This structure provides the gate of canvas editors.
A canvas editor gate allows the control of a complex graphic display. The design of the canvas editor gate is mostly oriented towards the Tk canvas widget (credits to the author).
List of Import References :
See BOOL
See BTUnion
See Char
See Com
See DENOTATION
See Int
See Nat
See Option
See Pair
See Real
See Seq
See Set
See String
See Void
See WinConfig
See WinEvent
See WinInternal
See WinTag
See WinTclTk
SIGNATURE WinCanvasEditor
$Date: 2010-09-30 18:24:17 +0200 (Do, 30. Sep 2010) $ ($Revision: 616 $)
IMPORT Nat ONLY nat
Real ONLY real
Void ONLY void
String ONLY string
Seq[point] ONLY seq
Set[tag, <] ONLY set
Pair[point,point] ONLY pair
IMPORT Com[tag] ONLY com
Com[void] ONLY com
Com[string] ONLY com ans:SORT
Com[ans[string]] ONLY com
Com[set[tag,<]] ONLY com
Com[canvasEditor] ONLY com
Com[pair[point,point]] ONLY com
IMPORT WinInternal ONLY view : SORT tag : SORT config : SORT
WinConfig ONLY
point : SORT
color : SORT
bitmap : SORT
WinTag ONLY < : tag ** tag -> bool
WinEvent ONLY event : SORT
eventInfo : SORT
A new canvas editor is constructed with the command below:
SORT canvasEditor FUN canvasEditor : com[canvasEditor]
A canvas editor is attached to a view with the configuration below:
FUN edit : canvasEditor -> config
At one time, one editor may be attached to only one view. Subsequent
applications of the editor configuration cancel the use of the
editor for previous views.
Currently, only canvas views (see WinCanvas) may have attached a canvas editor.
Note that any commands on canvas editors are disabled (i.e. will block) as long as the canvas editor is not attached to a view which is beeing displayed in a window. To execute e.g. a sequence of initialization commands on a canvas editor at a time a view isn't yet attached or displayed, an agent may be spawn; the commands will be executed as soon as the view will be displayed.
Each drawing item of a canvas has an associated set of tags which is defined via a configuration (see section about Drawings below). A single tag is used to adress drawing elements in most canvas editor commands. The commands interpret the tags in one of two ways: either they operate on all drawing items which have the given tag or tags, or they operate on the first item in the display list which has the given tag. Hereby, the order of the display list reflects the layering of drawings: a drawing item below another one comes first in the display list.
Beside of user defined tags attached to drawing items via configurations, each item also has a unique basic tag which is automatically assigned to it at creation time. The commands below identify the basic tags of items in serveral ways:
FUN withTag : canvasEditor ** tag -> com[set[tag, <]] FUN above : canvasEditor ** tag -> com[tag] FUN below : canvasEditor ** tag -> com[tag] FUN closest : canvasEditor ** point -> com[tag] FUN closest : canvasEditor ** point ** real -> com[tag] FUN enclosed : canvasEditor ** point ** point -> com[set[tag, <]] FUN overlapping : canvasEditor ** point ** point -> com[set[tag, <]]
The command withTag(Tag) returns the set of basic tags of all
drawing items which have the given tag. (This command is a kind of
idempotent.)
The command above(Tag) returns the basic tag of the item which is
displayed above of the first item which has Tag. Similar, the
command below behaves.
The command closest(Pt) return the basic tag of the item
which is closest to the given point. In the version with a real argument,
the distance of items which are considered to be close enough
is specified (in millimeters). If several items are close enough, the
first one in the display list is chosen.
The command enclosed(Pt1, Pt2) returns the basic tags of all
items which are completely enclosed in the rectangle specified by the
pair of points. The command overlapping(Pt1, Pt2) returns the basic
tags of all items which overlap the given rectangle.
The following tags have a predefined meaning in canvas editors:
FUN all : tag FUN current : tag
The tag all is associated with all drawing items. The tag
current is automatically maintained such that it is associated with
the drawing item currently below the pointer position.
