Version 16 of Rotated canvas text
Updated 2008-11-03 06:38:10 by kbk
Tom Krehbiel shared the following interesting code in the Tcl chatroom, which may display a large E in various rotation angles (X only, not on all Linuxes...):
tomk: Are you aware that it is possible to rotate single character in a Tk canvas?
kennykb: Rotate single char in Tk canvas? How?
tomk: I have some code that someone (smarter than me) posted. I don't remember when or who. You want me to sent you a copy?
kennykb: Sure, glad to look at it. This supposed to be Tcl code? Or is someone changing the canvas implementation?
proc rotmatrix {size angle} {
set size [expr {double($size)}]
set angle [expr {double($angle)*acos(0.0)/90.0}]; # In radians
set c [expr {$size*cos($angle)}]
set s [expr {$size*sin($angle)}]
# Due to Tk's XLFD (X Logical Font Description)
# parser, we need to round values
set s [format "\[%.f %.f %.f %.f\]" $c [expr {-$s}] $s $c]
regsub -all -- "-" $s ~ s
return $s
}
pack [scrollbar .vs -orient vertical -command {.c yview}] -side right -fill y
pack [scrollbar .hs -orient horizontal -command {.c xview}] -side bottom -fill x
pack [canvas .c -bg white -xscrollcommand {.hs set} -yscrollcommand {.vs set}]\
-side left -expand 1 -fill both
set nb 16
set size 24
set size 64
set text "The Quick Brown Fox jumps over the Lazy Black Dog"
set text "E"
.c configure -scrollregion [list -1000 0 1000 [expr {$size*$nb*2}]]
set x 100
for {set i 0} {$i < 16} {incr i} {
set y [expr {10+$i*$size*2}]
set angle [expr {360.0*$i/$nb}]
.c create text $x $y -text [format "%.1f° " $angle] -anchor ne -font \
-adobe-times-medium-r-*-*-$size-*-*-*-*-*-*-*
.c create text $x $y -text $text -anchor nw -font \
-adobe-times-medium-r-*-*-[rotmatrix $size $angle]-*-*-*-*-*-*-*
.c create rectangle [expr {$x-2}] [expr {$y-2}] [expr {$x+2}] [expr {$y+2}]\
-outline black -fill red
}suchenwi: WOW! YES!
tomk: I added the 64 font size and the text "E". If you remove them you get a string version.
kennykb Guys: Before you get too excited, this is Unix-only and not supported by every X server.
suchenwi: Works here on Solaris via Reflection, but not native on PC - there the E is only scaled smaller. But it's definitely only recommendable for a single letter...
bschwarz: doesn't work on linux
kennykb: The functionality is X, mostly. The comment about Tk's XLFD parser has to do with whether Tk will recognize the string as an XLFD or a Tk font name.
trb: works on my linux: 2.2.18. XFree86 v 3360 tk 8.3
DKF: Note that the above does not work with an IRIX Xserver.
The BLT extension can also rotate text on a canvas
GJS Wouldn't all this be easier if TK supported a rotate command. The syntax would be simple I think. Use a -rotate option on some of the widgets or pathname rotate
pathName create type cordList -rotate degrees pathName rotate tagOrId ?degrees?
In the second form if degrees was omitted the command would return the current rotation. Acceptable values for degrees should be integers ranging from -360 to 360, positive values rotating clockwise, negative values rotating counter-clockwise, 0 being defalualt. 360 and -360 should be understood as 0.
KBK 2008-11-03 I tried an entirely different approach to rotated text on a canvas as a "weekend fun project." Results are here: http://wiki.tcl.tk/_repo/hershey/ It's ugly, but might get somone out of occasional trouble.