Claude Rubinson <[email protected]> wrote:

I have a Tk app that has a series of photos arranged in a grid. Each
photo is embedded in its own canvas. I'd like to indicate that a photo
has been selected by the user by highlighting it with a translucent
overlay. Is this possible? My initial investigation indicates that Tk doesn't (yet) support alpha blending?

One 'workaround' if Tk does not support alpha blending is to have
present in the app two versions of the photo, one without and a second
with the overlay present. Then for a "selected" photo you swap the
"without" and "with" versions (remembering to "unswap" the last
selected one as well).

Of course this only works if the overlay is completely static.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

I have a Tk app that has a series of photos arranged in a grid. Each
photo is embedded in its own canvas. I'd like to indicate that a photo
has been selected by the user by highlighting it with a translucent
overlay. Is this possible? My initial investigation indicates that Tk
doesn't (yet) support alpha blending?

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

* Claude Rubinson <[email protected]>
| I have a Tk app that has a series of photos arranged in a grid. Each
| photo is embedded in its own canvas. I'd like to indicate that a
| photo has been selected by the user by highlighting it with a translucent
| overlay. Is this possible? My initial investigation indicates that
| Tk doesn't (yet) support alpha blending?

A different approach might be to add a border around each canvas and
highlight that to indicate the selected one:

grid [canvas .c1 -highlightthickness 3 -highlightcolor blue -borderwidth 2 -relief ridge] -row 0 -column 0 -sticky ewnw
grid [canvas .c2 -highlightthickness 3 -highlightcolor blue -borderwidth 2 -relief ridge] -row 0 -column 1 -sticky ewnw
grid [canvas .c3 -highlightthickness 3 -highlightcolor blue -borderwidth 2 -relief ridge] -row 1 -column 0 -sticky ewnw
grid [canvas .c4 -highlightthickness 3 -highlightcolor blue -borderwidth 2 -relief ridge] -row 1 -column 1 -sticky ewnw

bind .c1 <Button-1> {focus %W}
bind .c2 <Button-1> {focus %W}
bind .c3 <Button-1> {focus %W}
bind .c4 <Button-1> {focus %W}

grid rowconfigure . 0 -weight 1
grid rowconfigure . 1 -weight 1
grid columnconfigure . 0 -weight 1
grid columnconfigure . 1 -weight 1

HTH
R'

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