The following commands allow to display drawings and to modify them when they are displayed.
FUN display : canvasEditor ** drawing -> com[void] FUN delete : canvasEditor ** tag -> com[void] FUN set : canvasEditor ** tag ** config -> com[void] FUN move : canvasEditor ** tag ** point -> com[void] FUN scale : canvasEditor ** tag ** point ** real ** real -> com[void] FUN lower : canvasEditor ** tag -> com[void] FUN raise : canvasEditor ** tag -> com[void] FUN focus : canvasEditor ** tag -> com[void] FUN bbox : canvasEditor ** tag -> com[pair[point,point]]
The command displays displays the given drawing. The command
delete removes all drawing items which have the given tag.
The command set assigns a configuration to all drawing items which
have the given tag.
See the section about individual drawing items for which
configurations are sensitive. Note that if the configuration entails
a dynamic behaviour, such as the binding of an event or the connection to
a regulator, then not only items currently associated with the given tag
are addressed, but also all items which will be associated in the future
with this tag.
The command move moves each of the drawing items which have
the given tag by the relative distance specified by the given point.
The command Ed scale (Tag, Origin, XScale, YScale) scales all drawing
items with the given tag: the distance of each indivudal coordinate in
the drawing item to the Origin point is scaled by the given
scaling factors (where a factor of 1.0 specifies no change).
The command lower and raise change the display order
of items.
The command focus assigns the keyboard focus to the first
item with the given tag.
The command bbox returns a rectangle which solely encloses all items
which have the given tag.
Missing: select, postscript, canvasx, canvasy. Text insertion should be via a textEditor gate.
A drawing is an object with the possibility of being displayed through a canvas editor. Drawings are quite similar to views: basic drawings items such as lines, polygons and so on are configured and combined into new drawings.
SORT drawing
FUN with : drawing ** config -> drawing
FUN ++ : drawing ** drawing -> drawing
FUN {} : drawing
The coordinates of the elements of a given drawing may be moved by the function below:
FUN move : drawing ** point -> drawing
The following basic drawing items are supplied:
FUN line : seq[point] -> drawing FUN arc : point ** point -> drawing FUN pie : point ** point -> drawing FUN chord : point ** point -> drawing FUN rectangle : point ** point -> drawing FUN oval : point ** point -> drawing FUN polygon : seq[point] -> drawing FUN text : point -> drawing FUN bitmap : point -> drawing FUN image : point -> drawing FUN view : point ** view -> drawing
To each drawing item, one or more tags may be attached with the configurations below:
FUN tag : tag -> config FUN tags : set[tag, <] -> config FUN addTag : tag -> config FUN addTags : set[tag, <] -> config
Furthermore, each drawing item may have attached one of the following configurations:
bind regulate sync
FUN arrow : arrowWhere -> config TYPE arrowWhere == none first last both FUN arrowShape : real ** real ** real -> config FUN lineWidth : real -> config FUN cap : capStyle -> config TYPE capStyle == butt projecting round FUN join : joinStyle -> config TYPE joinStyle == bevel miter round FUN smooth : bool -> config FUN splineSteps : nat -> config
FUN start : real -> config FUN extent : real -> config FUN slice : real ** real -> config
FUN fill : color -> config FUN outline : color -> config FUN outlineStipple : bitmap -> config
FUN justify : justifyHow -> config TYPE justifyHow == left right center
Currently, the providing level of a canvas editor is completely oriented
towards Tk canvases. The command register(Win, Wid) registers
the Tk canvas widget Wid displayed by window Win to
be edited by the given canvas editor. Any previous registration is
discarded.
IMPORT WinInternal ONLY window:SORT
WinTclTk ONLY widget:SORT
FUN register : canvasEditor ** window ** widget -> com[void]
next node: Windows,
prev node: WinSelector,
up to node: Subsystem Opal Windows