Enum CallbackChange 

pub enum CallbackChange {
    ModifyWindowState {
        state: FullWindowState,
    },
    QueueWindowStateSequence {
        states: Vec<FullWindowState>,
    },
    CreateNewWindow {
        options: WindowCreateOptions,
    },
    CloseWindow,
    SetFocusTarget {
        target: FocusTarget,
    },
    StopPropagation,
    PreventDefault,
    AddTimer {
        timer_id: TimerId,
        timer: Timer,
    },
    RemoveTimer {
        timer_id: TimerId,
    },
    AddThread {
        thread_id: ThreadId,
        thread: Thread,
    },
    RemoveThread {
        thread_id: ThreadId,
    },
    ChangeNodeText {
        node_id: DomNodeId,
        text: AzString,
    },
    ChangeNodeImage {
        dom_id: DomId,
        node_id: NodeId,
        image: ImageRef,
        update_type: UpdateImageType,
    },
    UpdateImageCallback {
        dom_id: DomId,
        node_id: NodeId,
    },
    UpdateIFrame {
        dom_id: DomId,
        node_id: NodeId,
    },
    ChangeNodeImageMask {
        dom_id: DomId,
        node_id: NodeId,
        mask: ImageMask,
    },
    ChangeNodeCssProperties {
        dom_id: DomId,
        node_id: NodeId,
        properties: CssPropertyVec,
    },
    ScrollTo {
        dom_id: DomId,
        node_id: NodeHierarchyItemId,
        position: LogicalPosition,
    },
    ScrollIntoView {
        node_id: DomNodeId,
        options: ScrollIntoViewOptions,
    },
    AddImageToCache {
        id: AzString,
        image: ImageRef,
    },
    RemoveImageFromCache {
        id: AzString,
    },
    ReloadSystemFonts,
    OpenMenu {
        menu: Menu,
        position: Option<LogicalPosition>,
    },
    ShowTooltip {
        text: AzString,
        position: LogicalPosition,
    },
    HideTooltip,
    InsertText {
        dom_id: DomId,
        node_id: NodeId,
        text: AzString,
    },
    DeleteBackward {
        dom_id: DomId,
        node_id: NodeId,
    },
    DeleteForward {
        dom_id: DomId,
        node_id: NodeId,
    },
    MoveCursor {
        dom_id: DomId,
        node_id: NodeId,
        cursor: TextCursor,
    },
    SetSelection {
        dom_id: DomId,
        node_id: NodeId,
        selection: Selection,
    },
    SetTextChangeset {
        changeset: PendingTextEdit,
    },
    MoveCursorLeft {
        dom_id: DomId,
        node_id: NodeId,
        extend_selection: bool,
    },
    MoveCursorRight {
        dom_id: DomId,
        node_id: NodeId,
        extend_selection: bool,
    },
    MoveCursorUp {
        dom_id: DomId,
        node_id: NodeId,
        extend_selection: bool,
    },
    MoveCursorDown {
        dom_id: DomId,
        node_id: NodeId,
        extend_selection: bool,
    },
    MoveCursorToLineStart {
        dom_id: DomId,
        node_id: NodeId,
        extend_selection: bool,
    },
    MoveCursorToLineEnd {
        dom_id: DomId,
        node_id: NodeId,
        extend_selection: bool,
    },
    MoveCursorToDocumentStart {
        dom_id: DomId,
        node_id: NodeId,
        extend_selection: bool,
    },
    MoveCursorToDocumentEnd {
        dom_id: DomId,
        node_id: NodeId,
        extend_selection: bool,
    },
    SetCopyContent {
        target: DomNodeId,
        content: ClipboardContent,
    },
    SetCutContent {
        target: DomNodeId,
        content: ClipboardContent,
    },
    SetSelectAllRange {
        target: DomNodeId,
        range: SelectionRange,
    },
    RequestHitTestUpdate {
        position: LogicalPosition,
    },
    ProcessTextSelectionClick {
        position: LogicalPosition,
        time_ms: u64,
    },
    SetCursorVisibility {
        visible: bool,
    },
    ResetCursorBlink,
    StartCursorBlinkTimer,
    StopCursorBlinkTimer,
    ScrollActiveCursorIntoView,
    CreateTextInput {
        text: AzString,
    },
}

