Additional Grid Features

If you look at the documentation for grid, you'll see many other things you can do with grid. Here are a few of the more useful ones.

Querying and Changing Grid Options

Like widgets themselves, it's easy to introspect the various grid options or change them. Setting options when you first grid the widget is certainly convenient, but you can change them anytime you'd like.

The slaves method will tell you all the widgets that have been gridded inside a master, or optionally those within just a certain column or row. The info method will return a list of all the grid options for a widget and their values. Finally, the configure method lets you change one or more grid options on a widget.

These are illustrated in this interactive session:

#![allow(unused)]
fn main() {
let got = c.grid_slaves(())?;
let got = got
    .iter()
    .map( |widget| widget.path() )
    .collect::<Vec<_>>();
let expected = vec![ ".c.cancel", ".c.ok", ".c.three", ".c.two", ".c.one", ".c.name", ".c.namelbl", ".c.f" ]
    .into_iter()
    .collect::<Vec<_>>();
assert_eq!( got, expected );

let got = c.grid_slaves( -row(3) )?;
let got = got
    .iter()
    .map( |widget| widget.path() )
    .collect::<Vec<_>>();
let expected = vec![ ".c.cancel", ".c.ok", ".c.three", ".c.two", ".c.one" ]
    .into_iter()
    .collect::<Vec<_>>();
assert_eq!( got, expected );

let got = c.grid_slaves( -column(0) )?;
let got = got
    .iter()
    .map( |widget| widget.path() )
    .collect::<Vec<_>>();
let expected = vec![ ".c.one", ".c.f" ]
    .into_iter()
    .collect::<Vec<_>>();
assert_eq!( got, expected );

let got = c_namelbl.grid_info()?
    .into_iter()
    .map( |(key, val)| (key, val.get_string() ))
    .collect::<HashMap<_,_>>();

let mut expected = HashMap::new();

expected.insert( "-in"        .to_owned(), ".c".to_owned() );
expected.insert( "-column"    .to_owned(), "3" .to_owned() );
expected.insert( "-row"       .to_owned(), "0" .to_owned() );
expected.insert( "-columnspan".to_owned(), "2" .to_owned() );
expected.insert( "-rowspan"   .to_owned(), "1" .to_owned() );
expected.insert( "-ipadx"     .to_owned(), "0" .to_owned() );
expected.insert( "-ipady"     .to_owned(), "0" .to_owned() );
expected.insert( "-padx"      .to_owned(), "5" .to_owned() );
expected.insert( "-pady"      .to_owned(), "0" .to_owned() );
expected.insert( "-sticky"    .to_owned(), "nw".to_owned() );

assert_eq!( got, expected );

c_namelbl.grid_configure( -sticky("ew") )?;

let got = c_namelbl.grid_info()?
    .into_iter()
    .map( |(key, val)| (key, val.get_string() ))
    .collect::<HashMap<_,_>>();

let mut expected = HashMap::new();

expected.insert( "-in"        .to_owned(), ".c".to_owned() );
expected.insert( "-column"    .to_owned(), "3" .to_owned() );
expected.insert( "-row"       .to_owned(), "0" .to_owned() );
expected.insert( "-columnspan".to_owned(), "2" .to_owned() );
expected.insert( "-rowspan"   .to_owned(), "1" .to_owned() );
expected.insert( "-ipadx"     .to_owned(), "0" .to_owned() );
expected.insert( "-ipady"     .to_owned(), "0" .to_owned() );
expected.insert( "-padx"      .to_owned(), "5" .to_owned() );
expected.insert( "-pady"      .to_owned(), "0" .to_owned() );
expected.insert( "-sticky"    .to_owned(), "ew".to_owned() );

assert_eq!( got, expected );
}

Internal Padding

You saw how the padx and pady grid options added extra space around the outside of a widget. There's also a less used type of padding called "internal padding" controlled by the grid options ipadx and ipady.

The difference can be subtle. Let's say you have a frame that's 20x20, and specify normal (external) padding of 5 pixels on each side. The frame will request a 20x20 rectangle (its natural size) from the geometry manager. Normally, that's what it will be granted, so it'll get a 20x20 rectangle for the frame, surrounded by a 5-pixel border.

With internal padding, the geometry manager will effectively add the extra padding to the widget when figuring out its natural size, as if the widget has requested a 30x30 rectangle. If the frame is centered, or attached to a single side or corner (using sticky), we'll end up with a 20x20 frame with extra space around it. If, however, the frame is set to stretch (i.e., a sticky value of we, ns, or nwes), it will fill the extra space, resulting in a 30x30 frame, with no border.

Forget and Remove

The forget method of grid removes slaves from the grid they're currently part of. It takes a list of one or more slave widgets as arguments. This does not destroy the widget altogether but takes it off the screen as if it had not been gridded in the first place. You can grid it again later, though any grid options you'd originally assigned will have been lost.

The remove method of grid works the same, except that the grid options will be remembered if you grid it again later.

Run Example

cargo run --example querying_and_changing_grid_options