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diff --git a/man/9/canvas b/man/9/canvas new file mode 100644 index 00000000..6941cba0 --- /dev/null +++ b/man/9/canvas @@ -0,0 +1,1358 @@ +.TH CANVAS 9 +.SH NAME +canvas \- Create and manipulate canvas widgets +.SH SYNOPSIS +\f5canvas\fI \fIpathName \fR?\fIoptions\fR? +.SH STANDARD OPTIONS +.EX +-background -selectbackground -takefocus +-borderwidth -selectborderwidth -xscrollcommand +-relief -selectforeground -yscrollcommand +.EE +.SH "WIDGET-SPECIFIC OPTIONS" +.TP +.B -closeenough \fIdist\fP +Specifies a floating-point value indicating how close the mouse cursor +must be to an item before it is considered to be ``inside'' the item. +Defaults to 1.0. +.TP +.B -confine \fIboolean\fP +Specifies a boolean value that indicates whether or not it should be +allowable to set the canvas's view outside the region defined by the +\f5scrollRegion\fR argument. +Defaults to true, which means that the view will +be constrained within the scroll region. +.TP +.B -height \fIdist\fP +Specifies a desired window height that the canvas widget should request from +its geometry manager. The value may be specified in any +of the forms described in the COORDINATES section below. +.TP +.B -scrollregion \fIlist\fP +Specifies a list with four \fIdist\fP coordinates describing the left, top, right, and +bottom coordinates of a rectangular region. +This region is used for scrolling purposes and is considered to be +the boundary of the information in the canvas. +Each of the coordinates may be specified +in any of the forms given in the COORDINATES section below. +.TP +.B -width \fIdist\fP +Specifies a desired window width that the canvas widget should request from +its geometry manager. The value may be specified in any +of the forms described in the COORDINATES section below. +.br +.TP +.B -xscrollincrement \fIdist\fP +Specifies an increment for horizontal scrolling, in any of the usual forms +permitted for screen distances. If the value of this option is greater +than zero, the horizontal view in the window will be constrained so that +the canvas x coordinate at the left edge of the window is always an even +multiple of \f5xscrollicrement\fR; furthermore, the units for scrolling +(e.g., the change in view when the left and right arrows of a scrollbar +are selected) will also be \f5xscrollicrement\fR. If the value of +this option is less than or equal to zero, then horizontal scrolling +is unconstrained. +.TP +.B -yscrollincrement \fIdist\fP +Specifies an increment for vertical scrolling, in any of the usual forms +permitted for screen distances. If the value of this option is greater +than zero, the vertical view in the window will be constrained so that +the canvas y coordinate at the top edge of the window is always an even +multiple of \f5yscrollicrement\fR; furthermore, the units for scrolling +(e.g., the change in view when the top and bottom arrows of a scrollbar +are selected) will also be \f5yscrollicrement\fR. If the value of +this option is less than or equal to zero, then vertical scrolling +is unconstrained. +.TP +.B -buffer \fIwhat\fP +Specifies how much of the canvas region will be +backed by an offscreen bitmap buffer. +\fIWhat\fP can be one of \f5all\fP (the entire scroll region +will be buffered), \f5visible\fP (only the visible area), \f5none\fP +(no buffering) or \f5auto\fP (equivalent to either \f5none\fP +or \f5visible\fP depending on whether the canvas is packed inside +another canvas or not). + +.SH INTRODUCTION +The \f5canvas\fR command creates a new window (given +by the \fIpathName\fR argument) and makes it into a canvas widget. +Additional options, described above, may be specified on the +command line +to configure aspects of the canvas such as its colours and 3-D relief. +The \f5canvas\fR command returns its +\fIpathName\fR argument. At the time this command is invoked, +there must not exist a window named \fIpathName\fR. +.PP +Canvas widgets implement structured graphics. +A canvas displays any number of \fIitems\fR, which may be things like +rectangles, circles, lines, and text. +Items may be manipulated (e.g. moved or re-coloured) and commands may +be associated with items in much the same way that the \f5bind\fR +command allows commands to be bound to widgets. For example, +a particular command may be associated with the <Button-1> event +so that the command is invoked whenever button 1 is pressed with +the mouse cursor over an item. +This means that items in a canvas can have behaviours defined by +the Tk scripts bound to them. + +.SH "DISPLAY LIST" +The items in a canvas are ordered for purposes of display, +with the first item in the display list being displayed +first, followed by the next item in the list, and so on. +Items later in the display list obscure those that are +earlier in the display list and are sometimes referred to +as being ``on top'' of earlier items. +When a new item is created it is placed at the end of the +display list, on top of everything else. +Widget commands may be used to re-arrange the order of the +display list. + +.SH "ITEM IDS AND TAGS" +Items in a canvas widget may be named in either of two ways: +by id or by tag. +Each item has a unique identifying number which is assigned to +that item when it is created. The id of an item never changes +and id numbers are never re-used within the lifetime of a +canvas widget. +.PP +Each item may also have any number of \fItags\fR associated +with it. A tag is just a string of characters, and it may +take any form except that of an integer. +For example, ``x123'' is OK but ``123'' isn't. +The same tag may be associated with many different items. +This is commonly done to group items in various interesting +ways; for example, all selected items might be given the +tag ``selected''. +.PP +The tag \f5all\fR is implicitly associated with every item +in the canvas; it may be used to invoke operations on +all the items in the canvas. +.PP +The tag \f5current\fR is managed automatically by Tk; +it applies to the \fIcurrent item\fR, which is the +topmost item whose drawn area covers the position of +the mouse cursor. +If the mouse is not in the canvas widget or is not over +an item, then no item has the \f5current\fR tag. +.PP +When specifying items in canvas widget commands, if the +specifier is an integer then it is assumed to refer to +the single item with that id. +If the specifier is not an integer, then it is assumed to +refer to all of the items in the canvas that have a tag +matching the specifier. +The symbol \fItagOrId\fR is used below to indicate that +an argument specifies either an id that selects a single +item or a tag that selects zero or more items. +Some widget commands only operate on a single item at a +time; if \fItagOrId\fR is specified in a way that +names multiple items, then the normal behaviour is for +the command to use