Struct EventCtx 

pub struct EventCtx<'a, H> { /* private fields */ }

A context provided to event handlers registered with Ui::event.

EventCtx is the primary interface for nodes to respond to user input. It provides:

• State Updates: Methods to set focus, capture the pointer, or mark a node as active.
• Event Data: Access to specific event details like pointer coordinates or keyboard keys.
• Propagation Control: Ability to stop events from bubbling up the tree or to prevent default window actions.
• Layout Info: Access to the node’s computed size and position.

It also provides a handle to the platform, allowing the callback to trigger system-level actions like opening URLs or changing the cursor.

Implementations

impl<'a, H> EventCtx<'a, H>

pub fn platform(&self) -> &H

Returns a handle provided by the platform integration. The default platform integration returns a rosin::handle::WindowHandle.

pub fn set_active(&mut self, id: Option<NodeId>)

Sets the currently active node. This makes :active CSS selectors apply to the node. Purely cosmetic.

You can pass None to deactivate.

pub fn is_active(&self) -> bool

Returns true if the current node is active.

pub fn is_enabled(&self) -> bool

Returns true if the current node is enabled.

A node’s enabled status is controlled by a UIParam passed to Ui::enabled when building the tree.

pub fn set_focus(&mut self, id: Option<NodeId>)

Sets the currently focused node. This makes :focus CSS selectors apply to the node, and routes On::Keyboard events to it.

You can pass None to unfocus.

pub fn focus_next(&mut self)

Transfers focus to the next focusable node node in the tree. If nothing is focused, the first focusable node in the tree will gain focus.

pub fn focus_previous(&mut self)

Transfers focus to the previous focusable node node in the tree. If nothing is focused, the last focusable node in the tree will gain focus.

pub fn is_focused(&self) -> bool

Returns true if the current node is focused.

pub fn viewport_size(&self) -> Size

Returns the size of the total drawable area of the viewport in logical pixels.

pub fn style(&self) -> &Style

Returns the computed style for this node.

pub fn rect(&self) -> &RoundedRect

Returns the final laid-out rectangle of this node.

pub fn id(&self) -> Option<NodeId>

Return the current node’s id, if it has one.

• In debug builds, this will log an error if there is no id for the node.

pub fn event_type(&self) -> On

Returns the type of event that triggered this callback.

pub fn pointer_delta(&self) -> Option<Vec2>

Returns the change in position between this pointer event and the previous, if available. The first pointer event fired when the cursor enters the viewport will not have a delta.

pub fn perf_info(&self) -> &PerfInfo

Returns some information about how long it took to render the previous frame.

pub fn get_translation_map(&self) -> TranslationMap

Returns the global map of translations.

pub fn begin_pointer_capture(&mut self)

Begins capturing pointer events. When captured, the pointer is treated as if it is always inside the node, so On::PointerEnter and On::PointerLeave events will never fire.

• In debug builds, this will log an error if there is no id for the node.

pub fn end_pointer_capture(&mut self)

Releases the pointer capture, so other nodes can start receiving pointer events again.

pub fn is_pointer_captured(&self) -> bool

Returns true if this node has captured the pointer.

pub fn stop_propagation(&mut self)

Stop a pointer event from bubbling up to ancestor nodes. On::PointerEnter and On::PointerLeave events do not bubble.

• In debug builds, this will log an error if called from a non-pointer event.

pub fn emit_change(&mut self)

Requests an On::Change dispatch after this callback returns.

The dispatcher will queue On::Change on this node (if it handles it), otherwise on the first ancestor with an On::Change handler. If the current event is On::Change, it will only look for an ancestor to avoid re-queuing the same handler.

pub fn stop_window_close(&mut self)

Stops the window from closing.

• In debug builds, this will log an error if not called from the root node’s On::WindowClose handler.

pub fn pointer(&self) -> Option<&PointerEvent>

In pointer event handlers, this returns the complete pointer event info.

pub fn local_pointer_pos(&self) -> Option<Point>

If available, returns the position of the pointer event relative to the top-left of the current node.

pub fn keyboard(&self) -> Option<&KeyboardEvent>

In On::Keyboard handlers, this returns the keyboard event info.

pub fn dt(&self) -> Option<&Duration>

In On::AnimationFrame handlers, this returns the duration since the last animation frame.

pub fn file_dialog_response(&self) -> Option<&FileDialogResponse>

In On::FileDialog handlers, this returns the information returned by the requested file dialog.

pub fn command_id(&self) -> Option<CommandId>

In On::Command handlers, this returns the CommandId associated with the menu item picked.

pub fn action_request(&self) -> Option<&ActionRequest>

In On::AccessibilityAction handlers, this returns the AccessKit action request info.

pub fn info(&self) -> &EventInfo

Returns the raw event payload for this callback.

This is the same data accessed by the typed helpers like EventCtx::pointer, EventCtx::keyboard, etc.

pub fn padding_box(&self) -> Rect

Returns the rect just inside the borders of the node. Doesn’t account for rounded corners.

pub fn max_content_width(&self) -> f32

Returns the maximum width content could be before overflowing the node.