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Coordinate Systems
All coordinates used by the document and graphics objects are given in
the 
document coordinate system. This coordinate system has its
origin in the lower left corner of the page; x increases to the right, y
increases to the top. The unit for these coordinates is the DTP-point
(or PostScript-point), that is, 1/72 inch. Thus Skencil's document
coordinate system is the same as the default coordinate system of a
PostScript interpreter. Coordinates are stored as floats.
The page size is a user settable document property, usually `A4',
`letter' or something similar. Skencil can display the outline of the
page if desired to allow the user to position the drawing on the page.
When displaying the document in a window, the canvas widget (to be more
precise, the graphics device object the canvas uses) converts document
coordinates to 
window coordinates. These are the standard X-Window
coordinates with the origin in the top left corner of the window and x
increasing to the right and y increasing downwards. The unit is 1 pixel.
Skencil defines a few builtin objects to represent and manipulate
coordinates: Points, Rects and Transformations. All of the related
functions, objects and constants are exported by the 
Sketchpackage.
devguide-5.htmlPoint Objects
devguide-6.htmlRect Objects
devguide-7.htmlTransformation Objects
devguide-3.htmlGeneral Remarks devguide.htmlDeveloper's Guide devguide-8.htmlCurve Objects
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