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✏️ Editing: ctext.tcl

# ctext.tcl --
#
# This demonstration script creates a canvas widget with a text
# item that can be edited and reconfigured in various ways.

if {![info exists widgetDemo]} {
    error "This script should be run from the \"widget\" demo."
}

package require Tk

set w .ctext
catch {destroy $w}
toplevel $w
wm title $w "Canvas Text Demonstration"
wm iconname $w "Text"
positionWindow $w
set c $w.c

label $w.msg -font $font -wraplength 5i -justify left -text "This window displays a string of text to demonstrate the text facilities of canvas widgets.  You can click in the boxes to adjust the position of the text relative to its positioning point or change its justification, and on a pie slice to change its angle.  The text also supports the following simple bindings for editing:
  1. You can point, click, and type.
  2. You can also select with button 1.
  3. You can copy the selection to the mouse position with button 2.
  4. Backspace and Control+h delete the selection if there is one;
     otherwise they delete the character just before the insertion cursor.
  5. Delete deletes the selection if there is one; otherwise it deletes
     the character just after the insertion cursor."
pack $w.msg -side top

## See Code / Dismiss buttons
set btns [addSeeDismiss $w.buttons $w]
pack $btns -side bottom -fill x

canvas $c -relief flat -borderwidth 0 -width 500 -height 350
pack $w.c -side top -expand yes -fill both

set textFont {Helvetica 24}

$c create rectangle 245 195 255 205 -outline black -fill red

# First, create the text item and give it bindings so it can be edited.

$c addtag text withtag [$c create text 250 200 -text "This is just a string of text to demonstrate the text facilities of canvas widgets. Bindings have been been defined to support editing (see above)." -width 440 -anchor n -font $textFont -justify left]
$c bind text <1> "textB1Press $c %x %y"
$c bind text <B1-Motion> "textB1Move $c %x %y"
$c bind text <Shift-1> "$c select adjust current @%x,%y"
$c bind text <Shift-B1-Motion> "textB1Move $c %x %y"
$c bind text <KeyPress> "textInsert $c %A"
$c bind text <Return> "textInsert $c \\n"
$c bind text <Control-h> "textBs $c"
$c bind text <BackSpace> "textBs $c"
$c bind text <Delete> "textDel $c"
$c bind text <2> "textPaste $c @%x,%y"

# Next, create some items that allow the text's anchor position
# to be edited.

proc mkTextConfigBox {w x y option value color} {
    set item [$w create rect $x $y [expr {$x+30}] [expr {$y+30}] \
	    -outline black -fill $color -width 1]
    $w bind $item <1> "$w itemconf text $option $value"
    $w addtag config withtag $item
}
proc mkTextConfigPie {w x y a option value color} {
    set item [$w create arc $x $y [expr {$x+90}] [expr {$y+90}] \
	    -start [expr {$a-15}] -extent 30 -outline black -fill $color \
	    -width 1]
    $w bind $item <1> "$w itemconf text $option $value"
    $w addtag config withtag $item
}

set x 50
set y 50
set color LightSkyBlue1
mkTextConfigBox $c $x $y -anchor se $color
mkTextConfigBox $c [expr {$x+30}] [expr {$y   }] -anchor s      $color
mkTextConfigBox $c [expr {$x+60}] [expr {$y   }] -anchor sw     $color
mkTextConfigBox $c [expr {$x   }] [expr {$y+30}] -anchor e      $color
mkTextConfigBox $c [expr {$x+30}] [expr {$y+30}] -anchor center $color
mkTextConfigBox $c [expr {$x+60}] [expr {$y+30}] -anchor w      $color
mkTextConfigBox $c [expr {$x   }] [expr {$y+60}] -anchor ne     $color
mkTextConfigBox $c [expr {$x+30}] [expr {$y+60}] -anchor n      $color
mkTextConfigBox $c [expr {$x+60}] [expr {$y+60}] -anchor nw     $color
set item [$c create rect \
	[expr {$x+40}] [expr {$y+40}] [expr {$x+50}] [expr {$y+50}] \
	-outline black -fill red]
$c bind $item <1> "$c itemconf text -anchor center"
$c create text [expr {$x+45}] [expr {$y-5}] \
	-text {Text Position}  -anchor s  -font {Times 20}  -fill brown

# Now create some items that allow the text's angle to be changed.

set x 205
set y 50
set color Yellow
mkTextConfigPie $c $x $y   0 -angle  90 $color
mkTextConfigPie $c $x $y  30 -angle 120 $color
mkTextConfigPie $c $x $y  60 -angle 150 $color
mkTextConfigPie $c $x $y  90 -angle 180 $color
mkTextConfigPie $c $x $y 120 -angle 210 $color
mkTextConfigPie $c $x $y 150 -angle 240 $color
mkTextConfigPie $c $x $y 180 -angle 270 $color
mkTextConfigPie $c $x $y 210 -angle 300 $color
mkTextConfigPie $c $x $y 240 -angle 330 $color
mkTextConfigPie $c $x $y 270 -angle   0 $color
mkTextConfigPie $c $x $y 300 -angle  30 $color
mkTextConfigPie $c $x $y 330 -angle  60 $color
$c create text [expr {$x+45}] [expr {$y-5}] \
	-text {Text Angle}  -anchor s  -font {Times 20}  -fill brown

# Lastly, create some items that allow the text's justification to be
# changed.

set x 350
set y 50
set color SeaGreen2
mkTextConfigBox $c $x $y -justify left $color
mkTextConfigBox $c [expr {$x+30}] $y -justify center $color
mkTextConfigBox $c [expr {$x+60}] $y -justify right $color
$c create text [expr {$x+45}] [expr {$y-5}] \
	-text {Justification}  -anchor s  -font {Times 20}  -fill brown

$c bind config <Enter> "textEnter $c"
$c bind config <Leave> "$c itemconf current -fill \$textConfigFill"

set textConfigFill {}

proc textEnter {w} {
    global textConfigFill
    set textConfigFill [lindex [$w itemconfig current -fill] 4]
    $w itemconfig current -fill black
}

proc textInsert {w string} {
    if {$string == ""} {
	return
    }
    catch {$w dchars text sel.first sel.last}
    $w insert text insert $string
}

proc textPaste {w pos} {
    catch {
	$w insert text $pos [selection get]
    }
}

proc textB1Press {w x y} {
    $w icursor current @$x,$y
    $w focus current
    focus $w
    $w select from current @$x,$y
}

proc textB1Move {w x y} {
    $w select to current @$x,$y
}

proc textBs {w} {
    if {![catch {$w dchars text sel.first sel.last}]} {
	return
    }
    set char [expr {[$w index text insert] - 1}]
    if {$char >= 0} {$w dchar text $char}
}

proc textDel {w} {
    if {![catch {$w dchars text sel.first sel.last}]} {
	return
    }
    $w dchars text insert
}

MR SKB