Event Handlers

Window objects will call user-defined event handler functions in response to various interaction events. Event handlers are managed using a window member called ‘On’. This has sub-members for each GUI element with an ID, and those have members for each available event. To set up an event handler, define a function for it, then assign the function to the window’s On.ID.

Event member as follows:

def OnClose(ev):
        dispatcher.ExitLoop()

win.On.myWindow.Close = OnClose

Alternatively, if your object’s ID is stored in a string variable called ‘buttonID’, you could use:

win.On[buttonID].Clicked = OnButtonClicked

Important

Event handlers can be enabled or disabled for a given element by turning them on or off in the Events attribute:

ui.Slider({ 'ID': 'mySlider', 'Events': { 'SliderMoved': True } })

Some common events like Clicked or Close are enabled by default.

Many objects have specific events that can be handled:

Button

Clicked

Description

This event is triggered with a mouse click. (default=True)

Type: event

ui.Button({'ID':'buttonID', 'Text': "My Button"})

    def OnButtonClicked(ev):
    print(f"{win.Find('buttonID').Text} was clicked")

# assign event handlers
    win.On['buttonID'].Clicked = OnButtonClicked

Toggled

Description

This event is triggered if button is Toggled

Type: event

Note

Not tested yet

ui.Button({‘ID’:’buttonID’, ‘Text’: “My Button”})

def OnButtonToggled(ev):: print(f”{win.Find(‘buttonID’).Text} was Toggled”)

# assign event handlers win.On[‘buttonID’].Toggled = OnButtonToggled

Pressed

Description

This event is triggered button is pressed. (default=False)

Type: event

ui.Button({'ID':'buttonID', 'Text': "My Button", 'Events': { 'Pressed': True }})

def OnButtonPressed(ev):
    print(f"{win.Find('buttonID').Text} was Pressed")

# assign event handlers
win.On['buttonID'].Pressed = OnButtonPressed

Released

Description

This event is triggered when button is released. (default=False)

Type: event

ui.Button({'ID':'buttonID', 'Text': "My Button", 'Events': { 'Released': True }})

def OnButtonReleased(ev):
    print(f"{win.Find('buttonID').Text} was Released")

# assign event handlers
win.On['buttonID'].Released = OnButtonReleased

CheckBox

Clicked

Description

This event is triggered with a mouse click (default=True)

Type: event

ui.CheckBox({'ID':'my_checkbox', 'Text': "My CheckBox" })

def OnCheckBoxClicked(ev):
    print(f"{win.Find('my_checkbox').Text} was Clicked")

# assign event handlers
win.On['my_checkbox'].Clicked = OnCheckBoxClicked

Toggled

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_checkbox’].Toggled = OnCheckboxToggle

Pressed

Description

This event is triggered when CheckBox is pressed (default=False)

Type: event

ui.CheckBox({'ID':'my_checkbox', 'Text': "My CheckBox", 'Events': { 'Pressed': True } })

    def OnCheckBoxPressed(ev):
    print(f"{win.Find('my_checkbox').Text} was Pressed")

# assign event handlers
win.On['my_checkbox'].Pressed = OnCheckBoxPressed

Released

Description

This event is triggered when CheckBox is released (default=False)

Type: event

ui.CheckBox({'ID':'my_checkbox', 'Text': "My CheckBox", 'Events': { 'Released': True } })

def OnCheckBoxReleased(ev):
    print(f"{win.Find('my_checkbox').Text} was Released")

# assign event handlers
win.On['my_checkbox'].Released = OnCheckBoxReleased

ComboBox

CurrentIndexChanged

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_combobox’].CurrentIndexChanged = OnComboBoxCurrentIndexChanged

CurrentTextChanged

Description

This event is triggered each time the ComboBox current Text is changed

Type: event

ui.ComboBox({'ID':'combo_1', 'Text': "My ComboBox", 'Events': { 'CurrentTextChanged': True} })

    def OnComboBoxCurrentTextChanged(ev):
    print(f"ComboBox CurrentTextChanged changed")

# assign event handlers
win.On['combo_1'].CurrentTextChanged = OnComboBoxCurrentTextChanged

TextEdited

Description

This event is triggered when Text is edited by user in a ComboBox item. The ComboBox must be Editable

