library/demos/ruler.tcl

# ruler.tcl --
#
# This demonstration script creates a canvas widget that displays a ruler
# with tab stops that can be set, moved, and deleted.
#
# SCCS: @(#) ruler.tcl 1.8 96/04/12 12:12:27

# rulerMkTab --
# This procedure creates a new triangular polygon in a canvas to
# represent a tab stop.
#
# Arguments:
# c -       The canvas window.
# x, y -    Coordinates at which to create the tab stop.

proc rulerMkTab {c x y} {
    upvar #0 demo_rulerInfo v
    $c create polygon $x $y [expr $x+$v(size)] [expr $y+$v(size)] \
        [expr $x-$v(size)] [expr $y+$v(size)]
}

set w .ruler
global tk_library
catch {destroy $w}
toplevel $w
wm title $w "Ruler Demonstration"
wm iconname $w "ruler"
positionWindow $w
set c $w.c

label $w.msg -font $font -wraplength 5i -justify left -text "This canvas widget shows a mock-up of a ruler.  You can create tab stops by dragging them out of the well to the right of the ruler.  You can also drag existing tab stops.  If you drag a tab stop far enough up or down so that it turns dim, it will be deleted when you release the mouse button."
pack $w.msg -side top

frame $w.buttons
pack $w.buttons -side bottom -fill x -pady 2m
button $w.buttons.dismiss -text Dismiss -command "destroy $w"
button $w.buttons.code -text "See Code" -command "showCode $w"
pack $w.buttons.dismiss $w.buttons.code -side left -expand 1

canvas $c -width 14.8c -height 2.5c
pack $w.c -side top -fill x

set demo_rulerInfo(grid) .25c
set demo_rulerInfo(left) [winfo fpixels $c 1c]
set demo_rulerInfo(right) [winfo fpixels $c 13c]
set demo_rulerInfo(top) [winfo fpixels $c 1c]
set demo_rulerInfo(bottom) [winfo fpixels $c 1.5c]
set demo_rulerInfo(size) [winfo fpixels $c .2c]
set demo_rulerInfo(normalStyle) "-fill black"
if {[winfo depth $c] > 1} {
    set demo_rulerInfo(activeStyle) "-fill red -stipple {}"
    set demo_rulerInfo(deleteStyle) [list -fill red \
        -stipple @[file join $tk_library demos images gray25.bmp]]
} else {
    set demo_rulerInfo(activeStyle) "-fill black -stipple {}"
    set demo_rulerInfo(deleteStyle) [list -fill black \
        -stipple @[file join $tk_library demos images gray25.bmp]]
}

$c create line 1c 0.5c 1c 1c 13c 1c 13c 0.5c -width 1
for {set i 0} {$i < 12} {incr i} {
    set x [expr $i+1]
    $c create line ${x}c 1c ${x}c 0.6c -width 1
    $c create line $x.25c 1c $x.25c 0.8c -width 1
    $c create line $x.5c 1c $x.5c 0.7c -width 1
    $c create line $x.75c 1c $x.75c 0.8c -width 1
    $c create text $x.15c .75c -text $i -anchor sw
}
$c addtag well withtag [$c create rect 13.2c 1c 13.8c 0.5c \
    -outline black -fill [lindex [$c config -bg] 4]]
$c addtag well withtag [rulerMkTab $c [winfo pixels $c 13.5c] \
    [winfo pixels $c .65c]]

$c bind well <1> "rulerNewTab $c %x %y"
$c bind tab <1> "rulerSelectTab $c %x %y"
bind $c <B1-Motion> "rulerMoveTab $c %x %y"
bind $c <Any-ButtonRelease-1> "rulerReleaseTab $c"

# rulerNewTab --
# Does all the work of creating a tab stop, including creating the
# triangle object and adding tags to it to give it tab behavior.
#
# Arguments:
# c -       The canvas window.
# x, y -    The coordinates of the tab stop.

proc rulerNewTab {c x y} {
    upvar #0 demo_rulerInfo v
    $c addtag active withtag [rulerMkTab $c $x $y]
    $c addtag tab withtag active
    set v(x) $x
    set v(y) $y
    rulerMoveTab $c $x $y
}

# rulerSelectTab --
# This procedure is invoked when mouse button 1 is pressed over
# a tab.  It remembers information about the tab so that it can
# be dragged interactively.
#
# Arguments:
# c -       The canvas widget.
# x, y -    The coordinates of the mouse (identifies the point by
#       which the tab was picked up for dragging).

proc rulerSelectTab {c x y} {
    upvar #0 demo_rulerInfo v
    set v(x) [$c canvasx $x $v(grid)]
    set v(y) [expr $v(top)+2]
    $c addtag active withtag current
    eval "$c itemconf active $v(activeStyle)"
    $c raise active
}

# rulerMoveTab --
# This procedure is invoked during mouse motion events to drag a tab.
# It adjusts the position of the tab, and changes its appearance if
# it is about to be dragged out of the ruler.
#
# Arguments:
# c -       The canvas widget.
# x, y -    The coordinates of the mouse.

proc rulerMoveTab {c x y} {
    upvar #0 demo_rulerInfo v
    if {[$c find withtag active] == ""} {
    return
    }
    set cx [$c canvasx $x $v(grid)]
    set cy [$c canvasy $y]
    if {$cx < $v(left)} {
    set cx $v(left)
    }
    if {$cx > $v(right)} {
    set cx $v(right)
    }
    if {($cy >= $v(top)) && ($cy <= $v(bottom))} {
    set cy [expr $v(top)+2]
    eval "$c itemconf active $v(activeStyle)"
    } else {
    set cy [expr $cy-$v(size)-2]
    eval "$c itemconf active $v(deleteStyle)"
    }
    $c move active [expr $cx-$v(x)] [expr $cy-$v(y)]
    set v(x) $cx
    set v(y) $cy
}

# rulerReleaseTab --
# This procedure is invoked during button release events that end
# a tab drag operation.  It deselects the tab and deletes the tab if
# it was dragged out of the ruler.
#
# Arguments:
# c -       The canvas widget.
# x, y -    The coordinates of the mouse.

proc rulerReleaseTab c {
    upvar #0 demo_rulerInfo v
    if {[$c find withtag active] == {}} {
    return
    }
    if {$v(y) != [expr $v(top)+2]} {
    $c delete active
    } else {
    eval "$c itemconf active $v(normalStyle)"
    $c dtag active
    }
}