the first (lowest) of these items in +the display list that is suitable for the command. +Exceptions are noted in the widget command descriptions +below. +.SH COORDINATES +All coordinates related to canvases are stored as fixed-point +numbers. +Coordinates and distances are specified as documented +in the +.I dist +section of +.IR types (9). +.SH TRANSFORMATIONS +Normally the origin of the canvas coordinate system is at the +upper-left corner of the window containing the canvas. +It is possible to adjust the origin of the canvas +coordinate system relative to the origin of the window using the +\f5xview\fR and \f5yview\fR widget commands; this is typically used +for scrolling. +Canvases do not support scaling or rotation of the canvas coordinate +system relative to the window coordinate system. +.PP +Individual items may be moved or scaled using widget commands +described below, but they may not be rotated. + +.SH INDICES +Text items support the notion of an \fIindex\fR for identifying +particular positions within the item. +Indices are used for commands such as inserting text, deleting +a range of characters, and setting the insertion cursor position. +An index may be specified in any of a number of ways, and +different types of items may support different forms for +specifying indices. +Text items support the following forms for an index. +Note that it is possible to refer to the character just after +the last one in the text item; this is necessary for such +tasks as inserting new text at the end of the item. +.TP 10 +\fInumber\fR +A decimal number giving the position of the desired character +within the text item. +0 refers to the first character, 1 to the next character, and +so on. +A number less than 0 is treated as if it were zero, and a +number greater than the length of the text item is treated +as if it were equal to the length of the text item. +.TP 10 +\f5end\fR +Refers to the character just after the last one in the item +(same as the number of characters in the item). +.TP 10 +\f5insert\fR +Refers to the character just before which the insertion cursor +is drawn in this item. +.TP 10 +\f5sel.first\fR +Refers to the first selected character in the item. +If the selection isn't in this item then this form is illegal. +.TP 10 +\f5sel.last\fR +Refers to the last selected character in the item. +If the selection isn't in this item then this form is illegal. +.TP 10 +\f5@\fIx,y\fR +Refers to the character at the point given by \fIx\fR and +\fIy\fR, where \fIx\fR and \fIy\fR are specified in the coordinate +system of the canvas. +If \fIx\fR and \fIy\fR lie outside the coordinates covered by the +text item, then they refer to the first or last character in the +line that is closest to the given point. + +.SH "WIDGET COMMAND" +The \f5canvas\fR command creates a new Tk command whose +name is \fIpathName\fR. This +command may be used to invoke various +operations on the widget. It has the following general form: +.RS +.EX +\fIpathName option \fR?\fIarg arg ...\fR? +.EE +.RE +\fIOption\fR and the \fIarg\fRs +determine the exact behaviour of the command. +The following widget commands are possible for canvas widgets: +.TP +\fIpathName \f5addtag \fItag searchSpec \fR?\fIarg arg ...\fR? +For each item that meets the constraints specified by +\fIsearchSpec\fR and the \fIarg\fRs, add +\fItag\fR to the list of tags associated with the item if it +isn't already present on that list. +It is possible that no items will satisfy the constraints +given by \fIsearchSpec and \fIarg\fRs, in which case the +command has no effect. +This command returns an empty string as result. +\fISearchSpec\fR and \fIarg\fR's may take any of the following +forms: +.RS +.TP +\f5above \fItagOrId\fR +Selects the item just after (above) the one given by \fItagOrId\fR +in the display list. +If \fItagOrId\fR denotes more than one item, then the last (topmost) +of these items in the display list is used. +.TP +\f5all\fR +Selects all the items in the canvas. +.TP +\f5below \fItagOrId\fR +Selects the item just before (below) the one given by \fItagOrId\fR +in the display list. +If \fItagOrId\fR denotes more than one item, then the first (lowest) +of these items in the display list is used. +.TP +\f5closest \fIx y \fR?\fIhalo\fR? ?\fIstart\fR? +Selects the item closest to the point given by \fIx\fR and \fIy\fR. +If more than one item is at the same closest distance (e.g. two +items overlap the point), then the top-most of these items (the +last one in the display list) is used. +If \fIhalo\fR is specified, then it must be a non-negative +value. +Any item closer than \fIhalo\fR to the point is considered to +overlap it. +The \fIstart\fR argument may be used to step circularly through +all the closest items. +If \fIstart\fR is specified, it names an item using a tag or id +(if by tag, it selects the first item in the display list with +the given tag). +Instead of selecting the topmost closest item, this form will +select the topmost closest item that is below \fIstart\fR in +the display list; if no such item exists, then the selection +behaves as if the \fIstart\fR argument had not been specified. +.TP +\f5enclosed\fR \fIx1\fR \fIy1\fR \fIx2\fR \fIy2\fR +Selects all the items completely enclosed within the rectangular +region given by \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR. +\fIX1\fR must be no greater then \fIx2\fR and \fIy1\fR must be +no greater than \fIy2\fR. +.TP +\f5overlapping\fR \fIx1\fR \fIy1\fR \fIx2\fR \fIy2\fR +Selects all the items that overlap or are enclosed within the +rectangular region given by \fIx1\fR, \fIy1\fR, \fIx2\fR, +and \fIy2\fR. +\fIX1\fR must be no greater then \fIx2\fR and \fIy1\fR must be +no greater than \fIy2\fR. +.TP +\f5withtag \fItagOrId\fR +Selects all the items given by \fItagOrId\fR. +.RE +.TP +\fIpathName \f5bbox \fItagOrId\fR ?\fItagOrId tagOrId ...\fR? +Returns a list with four elements giving an approximate bounding box +for all the items named by the \fItagOrId\fR arguments. +The list has the form ``\fIx1 y1 x2 y2\fR'' such that the drawn +areas of all the named elements are within the region bounded by +\fIx1\fR on the left, \fIx2\fR on the right, \fIy1\fR on the top, +and \fIy2\fR on the bottom. +The return value may overestimate the actual bounding box by +a few pixels. +If no items match any of the \fItagOrId\fR arguments or if the +matching items have empty bounding boxes (i.e. they have nothing +to display) +then an empty string is returned. +.TP +\fIpathName \f5bind \fItagOrId\fR ?\fIsequence\fR? ?