Type: event

ui.ComboBox({'ID':'combo_1', 'Text': "My ComboBox", 'Editable': True, 'Events': { 'TextEdited': True} })

def OnComboBoxTextEdited(ev):
    print(f"ComboBox Text was Edited")

# assign event handlers
win.On['combo_1'].TextEdited = OnComboBoxTextEdited

EditTextChanged

Description

This event is triggered when modifications are made to a ComboBox item and ComboBox is changed. The ComboBox must be Editable

Type: event

Note

Not tested yet

win.On[‘my_combobox’].EditTextChanged = OnComboBoxEditTextChanged

EditingFinished

Description

This event is triggered The ComboBox must be Editable

Type: event

Note

Not tested yet

win.On[‘my_combobox’].EditingFinished = OnComboBoxEditingFinished

ReturnPressed

Description

This event is triggered when Return is pressed with the ComboBox item selected. Return will also add the modified ComboBox item to the list The ComboBox must be Editable

Type: event

ui.ComboBox({'ID':'combo_1', 'Text': "My ComboBox", 'Editable': True, 'Events': { 'ReturnPressed': True} })

    def OnComboBoxReturnPressed(ev):
    print(f"ReturnPressed on ComboBox")

# assign event handlers
win.On['combo_1'].ReturnPressed = OnComboBoxReturnPressed

Activated

Description

This event is triggered when activity is detected on the ComboBox.

Type: event

ui.ComboBox({'ID':'combo_1', 'Text': "My ComboBox", 'Events': { 'Activated': True } })

def OnComboBoxIActivated(ev):
    print(f"ComboBox was Activated")

# assign event handlers
win.On['combo_1'].Activated = OnComboBoxIActivated

SpinBox

ValueChanged

Description

This event is triggered when SpinBox value is changed. (default=True)

Type: event

ui.SpinBox({'ID':'spinbox_1'})

    def OnSpinBoxValueChanged(ev):
    print(f"Value Changed on SpinBox")

# assign event handlers
win.On['spinbox_1'].ValueChanged = OnSpinBoxValueChanged

EditingFinished

Description

This event is triggered when Edit are made to the SpinBox items. (default=False)

Type: event

ui.SpinBox({'ID':'spinbox_1', 'Events': { 'EditingFinished': True} })

def OnSpinBoxEditingFinished(ev):
    print(f"EditingFinished on SpinBox")

# assign event handlers
win.On['spinbox_1'].EditingFinished = OnSpinBoxEditingFinished

Slider

ValueChanged

Description

This event is triggered when Slider value is changed (default=True)

Type: event

ui.Slider({'ID':'slider_1'})

    def OnSliderValueChanged(ev):
    print(f"Slider value changed")

# assign event handlers
win.On['slider_1'].ValueChanged = OnSliderValueChanged

SliderMoved

Description

This event is triggered each time the slider is moved with mouse cursor. (default=False)

Type: event

ui.Slider({'ID':'slider_1', 'Events': {'SliderMoved': True } })

    def OnSliderSliderMoved(ev):
    print(f"Slider moved")

# assign event handlers
win.On['slider_1'].SliderMoved = OnSliderSliderMoved

ActionTriggered

Description

This event is triggered when activity is detected on the Slider. (default=False)

Type: event

ui.Slider({'ID':'slider_1', 'Events': { 'ActionTriggered': True}  })

def OnSliderActionTriggered(ev):
    print(f"Action Triggered")

# assign event handlers
win.On['slider_1'].ActionTriggered = OnSliderActionTriggered

SliderPressed

Description

This event is triggered each time the slider is pressed, even if not moved. (default=False)

Type: event

ui.Slider({'ID':'slider_1', 'Events': {'SliderPressed': True}  })

def OnSliderSliderPressed(ev):
    print(f"Slider pressed")

# assign event handlers
win.On['slider_1'].SliderPressed = OnSliderSliderPressed

SliderReleased

Description

This event is triggered each time the slider is released, even if not moved. (default=False)

Type: event

ui.Slider({'ID':'slider_1', 'Events': { 'SliderReleased': True}  })

def OnSliderSliderReleased(ev):
    print(f"Slider released")

# assign event handlers
win.On['slider_1'].SliderReleased = OnSliderSliderReleased

RangeChanged

Description

This event is triggered is Minimum or Maximum slider value is change. (default=False)

