PNG export of bitmap images

Guide target £1,570

In common with other mainstream operating systems, RISC OS has its own bitmap image format – the Sprite – which it uses for everything from the icons in the Filer to diagrams embedded in a wordprocessing document. Since Sprites are a native image format it can be difficult to share such images with users outside of the RISC OS world, without resorting to lossy JPEG images which are better suited to photographs.

Details

This bounty adds export of the native Sprite to the industry standard Portable Network Graphic image format directly from ChangeFSI and Paint. Since version 1.46 ChangeFSI can already read PNG files and turn them back into Sprites.

• Design of an application interface that can be used by both ChangeFSI and Paint
  • This may take the form of a new module or library, extending an existing module, or direct integration
  • Documentating the new API, in the style of a PRM entry, as text or a wiki page

• Writing the encoder
  • Losslessly converting all currently supported Sprite types
  • Offering at least one compression algorithm in addition to storing uncompressed
  • Adding the standard PNG header and footer tags
  • Optionally added metadata pertinent to the source Sprite

• Integration with the applications
  • In ChangeFSI, both in command line and desktop mode
  • In Paint
  • Updating or extending any existing application documentation

Deliverables

• C source code to any newly created PNG encoder
• Updated C source code to Paint
• Updated BASIC for ChangeFSI
• Revised text for the User Guide, if substantial in nature

Note that at the time of writing the Paint bounty is currently running, so any changes to Paint will need to be carefully combined with that work package.

Donations	2
Total	£450.00
State	Underway
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