, booleans, numbers etc.. This is similar to boxing of primitive types in other programming languages.
releasenotes.1533391477.txt.gz · Last modified: 2018/08/04 16:04 by christian