Type: event

ui.Slider({'ID':'slider_1', 'Events': { 'RangeChanged': True}  })

    def OnSliderRangeChanged(ev):
    print("Range Changed")

# assign event handlers
win.On['slider_1'].RangeChanged = OnSliderRangeChanged

    win.Find('slider_1').Maximum = 4  #trigger RangeChanged

LineEdit

TextChanged

Description

This event is triggered each time Text is modified in the LineEdit element. (default=True)

Type: event

ui.LineEdit({'ID':'le_1' })

def OnLineEditTextChanged(ev):
    print(f"LineEdit text changed")

# assign event handlersdfg
win.On['le_1'].TextChanged = OnLineEditTextChanged

TextEdited

Description

This event is triggered each time Text is modified in the LineEdit element. (default=False)

Type: event

ui.LineEdit({'ID':'le_1', 'Events': {'TextEdited': True } })

def OnLineEditTextEdited(ev):
    print(f"LineEdit Text Edited")

# assign event handlersdfg
win.On['le_1'].TextEdited = OnLineEditTextEdited

EditingFinished

Description

This event is triggered if, after a modification to the Text, Return is pressed or Focus change to another Element. (default=False)

Type: event

ui.LineEdit({'ID':'le_1', 'Events': { 'EditingFinished': True } })

    def OnLineEditEditingFinished(ev):
    print(f"Editing Finished")

# assign event handlersdfg
win.On['le_1'].EditingFinished = OnLineEditEditingFinished

ReturnPressed

Description

This event is triggered when Return is pressed with LineEdit element selected. (default=False)

Type: event

ui.LineEdit({'ID':'le_1', 'Events': { 'ReturnPressed': True } })

def OnLineEditReturnPressed(ev):
    print(f"Return Pressed")

# assign event handlersdfg
win.On['le_1'].ReturnPressed = OnLineEditReturnPressed

SelectionChanged

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_le’].SelectionChanged = OnLineEditSelectionChanged

CursorPositionChanged

Description

This event is triggered each time the cursor change position in the LineEdit Element. (default=False) Inserting new character also changes the cursor position.

Type: event

ui.LineEdit({'ID':'le_1', 'Events': { 'CursorPositionChanged': True} })

def OnLineEditCursorPositionChanged(ev):
    print(f"Cursor Position Changed")

# assign event handlersdfg
win.On['le_1'].CursorPositionChanged = OnLineEditCursorPositionChanged

TextEdit

TextChanged

Description

This event is triggered each time Text is modified in the TextEdit element. (default=True)

Type: event

ui.TextEdit({'ID':'te_1' })

def OnLineEditTextChanged(ev):
    print(f"TextEdit text changed")

# assign event handlersdfg
win.On['te_1'].TextChanged = OnTextEditTextChanged

SelectionChanged

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_te’].SelectionChanged = OnTextEditSelectionChanged

CursorPositionChanged

Description

This event is triggered each time the cursor change position in the TextEdit Element. (default=False) Inserting new character also changes the cursor position.

Type: event

ui.TextEdit({'ID':'te_1', 'Events': { 'CursorPositionChanged': True } })

def OnTextEditCursorPositionChanged(ev):
    print(f"Cursor Position Changed")

# assign event handlersdfg
win.On['te_1'].CursorPositionChanged = OnTextEditCursorPositionChanged

ColorPicker

ColorChanged

Description

This event is triggered when color is changed on ColorPicker element. (default=True)

Type: event

ui.ColorPicker({'ID':'colorpicker_1' })

def OnColorPickerColorChanged(ev):
    print(f"Color Changed")

# assign event handlersdfg
win.On['colorpicker_1'].ColorChanged = OnColorPickerColorChanged

TabBar

CurrentChanged

Description

This event is triggered each time Tab is changed. (default=True)

Type: event

ui.TabBar({'ID':'tabbar_1'})

def OnTabBarCurrentChanged(ev):
    print(f"Tab Changed")

# assign event handlersdfg
win.On['tabbar_1'].CurrentChanged = OnTabBarCurrentChanged

CloseRequested

Description

This event is triggered when a Tab is closed. (default=False) TabsClosable must be set to True

