Class: Tk::Canvas

Inherits:
Widget show all
Includes:
Cget, Configure
Defined in:
lib/ffi-tk/widget/canvas.rb,
lib/ffi-tk/widget/canvas/arc.rb,
lib/ffi-tk/widget/canvas/item.rb,
lib/ffi-tk/widget/canvas/line.rb,
lib/ffi-tk/widget/canvas/oval.rb,
lib/ffi-tk/widget/canvas/text.rb,
lib/ffi-tk/widget/canvas/image.rb,
lib/ffi-tk/widget/canvas/bitmap.rb,
lib/ffi-tk/widget/canvas/window.rb,
lib/ffi-tk/widget/canvas/polygon.rb,
lib/ffi-tk/widget/canvas/rectangle.rb

Overview

Canvas widgets implement structured graphics.

A canvas displays any number of items, which may be things like rectangles, circles, lines, and text. Items may be manipulated (e.g. moved or re-colored) and commands may be associated with items in much the same way that the bind 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 behaviors defined.

Defined Under Namespace

Classes: Arc, Bitmap, Image, Item, Line, Oval, Polygon, Rectangle, Text, Window

Constant Summary

Constants included from Cget

Tk::Cget::CGET_MAP

Constants included from WM

WM::WM_ATTRIBUTES_HINTS

Instance Attribute Summary

Attributes inherited from Widget

#tk_parent, #tk_pathname

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Cget

#cget, option_hash_to_tcl, option_to_ruby, type_to_ruby

Methods included from Configure

#configure

Methods inherited from Widget

#execute, #execute_only, #focus_next, #focus_prev, #initialize, #to_tcl

Methods included from Pack

configure, forget, info, pack, #pack, #pack_configure, #pack_forget, #pack_info, #pack_propagate, #pack_slaves, propagate, slaves

Methods included from Destroy

destroy, #destroy

Methods included from Bind

bind, unbind, #unbind

Methods included from Bindtags

bindtags, #bindtags

Methods included from WM

aspect, attributes, client, colormapwindows, command, deiconify, focusmodel, forget, frame, geometry, grid, group, iconbitmap, iconbitmap_default, iconify, iconmask, iconname, iconphoto, iconphoto_default, iconposition, iconwindow, manage, maxsize, minsize, overrideredirect, positionfrom, protocol, resizable, sizefrom, stackorder, state, title, transient, withdraw, #wm_aspect, #wm_aspect=, #wm_attributes, #wm_client, #wm_client=, #wm_colormapwindows, #wm_colormapwindows=, #wm_command, #wm_command=, #wm_deiconify, #wm_focusmodel, #wm_focusmodel=, #wm_forget, #wm_frame, #wm_geometry, #wm_geometry=, #wm_grid, #wm_grid=, #wm_group, #wm_group=, #wm_iconbitmap, #wm_iconbitmap=, #wm_iconbitmap_default, #wm_iconbitmap_default=, #wm_iconify, #wm_iconmask, #wm_iconmask=, #wm_iconname, #wm_iconname=, #wm_iconphoto, #wm_iconphoto=, #wm_iconphoto_default, #wm_iconphoto_default=, #wm_iconposition, #wm_iconposition=, #wm_iconwindow, #wm_iconwindow=, #wm_manage, #wm_maxsize, #wm_minsize, #wm_overrideredirect, #wm_overrideredirect=, #wm_positionfrom, #wm_positionfrom=, #wm_protocol, #wm_resizable, #wm_sizefrom, #wm_sizefrom=, #wm_stackorder, #wm_state, #wm_state=, #wm_title, #wm_title=, #wm_transient, #wm_transient=, #wm_withdraw

Methods included from Winfo

atom, atomname, cells, children, class_name, colormapfull, containing, depth, exists, fpixels, geometry, height, id, interps, ismapped, manager, name, parent, pathname, pixels, pointerx, pointerxy, pointery, reqheight, reqwidth, rgb, rootx, rooty, screen, screencells, screendepth, screenheight, screenmmheight, screenmmwidth, screenvisual, screenwidth, server, toplevel, viewable, visual, visualid, visualsavailable, vrootheight, vrootwidth, vrootx, vrooty, width, #winfo_atom, #winfo_atomname, #winfo_cells, #winfo_children, #winfo_class, #winfo_colormapfull, #winfo_containing, #winfo_depth, #winfo_exists, #winfo_fpixels, #winfo_geometry, #winfo_height, #winfo_id, #winfo_interps, #winfo_ismapped, #winfo_manager, #winfo_name, #winfo_parent, #winfo_pathname, #winfo_pixels, #winfo_pointerx, #winfo_pointerxy, #winfo_pointery, #winfo_reqheight, #winfo_reqwidth, #winfo_rgb, #winfo_rootx, #winfo_rooty, #winfo_screen, #winfo_screencells, #winfo_screendepth, #winfo_screenheight, #winfo_screenmmheight, #winfo_screenmmwidth, #winfo_screenvisual, #winfo_screenwidth, #winfo_server, #winfo_toplevel, #winfo_viewable, #winfo_visual, #winfo_visualid, #winfo_visualsavailable, #winfo_vrootheight, #winfo_vrootwidth, #winfo_vrootx, #winfo_vrooty, #winfo_width, #winfo_x, #winfo_y, x, y

