Mohab: Created page with "NOTOC {{Client event}} This event is triggered when a monitored property of a dgs element changes via dgsSetProperty. The property must be added to the listener using dgsAddPropertyListener for this event to fire. {{Note|This event only fires for properties that have been explicitly added as listeners using dgsAddPropertyListener}} {{Note|The event only triggers when using dgsSetProperty, not element-specific functions like dgsSetText}} {{Tip|Thi..."

2025-07-10T02:44:35Z

Created page with "__NOTOC__ {{Client event}} This event is triggered when a monitored property of a dgs element changes via dgsSetProperty. The property must be added to the listener using dgsAddPropertyListener for this event to fire. {{Note|This event only fires for properties that have been explicitly added as listeners using dgsAddPropertyListener}} {{Note|The event only triggers when using dgsSetProperty, not element-specific functions like dgsSetText}} {{Tip|Thi..."

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__NOTOC__
{{Client event}}
This event is triggered when a monitored property of a dgs element changes via [[dgsSetProperty]]. The property must be added to the listener using [[dgsAddPropertyListener]] for this event to fire.

{{Note|This event only fires for properties that have been explicitly added as listeners using [[dgsAddPropertyListener]]}}
{{Note|The event only triggers when using [[dgsSetProperty]], not element-specific functions like [[dgsSetText]]}}
{{Tip|This event does NOT fire for user input changes (like typing in edit boxes). For monitoring user text input, use [[onDgsTextChange]] instead}}
{{Note|The event will not fire if the new value is the same as the old value}}
{{Tip|This event is designed for programmatic property changes, not user interactions}}

==Parameters==
<syntaxhighlight lang="lua">string propertyName, mixed newValue, mixed oldValue</syntaxhighlight>
*'''propertyName:''' the name of the property that changed
*'''newValue:''' the new value that was set
*'''oldValue:''' the previous value before the change

==Source==
The source is the dgs element whose property was changed.

==Example==
This example shows how to monitor window position changes:
<syntaxhighlight lang="lua">
DGS = exports.dgs
local window = DGS:dgsCreateWindow(200, 200, 400, 300, "Property Monitor", false)

-- Add listener for position changes
DGS:dgsAddPropertyListener(window, "absPos")

-- Handle property changes
function handlePropertyChange(propertyName, newValue, oldValue)
if propertyName == "absPos" then
outputChatBox("Window moved from " .. oldValue[1] .. "," .. oldValue[2] ..
" to " .. newValue[1] .. "," .. newValue[2])
end
end
addEventHandler("onDgsPropertyChange", window, handlePropertyChange)

-- Test the listener
setTimer(function()
DGS:dgsSetProperty(window, "absPos", {300, 250})
end, 2000, 1)
</syntaxhighlight>

This example demonstrates onDgsPropertyChange with programmatic text updates:
<syntaxhighlight lang="lua">
DGS = exports.dgs
local window = DGS:dgsCreateWindow(300, 200, 320, 320, "Property Change Demo", false)
local nameEdit = DGS:dgsCreateEdit(20, 50, 280, 30, "", false, window)
local emailEdit = DGS:dgsCreateEdit(20, 100, 280, 30, "", false, window)
local submitBtn = DGS:dgsCreateButton(20, 150, 280, 40, "Submit (Disabled)", false, window)
local statusLabel = DGS:dgsCreateLabel(20, 200, 280, 40, "Click buttons to set text", false, window)
local setNameBtn = DGS:dgsCreateButton(20, 250, 135, 30, "Set Name", false, window)
local setEmailBtn = DGS:dgsCreateButton(165, 250, 135, 30, "Set Email", false, window)

DGS:dgsCreateLabel(20, 30, 100, 20, "Name:", false, window)
DGS:dgsCreateLabel(20, 80, 100, 20, "Email:", false, window)

-- Monitor text property changes
DGS:dgsAddPropertyListener(nameEdit, "text")
DGS:dgsAddPropertyListener(emailEdit, "text")

function validateForm()
local name = DGS:dgsGetProperty(nameEdit, "text")
local email = DGS:dgsGetProperty(emailEdit, "text")

local isValid = (name and name ~= "" and email and email ~= "" and string.find(email, "@"))

DGS:dgsSetProperty(submitBtn, "enabled", isValid)
if isValid then
DGS:dgsSetProperty(submitBtn, "text", "Submit (Ready!)")
DGS:dgsSetProperty(statusLabel, "text", "Form is valid!")
DGS:dgsSetProperty(statusLabel, "textColor", tocolor(0, 255, 0, 255))
else
DGS:dgsSetProperty(submitBtn, "text", "Submit (Disabled)")
DGS:dgsSetProperty(statusLabel, "text", "Fill both fields")
DGS:dgsSetProperty(statusLabel, "textColor", tocolor(255, 0, 0, 255))
end
end

function handlePropertyChange(propertyName, newValue, oldValue)
outputChatBox("Property '" .. propertyName .. "' changed to: " .. tostring(newValue))
validateForm()
end

addEventHandler("onDgsPropertyChange", nameEdit, handlePropertyChange)
addEventHandler("onDgsPropertyChange", emailEdit, handlePropertyChange)

-- Button handlers to trigger property changes
addEventHandler("onDgsMouseClick", setNameBtn, function()
DGS:dgsSetProperty(nameEdit, "text", "John Doe")
end)

addEventHandler("onDgsMouseClick", setEmailBtn, function()
DGS:dgsSetProperty(emailEdit, "text", "john@example.com")
end)

validateForm()
</syntaxhighlight>

This example shows onDgsPropertyChange with button properties:
<syntaxhighlight lang="lua">
DGS = exports.dgs
local button = DGS:dgsCreateButton(100, 100, 200, 50, "Click Me", false)

-- Monitor button properties
DGS:dgsAddPropertyListener(button, {"alpha", "enabled"})

function handleButtonChange(propertyName, newValue, oldValue)
outputChatBox("Button property '" .. propertyName .. "' changed from " ..
tostring(oldValue) .. " to " .. tostring(newValue))
end
addEventHandler("onDgsPropertyChange", button, handleButtonChange)

-- Test the property changes
setTimer(function()
DGS:dgsSetProperty(button, "alpha", 128)
DGS:dgsSetProperty(button, "enabled", false)
end, 2000, 1)
</syntaxhighlight>

This example shows monitoring multiple properties:
<syntaxhighlight lang="lua">
DGS = exports.dgs
local button = DGS:dgsCreateButton(100, 100, 200, 50, "Monitor Me", false)

-- Monitor multiple properties
DGS:dgsAddPropertyListener(button, {"text", "alpha", "visible"})

function handleButtonChange(propertyName, newValue, oldValue)
outputChatBox("Property '" .. propertyName .. "' changed from " ..
tostring(oldValue) .. " to " .. tostring(newValue))
end
addEventHandler("onDgsPropertyChange", button, handleButtonChange)

-- Test changes
setTimer(function()
DGS:dgsSetProperty(button, "text", "Changed!")
DGS:dgsSetProperty(button, "alpha", 128)
end, 1000, 1)
</syntaxhighlight>

{{Tip|Use [[dgsRemovePropertyListener]] to stop monitoring properties when no longer needed}}

'''Author:''' [[User:Mohab|Mohab]]

==See Also==
===DGS events===
{{DGSEVENTS}}

===DGS functions===
*[[dgsAddPropertyListener]]
*[[dgsRemovePropertyListener]]
*[[dgsGetListenedProperties]]
*[[dgsSetProperty]]
*[[dgsGetProperty]]

===Client event functions===
{{Client_event_functions}}

OnDgsPropertyChange - Revision history