canvas.tk

《Beginning Linux Programming》书的配置实例源代码。

#!/usr/bin/wish -f

# First we create the canvas and then some objects to display on it.

set c [canvas .c -width 400 -height 300 -relief sunken -bd 2]

set image [image create photo -file caption.gif -width 500 -height 200]
$c create image 150 150 -anchor center -image $image -tags item

$c create text 150 150 -text " Image Object"  -fill white

$c create text 10 10 -text " Move any Item \n using Mouse " -justify center \
                     -anchor nw -tags item  -fill red
$c create rectangle 200 10  250 40 -fill yellow -outline blue -tags item

pack .c

# Next, we bind the canvas so that we can operate on the items shown on it.
# We'll define the itemDragStart and dragItem  procedures next.

bind $c <1> "itemDragStart $c %x %y"
bind $c <B1-Motion> "dragItem $c %x %y"

# For the procedure's benefit, we need to define two global variables, lastX and lastY.

global lastX lastY

# event handler for the <1> event
proc itemDragStart {c x y} {
    global lastX lastY
    set lastX [$c canvasx $x]
    set lastY [$c canvasy $y]
}
# event handler for the <B1-Motion> event
proc dragItem {c x y} {
    global lastX lastY
    set x [$c canvasx $x]
    set y [$c canvasy $y]
    $c move current [expr $x-$lastX] [expr $y-$lastY]
    set lastX $x
    set lastY $y
}