ScrollView

A scrollable viewport that clips and pans its content. Content larger than the viewport can be scrolled via mouse wheel (desktop) or touch drag (mobile).

Header

#include <neoflux/widget/scroll_view.h>

Construction

auto scroll = std::make_shared<ScrollView>();

Methods

SetContent()

void SetContent(std::shared_ptr<Widget> content);

Sets the scrollable content. Replaces any existing content. The content is laid out at its natural size and clipped to the viewport.

ScrollTo()

void ScrollTo(float x, float y) noexcept;

Sets the scroll offset in pixels. Clamped to the valid range.

GetScrollOffset()

[[nodiscard]] Point GetScrollOffset() const noexcept;

Returns the current scroll offset.

GetContentSize()

[[nodiscard]] Size GetContentSize() const noexcept;

Returns the content size after layout.

Layout Behavior

• ScrollView sets flex_grow = 1 and flex_shrink = 1 to fill available space in its parent.
• Content is set to flex_shrink = 0 and align_self = flex-start so it keeps its natural size.
• overflow = hidden clips content to the viewport.

Example

auto scroll = std::make_shared<ScrollView>();

auto content = std::make_shared<Container>();
content->SetFlexDirection(FlexDirection::kColumn);
for (int i = 0; i < 20; ++i) {
  auto item = std::make_shared<Text>("Item " + std::to_string(i));
  content->AddChild(item);
}

scroll->SetContent(content);
parent->AddChild(scroll);

Painting

ScrollView::Paint():

1. Saves the current transform/clip state.
2. Applies a clip rect to the viewport bounds.
3. Translates by the negative scroll offset.
4. Paints children.
5. Restores the previous state.