Synthesizing Events

Built-in Controls

Event Type Reference

This topic provides a summary of each event type. Consult the API documentation for a complete description of each event member and its purpose.

Capture events

Events implementing IMouseCaptureEvent.

MouseCaptureEvent

MouseCaptureEvent is sent when an element takes the mouse capture.

target: The element that takes the capture.

MouseCaptureOutEvent

MouseCaptureOutEvent is sent when an element releases or otherwise loses the mouse capture.

target: The element that loses the capture.

Change events

Events implementing IChangeEvent.

ChangeEvent

ChangeEvent<T> is a generic event sent when the value of an element changes. This is typically sent when a control changes. For the InputEvent control, this event is not sent for every input event in the control, but only when the value changes. This is usually when either the control loses focus, or the Enter key is pressed.

<T>: The type of the value.
target: The element for which the change of value occured.
previousValue: The old control value.
newValue: The new control value.

Command events

Events implementing ICommandEvent.

target: The element with keyboard focus. This is null if no element has focus.
commandName: The command to validate or execute.

ValidateCommandEvent

This event is sent by IMGUI while it determines whether the command will be handled by an element in the panel.

ExecuteCommandEvent

This event is sent by IMGUI when an element in the panel should execute a command.

Drag and drop events

Events sent during a drag and drop operation.

DragExitedEvent

The drag and drop operation was cancelled. The drop target did not accept the dragged element.

DragUpdatedEvent

The dragged element moved over a drop target. If the drop target is willing to accept the dragged element, the callback for this event should set DragAndDrop.visualMode to ensure a DragPerformEvent is sent when the user releases the mouse button.

DragPerformEvent

The dragged element was dropped on a target that accepted them. The drag and drop operation is now finished.

DragEnterEvent

The dragged element entered a new VisualElement. In particular, this event is sent when the drag operation begins.

DragLeaveEvent

The dragged element exited the current drop target. In particular, this event is sent when the drag operation ends.

Layout events

GeometryChangedEvent

Event sent when either the position or the dimensions of an element changes. Events of this type are only sent to the event target. They are not propagated.

target: The element with a new geometry.
oldRect: The former position and dimensions of the element.
newRect: The new position and dimensions of the element.

Focus events

Events implementing IFocusEvent.

These events are sent when an element is given or loses keyboard focus. There are two sets of focus events:

FocusOutEvent and FocusInEvent are sent along the propagation path just before the focus change occurs.
FocusEvent and BlurEvent are sent to the event target only, immediately after the focus change.

FocusOutEvent

Event sent when an element is about to lose the focus.

target: The element that will lose the focus.
relatedTarget: The element that will gain the focus.

FocusInEvent

Event sent when an element is about to gain the focus.

target: The element that will gain the focus.
relatedTarget: The element that will lose the focus.

BlurEvent

Event sent after an element lost the focus.

target: The element that lost the focus.
relatedTarget: The element that gained the focus.

FocusEvent

Event sent after an element gained the focus.

target: The element that gained the focus.
relatedTarget: The element that lost the focus.

Input events

InputEvent

Event sent when data is input to a visual element, typically a control. This event differs from ChangeEvent in that it is sent for every input event in the control, even if the value of the control did not change.

target: The element where the input occured.
previousData: The former data.
newData: The new data.

Keyboard events

Events implementing IKeyboardEvent.

KeyDownEvent

Event sent when the user presses a key on the keyboard.

target: The element that has the keyboard focus. If no element has keyboard focus, this is the root element of the panel.

KeyUpEvent

Event sent when the user releases a key on the keyboard.

target: The element that has the keyboard focus. If no element has keyboard focus, this is the root element of the panel.

Mouse events

Events implementing IKeyboardEvent.

While an element is capturing the mouse, mouse events are only be sent to the capturing elements. There is no propagation.

MouseDownEvent

Event sent when the user presses one of the mouse buttons.

target: If an element took the mouse capture, this is the element capturing the mouse. Otherwise, this is the topmost pickable element under the cursor.

MouseUpEvent

Event sent when the user releases one of the mouse buttons.

target: If an element took the mouse capture, this is the element capturing the mouse. Otherwise, this is the topmost pickable element under the cursor.

MouseMoveEvent

Event went when the user moves the mouse.

target: If an element took the mouse capture, this is the element capturing the mouse. Otherwise, this is the topmost pickable element under the cursor.

ContextClickEvent (obsolete)

Event sent when the user presses and releases the third mouse button. This event only exists for backward compatibility with IMGUI.

WheelEvent

Event sent when the user activates the mouse wheel.

target: If an element took the mouse capture, this is the element capturing the mouse. Otherwise, this is the topmost pickable element under the cursor.

MouseEnterWindowEvent

Event sent when the mouse enters an window.

target: If an element took the mouse capture, this is the element capturing the mouse. Otherwise, this is the topmost pickable element under the cursor.

MouseLeaveWindowEvent

Event sent when the mouse leaves an window.

target: If an element took the mouse capture, this is the element capturing the mouse. Otherwise, this is null because the cursor is not over an element.

MouseEnterEvent

Event sent when the mouse enters an element or one of its descendant. This event differs from MouseOverEvent in that this event is sent to each element being entered by the mouse. This event does not propagate.

target: The element, or one of its decendants, under the mouse cursor.

MouseLeaveEvent

Event sent when the mouse leaves an element or one of its descendant. This event differs from MouseOutEvent in that this event is sent to each element being exited by the mouse. This event does not propagate.

target: The element has just been exited by the mouse cursor, or that has one of its descendant exited by the mouse cursor.

MouseOverEvent

Event sent when the mouse enters an element. This event differs from MouseEnterEvent in that this event is only sent to the entered element. . This event does not propagate.

target: The element that is now under the mouse cursor.

MouseOutEvent

Event sent when the mouse leaves an element. This event differs from MouseLeaveEvent in that this event is only sent to the exited element and that it propagates.

target: The element that has just been exited by the mouse cursor.

ContextualMenuPopulateEvent

Event sent by the ContextualMenuManager when the contextual menu needs to be populated with menu items.

target: The element for which the contextual menu is being built.

Panel events

AttachToPanelEvent

Event sent immediately after an element is attached to a IPanel. Since setting the panel is recursive, all descendants of the element also receive the event.

target: The element being attached to a panel.

DetachFromPanelEvent

Event sent just before an element is detached to a IPanel. Since setting the panel is recursive, all descendants of the element also receive the event.

target: The element being detached from a panel.

Tooltip event

TooltipEvent

Event sent just before a tooltip is displayed. The handler should set the TooltipEvent.tooltip string and the TooltipEvent.rect.

target: The element for which a tooltip needs to be displayed.

IMGUI events

IMGUIEvent

Event used to encapsulate IMGUI-specifc events.

2018–11–02 Page amended