Added a demo of simple animation to the widget tour.

3 files changed, 169 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 305e2f1..6e3cd26 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2004-11-07  Donal K. Fellows  <donal.k.fellows@man.ac.uk>
+
+	* library/demos/anilabel.tcl: Added a simple demonstration of how
+	to do animation using Tcl/Tk to the widget demo.
+
 2004-11-03  Don Porter  <dgp@users.sourceforge.net>
 
 	* tests/button.test: Update expected results to account for more
diff --git a/library/demos/anilabel.tcl b/library/demos/anilabel.tcl
new file mode 100644
index 0000000..43bbf13
--- /dev/null
+++ b/library/demos/anilabel.tcl
@@ -0,0 +1,160 @@
+# anilabel.tcl --
+#
+# This demonstration script creates a toplevel window containing
+# several animated label widgets.
+#
+# RCS: @(#) $Id: anilabel.tcl,v 1.1 2004/11/07 17:28:21 dkf Exp $
+
+if {![info exists widgetDemo]} {
+    error "This script should be run from the \"widget\" demo."
+}
+
+set w .anilabel
+catch {destroy $w}
+toplevel $w
+wm title $w "Animated Label Demonstration"
+wm iconname $w "anilabel"
+positionWindow $w
+
+label $w.msg -font $font -wraplength 4i -justify left -text "Four animated labels are displayed below; each of the labels on the left is animated by making the text message inside it appear to scroll, and the label on the right is animated by animating the image that it displays."
+pack $w.msg -side top
+
+## See Code / Dismiss buttons
+set btns [addSeeDismiss $w.buttons $w]
+pack $btns -side bottom -fill x
+
+# Ensure that this this is an array
+array set animationCallbacks {}
+
+## This callback is the core of how to do animation in Tcl/Tk; all
+## animations work in basically the same way, with a procedure that
+## uses the [after] command to reschedule itself at some point in the
+## future. Of course, the details of how to update the state will vary
+## according to what is being animated.
+proc RotateLabelText {w interval} {
+    global animationCallbacks
+
+    # Schedule the calling of this procedure again in the future
+    set animationCallbacks($w) [after $interval RotateLabelText $w $interval]
+
+    # We do marquee-like scrolling text by chopping characters off the
+    # front of the text and sticking them on the end.
+    set text [$w cget -text]
+    set newText [string range $text 1 end][string index $text 0]
+    $w configure -text $newText
+}
+
+## A helper procedure to start the animation happening.
+proc animateLabelText {w text interval} {
+    global animationCallbacks
+
+    # Install the text into the widget
+    $w configure -text $text
+
+    # Schedule the start of the animation loop
+    set animationCallbacks($w) [after $interval RotateLabelText $w $interval]
+
+    # Make sure that the animation stops and is cleaned up after itself
+    # when the animated label is destroyed.  Note that at this point we
+    # cannot manipulate the widget itself, as that has already died.
+    bind $w <Destroy> {
+	after cancel $animationCallbacks(%W)
+	unset animationCallbacks(%W)
+    }
+}
+
+## Next, a similar pair of procedures to animate a GIF loaded into a
+## photo image.
+proc SelectNextImageFrame {w interval} {
+    global animationCallbacks
+    set animationCallbacks($w) \
+	    [after $interval SelectNextImageFrame $w $interval]
+    set image [$w cget -image]
+
+    # The easy way to animate a GIF!
+    set idx -1
+    scan [$image cget -format] "GIF -index %d" idx
+    if {[catch {
+	# Note that we get an error if the index is out of range
+	$image configure -format "GIF -index [incr idx]"
+    }]} then {
+	$image configure -format "GIF -index 0"
+    }
+}
+proc animateLabelImage {w imageData interval} {
+    global animationCallbacks
+
+    # Create a multi-frame GIF from base-64-encoded data
+    set image [image create photo -format GIF -data $imageData]
+
+    # Install the image into the widget
+    $w configure -image $image
+
+    # Schedule the start of the animation loop
+    set animationCallbacks($w) \
+	    [after $interval SelectNextImageFrame $w $interval]
+
+    # Make sure that the animation stops and is cleaned up after itself
