Macro float 

macro_rules! float {
    ( $( $ee:expr ),* ) => { ... };
    ( $( $ee:expr ),+ , ) => { ... };
}

Make a Float widget

Syntax

Collection :
   float! [ Items^? ]

Items :
   (Item ,)^* Item ,^?

Stand-alone usage

When used as a stand-alone macro, float! [/* ... */] is just syntactic sugar for Float::new(kas::collection! [/* ... */]).

In this case, Item may be:

• A string literal (interpreted as a label widget), optionally followed by an align or pack method call
• An expression yielding an object implementing Widget<Data = _A>

In case all Item instances are a string literal, the data type of the float! widget will be (); otherwise the data type of the widget is _A where _A is a generic type parameter of the widget.

Usage within widget layout syntax

When called within widget layout syntax, float! may be evaluated as a recursive macro and the result does not have a specified type, except that methods map_any, align and pack are supported via emulation.

In this case, Item is evaluated using widget layout syntax. This is broadly similar to the above with a couple of exceptions:

• Supported layout macros do not need to be imported to the module scope
• An Item may be a #[widget] field of the widget

Example

let my_widget = kas_widgets::float! [
    "one".pack(AlignHints::TOP_LEFT),
    "two".pack(AlignHints::BOTTOM_RIGHT),
    "some text\nin the\nbackground"
];

Cost

Warning: each child beyond the first requires a new draw pass. The number of passes used can have a substantial performance impact, potentially more on GPU communication than CPU usage.