Methods included from Grid

anchor, bbox, columnconfigure, configure, forget, #grid_anchor, #grid_bbox, #grid_columnconfigure, #grid_configure, #grid_forget, #grid_info, #grid_location, #grid_propagate, #grid_remove, #grid_rowconfigure, #grid_size, #grid_slave, #grid_slaves, info, location, propagate, remove, rowconfigure, size, slave, slaves

Methods included from Clipboard

append, clear, #clipboard_append, #clipboard_clear, #clipboard_get, #clipboard_set, get, set

Methods included from Place

configure, forget, info, place, #place, #place_configure, #place_forget, #place_info, #place_slaves, slaves

Methods included from TkCmd

appname, caret, inactive, scaling, #tk_appname, #tk_appname=, #tk_caret, #tk_inactive, #tk_scaling, #tk_scaling=, #tk_useinputmethods, #tk_useinputmethods=, #tk_windowingsystem, useinputmethods, windowingsystem

Constructor Details

This class inherits a constructor from Tk::Widget

Class Method Details

.tk_command ⇒ Object 



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# File 'lib/ffi-tk/widget/canvas.rb', line 27

def self.tk_command; 'canvas'; end

Instance Method Details

#addtag(tag, search_spec, *args) ⇒ Object

For each item that meets the constraints specified by search_spec and the args, add tag to the list of tags associated with the item if it is not already present on that list. It is possible that no items will satisfy the constraints given by search_spec and args, in which case the command has no effect.



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# File 'lib/ffi-tk/widget/canvas.rb', line 34

def addtag(tag, search_spec, *args)
  execute_only(:addtag, tag, search_spec, *args)
end

#addtag_above(tag, tag_or_id) ⇒ Object

Selects the item just after (above) the one given by tag_or_id in the display list. If tag_or_id denotes more than one item, then the last (topmost) of these items in the display list is used.



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# File 'lib/ffi-tk/widget/canvas.rb', line 42

def addtag_above(tag, tag_or_id)
  execute_only(:addtag, tag, :above, tag_or_id)
end

#addtag_all(tag) ⇒ Object

Selects all the items in the canvas.



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# File 'lib/ffi-tk/widget/canvas.rb', line 47

def addtag_all(tag)
  execute_only(:addtag, tag, :all)
end

#addtag_below(tag, tag_or_id) ⇒ Object

Selects the item just before (below) the one given by tag_or_id in the display list. If tag_or_id denotes more than one item, then the first (lowest) of these items in the display list is used.



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# File 'lib/ffi-tk/widget/canvas.rb', line 55

def addtag_below(tag, tag_or_id)
  execute_only(:addtag, tag, :below, tag_or_id)
end

#addtag_closest(tag, x, y, halo = None, start = None) ⇒ Object

Selects the item closest to the point given by x and y. 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 halo is specified, then it must be a non-negative value. Any item closer than halo to the point is considered to overlap it.

The start argument may be used to step circularly through all the closest items. If start 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 start in the display list; if no such item exists, then the selection behaves as if the start argument had not been specified.



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# File 'lib/ffi-tk/widget/canvas.rb', line 75

def addtag_closest(tag, x, y, halo = None, start = None)
  execute_only(:addtag, tag, :closest, x, y, halo, start)
end

#addtag_enclosed(tag, x1, y1, x2, y2) ⇒ Object

Selects all the items completely enclosed within the rectangular region given by x1, y1, x2, and y2. x1 must be no greater then x2 and y1 must be no greater than y2.



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# File 'lib/ffi-tk/widget/canvas.rb', line 82

def addtag_enclosed(tag, x1, y1, x2, y2)
  execute_only(:addtag, tag, :enclosed, x1, y1, x2, y2)
end

#addtag_overlapping(tag, x1, y1, x2, y2) ⇒ Object

Selects all the items that overlap or are enclosed within the rectangular region given by x1, y1, x2, and y2. x1 must be no greater then x2 and y1 must be no greater than y2.



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# File 'lib/ffi-tk/widget/canvas.rb', line 89

def addtag_overlapping(tag, x1, y1, x2, y2)
  execute_only(:addtag, tag, :overlapping, x1, y1, x2, y2)
end

#addtag_withtag(tag, tag_or_id) ⇒ Object

Selects all the items given by tag_or_id.



