Tcl/Tk 8.5.8: How to check the existence of an image in memory?
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From: George Petasis on 26 Jul 2010 12:33 Στις 26/7/2010 7:17 μμ, ο/η jmc έγραψε: > Hello, > > On the console, I create an image, and after, try to verify this image > is actually created : > > Here is a "copy and paste" for what I did : > > (Images) 32 % image create photo testRawImage -data $rawData > testRawImage > (Images) 33 % info exists testRawImage > 0 > > > I believe "info exists" (Tcl) is not the right tool to make a check > for the result of a Tk command, but looking in the doc either for > "winfo" or "info" command, I can't find anything which suit my need. > > Thanks in advance. > > > Jean-Marie There are several way to check: 1) image names returns a list of all images. You can check if the image is in the returned list. 2) Another way is to check commands, if you know the image command name: llength [info commands image_name] == 1 3) Call the image command directly: <image_name> cget - height, around a catch statement. George
From: Gerald W. Lester on 26 Jul 2010 13:33 jmc wrote: > Hello, > > On the console, I create an image, and after, try to verify this image > is actually created : > > Here is a "copy and paste" for what I did : > > (Images) 32 % image create photo testRawImage -data $rawData > testRawImage > (Images) 33 % info exists testRawImage > 0 > > > I believe "info exists" (Tcl) is not the right tool to make a check > for the result of a Tk command, but looking in the doc either for > "winfo" or "info" command, I can't find anything which suit my need. While George gave you a solution, I'd like to point out why [info exists] did not work -- it checks for the existence of a *variable* not a command. The [image create] command creates a new command, not a variable. -- +------------------------------------------------------------------------+ | Gerald W. Lester, President, KNG Consulting LLC | | Email: Gerald.Lester(a)kng-consulting.net | +------------------------------------------------------------------------+
From: Craig on 26 Jul 2010 17:07 sometimes it takes less time to test your theory than to posit it, though :^) On 7/26/2010 1:39 PM, jmc wrote: > b) It seems that this kind of user defined command in Tcl/Tk has not > the same meaning as others like "proc". I'm not sure but reading the > doc I would bet that "info command" doesn't output image names > (defined as command). >
From: Gerald W. Lester on 26 Jul 2010 17:12 jmc wrote: > On 26 juil, 19:33, "Gerald W. Lester" <Gerald.Les...(a)KnG- > Consulting.net> wrote: >> jmc wrote: >>> Hello, >>> On the console, I create an image, and after, try to verify this image >>> is actually created : >>> Here is a "copy and paste" for what I did : >>> (Images) 32 % image create photo testRawImage -data $rawData >>> testRawImage >>> (Images) 33 % info exists testRawImage >>> 0 >>> I believe "info exists" (Tcl) is not the right tool to make a check >>> for the result of a Tk command, but looking in the doc either for >>> "winfo" or "info" command, I can't find anything which suit my need. >> While George gave you a solution, I'd like to point out why [info exists] >> did not work -- it checks for the existence of a *variable* not a command. >> The [image create] command creates a new command, not a variable. > > Thanks Gerald for this precision. I read this in the doc and forget it > quite immediately because it is not clear to me : > > a) on what does act this "command" (the name of an image for > instance) ? It acts on the created image. The particular subcommands depend on the type of image, photo or bitmap. To see what subcommands are available look at the appropriate man/help page (photo or bitmap). > b) It seems that this kind of user defined command in Tcl/Tk has not > the same meaning as others like "proc". I'm not sure but reading the > doc I would bet that "info command" doesn't output image names > (defined as command). It indeed has the exact same meaning as other commands. BTW, you lose your bet on the [info command] -- you owe me a bottle of good beer! :) Try: image create photo testRawImage -data $rawData info command *RawImage -- +------------------------------------------------------------------------+ | Gerald W. Lester, President, KNG Consulting LLC | | Email: Gerald.Lester(a)kng-consulting.net | +------------------------------------------------------------------------+
From: Spam on 26 Jul 2010 19:24
On Mon, 26 Jul 2010, jmc wrote: > Hello, > > On the console, I create an image, and after, try to verify this image > is actually created : > > Here is a "copy and paste" for what I did : > > (Images) 32 % image create photo testRawImage -data $rawData > testRawImage > (Images) 33 % info exists testRawImage > 0 > > > I believe "info exists" (Tcl) is not the right tool to make a check > for the result of a Tk command, but looking in the doc either for > "winfo" or "info" command, I can't find anything which suit my need. > > Thanks in advance. > > > Jean-Marie Jean-Marie, I took the slightly different approach of creating the image when needed, and then caching it, so that you use a simple interface to reference ALL images ... namespace eval img { array set pic {} proc getImage { clr btn } { set idx [format "%s_%s" $clr $btn] set ix [lsearch [array names img::pic] $idx] if { $ix < 0 } { return [img::newImage $clr $btn] } return $img::pic($idx) } proc newImage { clr btn } { set idx [format "%s_%s" $clr $btn] set img::pic($idx) {} if [file exists images/$clr/$btn.gif ] { set img::pic($idx) [image create photo img_$idx] $img::pic($idx) read images/$clr/$btn.gif } return $img::pic($idx) } } grid configure [ttk::button $btn -image [img::getImage $clr $b] -command doSomething ] -row $r -column $c This uses namespaces, and creates an array indexed by the colour and name of the image file ... if the image exists, the pre-created reference is returned by getImage, and if not, getImage references newImage to create it, and saves the reference ... In my case it was convenient to index by colour and name, but this is entirely dependant upon your problem domain ... it is particularly useful for icons and button labels ... HTH, Cheers, Rob Sciuk. |