Type: event

ui.TabBar({'ID':'tabbar_1', 'TabsClosable': True, 'Events': {'CloseRequested': True} })

    def OnTabBarCloseRequested(ev):
    print(f"Tab Close Requested")

# assign event handlersdfg
win.On['tabbar_1'].CloseRequested = OnTabBarCloseRequested

TabMoved

Description

This event is triggered when a Tab is moved. (default=False) TabBar must be Movable

Type: event

ui.TabBar({'ID':'tabbar_1', 'Movable': True, 'Events': {'TabMoved': True} })

    def OnTabBarTabMoved(ev):
    print(f"Tab Moved")

# assign event handlersdfg
win.On['tabbar_1'].TabMoved = OnTabBarTabMoved

TabBarClicked

Description

This event is triggered each time the TabBar is clicked. (default=False)

Type: event

ui.TabBar({'ID':'tabbar_1', 'Events': {'TabBarClicked': True} })

def OnTabBarClicked(ev):
    print(f"TabBar Clicked")

# assign event handlersdfg
win.On['tabbar_1'].TabBarClicked = OnTabBarClicked

TabBarDoubleClicked

Description

This event is triggered each time the TabBar is double clicked. (default=False)

Type: event

ui.TabBar({'ID':'tabbar_1', 'Events': {'TabBarDoubleClicked': True} })

def OnTabBarDoubleClicked(ev):
    print(f"TabBar Double Clicked")

# assign event handlersdfg
win.On['tabbar_1'].TabBarDoubleClicked = OnTabBarDoubleClicked

Tree

CurrentItemChanged

Description

This event is triggered when the TreeItem is changed. (default=True)

Type: event

ui.Tree({'ID':'tree_1'})

def OnCurrentItemChanged(ev):
        print('TreeItem was changed')

win.On['my_tree'].CurrentItemChanged = OnCurrentItemChanged

ItemClicked

Description

This event is triggered when a TreeItem is Clicked. (default=True)

Type: event

ui.Tree({'ID':'my_tree' })

def OnTreeItemClicked(ev):
        print('Item was clicked')

win.On['my_tree'].ItemClicked = OnTreeItemClicked

ItemPressed

Description

This event is triggered when a TreeItem is Clicked. (default=False)

Type: event

ui.Tree({'ID':'my_tree' })

def OnTreeItemPressed(ev):
        print('Item was pressed')

win.On['my_tree'].ItemPressed = OnTreeItemPressed

ItemActivated

Description

This event is triggered when a TreeItem is DoubleClicked or… (default=False)

Type: event

ui.Tree({'ID':'my_tree', 'Events' : { 'ItemDouItemActivatedbleClicked' : True } })

def OnTreeItemActivated(ev):
        print('Item was activated')

win.On['my_tree'].ItemActivated = OnTreeItemActivated

ItemDoubleClicked

Description

This event is triggered when a TreeItem is DoubleClicked. (default=False)

Type: event

ui.Tree({'ID':'my_tree', 'Events' : { 'ItemDoubleClicked' : True } })

def OnTreeItemDoubleClicked(ev):
        print('Item was double clicked')

win.On['my_tree'].ItemDoubleClicked = OnTreeItemDoubleClicked

ItemChanged

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_tree’].ItemChanged = OnTreeItemChanged

ItemEntered

Description

This event is triggered when Enter is pressed on a TreeItem. (default=False)

Type: event

Note

Not tested yet

ui.Tree({‘ID’:’tree_1’, ‘Events’: {‘ItemEntered’: True} })

def OnItemEntered(ev):: print(f”Item Entered”)

# assign event handlers win.On[‘tree_1’].ItemEntered = OnItemEntered

ItemExpanded

Description

This event is triggered when a TreeItem with Child is Expanded. (default=False)

Type: event

    ui.Tree({'ID':'tree_1', 'Events': {'ItemExpanded': True} })

def OnItemExpanded(ev):
    print(f"Item Expanded")

# assign event handlers
win.On['tree_1'].ItemExpanded = OnItemExpanded

ItemCollapsed

Description

This event is triggered when a TreeItem with Child is Collapsed. (default=False)

Type: event

    ui.Tree({'ID':'tree_1', 'Events': {'ItemCollapsed': True} })

def OnItemExpanded(ev):
    print(f"Item Collapsed")