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# File 'lib/ffi-tk/widget/canvas.rb', line 94

def addtag_withtag(tag, tag_or_id)
  execute_only(:addtag, tag, :withtag, tag_or_id)
end

#bbox(*tags_or_ids) ⇒ Object

Returns a list with four elements giving an approximate bounding box for all the items named by the tags_or_ids argument. The list has the form ‘[x1, y1, x2, y2]` such that the drawn areas of all the named elements are within the region bounded by x1 on the left, x2 on the right, y1 on the top, and y2 on the bottom. The return value may overestimate the actual bounding box by a few pixels. If no items match any of the tags_or_ids argument or if the matching items have empty bounding boxes (i.e. they have nothing to display) then nil is returned.



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# File 'lib/ffi-tk/widget/canvas.rb', line 107

def bbox(*tags_or_ids)
  execute(:bbox, *tags_or_ids).to_a?(&:to_i)
end

#bind(tag_or_id, sequence = None, &script) ⇒ Object

This method associates command with all the items given by tag_or_id such that whenever the event sequence given by sequence occurs for one of the items the command will be invoked.

This widget command is similar to the bind command except that it operates on items in a canvas rather than entire widgets. See the bind manual entry for complete details on the syntax of sequence and the substitutions performed on command before invoking it.

If all arguments are specified then a new binding is created, replacing any existing binding for the same sequence and tag_or_id. See [bind_append] for information of how augment an existing binding instead of replacing it.

In this case the return value is nil.

If command is omitted then the method returns the command associated with tag_or_id and sequence (an error occurs if there is no such binding). If both command and sequence are omitted then the command returns a list of all the sequences for which bindings have been defined for tag_or_id.

The only events for which bindings may be specified are those related to the mouse and keyboard (such as Enter, Leave, ButtonPress, Motion, and KeyPress) or virtual events. The handling of events in canvases uses the current item defined in ITEM IDS AND TAGS above. Enter and Leave 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 Enter and Leave 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 focus widget command below for more on this). If a virtual event is used in a binding, that binding can trigger only if the virtual event is defined by an underlying mouse-related or keyboard-related event. 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 all 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 continue command in a binding script terminates that script, and a break command terminates that script and skips any remaining scripts for the event, just as for the bind command. If bindings have been created for a canvas window using the bind command, then they are invoked in addition to bindings created for the canvas’s items using the bind widget command. The bindings for items will be invoked before any of the bindings for the window as a whole.



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# File 'lib/ffi-tk/widget/canvas.rb', line 163

def bind(tag_or_id, sequence = None, &script)
  unless script
    if None == sequence
      return Tk.execute(tk_pathname, :bind, tag_or_id)
    else
      return Tk.execute(tk_pathname, :bind, tag_or_id, sequence)
    end
  end

  name = "#{tag_or_id}".scan(/\w+/).join('_')
  @events ||= {}
  # unregister_event(name)

  Event::Handler.register_custom(script) do |id|
    code = "%s bind %s %s { ::RubyFFI::event %d %s %s }"
    props = Event::Data::PROPERTIES.transpose[0].join(' ')
    tcl = code % [tk_pathname, tag_or_id, sequence, id, sequence, props]
    Tk.interp.eval(tcl)
    @events[name] = id
  end
end

#canvasx(screenx, gridspacing = false) ⇒ Object

Given a window x-coordinate in the canvas screenx, this command returns the canvas x-coordinate that is displayed at that location. If gridspacing is true, then the canvas coordinate is rounded to the nearest multiple of gridspacing units.



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# File 'lib/ffi-tk/widget/canvas.rb', line 189

def canvasx(screenx, gridspacing = false)
  execute(:canvasx, screenx, gridspacing ? :gridspacing : None)
end

#canvasy(screeny, gridspacing = false) ⇒ Object

Given a window y-coordinate in the canvas screeny this command returns the canvas y-coordinate that is displayed at that location. If gridspacing is true, then the canvas coordinate is rounded to the nearest multiple of gridspacing units.



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# File 'lib/ffi-tk/widget/canvas.rb', line 197

def canvasy(screeny, gridspacing = false)
  execute(:canvasy, screeny, gridspacing ? :gridspacing : None)
end

#coords(tag_or_id, *coord_list) ⇒ Object

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 tag_or_id. If coordinates are specified, then they replace the current coordinates for the named item. If tag_or_id refers to multiple items, then the first one in the display list is used.



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# File 'lib/ffi-tk/widget/canvas.rb', line 208

def coords(tag_or_id, *coord_list)
  if coord_list.empty?
    execute(:coords, tag_or_id).to_a
  else
    execute_only(:coords, tag_or_id, *coord_list.flatten)
  end
end

#create(type, coord_list, options = {}) ⇒ Object

Create a new item in pathName of type type. The exact format of the arguments after type depends on type, 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.