\fIcommand\fR? +This command associates \fIcommand\fR with all the items given by +\fItagOrId\fR such that whenever the event sequence given by +\fIsequence\fR occurs for one of the items the command will +be invoked. +This widget command is similar to the \f5bind\fR command except that +it operates on items in a canvas rather than entire widgets. +See the \f5bind\fR manual entry for complete details +on the syntax of \fIsequence\fR and the substitutions performed +on \fIcommand\fR before invoking it. +If all arguments are specified then a new binding is created, replacing +any existing binding for the same \fIsequence\fR and \fItagOrId\fR +(if the first character of \fIcommand\fR is ``+'' then \fIcommand\fR +augments an existing binding rather than replacing it). +In this case the return value is an empty string. +If \fIcommand\fR is omitted then the command returns the \fIcommand\fR +associated with \fItagOrId\fR and \fIsequence\fR (an error occurs +if there is no such binding). +If both \fIcommand\fR and \fIsequence\fR are omitted then the command +returns a list of all the sequences for which bindings have been +defined for \fItagOrId\fR. +.RS +.PP +The only events for which bindings may be specified are those related +to the mouse and keyboard, such as \f5Enter\fR, \f5Leave\fR, +\f5ButtonPress\fR, \f5Motion\fR, and \f5KeyPress\fR. +The handling of events in canvases uses the current item defined +in ITEM IDS AND TAGS above. +\f5Enter\fR and \f5Leave\fR events trigger for an item when it +becomes the current item or ceases to be the current item; note +that these events are different than \f5Enter\fR and \f5Leave\fR +events for windows. +Mouse-related events are directed to the current item, if any. +Keyboard-related events are directed to the focus item, if any +(see the \f5focus\fR widget command below for more on this). +.PP +It is possible for multiple bindings to match a particular event. +This could occur, for example, if one binding is associated with the +item's id and another is associated with one of the item's tags. +When this occurs, all of the matching bindings are invoked. +A binding associated with the \f5all\fR tag is invoked first, +followed by one binding for each of the item's tags (in order), +followed by a binding associated with the item's id. +If there are multiple matching bindings for a single tag, +then only the most specific binding is invoked. +A \f5continue\fR command in a binding script terminates that +script, and a \f5break\fR command terminates that script +and skips any remaining scripts for the event, just as for the +\f5bind\fR command. +.PP +If bindings have been created for a canvas window using the \f5bind\fR +command, then they are invoked in addition to bindings created for +the canvas's items using the \f5bind\fR widget command. +The bindings for items will be invoked before any of the bindings +for the window as a whole. +.RE +.TP +\fIpathName \f5canvasx \fIscreenx\fR ?\fIgridspacing\fR? +Given a window x-coordinate in the canvas \fIscreenx\fR, this command returns +the canvas x-coordinate that is displayed at that location. +If \fIgridspacing\fR is specified, then the canvas coordinate is +rounded to the nearest multiple of \fIgridspacing\fR units. +.TP +\fIpathName \f5canvasy \fIscreeny\fR ?\fIgridspacing\fR? +Given a window y-coordinate in the canvas \fIscreeny\fR this command returns +the canvas y-coordinate that is displayed at that location. +If \fIgridspacing\fR is specified, then the canvas coordinate is +rounded to the nearest multiple of \fIgridspacing\fR units. +.TP +\fIpathName \f5cget\fR \fIoption\fR +Returns the current value of the configuration option given +by \fIoption\fR. +\fIOption\fR may have any of the values accepted by the \f5canvas\fR +command. +.TP +\fIpathName \f5configure ?\fIoption\fR? ?\fIvalue\fR? ?\fIoption value ...\fR? +Query or modify the configuration options of the widget. +If no \fIoption\fR is specified, returns a list of all of +the available options for \fIpathName\fR. If +one or more \fIoption-value\fR pairs are specified, then the command +modifies the given widget option(s) to have the given value(s); in +this case the command returns an empty string. +\fIOption\fR may have any of the values accepted by the \f5canvas\fR +command. +.TP +\fIpathName\fR \f5coords \fItagOrId \fR?\fIx0 y0 ...\fR? +Query or modify the coordinates that define an item. +If no coordinates are specified, this command returns a list +whose elements are the coordinates of the item named by +\fItagOrId\fR. +If coordinates are specified, then they replace the current +coordinates for the named item. +If \fItagOrId\fR refers to multiple items, then +the first one in the display list is used. +.TP +\fIpathName \f5create \fItype x y \fR?\fIx y ...\fR? ?\fIoption value ...\fR? +Create a new item in \fIpathName\fR of type \fItype\fR. +The exact format of the arguments after \f5type\fR depends +on \f5type\fR, but usually they consist of the coordinates for +one or more points, followed by specifications for zero or +more item options. +See the subsections on individual item types below for more +on the syntax of this command. +This command returns the id for the new item. +.TP +\fIpathName \f5dchars \fItagOrId first \fR?\fIlast\fR? +For each item given by \fItagOrId\fR, delete the characters +in the range given by \fIfirst\fR and \fIlast\fR, +inclusive. +If some of the items given by \fItagOrId\fR don't support +text operations, then they are ignored. +\fIFirst\fR and \fIlast\fR are indices of characters +within the item(s) as described in INDICES above. +If \fIlast\fR is omitted, it defaults to \fIfirst\fR. +This command returns an empty string. +.TP +\fIpathName \f5delete \fR?\fItagOrId tagOrId ...\fR? +Delete each of the items given by each \fItagOrId\fR, and return +an empty string. +.TP +\fIpathName \f5dtag \fItagOrId \fR?\fItagToDelete\fR? +For each of the items given by \fItagOrId\fR, delete the +tag given by \fItagToDelete\fR from the list of those +associated with the item. +If an item doesn't have the tag \fItagToDelete\fR then +the item is unaffected by the command. +If \fItagToDelete\fR is omitted then it defaults to \fItagOrId\fR. +This command returns an empty string. +.TP +\fIpathName \f5find \fIsearchCommand \fR?\fIarg arg ...\fR? +This command returns a list consisting of all the items that +meet the constraints specified by \fIsearchCommand\fR and +\fIarg\fR's. +\fISearchCommand\fR and \fIargs\fR have any of the forms +accepted by the \f5addtag\fR command. +If \fIsearchCommand\fR is \f5enclosed\fR, \f5overlapping\fR, +or \f5all\fR, the items are returned in display-list order, +i.e. bottommost first. +.TP +\fIpathName \f5focus \fR?