# assign event handlers
win.On['tree_1'].ItemCollapsed = OnItemCollapsed

CurrentItemChanged

Description

This event is triggered when the selected Tree item is changed. (default=True)

Type: event

Note

Not tested yet

ui.Tree({‘ID’:’tree_1’})

def OnCurrentItemChanged(ev):: print(f”Current Item Changed”)

# assign event handlers win.On[‘tree_1’].CurrentItemChanged = OnCurrentItemChanged

ItemSelectionChanged

Description

This event is triggered when the selected Tree item is changed. (default=False)

Type: event

    ui.Tree({'ID':'tree_1', 'Events': {'ItemSelectionChanged': True}  })

def OnItemSelectionChanged(ev):
    print(f"Item Selection Changed")

# assign event handlers
win.On['tree_1'].ItemSelectionChanged = OnItemSelectionChanged

Window

Close

Description

This event is triggered when the Window close button is pressed. (default=True)

Type: event

# Event handlers
def OnWindowClose(ev):
    dispatcher.ExitLoop()

    win.On['my_window'].Close = OnWindowClose

Show

Description

This event is triggered when the Window is shown or returns from a hidden state.

Type: event

win = dispatcher.AddWindow({
    'ID': "my_window",
    'Geometry': [ 400,200,250,125 ],
    'WindowTitle': 'My Window',
    'Events': {'Show': True, 'Clicked': True, 'Close': True}
    },
    ui.VGroup([
            ui.Label({'ID':'label_1', 'Text': 'My label' })
    ])
)

def OnWindowShow(ev):
    print(f"Show")

    # assign event handlers
    win.On['my_window'].Show = OnWindowShow

Hide

Description

This event is triggered when the Window is hidden by another Window

Type: event

win = dispatcher.AddWindow({
    'ID': "my_window",
    'Geometry': [ 400,200,250,125 ],
    'WindowTitle': 'My Window',
    'Events': {'Hide': True, 'Clicked': True, 'Close': True}
    },
    ui.VGroup([
            ui.Label({'ID':'label_1', 'Text': 'My label' })
    ])
)

def OnWindowHide(ev):
    print(f"Hidden")

    # assign event handlers
    win.On['my_window'].Hide = OnWindowHide

Resize

Description

This event is triggered each time the Window is resized. (default=False)

Type: event

win = dispatcher.AddWindow({
    'ID': "my_window",
    'Events': {'Resize': True, 'Clicked': True, 'Close': True}
    },
    ui.VGroup([
            ui.Label({'ID':'label_1', 'Text': 'My label' })
    ])
)

    def OnWindowResize(ev):
    print(f"Window resized")

# assign event handler
    win.On['my_window'].Resize = OnWindowResize

MousePress

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].MousePress = OnWindowMousePress

MouseRelease

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].MouseRelease = OnWindowMouseRelease

MouseDoubleClick

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].MouseDoubleClick = OnWindowMouseDoubleClick

MouseMove

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].MouseMove = OnWindowMouseMove

Wheel

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].Wheel = OnWindowWheel

KeyPress

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].KeyPress = OnWindowKeyPress

KeyRelease

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].KeyRelease = OnWindowKeyRelease

FocusIn

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].FocusIn = OnWindowFocusIn

FocusOut

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].FocusOut = OnWindowFocusOut

ContextMenu

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].ContextMenu = OnWindowContextMenu

Enter

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].Enter = OnWindowEnter

Leave

Description

This event is triggered

Type: event

Note

Not tested yet

win.On[‘my_window’].Leave = OnWindowLeave

Event handler functions are called with a dictionary of related attributes such as who, what, when, sender, and modifiers.

Common events and some additional attributes they receive include:

MousePress: Pos, GlobalPos, Button, Buttons
MouseRelease: Pos, GlobalPos, Button, Buttons
MouseDoubleClick: Pos, GlobalPos, Button, Buttons
MouseMove: Pos, GlobalPos, Button, Buttons
Wheel: Pos, GlobalPos, Buttons, Delta, PixelDelta, AngleDelta, Orientiation, Phase
KeyPress: Key, Text, IsAutoRepeat, Count
KeyRelease: Key, Text, IsAutoRepeat, Count
ContextMenu: Pos, GlobalPos
Move: Pos, OldPos
FocusIn: Reason
FocusOut: Reason