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# File 'lib/ffi-tk/widget/canvas.rb', line 223

def create(type, coord_list, options = {})
  options = options ? options.to_tcl_options : None
  id = execute(:create, type, coord_list, options).to_i
  Item.create(self, type, id)
end

#create_arc(x1, y1, x2, y2, options = {}) ⇒ Object

Items of type arc appear on the display as arc-shaped regions. An arc is a section of an oval delimited by two angles (specified by the :start and :extent options) and displayed in one of several ways (specified by the :style option).



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# File 'lib/ffi-tk/widget/canvas.rb', line 233

def create_arc(x1, y1, x2, y2, options = {})
  create(:arc, [x1, y1, x2, y2], options)
end

#create_bitmap(x, y, options = {}) ⇒ Object

Items of type bitmap appear on the display as images with two colors, foreground and background.



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# File 'lib/ffi-tk/widget/canvas.rb', line 239

def create_bitmap(x, y, options = {})
  create(:bitmap, [x, y], options)
end

#create_image(x, y, options = {}) ⇒ Object

Items of type image are used to display images on a canvas.



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# File 'lib/ffi-tk/widget/canvas.rb', line 244

def create_image(x, y, options = {})
  create(:image, [x, y], options)
end

#create_line(*arguments) ⇒ Object

Items of type line appear on the display as one or more connected line segments or curves. Line items support coordinate indexing operations using the methods [dchars], [index], and [insert].



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# File 'lib/ffi-tk/widget/canvas.rb', line 252

def create_line(*arguments)
  options, coords = arguments.partition{|arg| arg.respond_to?(:to_tcl_options) }
  create(:line, coords, options.first)
end

#create_oval(x1, y1, x2, y2, options = {}) ⇒ Object

Items of type oval appear as circular or oval regions on the display. Each oval may have an outline, a fill, or both.



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# File 'lib/ffi-tk/widget/canvas.rb', line 259

def create_oval(x1, y1, x2, y2, options = {})
  create(:oval, [x1, y1, x2, y2], options)
end

#create_polygon(*arguments) ⇒ Object

Items of type polygon appear as polygonal or curved filled regions on the display. Polygon items support coordinate indexing operations using the methods [dchars], [index], or [insert].



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# File 'lib/ffi-tk/widget/canvas.rb', line 266

def create_polygon(*arguments)
  options, coords = arguments.partition{|arg| arg.respond_to?(:to_tcl_options) }
  create(:polygon, coords, options.first)
end

#create_rectangle(x1, y1, x2, y2, options = {}) ⇒ Object

Items of type rectangle appear as rectangular regions on the display. Each rectangle may have an outline, a fill, or both.



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# File 'lib/ffi-tk/widget/canvas.rb', line 273

def create_rectangle(x1, y1, x2, y2, options = {})
  create(:rectangle, [x1, y1, x2, y2], options)
end

#create_text(x, y, options = {}) ⇒ Object

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 methods: [dchars], [focus], [icursor], [index], [insert], and [select].



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# File 'lib/ffi-tk/widget/canvas.rb', line 281

def create_text(x, y, options = {})
  create(:text, [x, y], options)
end

#create_window(x, y, options = {}) ⇒ Object

Items of type window cause a particular window to be displayed at a given position on the canvas.



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# File 'lib/ffi-tk/widget/canvas.rb', line 287

def create_window(x, y, options = {})
  create(:window, [x, y], options)
end

#dchars(tag_or_id, first, last = None) ⇒ Object

For each item given by tag_or_id, delete the characters, or coordinates, in the range given by first and last, inclusive. If some of the items given by tag_or_id do not support indexing operations then they ignore dchars. Text items interpret first and last as indices to a character, line and polygon items interpret them indices to a coordinate (an x,y pair). Indices are described in INDICES above. If last is omitted, it defaults to first. This command returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 300

def dchars(tag_or_id, first, last = None)
  execute_only(:dchars, tag_or_id, first, last)
end

#delete(*tags_or_ids) ⇒ Object

Delete the items associated with the given tags_or_ids, and return nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 305

def delete(*tags_or_ids)
  execute_only(:delete, *tags_or_ids)
end

#dtag(tag_or_id, tag_to_delete = None) ⇒ Object

For each of the items given by tag_or_id, delete the tag given by tag_to_delete from the list of those associated with the item. If an item does not have the tag tag_to_delete then the item is unaffected by the command. If tag_to_delete is omitted then it defaults to tag_or_id. This command returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 315

def dtag(tag_or_id, tag_to_delete = None)
  execute_only(:dtag, tag_or_id, tag_to_delete)
end

#find(search_command, *args) ⇒ Object

This command returns a list consisting of all the items that meet the constraints specified by search_command and args. search_command and args have any of the forms accepted by the [addtag] method. The items are returned in stacking order, with the lowest item first.