\fItagOrId\fR? +Set the keyboard focus for the canvas widget to the item given by +\fItagOrId\fR. +If \fItagOrId\fR refers to several items, then the focus is set +to the first such item in the display list that supports the +insertion cursor. +If \fItagOrId\fR doesn't refer to any items, or if none of them +support the insertion cursor, then the focus isn't changed. +If \fItagOrId\fR is an empty +string, then the focus item is reset so that no item has the focus. +If \fItagOrId\fR is not specified then the command returns the +id for the item that currently has the focus, or an empty string +if no item has the focus. +.RS +.PP +Once the focus has been set to an item, the item will display +the insertion cursor and all keyboard events will be directed +to that item. +The focus item within a canvas and the focus window on the +screen (set with the \f5focus\fR command) are totally independent: +a given item doesn't actually have the input focus unless (a) +its canvas is the focus window and (b) the item is the focus item +within the canvas. +In most cases it is advisable to follow the \f5focus\fR widget +command with the \f5focus\fR command to set the focus window to +the canvas (if it wasn't there already). +.RE +.TP +\fIpathName \f5gettags\fR \fItagOrId\fR +Return a list whose elements are the tags associated with the +item given by \fItagOrId\fR. +If \fItagOrId\fR refers to more than one item, then the tags +are returned from the first such item in the display list. +If \fItagOrId\fR doesn't refer to any items, then an error is returned. If the item +contains no tags, then an empty string is returned. +.TP +\fIpathName \f5grab\fR \fIwhat\fR \fItagOrId\fR +Does for canvas widgets what \fIgrab\fR(9) does for +normal tk widgets: mouse events will only be delivered +to \fItagOrId\fR. If \fItagOrId\fR refers to more than one item, +then the first such item in the display list is grabbed. +\fIWhat\fR is as described in +.IR grab (9). +.PP +Note that the canvas grab item, as set by this command, +and the tk grab item, as set by +.IR grab (9) +are totally independent; a canvas item doesn't actually grab +the mouse unless a) the canvas itself has grabbed the mouse +or b) the mouse events are being delivered to the canvas as +a matter of course. +.TP +\fIpathName \f5icursor \fItagOrId index\fR +Set the position of the insertion cursor for the item(s) +given by \fItagOrId\fR +to just before the character whose position is given by \fIindex\fR. +If some or all of the items given by \fItagOrId\fR don't support +an insertion cursor then this command has no effect on them. +See INDICES above for a description of the +legal forms for \fIindex\fR. +Note: the insertion cursor is only displayed in an item if +that item currently has the keyboard focus (see the widget +command \f5focus\fR, below), but the cursor position may +be set even when the item doesn't have the focus. +This command returns an empty string. +.TP +\fIpathName \f5index \fItagOrId index\fR +This command returns a decimal string giving the numerical index +within \fItagOrId\fR corresponding to \fIindex\fR. +\fIIndex\fR gives a textual description of the desired position +as described in INDICES above. +The return value is guaranteed to lie between 0 and the number +of characters within the item, inclusive. +If \fItagOrId\fR refers to multiple items, then the index +is processed in the first of these items that supports indexing +operations (in display list order). +.TP +\fIpathName \f5insert \fItagOrId beforeThis string\fR +For each of the items given by \fItagOrId\fR, if the item supports +text insertion then \fIstring\fR is inserted into the item's +text just before the character whose index is \fIbeforeThis\fR. +See INDICES above for information about the forms allowed +for \fIbeforeThis\fR. +This command returns an empty string. +.TP +\fIpathName \f5itemcget\fR \fItagOrId\fR \fIoption\fR +Returns the current value of the configuration option for the +item given by \fItagOrId\fR whose name is \fIoption\fR. +This command is similar to the \f5cget\fR widget command except that +it applies to a particular item rather than the widget as a whole. +\fIOption\fR may have any of the values accepted by the \f5create\fR +widget command when the item was created. +If \fItagOrId\fR is a tag that refers to more than one item, +the first (lowest) such item is used. +.TP +\fIpathName \f5itemconfigure \fItagOrId\fR ?\fIoption\fR? ?\fIvalue\fR? ?\fIoption value ...\fR? +This command is similar to the \f5configure\fR widget command except +that it modifies item-specific options for the items given by +\fItagOrId\fR instead of modifying options for the overall +canvas widget. +If +one or more \fIoption-value\fR pairs are specified, then the command +modifies the given widget option(s) to have the given value(s) in +each of the items given by \fItagOrId\fR; in +this case the command returns an empty string. +The \fIoption\fRs and \fIvalue\fRs are the same as those permissible +in the \f5create\fR widget command when the item(s) were created; +see the sections describing individual item types below for details +on the legal options. +.TP +\fIpathName \f5lower \fItagOrId \fR?\fIbelowThis\fR? +Move all of the items given by \fItagOrId\fR to a new position +in the display list just before the item given by \fIbelowThis\fR. +If \fItagOrId\fR refers to more than one item then all are moved +but the relative order of the moved items will not be changed. +\fIBelowThis\fR is a tag or id; if it refers to more than one +item then the first (lowest) of these items in the display list is used +as the destination location for the moved items. +This command returns an empty string. +.TP +\fIpathName \f5move \fItagOrId xAmount yAmount\fR +Move each of the items given by \fItagOrId\fR in the canvas coordinate +space by adding \fIxAmount\fR to the x-coordinate of each point +associated with the item and \fIyAmount\fR to the y-coordinate of +each point associated with the item. +This command returns an empty string. +.TP +\fIpathName \f5raise \fItagOrId \fR?\fIaboveThis\fR? +Move all of the items given by \fItagOrId\fR to a new position +in the display list just after the item given by \fIaboveThis\fR. +If \fItagOrId\fR refers to more than one item then all are moved +but the relative order of the moved items will not be changed. +\fIAboveThis\fR is a tag or id; if it refers to more than one +item then the last (topmost) of these items in the display list is used +as the destination location for the moved items. +This command returns an empty string. +.TP +\fIpathName \f5scale \fItagOrId xOrigin yOrigin xScale yScale\fR +Rescale all of the items given by \fItagOrId\fR in canvas coordinate +space. +\fIXOrigin\fR and \fIyOrigin\fR identify the origin for the scaling +operation and \fIxScale\fR and \fIyScale\fR identify the scale +factors for x- and y-coordinates, respectively (a scale factor of +1.0 implies no change to that coordinate). +For each of the points defining each item, the x-coordinate is +adjusted to change the distance from \fIxOrigin\fR by a factor +of \fIxScale\fR. +Similarly, each y-coordinate is adjusted to change the distance +from \fIyOrigin\fR by a factor of \fIyScale\fR. +This command returns an empty string. +.TP +\fIpathName \f5screenx \fIcanvasx\fR +Given an x-coordinate \fIcanvasx\fR in the canvas, this command returns +the equivalent screen x-coordinate. +.TP +\fIpathName \f5screeny \fIcanvasy\fR +Given an x-coordinate \fIcanvasy\fR in the canvas, this command returns +the equivalent screen y-coordinate. +.TP +\fIpathName \f5see \fIx1 y1\fR ?