Represents a change made by a callback that will be applied after the callback returns

This transaction-based system provides:

• Clear separation between read-only queries and modifications
• Atomic application of all changes
• Easy debugging and logging of callback actions
• Future extensibility for new change types

Variants

ModifyWindowState

Modify the window state (size, position, title, etc.)

Fields

state: FullWindowState

QueueWindowStateSequence

Queue multiple window state changes to be applied in sequence across frames. This is needed for simulating clicks (mouse down → wait → mouse up) where each state change needs to trigger separate event processing.

Fields

states: Vec<FullWindowState>

CreateNewWindow

Create a new window

Fields

options: WindowCreateOptions

CloseWindow

Close the current window (via Update::CloseWindow return value, tracked here for logging)

SetFocusTarget

Change keyboard focus to a specific node or clear focus

Fields

target: FocusTarget

StopPropagation

Stop event from propagating to parent nodes

PreventDefault

Prevent default browser behavior (e.g., block text input from being applied)

AddTimer

Add a new timer to the window

Fields

timer_id: TimerId

timer: Timer

RemoveTimer

Remove an existing timer

Fields

timer_id: TimerId

AddThread

Add a new background thread

Fields

thread_id: ThreadId

thread: Thread

RemoveThread

Remove an existing thread

Fields

thread_id: ThreadId

ChangeNodeText

Change the text content of a node

Fields

node_id: DomNodeId

text: AzString

ChangeNodeImage

Change the image of a node

Fields

dom_id: DomId

node_id: NodeId

image: ImageRef

update_type: UpdateImageType

UpdateImageCallback

Re-render an image callback (for resize/animation) This triggers re-invocation of the RenderImageCallback

Fields

dom_id: DomId

node_id: NodeId

UpdateIFrame

Trigger re-rendering of an IFrame with a new DOM This forces the IFrame to call its callback and update the display list

Fields

dom_id: DomId

node_id: NodeId

ChangeNodeImageMask

Change the image mask of a node

Fields

dom_id: DomId

node_id: NodeId

mask: ImageMask

ChangeNodeCssProperties

Change CSS properties of a node

Fields

dom_id: DomId

node_id: NodeId

properties: CssPropertyVec

ScrollTo

Scroll a node to a specific position

Fields

dom_id: DomId

node_id: NodeHierarchyItemId

position: LogicalPosition

ScrollIntoView

Scroll a node into view (W3C scrollIntoView API) The scroll adjustments are calculated and applied when the change is processed

Fields

node_id: DomNodeId

options: ScrollIntoViewOptions

AddImageToCache

Add an image to the image cache

Fields

id: AzString

image: ImageRef

RemoveImageFromCache

Remove an image from the image cache

Fields

id: AzString

ReloadSystemFonts

Reload system fonts (expensive operation)

OpenMenu

Open a context menu or dropdown menu Whether it’s native or fallback depends on window.state.flags.use_native_context_menus

Fields

menu: Menu

position: Option<LogicalPosition>

Optional position override (if None, uses menu.position)

ShowTooltip

Show a tooltip at a specific position

Platform-specific implementation:

• Windows: Uses native tooltip window (TOOLTIPS_CLASS)
• macOS: Uses NSPopover or custom NSWindow with tooltip styling
• X11: Creates transient window with _NET_WM_WINDOW_TYPE_TOOLTIP
• Wayland: Creates surface with zwlr_layer_shell_v1 (overlay layer)

