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manips(3U) InterViews Reference Manual manips(3U)

NAME

ConnectManip, DragManip, ManipGroup, TextManip, VertexManip -Manipulator subclasses for defining common direct-manipulationsemantics

SYNOPSIS

#include <Unidraw/manips.h>

DESCRIPTION

Manipulator is an abstract base class for objects that encapsulate themechanics of direct manipulation. Subclasses support differentmanipulation semantics. The DragManip subclass implements adownclick-drag-upclick style of interaction, with optional constraintson motion (for example, horizontal or vertical only). ConnectManip isa DragManip subclass that adds a gravitational bias towards connectorviews. VertexManip is a DragManip that supports multipledownclick-and-drag interactions terminated by a distinguisheddownclick. TextManip provides a text editing interface. Finally,ManipGroup composes manipulator instances so that their interactionmay proceed concurrently.

DRAGMANIPPUBLICOPERATIONS

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A DragManip uses a rubberband to animate the manipulation. Theconstructor takes the rubberband as a parameter along with the viewerin which it should appear, a transformer reflecting the transformationthat component views undergo in the viewer, the tool that created themanipulator, and a DragConstraint that effectively restricts mousemotion in one or more ways. By default, motion is constrained whenthe Shift key is held down. The second constructor adds two Coordparameters. The DragManip will use these values to override theevent coordinates when Grasp is first called.
DragManip redefines Grasp operation to call the rubberband's Trackoperation, supplying the coordinates in the event. Grasp callsConstrain (described below) on the event prior to passing thecoordinate information. The rubberband will not be drawn until Graspis called.
If the event is a MotionEvent, Manipulating calls Track with theevent's coordinates and returns true. Manipulating simply returns false if the event is an UpEvent. Like DragManip::Grasp, this operation calls Constrain on the event prior to passing the coordinate information.
Effect simply erases the rubberband by calling its Erase operation.
Set and get the various parameters supplied to the DragManip in itsconstructor.
Return the event supplied to the last call to Grasp.

DRAGMANIPPROTECTEDOPERATIONS

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Assign the various constructor values common to both DragManipconstructors.
Constrain the event to reflect the DragConstraint. Theevent coordinates are constrained when the event indicates that theshift key is held down for all DragConstraint values except Gravity,which constrains the coordinates unconditionally with the viewer'sConstrain operation.

CONNECTMANIPPUBLICOPERATIONS

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ConnectManip supports the same type of interaction as DragManip,except the rubberband tracking is affected by a graviational biastowards connector views. Whenever the user drags near a connectorview, the tracking coordinates are suddenly constrained to coincidewith the center of the connector view. The rubberband will not changeits appearance thereafter until the user drags beyond the gravitythreshold, which corresponds to SLOP (see globals(3U)) units beyondthe nearest point on the connector view.
ConnectManip redefines Manipulating to support the gravitationaleffect.
Return the connector view that has captured the rubberband, if any.

VERTEXMANIPPUBLICOPERATIONS

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VertexManip is like DragManip but supports multiple drags and clicksin one manipulation. The VertexManip constructor restricts therubberband to be an instance of GrowingVertices.
This operation is similar to DragManip's, except it calls AppendVertexon the GrowingVertices rubberband on each down-click and returnsfalse if and only if the middle button is pressed.
Return the GrowingVertices instance. Use this operation as analternative to GetRubberband when that operation isn't specific enough.

TEXTMANIPPUBLICOPERATIONS

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Create a TextManip, supplying (at minimum) a viewer, a painter withwhich to draw (usually reflecting graphics attributes defined by theenclosing editor object), and the width of a tab character. Tabcharacters in the text will position the following character at anintegral multiple of tabwidth from the beginning of the line. The distance between baselines in the text can be specified with the second constructor; this value corresponds to the font height by default. These constructors create text manipulators containing no text initially; the lower left corner of the first line of text (including the descender) will be positioned at the coordinates in the event passed to the Grasp operation.
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Create text manipulators initialized with text by passing a buffer oftext and its size. A copy of the buffer is used internally. Thex and y parameters specify the position of the lower left corner of the first line of text (including the descender). These coordinates will override the coordinates specified by the event passed to Grasp.
Positions and draws the text. If the position-specifing constructorswere used to create the instance, then the manipulator will use the eventcoordinates to set the insertion point's position in the text.
Handle keystrokes and/or mouse motion events to support basic textediting. Motion events are interpreted to support text selection;selected text is displayed in reverse colors. The Manipulatingoperation returns false if a downclick is detected outside the text or if HandleKey (described below) returns false.
Effect damages the viewer area that TextManip corrupted duringediting.
Return various parameters specified in the constructor. GetTextreturns a pointer to the internal buffer containing the text;the reference parameter returns the buffer's size.
Return the event supplied to the last call to Grasp.

