rat_widget

Module clipper

Source
Expand description

An alternative view widget.

The extra requirement for this one is that you can create a Layout that defines the bounds of all widgets that can be rendered.

It works in 4 phases:

use rat_focus::FocusFlag;
use rat_widget::layout::GenericLayout;
    ///
    /// Create the layout. The layout can be stored long-term
    /// and needs to be rebuilt only if your widget layout changes.
    ///
    ///> __Note__: add() returns a handle for the area. Can be used later
    ///> to refer to the stored area.

    if state.clipper.layout.is_empty() {
        let mut cl = GenericLayout::new();
        for i in 0..100 {
            cl.add(state.check_states[i].focus.clone(),
                Rect::new(10, i as u16 *11, 15, 10),
                None,
                Rect::default()
            );
        }
    }

    /// The given area plus the current scroll offset define the
    /// view area. With the view area a temporary buffer is created
    /// that is big enough to fit all widgets that are at least
    /// partially visible.

    let clipper = Clipper::new();

    let mut clip_buf = clipper
        .into_buffer(l2[1], &mut state.clipper);

    ///
    /// The widgets are rendered to that buffer.
    ///
    for i in 0..100 {
        // refer by handle
        clip_buf.render(
            state.check_states[i].focus.clone(),
            || {
                Checkbox::new()
                .text(format!("{:?}", i))
            },
            &mut state.check_states[i],
        );
    }

    ///
    /// The last step clips and copies the buffer to the frame buffer.
    ///

    clip_buf
        .into_widget()
        .render(l2[1], &mut buf, &mut state.clipper);

StatefulWidget

For this to work with StatefulWidgets they must cooperate by implementing the RelocatableState trait. With this trait the widget can clip/hide all areas that it stores in its state.

See

example

Structsยง