\fIx2 y2\fR? +Adjusts the view in the window such that, if possible +the point [\fIx1\fR, \fIy1\fR] (and, if given, the point +[\fIx2\fR, \fIy2\fR]) are made visible. +.TP +\fIpathName \f5select \fIoption\fR ?\fItagOrId arg\fR? +Manipulates the selection in one of several ways, depending on +\fIoption\fR. +The command may take any of the forms described below. +In all of the descriptions below, \fItagOrId\fR must refer to +an item that supports indexing and selection; if it refers to +multiple items then the first of +these that supports indexing and the selection is used. +\fIIndex\fR gives a textual description of a position +within \fItagOrId\fR, as described in INDICES above. +.RS +.TP +\fIpathName \f5select adjust \fItagOrId index\fR +Locate the end of the selection in \fItagOrId\fR nearest +to the character given by \fIindex\fR, and adjust that +end of the selection to be at \fIindex\fR (i.e. including +but not going beyond \fIindex\fR). +The other end of the selection is made the anchor point +for future \f5select to\fR commands. +If the selection isn't currently in \fItagOrId\fR then +this command behaves the same as the \f5select to\fR widget +command. +Returns an empty string. +.TP +\fIpathName \f5select clear\fR +Clear the selection if it is in this widget. +If the selection isn't in this widget then the command +has no effect. +Returns an empty string. +.TP +\fIpathName \f5select from \fItagOrId index\fR +Set the selection anchor point for the widget to be just +before the character +given by \fIindex\fR in the item given by \fItagOrId\fR. +This command doesn't change the selection; it just sets +the fixed end of the selection for future \f5select to\fR +commands. +Returns an empty string. +.TP +\fIpathName \f5select item\fR +Returns the id of the selected item, if the selection is in an +item in this canvas. +If the selection is not in this canvas then an empty string +is returned. +.TP +\fIpathName \f5select to \fItagOrId index\fR +Set the selection to consist of those characters of \fItagOrId\fR +between the selection anchor point and +\fIindex\fR. +The new selection will include the character given by \fIindex\fR; +it will include the character given by the anchor point only if +\fIindex\fR is greater than or equal to the anchor point. +The anchor point is determined by the most recent \f5select adjust\fR +or \f5select from\fR command for this widget. +If the selection anchor point for the widget isn't currently in +\fItagOrId\fR, then it is set to the same character given +by \fIindex\fR. +Returns an empty string. +.RE +.TP +\fIpathName \f5type\fI tagOrId\fR +Returns the type of the item given by \fItagOrId\fR, such as +\f5rectangle\fR or \f5text\fR. +If \fItagOrId\fR refers to more than one item, then the type +of the first item in the display list is returned. +If \fItagOrId\fR doesn't refer to any items at all then +an empty string is returned. +.TP +\fIpathName \f5xview \fR?\fIargs\fR? +This command is used to query and change the horizontal position of the +information displayed in the canvas's window. +It can take any of the following forms: +.RS +.TP +\fIpathName \f5xview\fR +Returns a list containing two elements. +Each element is a real fraction between 0 and 1; together they describe +the horizontal span that is visible in the window. +For example, if the first element is .2 and the second element is .6, +20% of the canvas's area (as defined by the \f5-scrollregion\fR option) +is off-screen to the left, the middle 40% is visible +in the window, and 40% of the canvas is off-screen to the right. +These are the same values passed to scrollbars via the \f5-xscrollcommand\fR +option. +.TP +\fIpathName \f5xview moveto\fI fraction\fR +Adjusts the view in the window so that \fIfraction\fR of the +total width of the canvas is off-screen to the left. +\fIFraction\fR must be a fraction between 0 and 1. +.TP +\fIpathName \f5xview scroll \fInumber what\fR +This command shifts the view in the window left or right according to +\fInumber\fR and \fIwhat\fR. +\fINumber\fR must be an integer. +\fIWhat\fR must be either \f5units\fR or \f5pages\fR. +If \fIwhat\fR is \f5units\fR, the view adjusts left or right in units +of the \f5xscrollicrement\fR option, if it is greater than zero, +or in units of one-tenth the window's width otherwise. +If \fIwhat is \f5pages\fR then the view +adjusts in units of nine-tenths the window's width. +If \fInumber\fR is negative then information farther to the left +becomes visible; if it is positive then information farther to the right +becomes visible. +.RE +.TP +\fIpathName \f5yview \fI?args\fR? +This command is used to query and change the vertical position of the +information displayed in the canvas's window. +It can take any of the following forms: +.RS +.TP +\fIpathName \f5yview\fR +Returns a list containing two elements. +Each element is a real fraction between 0 and 1; together they describe +the vertical span that is visible in the window. +For example, if the first element is .6 and the second element is 1.0, +the lowest 40% of the canvas's area (as defined by the \f5-scrollregion\fR +option) is visible in the window. +These are the same values passed to scrollbars via the \f5-yscrollcommand\fR +option. +.TP +\fIpathName \f5yview moveto\fI fraction\fR +Adjusts the view in the window so that \fIfraction\fR of the canvas's +area is off-screen to the top. +\fIFraction\fR is a fraction between 0 and 1. +.TP +\fIpathName \f5yview scroll \fInumber what\fR +This command adjusts the view in the window up or down according to +\fInumber\fR and \fIwhat\fR. +\fINumber\fR must be an integer. +\fIWhat\fR must be either \f5units\fR or \f5pages\fR. +If \fIwhat\fR is \f5units\fR, the view adjusts up or down in units +of the \f5yscrollicrement\fR option, if it is greater than zero, +or in units of one-tenth the window's height otherwise. +If \fIwhat\fR is \f5pages\fR then +the view adjusts in units of nine-tenths the window's height. +If \fInumber\fR is negative then higher information becomes +visible; if it is positive then lower information +becomes visible. +.RE + +.SH "OVERVIEW OF ITEM TYPES" +The sections below describe the various types of items supported +by canvas widgets. Each item type is characterized by two things: +first, the form of the \f5create\fR command used to create +instances of the type; and second, a set of configuration options +for items of that type, which may be used in the +\f5create\fR and \f5itemconfigure\fR widget commands. +Most items don't support indexing or selection or the commands +related to them, such as \f5index\fR and \f5insert\fR. +Where items do support these facilities, it is noted explicitly +in