21 canvas - Controlling output file and format

 

class canvas.T
Canvas is an object that corresponds to a single output file. It provides a set of methods for drawing lines, polygons, texts, and other things in a manner independent of the file's format. Canvas is usually hidden from the user, as PyChart creates a "default" canvas when it starts up and implicitly writes all charts on the default canvas (unless the user specifies otherwise; more on that later). There are some occasions, however, in which you might want to manipulate a canvas explicitly, e.g., when you want to create multiple graphs from a single file, or you just want to add lines and texts directly.

Class canvas.T is an abstract base class. PyChart provides several subclasses that correspond to specific file formats. For example, pscanvas.T implements methods for PostScript output. Class pdfcanvas.T implements methods for PDF output.  format


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