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Blt provides the winop command (manpage) which has sub-commands for window and image manipulation. This can be used in conjunction with the photo copy extensions.

The image sub-commands

The winop image sub-commands provide image manipulation.


Gradient images are widely used in application and web pages for enhancing the appearance of user interfaces.


merge allows on-the-fly composting of sophisticated images.

For example, the following screenshot displays:

  1. A "lines" gradient
  2. A "rectangle" gradient
  3. A gradient with skew
  4. Merging a gradient with a tile.
  5. Merging a picture with tile.

(:showex div=todex:)

Here is the source for producing the above images (which also requires downloading beach.jpg).

For the image 1 run wize grad.tcl 1, etc.

#!/usr/bin/env wize
# grad.tcl: a script demonstrate use of two winop commands:
# gradient and merge.
# In all tests, an image is created and used to setup
# the background tile.  Then a couple of widgets are created.

set tst [lindex $argv 0]
wm title . "Winop test: $tst"

switch -- $tst {
  1 - 2 - 3 {
    set img [image create photo -width 400 -height 300]
    if {$tst == "1"} {
      winop image gradient $img Red DarkBlue lines
    } elseif {$tst == "2"} {
      winop image gradient $img Red DarkBlue rectangular
    } else {
      winop image gradient $img DarkBlue Red lines .3
    set img2 [image create photo]
    $img2 copy $img
    . conf -tile $img2
    wm geom . [image width $img2]x[image height $img2]
    option add *tile $img2
    place [button .b -text Begin] -relx .3 -rely .3
    place [text .t -width 20 -height 5] -relx .3 -rely .4
    .t insert end " Enter info..."
  4 - 5 {
    set i [image create photo -file /zvfs/img/tile/tile-swirl.gif]
    set i2 [image create photo -file beach.jpg]
    set i3 [image create photo]
    set img [image create photo]

    if {$tst != 4} {
      $img copy $i -to 0 0 [image width $i2] [image height $i2]
      winop merge $i2 $img $i3 .25
    } else {
      $img copy $i -to 0 0 [image width $i2] [image height $i]
      set i4 [image create photo -width [image width $i2] -height [image height $i]]
      winop image gradient $i4 Cyan Purple lines
      winop image merge $i4 $img $i3 .25
    option add *tile $i3
    . conf -tile $i3 
    wm geom . [image width $i2]x[image height $i2]

    pack [set t [Tabset new . -slant right]] -padx 20 -pady 20 -fill both -expand y 
    set tf [Frame new $t.] 
    pack [set t1 [Text new $tf.]] -fill both -expand y
    Text insert $t1 end [join [info commands *] \n]
    Tabset insert $t end Main -window $tf
    pack [set t1 [Button new $tf. -text Done]] -pady 10

    set t2 [Text new $t.]
    Tabset insert $t end Secondary -window $t2 -fill both

  default {
     puts "usage: $argv0 1 | 2 | 3 | 4 | 5"
     exit 0

resample and subsample

These commands are used to resize and optionally filter images. eg.

  set i2 [image create photo -width 48 -height 48]
  winop image resample $i1 $i2


The alpha sub-command is used to make one color transparent in an image. This can be useful for making shaped toplevel windows (which take their shape from the transparency) or shaped buttons like this:

(:showex div=totran:)

The following script demonstrates using a canvas to draw an arbitrary polygon upon a white background. This is saved to an image and the White converted to transparent. This image could then be used as a shaped button or toplevel window.

#!/usr/bin/env wize

pack  [frame .f] -fill both -expand 1
canvas [set c .f.c] -bg White  -bd 0 -width 100 -height 100
pack  $c -s top -e 0 -f none -padx 0 -pady 0
set tfile /zvfs/img/tile/blueplasma.gif
if {![file exists $tfile]} {
  $c create polygon "10 10 10 100 50 50" -smooth 1 -fill red
} else {
  set tile [image create photo -file $tfile]
  $c create polygon "10 10 10 100 50 50" -smooth 1 -tile $tile -outline black
after 1000

set image [image create photo -format window -data .]
set img2 [image create photo]
winop image alpha $image $img2 White
$img2 write -format gif transimg.gif

pack [button .b -bg green -image $img2]

Note that an alternative approach is to use a pixmap.


The mirror sub-command flips an image. eg.

  winop image mirror $i1 $i2 x;  # Flip x axis.
  winop image mirror $i1 $i2 y;  # Flip y axis.
  winop image mirror $i1 $i2;    # Flip both.
  winop image mirror $i1 $i2 tile

The tile operation is used to generate a tile-able image.

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Page last modified on May 14, 2010, at 12:40 PM