the descriptions below (at present, only text items provide +this support). + +.SH "ARC ITEMS" +Items of type \f5arc\fR appear on the display as arc-shaped regions. +An arc is a section of an oval delimited by two angles (specified +by the \f5-start\fR and \f5-extent\fR options) and displayed in +one of several ways (specified by the \f5-style\fR option). +Arcs are created with widget commands of the following form: +.RS +.EX +\fIpathName \f5create arc \fIx1 y1 x2 y2 \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR give +the coordinates of two diagonally opposite corners of a +rectangular region enclosing the oval that defines the arc. +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for arcs: +.TP +\f5-extent \fIdegrees\fR +Specifies the size of the angular range occupied by the arc. +The arc's range extends for \fIdegrees\fR degrees counter-clockwise +from the starting angle given by the \f5-start\fR option. +\fIDegrees\fR may be negative. +If it is greater than 360 or less than -360, then \fIdegrees\fR +modulo 360 is used as the extent. +.TP +\f5-fill \fIcolour\fR +Fill the region of the arc with \fIcolour\fR. +If \fIcolour\fR is an empty string (the default), then +the arc will not be filled. +.TP +\f5-outline \fIcolour\fR +\fIColour\fR specifies a colour to use for drawing the arc's +outline. +This option defaults to \f5black\fR. If \fIcolour\fR is specified +as an empty string then no outline is drawn for the arc. +.TP +\f5-start \fIdegrees\fR +Specifies the beginning of the angular range occupied by the +arc. +\fIDegrees\fR is given in units of degrees measured counter-clockwise +from the 3-o'clock position; it may be either positive or negative. +.TP +\f5-stipple \fIbitmap\fR +Indicates that the arc should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use. +If the \f5-fill\fR option hasn't been specified then this option +has no effect. +If \fIbitmap\fR is an empty string (the default), then filling is done +in a solid fashion. +The results are undefined if \fIbitmap\fR is not +a 1-bit image. +.TP +\f5-style \fItype\fR +Specifies how to draw the arc. If \fItype\fR is \f5pieslice\fR +(the default) then the arc's region is defined by a section +of the oval's perimeter plus two line segments, one between the center +of the oval and each end of the perimeter section. +If \fItype\fR is \f5chord\fR then the arc's region is defined +by a section of the oval's perimeter plus a single line segment +connecting the two end points of the perimeter section. +This type is not implemented at the moment. It behaves as \f5arc\fR. +If \fItype\fR is \f5arc\fR then the arc's region consists of +a section of the perimeter alone. +In this last case the \f5-fill\fR option is ignored. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\f5-width \fIoutlineWidth\fR +Specifies the width of the outline to be drawn around +the arc's region, in any of the forms described in the COORDINATES +section above. +If the \f5-outline\fR option has been specified as an empty string +then this option has no effect. +Wide outlines will be drawn centered on the edges of the arc's region. +This option defaults to 1.0. + +.SH "BITMAP ITEMS" +Items of type \f5bitmap\fR appear on the display as images with +two colours, foreground and background. +Bitmaps are created with widget commands of the following form: +.RS +.EX +\fIpathName \f5create bitmap \fIx y \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx\fR and \fIy\fR specify the coordinates of a +point used to position the bitmap on the display (see the \f5-anchor\fR +option below for more information on how bitmaps are displayed). +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for bitmaps: +.TP +\f5-anchor \fIanchorPos\fR +\fIAnchorPos\fR tells how to position the bitmap relative to the +positioning point for the item. For example, if \fIanchorPos\fR +is \f5center\fR then the bitmap is centered on the point; if +\fIanchorPos\fR is \f5n\fR then the bitmap will be drawn so that +its top center point is at the positioning point. +This option defaults to \f5center\fR. +.TP +\f5-bitmap \fIbitmap\fR +Specifies the bitmap to display in the item. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. + +.SH "IMAGE ITEMS" +Items of type \f5image\fR are used to display images on a +canvas. +Images are created with widget commands of the following form: +.RS +.EX +\fIpathName \f5create image \fIx y \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx\fR and \fIy\fR specify the coordinates of a +point used to position the image on the display (see the \f5-anchor\fR +option below for more information). +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for images: +.TP +\f5-anchor \fIanchorPos\fR +\fIAnchorPos\fR tells how to position the image relative to the +positioning point for the item. For example, if \fIanchorPos\fR +is \f5center\fR then the image is centered on the point; if +\fIanchorPos\fR is \f5n\fR then the image will be drawn so that +its top center point is at the positioning point. +This option defaults to \f5center\fR. +.TP +\f5-image \fIname\fR +Specifies the name of the image to display in the item. +This image must have been created previously with the +\f5image create\fR command. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item; it may be an empty list. + +.SH "LINE ITEMS" +Items of type \f5line\fR appear on the display as one or more connected +line segments or curves. +Lines are created with widget commands of the following form: +.RS +.EX +\fIpathName \f5create line \fIx1 y1... xn yn \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx1\fR through \fIyn\fR give +the coordinates for a series of two or more points that describe +a series of connected line segments. +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for lines: +.TP +\f5-arrow \fIwhere\fR +Indicates whether or not arrowheads are to be drawn at one or both +ends of the line. +\fIWhere\fR must have one of the values \f5none\fR (for no arrowheads), +\f5first\fR (for an arrowhead at the first point of the line), +\f5last\fR (for an arrowhead at the last point of the line), or +\f5both\fR (for arrowheads at both ends). +This option defaults to \f5none\fR. +.TP +\f5-arrowshape \fIshape\fR +This option indicates how to draw arrowheads. +The \fIshape\fR argument must be a list with three elements, each +specifying a distance in any of the forms described in +the COORDINATES section above. +The first element of the list gives the distance along the line +from the neck of the arrowhead to its tip. +The second element gives the distance along the line from the +trailing points of the arrowhead to the tip, and the third +element gives the distance from the outside edge of the line to the +trailing points. +If this option isn't specified then Tk picks a ``reasonable'' shape. +.TP +\f5-capstyle \fIstyle\fR +Specifies the ways in which caps are