Re: [gtkmm] Creating and setting pixmaps with strings

[Christopher David <DavidC mail lafayette edu>]

Thanks for the help, I can work on getting this to work in the mean 
time.  However, I guess I didn't specify the problem exactly.  I am not 
trying to use strings to identify variable names.  The pixmap 
constructor and set method takes a string (or more specifically an 
nstring) that contains the actual file name with path and all.  So, 
according to what I have seen, you sould be able to do something like this,

pixmapGnim01->set("../../GimsImg/gnim01lrg.xpm");

or if the file is in the current directory,

pixmapGnim01->set("./gnim01lrg.xpm");

Of course this would be a lot easier if I could get this to work because 
I can just pass in a string or nstring varaiable that containes the file 
path.  Unfortunately, contrary to what the refference and tutorial 
suggest, I can't get it to work like that.

Daniel Bausch wrote:

> Hello!
>
> I have understood your problem. As you correctly noticed, the problem can not 
> be solved the way you tried.
> A string constant like "bla" or "gnim01lrg_xpm" can not be used as a reference 
> to a variable or constant with that name, because the computer does not know 
> the name of the variable after the compilation of your sourcecode. This is 
> not a limitation of gtkmm but a limitation of the C++ language.
> What you need is a map (see your C++ reference), to store pairs of strings and 
> pointers to your dataconstructs, which then contain your pixmap data. Then 
> you can use code like this:
>
> Initialization:
>
> #include <map>
>
> ...
>
> map<string, char **> images;
> images["a picture"] = gnim01lrg_xpm;
> images["a other picture"] = gnim02lrg_xpm;
>
> Usage:
>
> pixmapGnim01->set(images["a picture"]);
>
> Or:
>
> string picture_identifier;
> picture_identifier = result_of_choose_box();
> pixmapGnim01->set(images[some_picture_identifier]);
>
> I hope I could help you.
> The map has an additional advantage. If you read the reference, you will 
> notice, that you can use the list of identifier strings at another place in 
> your program and not only to index the map. Imagine use these strings to 
> display them in a choose box. Then you have to manage these strings only one 
> time in your program.
>
> Good luck.
>
> Daniel Bausch
>
> Am Saturday, 12. April 2003 18:41 schrieb Christopher David:
>
> > Hi all,
> >
> > I'm currently working on a group project using Gtkmm 1.2 that uses
> > pixmaps.  According to the Gtk-- Reference, you should be able to create
> > a pixmap from an .xpm file by passing a string, or more specifically, an
> > nstring a a parameter (as long as you include the pixmap file of
> > course).  Now, I have gotten something like this to work:
> >
> > pixmapGnim01->set(gnim01lrg_xpm);
> > Gtk::Pixmap *pix = new Gtk::Pixmap(gnim01lrg_xpm);
> >
> > where it uses the string in the pixmap header file "gnim01lrg_xpm".
> > However, I have not been able to so this:
> >
> > pixmapGnim01->set("gnim01lrg_xpm");
> > or
> > string pixName = "gnim01lrg_xpm";
> > pixmapGnim01->set(pixName);
> > or
> > Gtk::nstring *pixName = new Gtk::nstring(currPixmapName);
> > Gtk::Pixmap *pix = new Gtk::Pixmap(*pixName);
> > or
> > Gtk::nstring *pixName = new Gtk::nstring(currPixmapName);
> > pixmapGnim01->set(pixName);
> >
> > and so on...
> >
> > As you can see, a string or nstring variable won't work, not even a real
> > string of "gnim01lrg_xpm" won't work.
> > But put in gnim01lrg_xpm by itself without quotation marks and it does
> > work fine.  I can't figure out what I am doing wrong.  We really need to
> > store the strings and pass them into the set or constructor methods so
> > we can change a pixmap dynamically.  I know you can change a pixmap at
> > runtime, but we need to store the information so when we load a saved
> > program, all of the pixmaps will initialize to whatever string they are
> > assigned to.  BTW, I know Gtkmm 1.2 is a bit old, but we have no choice
> > in the matter and cannot upgrade at all.  We MUST use Gtkmm 1.2 .  Any
> > help here would be appreciated a lot.  Thanks.
> >
> > Chris David
> >
> >
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