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LinkComp(3U) InterViews Reference Manual LinkComp(3U)


LinkComp, LinkView, PSLink - component subject, view, and PostScript external representation for lines with connectable endpoints


#include <Unidraw/Components/link.h>


LinkComp is a GraphicComp defining a line with two pins on each end. The line's endpoints will always coincide with the pins, even if they are moved, thereby maintaining a graphical link between the objects to which it is connected. LinkComp uses an Line graphic to define its initial geometry and graphical attributes. LinkView is a GraphicView for displaying the link. PSLink is a PostScriptView that externalizes the subject's information in PostScript form.


The constructor takes an optional line graphic to define its initial appearance.
In addition to (un)interpreting the commands GraphicComp (un)interprets, LinkComp also (un)interprets DeleteCmd and CutCmd by passing these commands to its pins for (un)interpretation.
When the LinkComp's pins move to maintain connectivity, LinkComp will reorient the line so that its endpoints and the pins coincide.
LinkComp redefines GraphicComp's traversal operations to make its pins accessible to the Unidraw library. Thus Unidraw can determine the connectors that belong to the component and call its Update operation only once for efficiency. The traversal does not include the line.
Return the Line graphic that defines the link's attributes. GetLine is simply a more specific form of the GetGraphic operation.
Return the LinkView's pins, which are stored in the _conn1 and _conn2 protected members.


Create an LinkView, optionally supplying the subject.
LinkView redefines its response to manipulation with a GraphicCompTool. The user clicks to specify the first endpoint of the link and then drags to position the remaining endpoint. (Up)clicking on an existing connector will establish a connection between it and the LinkComp's first (second) pin. LinkView uses a ConnectManip to produce a gravitational attraction between existing connectors and the second pin as the user drags to position it. The endpoints will not be constrained by gravity. LinkView will use ConnectCmds to connect the pin(s) to their target(s). Pin(s) connected in this way will receive floating mobility; unconnected pin(s) will be fixed.
LinkView redefines GraphicView's traversal operations to make its pins accessible to the Unidraw library. Thus Unidraw can determine the connectors that belong to the component, for example, to support ConnectManip's gravitational attraction effect.
Return the link's endpoints, in canvas coordinates.
Return the subject.


LinkView redefines CreateHandles to use a RubberHandles object with two handles, one at each endpoint of the link.
Return the line that LinkView draws between its pins.
A helper function that creates a LinkComp subject with the given line graphic. This function produces the proper subject when the GraphicCompTool's manipulator is interpreted. Subclasses can redefine this operation to return a LinkComp subclass, thus eliminating the need to reimplement InterpretManipulator.
Helper functions that CreateManipulator and InterpretManipulator use to create and interpret the manipulator for GraphicCompTool.


Construct a PostScript external representation of the given subject, if any.


Event(3I), Graphic(3U), GraphicComp(3U), GraphicCompTool(3U), GraphicView(3U), Grid(3U), PinComp(3U), PostScriptView(3U), Transformer(3I), align(3U), edit(3U), manips(3U)

22 January 1991 Unidraw