to be drawn at the endpoints +of the line. +\fIStyle\fR may one of +\f5butt\fR, \f5projecting\fR, or \f5round\fR. +If this option isn't specified then it defaults to \f5butt\fR. +Where arrowheads are drawn the cap style is ignored. Note that the first two options +currently have the same effect. +.TP +\f5-fill \fIcolour\fR +\fIColour\fR specifies a colour to use for drawing the line. It may also be an +empty string, in which case the line will be transparent. +This option defaults to \f5black\fR. +.TP +\f5-smooth \fIboolean\fR +\fIBoolean\fR indicates whether or not the line should be drawn as a curve. +If so, the line is rendered as a set of Bezier splines: one spline +is drawn for the first and second line segments, one for the second +and third, and so on. Straight-line segments can be generated within +a curve by duplicating the end-points of the desired line segment. +.TP +\f5-stipple \fIbitmap\fR +Indicates that the line should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use. +If \fIbitmap\fR is an empty string (the default), then filling is +done in a solid fashion. +The results are undefined if \fIbitmap\fR is not +a 1-bit image. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\f5-width \fIlineWidth\fR +\fILineWidth\fR specifies the width of the line, in any of the forms +described in the COORDINATES section above. +Wide lines will be drawn centered on the path specified by the +points. +If this option isn't specified then it defaults to 1.0. + +.SH "OVAL ITEMS" +Items of type \f5oval\fR appear as circular or oval regions on +the display. Each oval may have an outline, a fill, or +both. Ovals are created with widget commands of the +following form: +.RS +.EX +\fIpathName \f5create oval \fIx1 y1 x2 y2 \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR give +the coordinates of two diagonally opposite corners of a +rectangular region enclosing the oval. +The oval will include the top and left edges of the rectangle +not the lower or right edges. +If the region is square then the resulting oval is circular; +otherwise it is elongated in shape. +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for ovals: +.TP +\f5-fill \fIcolour\fR +Fill the area of the oval with \fIcolour\fR. +If \fIcolour\fR is an empty string (the default), then +then the oval will not be filled. +.TP +\f5-outline \fIcolour\fR +\fIColour\fR specifies a colour to use for drawing the oval's +outline. +This option defaults to \f5black\fR. +If \fIcolour\fR is an empty string then no outline will be +drawn for the oval. +.TP +\f5-stipple \fIbitmap\fR +Indicates that the oval should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use. +If the \f5-fill\fR option hasn't been specified then this option +has no effect. +If \fIbitmap\fR is an empty string (the default), then filling is done +in a solid fashion. +The results are undefined if \fIbitmap\fR is not +a 1-bit image. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\f5-width \fIoutlineWidth\fR +\fIoutlineWidth\fR specifies the width of the outline to be drawn around +the oval, in any of the forms described in the COORDINATES section above. +If the \f5-outline\fR option hasn't been specified then this option +has no effect. +Wide outlines are drawn centered on the oval path defined by +\fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR. +This option defaults to 1.0. + +.SH "POLYGON ITEMS" +Items of type \f5polygon\fR appear as polygonal or curved filled regions +on the display. +Polygons are created with widget commands of the following form: +.RS +.EX +\fIpathName \f5create polygon \fIx1 y1 ... xn yn \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx1\fR through \fIyn\fR specify the coordinates for +three or more points that define a closed polygon. +The first and last points may be the same; whether they are or not, +Tk will draw the polygon as a closed polygon. +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for polygons: +.TP +\f5-fill \fIcolour\fR +\fIColour\fR specifies a colour to use for filling the area of the +polygon. +If \fIcolour\fR is an empty string then the polygon will be +transparent. +This option defaults to the empty string (transparent). +.TP +\f5-outline \fIcolour\fR +\fIColour\fR specifies a colour to use for drawing the polygon's +outline. +If \fIcolour\fR is an empty string then no outline will be +drawn for the polygon. +This option defaults to black. +.TP +\f5-smooth \fIboolean\fR +\fIBoolean\fP indicates whether or not the polygon should be drawn with a +curved perimeter. +If so, the outline of the polygon becomes a set of Bezier splines, +one spline for the first and second line segments, one for the second +and third, and so on. Straight-line segments can be generated in a +smoothed polygon by duplicating the end-points of the desired line segment. +.TP +\f5-stipple \fIbitmap\fR +Indicates that the polygon should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use. +If \fIbitmap\fR is an empty string (the default), then filling is +done in a solid fashion. +The results are undefined if \fIbitmap\fR is not +a 1-bit image. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\f5-winding \fItype\fR +Specifies the winding rule to use when filling the polygon. +\fIType\fR can be either \f5nonzero\fR (the default) +or \f5odd\fR +See \f5fillpoly\fR in +.IR draw-image(2) +for an explanation. +.TP +\f5-width \fIoutlineWidth\fR +\fIOutlineWidth\fR specifies the width of the outline to be drawn around +the polygon, in any of the forms described in the COORDINATES section above. +If the \f5-outline\fR option hasn't been specified then this option +has no effect. This option defaults to 1.0. +.PP +Polygon items are different from other items such as rectangles, ovals +and arcs in that interior points are considered to be ``inside'' a +polygon (e.g. for purposes of the \f5find closest\fR and +\f5find overlapping\fR widget commands) even if it is not filled. +For most other item types, an +interior point is considered to be inside the item only if the item +is filled or if it has neither a fill nor an outline. If you would +like an unfilled polygon whose interior points are not considered +to be inside the polygon, use a line item instead. + +.SH "RECTANGLE ITEMS" +Items of type \f5rectangle\fR appear as rectangular regions on +the display. Each rectangle may have an outline, a fill, or +both. Rectangles are created with widget commands of the +following form: +.RS +.EX +\fIpathName \f5create rectangle \fIx1 y1 x2 y2 \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR give +the coordinates of two diagonally opposite corners of the rectangle +(the rectangle will include its upper and left edges but not +its lower or right edges). +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for rectangles: +.TP +\f5-fill \fIcolour\fR +Fill the area of the rectangle with \fIcolour\fR. +If \fIcolour\fR is an empty string (the default), +then the rectangle will not be filled. +.TP +\f5-outline \fIcolour\fR +Draw an outline around the edge of the rectangle in \fIcolour\fR. +This option defaults to \f5black\fR. +If \fIcolour\fR is an empty string then no outline will be +drawn for the rectangle. +.TP +\f5-stipple \fIbitmap\fR +Indicates that the rectangle should be filled in a stipple pattern; +\fIbitmap\fR specifies the stipple pattern to use. +If the \f5-fill\fR option hasn't been specified then this option +has no effect. +If \fIbitmap\fR is an empty string (the default), then filling +is done in a solid fashion. +The results are undefined if \fIbitmap\fR is not +a 1-bit image. