Fill¶

Header: winui/ui/panels/Fill.hpp. Spec: winui/ui/panels/Fill.hpp.

A child of a stack that is given the room the other children leave. Built by ui::Fill.

A StackControl measures its children unbounded along its axis. A fill is measured last, with the room left over as its bound, so a scrolling child inside it (a Scroll, a ListView) gets a real height and scrolls. Several fills, and the stack's spacers, share the room by their weight. Where the stack itself has no bound along its axis (inside a Scroll) there is nothing to share, and a fill is as big as its content. Outside a stack it is a plain one-child container.

Example:

auto  page = std::make_unique<ui::StackControl>(ui::Orientation::Vertical);
page->add(std::make_unique<ui::TextControl>("Inbox"));
auto* fill = page->add(std::make_unique<ui::FillControl>());
fill->set_child(std::make_unique<ui::ScrollControl>());
page->add(std::make_unique<ui::TextControl>("3 unread"));

ui::Fill¶

Gives one child of a stack the room the other children leave. Builds a ui::FillControl.

In a VerticalStack of a header, a list and a footer, putting the list in a Fill keeps the footer at the bottom and lets the list scroll in between.

A stack gives each child what it asks for along its axis, with no limit, so a list in a plain stack grows as long as its items and never scrolls. A Fill is measured with the room the other children leave. Several fills share that room by .weight, together with the stack's spacers. A ui::Spacer is a Fill with nothing in it. In a stack that has no limit itself (one inside a Scroll) a Fill is measured as big as its content, and takes what room the stack is arranged with beyond that.

Example:

ui::Property<std::vector<std::string>> messages;
ui::Property<int>                      unread{0};

window.set_content(ui::VerticalStack{
    .spacing = 8,
    .content = {
        ui::Text{.text = "Inbox", .role = ui::TextRole::Subtitle},
        ui::Fill{.content = ui::ListView<std::string>{.items = messages}},
        ui::Text{.text = ui::bind(unread, [](int n) { return std::format("{} unread", n); })},
    },
});

Every field, in the order a designated initializer names them:

ui::Fill{
    .weight, .style, .margin, .width, .height, .min_width, .min_height, .max_width,
    .max_height, .horizontal_alignment, .vertical_alignment, .visible, .tool_tip,
    .accessibility, .on_pointer_entered, .on_pointer_exited, .on_got_focus, .on_lost_focus,
    .on_key_down, .on_wheel, .control, .content
}

Fields, in declaration order (designators must follow it):

Plus the common fields style, margin, width, height, min_width, min_height, max_width, max_height, horizontal_alignment, vertical_alignment, visible, tool_tip, accessibility every spec carries (conventions).

build¶

std::unique_ptr<Element> build()&&

Consumes the spec and returns the built ui::FillControl; the caller owns it.

ui::FillControl¶

Derives from ui::ContentHost.

A child of a stack that is given the room the other children leave. Built by ui::Fill.

A StackControl measures its children unbounded along its axis. A fill is measured last, with the room left over as its bound, so a scrolling child inside it (a Scroll, a ListView) gets a real height and scrolls. Several fills, and the stack's spacers, share the room by their weight. Where the stack itself has no bound along its axis (inside a Scroll) there is nothing to share, and a fill is as big as its content. Outside a stack it is a plain one-child container.

Example:

auto  page = std::make_unique<ui::StackControl>(ui::Orientation::Vertical);
page->add(std::make_unique<ui::TextControl>("Inbox"));
auto* fill = page->add(std::make_unique<ui::FillControl>());
fill->set_child(std::make_unique<ui::ScrollControl>());
page->add(std::make_unique<ui::TextControl>("3 unread"));

FillControl¶

FillControl() = default

An empty fill of weight 1.

weight¶

float weight() const

This fill's share of the leftover room, relative to the other fills and spacers in the same stack.

set_weight¶

void set_weight(float weight)

Sets the share; negative is treated as 0. Updates the layout.

Tests¶

• tests/test_stack.cpp