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# File 'lib/ffi-tk/widget/canvas.rb', line 324

def find(search_command, *args)
  execute(:find, search_command, *args)
end

#find_above(tag, tag_or_id) ⇒ Object 



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# File 'lib/ffi-tk/widget/canvas.rb', line 328

def find_above(tag, tag_or_id)
  execute(:find, tag, :above, tag_or_id)
end

#find_all ⇒ Object 



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# File 'lib/ffi-tk/widget/canvas.rb', line 332

def find_all
  execute(:find, :all)
end

#find_below(tag_or_id) ⇒ Object 



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# File 'lib/ffi-tk/widget/canvas.rb', line 336

def find_below(tag_or_id)
  execute(:find, :below, tag_or_id)
end

#find_closest(x, y, halo = None, start = None) ⇒ Object 



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# File 'lib/ffi-tk/widget/canvas.rb', line 340

def find_closest(x, y, halo = None, start = None)
  execute(:find, :closest, x, y, halo, start)
end

#find_enclosed(x1, y1, x2, y2) ⇒ Object 



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# File 'lib/ffi-tk/widget/canvas.rb', line 344

def find_enclosed(x1, y1, x2, y2)
  execute(:find, :enclosed, x1, y1, x2, y2)
end

#find_overlapping(x1, y1, x2, y2) ⇒ Object 



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# File 'lib/ffi-tk/widget/canvas.rb', line 348

def find_overlapping(x1, y1, x2, y2)
  execute(:find, :overlapping, x1, y1, x2, y2)
end

#find_withtag(tag_or_id) ⇒ Object 



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# File 'lib/ffi-tk/widget/canvas.rb', line 352

def find_withtag(tag_or_id)
  execute(:find, :withtag, tag_or_id)
end

#focus(tag_or_id = None) ⇒ Object

Set the keyboard focus for the canvas widget to the item given by tag_or_id. If tag_or_id refers to several items, then the focus is set to the first such item in the display list that supports the insertion cursor. If tag_or_id does not refer to any items, or if none of them support the insertion cursor, then the focus is not changed. If tag_or_id is an empty string, then the focus item is reset so that no item has the focus. If tag_or_id 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. 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 focus command) are totally independent: a given item does not 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 focus widget command with the focus command to set the focus window to the canvas (if it was not there already).



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# File 'lib/ffi-tk/widget/canvas.rb', line 375

def focus(tag_or_id = None)
  if None == tag_or_id
    execute(:focus)
  else
    execute_only(:focus, tag_or_id)
  end
end

#gettags(tag_or_id) ⇒ Object

Return a list whose elements are the tags associated with the item given by tag_or_id. If tag_or_id refers to more than one item, then the tags are returned from the first such item in the display list. If tag_or_id does not refer to any items, or if the item contains no tags, then an empty string is returned.



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# File 'lib/ffi-tk/widget/canvas.rb', line 389

def gettags(tag_or_id)
  execute(:gettags, tag_or_id).to_a
end

#icursor(tag_or_id, index) ⇒ Object

Set the position of the insertion cursor for the item(s) given by tag_or_id to just before the character whose position is given by index. If some or all of the items given by tag_or_id do not support an insertion cursor then this command has no effect on them. See INDICES above for a description of the legal forms for index. Note: the insertion cursor is only displayed in an item if that item currently has the keyboard focus (see the widget command focus, below), but the cursor position may be set even when the item does not have the focus. This command returns an empty string.



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# File 'lib/ffi-tk/widget/canvas.rb', line 402

def icursor(tag_or_id, index)
  execute_only(:icursor, tag_or_id, index)
end

#index(tag_or_id, index) ⇒ Object

This command returns a decimal string giving the numerical index within tag_or_id corresponding to index. Index gives a textual description of the desired position as described in INDICES above. Text items interpret index as an index to a character, line and polygon items interpret it as an index to a coordinate (an x,y pair). The return value is guaranteed to lie between 0 and the number of characters, or coordinates, within the item, inclusive. If tag_or_id refers to multiple items, then the index is processed in the first of these items that supports indexing operations (in display list order).



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# File 'lib/ffi-tk/widget/canvas.rb', line 417

def index(tag_or_id, index)
  execute(:index, tag_or_id, index)
end

#insert(tag_or_id, before, string) ⇒ Object

For each of the items given by tag_or_id, if the item supports text or coordinate, insertion then string is inserted into the item’s text just before the character, or coordinate, whose index is before. Text items interpret before as an index to a character, line and polygon items interpret it as an index to a coordinate (an x,y pair). For lines and polygons the string must be a valid coordinate sequence. See INDICES above for information about the forms allowed for before. This command returns an empty string.



