First Name: Christian Last Name: Haider youtube: https://youtu.be/ehCPF89iruE Title: PDF for Gemstone Type: Talk Abstract: The PDF library PDF4Smalltalk is available in a new version under a new name: PDFtalk. Some of the improvements are: support for bitmap pictures, annotations and the redesign of PDF types. New is also a version for Gemstone. For this purpose, a new “VisualWorks to Gemstone” fileOut library was written. The approach will be presented. Bio: Christian Haider is using Smalltalk since 1992 and never had to leave it since. He experienced large projects as employee and consultant. Since 2002 he works in on "smallCharts", a charting tool for newspapers. 2011 he published a PDF Library for VisualWorks. His interest is in Graphics and User interfaces

1. PDFtalk for Gemstone
Christian Haider

2. PDFtalk
Overview
• News from the PDF library for VisualWorks
• New „PDFtalk for Gemstone“
• New goodie for porting VW code to
Gemstone
„Gemstone Fileout Project“
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3. PDFtalk
PDFtalk – PDF library version 2
• Commercial intent
– More professional support
– End user tools
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4. PDFtalk
Whats new in PDFtalk
• Typing redesigned
• Added basic support for annotations
• (older) support for bitmapped images
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5. PDFtalk
Typing in PDFtalk
• PDF objects are typed
– Some explicitely
– Some implicitely
• (acquired by being in an attribute of an object)
(show)
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6. PDFtalkESUG 2017 6

7. PDFtalk
Typing in PDFtalk
• Advantages of the new typing design
– Aids porting to non-namespace Smalltalks
– Ordinary classes can act as PDF objects
• UndefinedObject, Boolean, Number (to be done)
(show)
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8. PDFtalk
Change for the user
• Instead of using the class itself
Page
• one should use
PDF classAt: #Page
• The implementation classes can be named
different now
• Often used classes can be accessed directly
PDF Dictionary
– Instead of (PDF classAt: #Dictionary)
– the implementation class is now PDFDictionary
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9. PDFtalk
PDFtalk for Gemstone
• Free MIT licence
• Paid work for a HTS
– To create PDFs from a Seaside application
– Using the report tool of Bob Nemec
• Just the server part – no tools or UI
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10. PDFtalk
PDFtalk namespaces in Gemstone
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Globals
PDFtalkLibrary
UserGlobals
Published
PDFtalk Fonts
CFF
OpenType
PDFtalk.Fonts.Type1Font (in VisualWorks)
(PDFtalk at: #Fonts) at: #Type1Font (in Gemstone)
(All PDF objects) (Font objects)
Type1Font
…

11. PDFtalk
Porting challenges
• Learning Gemstone
• Something similar to namespaces
• Different approaches
• Other tools
– No support for namespaces
– No tests
• => Rolled my own
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12. PDFtalk
Porting approach
• Generate Topaz input file from VW
• Based on GLASS (with seaside loaded)
• No changes to the origin
• No compatibility libraries for VW or GS
• Describe the transformation declaritively
only
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13. PDFtalk
Porting Strategy
• File in
– Missing superclasses
– Missing classes for extensions
– Missing referenced classes
– Syntactical differences
• Dotted names
• If(Not)Nil: needs a block
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14. PDFtalk
Porting Strategy II
• Make the tests pass
– Reimplement items depending on VW infrastructure
• Encoders
• Font support
• UninterpretedBytes -> Byte(Read|Write)Stream
– Create common abstractions
• Pragmas
– Understand differences
• Streams (Line end convention (cr / lf)), different
semantics
• Numbers (LargeIntegers, printString of Floats)
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15. PDFtalk
More differences
• Some classes don‘t like #new
• printString is usually different
• Different error class hierarchy
• #thisContext not in Gemstone
• Announcers need to be subclass of Announcer
• Streams: different semantics
• Timestamp: includes offset (time zone) in GS
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16. PDFtalk
Fun Facts I
• Colors
– Representation
• VW: 13 bit per component
• Squeak: 10 bits
– Names
• VW: 31
• GS: 35
• Common: 18
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17. PDFtalk
Fun Facts II
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black
white
red
green
blue
cyan
magenta
yellow
gray
lightGray
veryLightGray
darkGray
veryDarkGray
brown
lightCyan
orange
paleGreen
lightYellow
VW GS VW GS

18. PDFtalk
Fun Facts III
(show)
• Different base dates
– Unix: 1.1.1970
– VW: 1.1.1900
– GS: 1.1.1900 and 1.1.2000
– OpenType: 1.1.1904
• Dont use #fromSeconds: and #asSeconds
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19. PDFtalk
Porting Strategy
• VW is the source
• VW should not change
• Output by transformations
– Add method
– Add system method
– Ignore method
– Replace method
– Rewrite method
(show)
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20. PDFtalk
Gemstone Fileout
• Open source with MIT licence
• Describe the differences as a Value
– Measure of portability
– General transforms
– Specific transforms
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21. PDFtalk
Thank you for your attention!
Questions?
More information at http://wiki.pdftalk.de
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