canvas::edit::polyline - Editing a polyline on a canvas
This package provides a class whose instances handle editing a single poly-line on a canvas. Instances can be configured with regard to the visual appearance (regular, and highlighted) of the markers denoting the line's vertices. Note that instances do not store the edited polyline themselves, but delegate this to a configurable object.
This, the class command, creates and configures a new instance of a polyline editor, named objectName. The instance will be connected to the specified canvas widget.
The result of the command is the fully qualified name of the instance command.
The options accepted here, and their values, are explained in the section Options.
Instances of the polyline editors provide the following API:
This method destroys the polyline editor and releases all its internal resources.
Note that this operation does not destroy the items the editor managed on the attached canvas, nor the canvas itself.
The result of the method is an empty string.
This method activates editing of the polyline on the canvas. This is the default after instance creation. A call is ignored if the editor is already active.
The result of the method is an empty string.
The complementary method is disable. The interogatory method for the current state is active.
This method disables editing of the polyline on the canvas. A call is ignored if the editor is already disabled.
The result of the method is an empty string.
The complementary method is enable. The interogatory method for the current state is active.
This method queries the editor state.
The result of the method is a boolean value, true if the editor is active, and false otherwise, i.e. disabled.
The methods to change the state are enable and disable.
This method programmatically adds a vertex at the specified location to the line.
The result of the method is an empty string.
Note that this method goes through the whole set of callbacks invoked when the user interactively creates a vertex, i.e. -create-cmd, and, more importantly, -data-cmd.
One important difference however. The new vertex is always added at the end of the line, whereas interactive creation uses heuristics to splice it into the line at a suitable location.
This is the method through which to load the vertices of a pre-existing line into an editor instance.
This method programmatically removes all vertices from the editor, essentially removing the whole line.
The result of the method is an empty string.
Note that this method goes through the same callbacks invoked when the user interactively removes a vertex, i.e. -data-cmd.
The class command accepts the following options
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category canvas of the Tklib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.