Fields

text: AzString

position: LogicalPosition

HideTooltip

Hide the currently displayed tooltip

InsertText

Insert text at the current cursor position or replace selection

Fields

dom_id: DomId

node_id: NodeId

text: AzString

DeleteBackward

Delete text backward (backspace) at cursor

Fields

dom_id: DomId

node_id: NodeId

DeleteForward

Delete text forward (delete key) at cursor

Fields

dom_id: DomId

node_id: NodeId

MoveCursor

Move cursor to a specific position

Fields

dom_id: DomId

node_id: NodeId

cursor: TextCursor

SetSelection

Set text selection range

Fields

dom_id: DomId

node_id: NodeId

selection: Selection

SetTextChangeset

Set/override the text changeset for the current text input operation This allows callbacks to modify what text will be inserted during text input events

Fields

changeset: PendingTextEdit

MoveCursorLeft

Move cursor left (arrow left)

Fields

dom_id: DomId

node_id: NodeId

extend_selection: bool

MoveCursorRight

Move cursor right (arrow right)

Fields

dom_id: DomId

node_id: NodeId

extend_selection: bool

MoveCursorUp

Move cursor up (arrow up)

Fields

dom_id: DomId

node_id: NodeId

extend_selection: bool

MoveCursorDown

Move cursor down (arrow down)

Fields

dom_id: DomId

node_id: NodeId

extend_selection: bool

MoveCursorToLineStart

Move cursor to line start (Home key)

Fields

dom_id: DomId

node_id: NodeId

extend_selection: bool

MoveCursorToLineEnd

Move cursor to line end (End key)

Fields

dom_id: DomId

node_id: NodeId

extend_selection: bool

MoveCursorToDocumentStart

Move cursor to document start (Ctrl+Home)

Fields

dom_id: DomId

node_id: NodeId

extend_selection: bool

MoveCursorToDocumentEnd

Move cursor to document end (Ctrl+End)

Fields

dom_id: DomId

node_id: NodeId

extend_selection: bool

SetCopyContent

Override clipboard content for copy operation

Fields

target: DomNodeId

content: ClipboardContent

SetCutContent

Override clipboard content for cut operation

Fields

target: DomNodeId

content: ClipboardContent

SetSelectAllRange

Override selection range for select-all operation

Fields

target: DomNodeId

range: SelectionRange

RequestHitTestUpdate

Request a hit test update at a specific position

This is used by the Debug API to update the hover manager’s hit test data after modifying the mouse position, ensuring that callbacks can find the correct nodes under the cursor.

Fields

position: LogicalPosition

ProcessTextSelectionClick

Process a text selection click at a specific position

This is used by the Debug API to trigger text selection directly, bypassing the normal event pipeline. The handler will:

1. Hit-test IFC roots to find selectable text at the position
2. Create a text cursor at the clicked position
3. Update the selection manager with the new selection

Fields

position: LogicalPosition

time_ms: u64

SetCursorVisibility

Set the cursor visibility state (called by blink timer)

Fields

visible: bool

ResetCursorBlink

Reset cursor blink state on user input (makes cursor visible, records time)

StartCursorBlinkTimer

Start the cursor blink timer for the focused contenteditable element

StopCursorBlinkTimer

Stop the cursor blink timer (when focus leaves contenteditable)

ScrollActiveCursorIntoView

Scroll the active text cursor into view within its scrollable container This is automatically triggered after text input or cursor movement

CreateTextInput

Create a synthetic text input event

This simulates receiving text input from the OS. The text input flow will:

1. Record the text in TextInputManager (creating a PendingTextEdit)
2. Generate synthetic TextInput events
3. Invoke user callbacks (which can intercept/reject via preventDefault)
4. Apply the changeset if not rejected
5. Mark dirty nodes for re-render

Fields

text: AzString

The text to insert

Trait Implementations

impl Clone for CallbackChange

fn clone(&self) -> CallbackChange

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CallbackChange

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.