TEXTMANIPPROTECTEDOPERATIONS

This operation defines TextManip's default key bindings as describedbelow. Unless otherwise noted below, this function returnstrue.

(^P)backward line

(^N)forward line

(^B)backward character

(^F)forward character

(ESC)terminate text entry, causing HandleKey to return false

(^A)beginning of line

(^E)end of line

(^D)delete character

(DEL) (^H)delete backward character

The current selection is bounded by two indices into the text buffer.By convention these indices are called dot and mark. Dot is theposition at which text will be inserted and deleted. Mark locates theend of the selection that moves as the selection is modified. Whenthe selection is empty (an insertion point), dot and mark are equal.
Edit the text buffer at the current selection. InsertText insertscount characters from string after dot. The selection becomes aninsertion point following the newly inserted text. InsertCharacterreplaces the selected characters with a single character. DeleteTextdeletes count characters at dot. If count is positive, the charactersfollowing dot are deleted; if count is negative the characters beforedot are deleted. The selection becomes an insertion point in theplace of the deleted text. DeleteSelection deletes the text betweendot and mark, changing the selection to an insertion point.DeleteCharacter is identical to DeleteText if the dot and mark are notthe same; otherwise it is identical to DeleteSelection.DeleteCharacter provides a convenient way to express the behavior ofthe backspace and delete operations. Finally, DeleteLine deletes theline of text containing mark. The selection becomes an insertionpoint at mark.
Move the current selection forward or backward by the specified numberof the specified units. The default movement is one unit. Theselection is not moved before the beginning of after the end of thetext.
Move the current selection forwards or backwards to the specifiedfeature of the text.
Modify the current selection in terms of text indices. With a singleparameter, Select moves both dot and mark to the specified index.With two parameters, dot and mark can be controlled independently.SelectMore leaves dot unchanged and moves mark. SelectAll sets dot tothe end of the text and mark to the beginning.
Locate returns the text index most closely matching the point(x, y). Contains returns whether the text contains the point (x, y).

MANIPGROUPPUBLICOPERATIONS

Create a ManipGroup, optionally supplying a viewer and a tool.
The Grasp operation simply calls Grasp on each child in insertion order.
Manipulating calls the corresponding operation on each child, skippingthose children that have returned false in previous calls (up to the last Grasp). This function returns false when all children have done so.
ManipGroup's Effect operation calls Effect on each child.
Set and get the ManipGroup's viewer and tool. The set operations setthe ManipGroup's values for these parameters and call thecorresponding operations on their children. The get operations simplyreturn the ManipGroup's values.
Operations for iterating over the ManipGroup's children, if any.First and Last initialize an iterator to point to the beginning andend of the list of children, respectively. Next increments theiterator to point to the following child, while Prev decrements theiterator to point to the preceding child. Done returns whether or notthe iterator points beyond the first or last child in the list.
GetManip returns the child manipulator to which an iterator points.SetManip initializes an iterator to point to a particular child; itinitializes the iterator to point to a nil instance if the givenManipulator is not a child of the ManipGroup.
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Operations for modifying the ManipGroup's list of children. Appendand Prepend add up to four child manipulators, in order, to the endand the beginning of the list, respectively. InsertAfter andInsertBefore insert a child after and before the manipulator pointedto by the iterator, respectively. The Remove operations remove achild from the list (without deleting it). You can remove a child byreferring to it explicitly or by specifying an iterator. If aniterator is supplied, the Remove operation will advance it to point tothe following child as a side effect.

MANIPGROUPPROTECTEDOPERATIONS

ManipGroup stores its children on a UList, which is accessible via the_kids protected member. The Selection's iteration operations store the UList containing the current child in their iterator. Elem is a convenience function for returning the UList to which an iterator points, and Manip extracts the child that a UList element contains.

SEEALSO

Connector(3U), Event(3I), Iterator(3U), Manipulator(3U), Painter(3I),Rubband(3I), Tool(3U), Transformer(3I), UList(3U), Viewer(3U),globals(3U)

1 August 1990 Unidraw