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# File 'lib/ffi-tk/widget/canvas.rb', line 429

def insert(tag_or_id, before, string)
  execute(:insert, tag_or_id, before, string)
end

#itemcget(tag_or_id, option) ⇒ Object

Returns the current value of the configuration option for the item given by tag_or_id whose name is option. This command is similar to the cget widget command except that it applies to a particular item rather than the widget as a whole. Option may have any of the values accepted by the create widget command when the item was created. If tag_or_id is a tag that refers to more than one item, the first (lowest) such item is used.



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# File 'lib/ffi-tk/widget/canvas.rb', line 441

def itemcget(tag_or_id, option)
  execute(:itemcget, tag_or_id, option.to_tcl_option)
end

#itemconfigure(tag_or_id, options = None) ⇒ Object

This command is similar to the configure widget command except that it modifies item-specific options for the items given by tag_or_id instead of modifying options for the overall canvas widget. If no option is specified, returns a list describing all of the available options for the first item given by tag_or_id (see Tk_ConfigureInfo for information on the format of this list). If option is specified with no value, then the command returns a list describing the one named option (this list will be identical to the corresponding sublist of the value returned if no option is specified). If one or more option-value 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 tag_or_id; in this case the command returns an empty string. The options and values are the same as those permissible in the create widget command when the item(s) were created; see the sections describing individual item types below for details on the legal options.



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# File 'lib/ffi-tk/widget/canvas.rb', line 460

def itemconfigure(tag_or_id, options = None)
  common_configure([:itemconfigure, tag_or_id], options)
end

#lower(tag_or_id, below = None) ⇒ Object

Move all of the items given by tag_or_id to a new position in the display list just before the item given by belowThis. If tag_or_id refers to more than one item then all are moved but the relative order of the moved items will not be changed. BelowThis 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.

Note: this command has no effect on window items. Window items always obscure other item types, and the stacking order of window items is determined by the raise and lower commands, not the raise and lower widget commands for canvases. This command returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 477

def lower(tag_or_id, below = None)
  execute_only(:lower, tag_or_id, below)
end

#move(tag_or_id, x_amount, y_amount) ⇒ Object

Move each of the items given by tag_or_id in the canvas coordinate space by adding x_amount to the x-coordinate of each point associated with the item and y_amount to the y-coordinate of each point associated with the item. This command returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 486

def move(tag_or_id, x_amount, y_amount)
  execute_only(:move, tag_or_id, x_amount, y_amount)
end

#postscript(options = {}) ⇒ Object

Generate a Postscript representation for part or all of the canvas.

If the :file option is specified then the Postscript is written to a file and an empty string is returned; otherwise the Postscript is returned as the result of the command. If the interpreter that owns the canvas is marked as safe, the operation will fail because safe interpreters are not allowed to write files.

If the :channel option is specified, the argument denotes the name of a channel already opened for writing. The Postscript is written to that channel, and the channel is left open for further writing at the end of the operation.

The Postscript is created in Encapsulated Postscript form using version 3.0 of the Document Structuring Conventions.

Note: by default Postscript is only generated for information that appears in the canvas’s window on the screen. If the canvas is freshly created it may still have its initial size of 1x1 pixel so nothing will appear in the Postscript. To get around this problem either invoke the update command to wait for the canvas window to reach its final size, or else use the :width and :height options to specify the area of the canvas to print.

The options argument provides additional information to control the generation of Postscript.

The following options are supported:

colormap: var_name

var_name must be the name of an array variable that specifies a color
mapping to use in the Postscript.
Each element of var_name must consist of Postscript code to set a
particular color value (e.g.
"1.0 1.0 0.0 setrgbcolor").
When outputting color information in the Postscript, Tk checks to see if
there is an element of var_name with the same name as the color.
If so, Tk uses the value of the element as the Postscript command to set
the color.
If this option has not been specified, or if there is no entry in
var_name for a given color, then Tk uses the red, green, and blue
intensities from the X color.

colormode: mode

Specifies how to output color information.
Mode must be either color (for full color output), gray (convert all
colors to their gray-scale equivalents) or mono (convert all colors to
black or white).

file: file_name

Specifies the name of the file in which to write the Postscript.
If this option is not specified then the Postscript is returned as the
result of the command instead of being written to a file.