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\f5-width \fIoutlineWidth\fR +\fIOutlineWidth\fR specifies the width of the outline to be drawn around +the rectangle, in any of the forms described in the COORDINATES section above. +If the \f5-outline\fR option hasn't been specified then this option +has no effect. +Wide outlines are drawn centered on the rectangular path +defined by \fIx1\fR, \fIy1\fR, \fIx2\fR, and \fIy2\fR. +This option defaults to 1.0. + +.SH "TEXT ITEMS" +A text item displays a string of characters on the screen in one +or more lines. +Text items support indexing and selection, along with the +following text-related canvas widget commands: \f5dchars\fR, +\f5focus\fR, \f5icursor\fR, \f5index\fR, \f5insert\fR, +\f5select\fR. +Text items are created with widget commands of the following +form: +.RS +.EX +\fIpathName \f5create text \fIx y \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx\fR and \fIy\fR specify the coordinates of a +point used to position the text on the display (see the options +below for more information on how text is displayed). +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for text items: +.TP +\f5-anchor \fIanchorPos\fR +\fIAnchorPos\fR tells how to position the text relative to the +positioning point for the text. For example, if \fIanchorPos\fR +is \f5center\fR then the text is centered on the point; if +\fIanchorPos\fR is \f5n\fR then the text will be drawn such that +the top center point of the rectangular region occupied by the +text will be at the positioning point. +This option defaults to \f5center\fR. +.TP +\f5-fill \fIcolour\fR +\fIColour\fR specifies a colour to use for filling the text characters. +If this option isn't specified then it defaults to \f5black\fR. +.TP +\f5-font \fIfont\fR +Specifies the font to use for the text item. +If this option isn't specified, it defaults to a system-dependent +font. +.TP +\f5-justify \fIhow\fR +Specifies how to justify the text within its bounding region. +\fIHow\fR must be one of the values \f5left\fR, \f5right\fR, +or \f5center\fR. +This option will only matter if the text is displayed as multiple +lines. +If the option is omitted, it defaults to \f5left\fR. +.TP +\f5-stipple \fIbitmap\fR +Indicates that the text should be drawn in a stippled pattern +rather than solid; +\fIbitmap\fR specifies the stipple pattern to use. +If \fIbitmap\fR is an empty string (the default) then the text +is drawn in a solid fashion. +The results are undefined if \fIbitmap\fR is not +a 1-bit image. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\f5-text \fIstring\fR +\fIString\fR specifies the characters to be displayed in the text item. +Newline characters cause line breaks. +The characters in the item may also be changed with the +\f5insert\fR and \f5delete\fR widget commands. +This option defaults to an empty string. +.TP +\f5-width \fIlineLength\fR +Specifies a maximum line length for the text, in any of the forms +described in the COORDINATES section above. +If this option is zero (the default) the text is broken into +lines only at newline characters. +However, if this option is non-zero then any line that would +be longer than \fIlineLength\fR is broken just before a space +character to make the line shorter than \fIlineLength\fR; the +space character is treated as if it were a newline +character. + +.SH "WINDOW ITEMS" +Items of type \f5window\fR cause a particular window to be displayed +at a given position on the canvas. +Window items are created with widget commands of the following form: +.RS +.EX +\fIpathName \f5create window \fIx y \fR?\fIoption value option value ...\fR? +.EE +.RE +The arguments \fIx\fR and \fIy\fR specify the coordinates of a +point used to position the window on the display (see the \f5-anchor\fR +option below for more information on how bitmaps are displayed). +After the coordinates there may be any number of \fIoption\fR-\fIvalue\fR +pairs, each of which sets one of the configuration options +for the item. These same \fIoption\fR-\fIvalue\fR pairs may be +used in \f5itemconfigure\fR widget commands to change the item's +configuration. +The following options are supported for window items: +.TP +\f5-anchor \fIanchorPos\fR +\fIAnchorPos\fR tells how to position the window relative to the +positioning point for the item. For example, if \fIanchorPos\fR +is \f5center\fR then the window is centered on the point; if +\fIanchorPos\fR is \f5n\fR then the window will be drawn so that +its top center point is at the positioning point. +This option defaults to \f5center\fR. +.TP +\f5-height \fIdist\fR +Specifies the height to assign to the item's window. +\fIDist\fR may have any of the +forms described in the COORDINATES section above. +If this option isn't specified, or if it is specified as an empty +string, then the window is given whatever height it requests internally. +.TP +\f5-tags \fItagList\fR +Specifies a set of tags to apply to the item. +\fITagList\fR consists of a list of tag names, which replace any +existing tags for the item. +\fITagList\fR may be an empty list. +.TP +\f5-width \fIdist\fR +Specifies the width to assign to the item's window. +\fIDist\fR may have any of the +forms described in the COORDINATES section above. +If this option isn't specified, or if it is specified as an empty +string, then the window is given whatever width it requests internally. +.TP +\f5-window \fIpathName\fR +Specifies the window to associate with this item. +The window specified by \fIpathName\fR must either be a child of +the canvas widget or a child of some ancestor of the canvas widget. +\fIPathName\fR may not refer to a top-level window. + +.SH BINDINGS +In the current implementation, new canvases are not given any +default behaviour: you'll have to execute explicit Tk commands +to give the canvas its behaviour. + +.SH CREDITS +Tk's canvas widget is a blatant ripoff of ideas from Joel Bartlett's +\fIezd\fR program. \fIEzd\fR provides structured graphics in a Scheme +environment and preceded canvases by a year or two. Its simple +mechanisms for placing and animating graphical objects inspired the +functions of canvases. + +.SH SEE ALSO +.IR options (9), +.IR types (9) |