+    # when the animated label is destroyed.  Note that at this point we
+    # cannot manipulate the widget itself, as that has already died.
+    # Also note that this script is in double-quotes; this is always OK
+    # because image names are chosen automatically to be simple words.
+    bind $w <Destroy> "
+	after cancel \$animationCallbacks(%W)
+	unset animationCallbacks(%W)
+	rename $image {}
+    "
+}
+
+# Make some widgets to contain the animations
+labelframe $w.left -text "Scrolling Texts"
+labelframe $w.right -text "GIF Image"
+pack $w.left $w.right -side left -padx 10 -pady 10 -expand yes
+
+# This method of scrolling text looks far better with a fixed-width font
+label $w.left.l1 -bd 4 -relief ridge -font fixedFont
+label $w.left.l2 -bd 4 -relief groove -font fixedFont
+label $w.left.l3 -bd 4 -relief flat -font fixedFont -width 18
+pack $w.left.l1 $w.left.l2 $w.left.l3 -side top -expand yes -padx 10 -pady 10 -anchor w
+# Don't need to do very much with this label except turn off the border
+label $w.right.l -bd 0
+pack $w.right.l -side top -expand yes -padx 10 -pady 10
+
+# This is a base-64-encoded animated GIF file.
+set tclPoweredData {
+    R0lGODlhKgBAAPQAAP//////zP//AP/MzP/Mmf/MAP+Zmf+ZZv+ZAMz//8zM
+    zMyZmcyZZsxmZsxmAMwzAJnMzJmZzJmZmZlmmZlmZplmM5kzM2aZzGZmzGZm
+    mWZmZmYzZmYzMzNmzDMzZgAzmSH+IE1hZGUgd2l0aCBHSU1QIGJ5IExARGVt
+    YWlsbHkuY29tACH5BAVkAAEALAAAAAAqAEAAAAX+YCCOZEkyTKM2jOm66yPP
+    dF03bx7YcuHIDkGBR7SZeIyhTID4FZ+4Es8nQyCe2EeUNJ0peY2s9mi7PhAM
+    ngEAMGRbUpvzSxskLh1J+Hkg134OdDIDEB+GHxtYMEQMTjMGEYeGFoomezaC
+    DZGSHFmLXTQKkh8eNQVpZ2afmDQGHaOYSoEyhhcklzVmMpuHnaZmDqiGJbg0
+    qFqvh6UNAwB7VA+OwydEjgujkgrPNhbTI8dFvNgEYcHcHx0lB1kX2IYeA2G6
+    NN0YfkXJ2BsAMuAzHB9cZMk3qoEbRzUACsRCUBK5JxsC3iMiKd8GN088SIyT
+    0RAFSROyeEg38caDiB/+JEgqxsODrZJ1BkT0oHKSmI0ceQxo94HDpg0qsuDk
+    UmRAMgu8OgwQ+uIJgUMVeGXA+IQkzEeHGvD8cIGlDXsLiRjQ+EHroQhea7xY
+    8IQBSgYYDi1IS+OFBCgaDMGVS3fGi5BPJpBaENdQ0EomKGD56IHwO39EXiSC
+    Ysgxor5+Xfgq0qByYUpiXmwuoredB2aYH4gWWda0B7SeNENpEJHC1ghi+pS4
+    AJpIAwWvKPBi+8YEht5EriEqpFfMlhEdkBNpx0HUhwypx5T4IB1MBg/Ws2sn
+    wV3MSQOkzI8fUd48Aw3dOZto71x85hHtHijYv18Gf/3GqCdDCXHNoICBobSo
+    IqBqJLyCoH8JPrLgdh88CKCFD0CGmAiGYPgffwceZh6FC2ohIIklnkhehTNY
+    4CIHHGzgwYw01ujBBhvAqKOLLq5AAk9kuSPkkKO40NB+h1gnypJIIvkBf09a
+    N5QIRz5p5ZJXJpmlIVhOGQA2TmIJZZhKKmmll2BqyWSXWUrZpQtpatlmk1c2
+    KaWRHeTZEJF8SqLDn/hhsOeQgBbqAh6DGqronxeARUIIACH5BAUeAAAALAUA
+    LgAFAAUAAAUM4CeKz/OV5YmqaRkCACH5BAUeAAEALAUALgAKAAUAAAUUICCK
+    z/OdJVCaa7p+7aOWcDvTZwgAIfkEBR4AAQAsCwAuAAkABQAABRPgA4zP95zA
+    eZqoWqqpyqLkZ38hACH5BAUKAAEALAcALgANAA4AAAU7ICA+jwiUJEqeKau+
+    r+vGaTmac63v/GP9HM7GQyx+jsgkkoRUHJ3Qx0cK/VQVTKtWwbVKn9suNunc
+    WkMAIfkEBQoAAAAsBwA3AAcABQAABRGgIHzk842j+Yjlt5KuO8JmCAAh+QQF
+    CgAAACwLADcABwAFAAAFEeAnfN9TjqP5oOWziq05lmUIACH5BAUKAAAALA8A
+    NwAHAAUAAAUPoPCJTymS3yiQj4qOcPmEACH5BAUKAAAALBMANwAHAAUAAAUR
+    oCB+z/MJX2o+I2miKimiawgAIfkEBQoAAAAsFwA3AAcABQAABRGgIHzfY47j
+    Q4qk+aHl+pZmCAAh+QQFCgAAACwbADcABwAFAAAFEaAgfs/zCV9qPiNJouo7
+    ll8IACH5BAUKAAAALB8ANwADAAUAAAUIoCB8o0iWZggAOw==
+}
+
+# Finally, set up the text scrolling animation
+animateLabelText $w.left.l1 "* Slow Animation *" 300
+animateLabelText $w.left.l2 "* Fast Animation *" 80
+animateLabelText $w.left.l3 "This is a longer scrolling text in a widget that will not show the whole message at once. " 150
+animateLabelImage $w.right.l $tclPoweredData 100
diff --git a/library/demos/widget b/library/demos/widget
index 67d3b6a..36b9871 100644
--- a/library/demos/widget
+++ b/library/demos/widget
@@ -11,7 +11,7 @@ exec wish "$0" "$@"
 # ".tcl" files is this directory, which are sourced by this script
 # as needed.
 #
-# RCS: @(#) $Id: widget,v 1.24 2004/09/10 12:13:43 vincentdarley Exp $
+# RCS: @(#) $Id: widget,v 1.25 2004/11/07 17:28:21 dkf Exp $
 
 package require Tcl	8.5
 package require Tk	8.5
@@ -327,6 +327,9 @@ addDemoSection "Common Dialogs" {
     filebox	"File selection dialog"
     clrpick	"Color picker"
 }
+addDemoSection "Animation" {
+    anilabel	"Animated labels"
+}
 addDemoSection "Miscellaneous" {
     bitmap	"The built-in bitmaps"
     dialog1	"A dialog box with a local grab"