fontmap: var_name

var_name must be the name of an array variable that specifies a font
mapping to use in the Postscript.
Each element of var_name must consist of a Tcl list with two elements,
which are the name and point size of a Postscript font.
When outputting Postscript commands for a particular font, Tk checks to
see if var_name contains an element with the same name as the font.
If there is such an element, then the font information contained in that
element is used in the Postscript.
Otherwise Tk attempts to guess what Postscript font to use.
Tk's guesses generally only work for well-known fonts such as Times and
Helvetica and Courier, and only if the X font name does not omit any
dashes up through the point size.
For example, -*-Courier-Bold-R-Normal--*-120-* will work but
*Courier-Bold-R-Normal*120* will not; Tk needs the dashes to parse the
font name).

height: size

Specifies the height of the area of the canvas to print.
Defaults to the height of the canvas window.

pageanchor: anchor

Specifies which point of the printed area of the canvas should appear
over the positioning point on the page (which is given by the :pagex and
:pagey options).
For example, pageanchor: n means that the top center of the area of the
canvas being printed (as it appears in the canvas window) should be over
the positioning point.
Defaults to center.

pageheight: size

Specifies that the Postscript should be scaled in both x and y so that
the printed area is size high on the Postscript page.
Size consists of a floating-point number followed by c for centimeters,
i for inches, m for millimeters, or p or nothing for printer's points
(1/72 inch).
Defaults to the height of the printed area on the screen.
If both :pageheight and :pagewidth are specified then the scale factor
from :pagewidth is used (non-uniform scaling is not implemented).

pagewidth: size

Specifies that the Postscript should be scaled in both x and y so that
the printed area is size wide on the Postscript page.
Size has the same form as for -pageheight.
Defaults to the width of the printed area on the screen.
If both -pageheight and -pagewidth are specified then the scale factor
from -pagewidth is used (non-uniform scaling is not implemented).

pagex: position

Position gives the x-coordinate of the positioning point on the
Postscript page, using any of the forms allowed for -pageheight.
Used in conjunction with the -pagey and -pageanchor options to determine
where the printed area appears on the Postscript page.
Defaults to the center of the page.

pagey: position

Position gives the y-coordinate of the positioning point on the
Postscript page, using any of the forms allowed for -pageheight.
Used in conjunction with the -pagex and -pageanchor options to determine
where the printed area appears on the Postscript page.
Defaults to the center of the page.

rotate: boolean

Boolean specifies whether the printed area is to be rotated 90 degrees.
In non-rotated output the x-axis of the printed area runs along the
short dimension of the page ("portrait" orientation); in rotated output
the x-axis runs along the long dimension of the page
("landscape" orientation). Defaults to non-rotated.

width:

size Specifies the width of the area of the canvas to print.
Defaults to the width of the canvas window.

x: position

Specifies the x-coordinate of the left edge of the area of the canvas
that is to be printed, in canvas coordinates, not window coordinates.
Defaults to the coordinate of the left edge of the window.

y: position

Specifies the y-coordinate of the top edge of the area of the canvas
that is to be printed, in canvas coordinates, not window coordinates.
Defaults to the coordinate of the top edge of the window.



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# File 'lib/ffi-tk/widget/canvas.rb', line 626

def postscript(options = {})
  execute(:postscript, options.to_tcl_options).to_s?
end

#raise(tag_or_id, above = None) ⇒ Object

Move all of the items given by tag_or_id to a new position in the display list just after the item given by above. If tag_or_id refers to more than one item then all are moved but the relative order of the moved items will not be changed. AboveThis 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.

Note: this command has no effect on window items. Window items always obscure other item types, and the stacking order of window items is determined by the raise and lower commands, not the raise and lower widget commands for canvases. This command returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 643

def raise(tag_or_id, above = None)
  execute_only(:raise, tag_or_id, above)
end

#scale(tag_or_id, x_origin, y_origin, x_scale, y_scale) ⇒ Object

Rescale all of the items given by tag_or_id in canvas coordinate space. x_origin and y_origin identify the origin for the scaling operation and x_scale and y_scale 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 x_origin by a factor of x_scale. Similarly, each y-coordinate is adjusted to change the distance from y_origin by a factor of y_scale. This command returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 657

def scale(tag_or_id, x_origin, y_origin, x_scale, y_scale)
  execute(:scale, tag_or_id, x_origin, y_origin, x_scale, y_scale)
end

#scan_dragto(x, y, gain = None) ⇒ Object

This command computes the difference between its x and y arguments (which are typically mouse coordinates) and the x and y arguments to the last scan mark command for the widget. It then adjusts the view by gain times the difference in coordinates, where gain defaults to 10. This command is typically associated with mouse motion events in the widget, to produce the effect of dragging the canvas at high speed through its window. The return value is nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 679

def scan_dragto(x, y, gain = None)
  execute_only(:scan, :dragto, x, y, gain)
end

