proc + {n1 n2} {
expr {$n1 + $n2}
}
proc - {n1 n2} {
expr {$n1 - $n2}
}
proc * {n1 n2} {
expr {$n1 * $n2}
}
proc / {n1 n2} {
expr {$n1 / $n2}
}
proc toInt {n} {
expr int($n)
}
proc drawGradient {win type col1Str col2Str} {
$win delete gradient
set width [winfo width $win]
set height [winfo height $win]
foreach {r1 g1 b1} [winfo rgb $win $col1Str] break
foreach {r2 g2 b2} [winfo rgb $win $col2Str] break
set rRange [- $r2.0 $r1]
set gRange [- $g2.0 $g1]
set bRange [- $b2.0 $b1]
if {$type == "x"} {
set rRatio [/ $rRange $width]
set gRatio [/ $gRange $width]
set bRatio [/ $bRange $width]
for {set x 0} {$x < $width} {incr x} {
set nR [toInt [+ $r1 [* $rRatio $x]]]
set nG [toInt [+ $g1 [* $gRatio $x]]]
set nB [toInt [+ $b1 [* $bRatio $x]]]
set col [format {%4.4x} $nR]
append col [format {%4.4x} $nG]
append col [format {%4.4x} $nB]
$win create line $x 0 $x $height -tags gradient -fill #${col}
}
} else {
set rRatio [/ $rRange $height]
set gRatio [/ $gRange $height]
set bRatio [/ $bRange $height]
for {set y 0} {$y < $height} {incr y} {
set nR [toInt [+ $r1 [* $rRatio $y]]]
set nG [toInt [+ $g1 [* $gRatio $y]]]
set nB [toInt [+ $b1 [* $bRatio $y]]]
set col [format {%4.4x} $nR]
append col [format {%4.4x} $nG]
append col [format {%4.4x} $nB]
$win create line 0 $y $width $y -tags gradient -fill #${col}
}
}
return $win
}
canvas .grad1
bind .grad1 <Configure> [list drawGradient .grad1 x red royalblue]
canvas .grad2
bind .grad2 <Configure> [list drawGradient .grad2 y yellow red]
pack .grad1 .grad2 -fill both -expand 1Here's a slightly more portable version of that code with some error-checking thrown in for good measure. -- Damon Courtney
proc DrawGradient {win axis col1Str col2Str} {
if {[winfo class $win] != "Canvas"} {
return -code error "$win must be a canvas widget"
}
$win delete gradient
set width [winfo width $win]
set height [winfo height $win]
switch -- $axis {
"x" { set max $width; set x 1 }
"y" { set max $height; set x 0 }
default {
return -code error "Invalid axis $axis: must be x or y"
}
}
if {[catch {winfo rgb $win $col1Str} color1]} {
return -code error "Invalid color $col1Str"
}
if {[catch {winfo rgb $win $col2Str} color2]} {
return -code error "Invalid color $col2Str"
}
foreach {r1 g1 b1} $color1 break
foreach {r2 g2 b2} $color2 break
set rRange [expr $r2.0 - $r1]
set gRange [expr $g2.0 - $g1]
set bRange [expr $b2.0 - $b1]
set rRatio [expr $rRange / $max]
set gRatio [expr $gRange / $max]
set bRatio [expr $bRange / $max]
for {set i 0} {$i < $max} {incr i} {
set nR [expr int( $r1 + ($rRatio * $i) )]
set nG [expr int( $g1 + ($gRatio * $i) )]
set nB [expr int( $b1 + ($bRatio * $i) )]
set col [format {%4.4x} $nR]
append col [format {%4.4x} $nG]
append col [format {%4.4x} $nB]
if {$x} {
$win create line $i 0 $i $height -tags gradient -fill #${col}
} else {
$win create line 0 $i $width $i -tags gradient -fill #${col}
}
}
bind $win <Configure> [list DrawGradient $win $axis $col1Str $col2Str]
return $win
}
canvas .grad1
DrawGradient .grad1 y darkblue royalblue
canvas .grad2
DrawGradient .grad2 x yellow red
pack .grad1 .grad2 -fill both -expand 1DKF: Both versions are cool!