#scan_mark(x, y) ⇒ Object

Records x and y and the canvas’s current view; used in conjunction with later scan dragto commands. Typically this command is associated with a mouse button press in the widget and x and y are the coordinates of the mouse. It returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 666

def scan_mark(x, y)
  execute_only(:scan, :mark, x, y)
end

#select_adjust(tag_or_id, index) ⇒ Object

Locate the end of the selection in tag_or_id nearest to the character given by index, and adjust that end of the selection to be at index (i.e. including but not going beyond index). The other end of the selection is made the anchor point for future select to commands. If the selection is not currently in tag_or_id then this command behaves the same as the select to widget command. Returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 691

def select_adjust(tag_or_id, index)
  execute_only(:select, :adjust, tag_or_id, index)
end

#select_clear ⇒ Object

Clear the selection if it is in this widget. If the selection is not in this widget then the command has no effect. Returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 698

def select_clear
  execute_only(:select, :clear)
end

#select_from(tag_or_id, index) ⇒ Object

Set the selection anchor point for the widget to be just before the character given by index in the item given by tag_or_id. This command does not change the selection; it just sets the fixed end of the selection for future select to commands. Returns nil.



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# File 'lib/ffi-tk/widget/canvas.rb', line 707

def select_from(tag_or_id, index)
  execute(:select, :from, tag_or_id, index)
end

#select_item ⇒ Object

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 nil is returned.



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# File 'lib/ffi-tk/widget/canvas.rb', line 714

def select_item
  execute(:select, :item).to_s?
end

#select_to(tag_or_id, index) ⇒ Object

Set the selection to consist of those characters of tag_or_id between the selection anchor point and index. The new selection will include the character given by index; it will include the character given by the anchor point only if index is greater than or equal to the anchor point. The anchor point is determined by the most recent select adjust or select from command for this widget. If the selection anchor point for the widget is not currently in tag_or_id, then it is set to the same character given by index. Returns an empty string.



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# File 'lib/ffi-tk/widget/canvas.rb', line 728

def select_to(tag_or_id, index)
  execute(:select, :to, tag_or_id, index)
end

#type(tag_or_id) ⇒ Object

Returns the type of the item given by tag_or_id, such as rectangle or text. If tag_or_id refers to more than one item, then the type of the first item in the display list is returned. If tag_or_id does not refer to any items at all then nil is returned.



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# File 'lib/ffi-tk/widget/canvas.rb', line 736

def type(tag_or_id)
  execute(:type, tag_or_id).to_sym?
end

#xview ⇒ Object

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 -scrollregion 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 -xscrollcommand option.



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# File 'lib/ffi-tk/widget/canvas.rb', line 749

def xview
  execute(:xview).to_a(&:to_f)
end

#xview_moveto(fraction) ⇒ Object

Adjusts the view in the window so that fraction of the total width of the canvas is off-screen to the left. Fraction must be a fraction between 0 and 1.



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# File 'lib/ffi-tk/widget/canvas.rb', line 756

def xview_moveto(fraction)
  execute_only(:xview, :moveto, fraction)
end

#xview_scroll(number, what) ⇒ Object

This command shifts the view in the window left or right according to number and what. Number must be an integer. What must be either units or pages or an abbreviation of one of these. If what is units, the view adjusts left or right in units of the xScrollIncrement option, if it is greater than zero, or in units of one-tenth the window’s width otherwise. If what is pages then the view adjusts in units of nine-tenths the window’s width. If number is negative then information farther to the left becomes visible; if it is positive then information farther to the right becomes visible.



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# File 'lib/ffi-tk/widget/canvas.rb', line 772

def xview_scroll(number, what)
  execute_only(:xview, :scroll, number, what)
end

#yview ⇒ Object

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 -scrollregion option) is visible in the window. These are the same values passed to scrollbars via the -yscrollcommand option.



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# File 'lib/ffi-tk/widget/canvas.rb', line 784

def yview
  execute(:yview)
end

#yview_moveto(fraction) ⇒ Object

Adjusts the view in the window so that fraction of the canvas’s area is off-screen to the top. Fraction is a fraction between 0 and 1.



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# File 'lib/ffi-tk/widget/canvas.rb', line 791

def yview_moveto(fraction)
  execute(:yview, :moveto, fraction)
end

#yview_scroll(number, what) ⇒ Object

This command adjusts the view in the window up or down according to number and what. Number must be an integer. What must be either units or pages. If what is units, the view adjusts up or down in units of the yScrollIncrement option, if it is greater than zero, or in units of one-tenth the window’s height otherwise. If what is pages then the view adjusts in units of nine-tenths the window’s height. If number is negative then higher information becomes visible; if it is positive then lower information becomes visible.



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# File 'lib/ffi-tk/widget/canvas.rb', line 806

def yview_scroll(number, what)
  execute(:yview, :scroll, number, what)
end