Interop communication between the Lua environment and the .NET CoronaPanel XAML control loads a Corona project, it raises a “Loaded” event which provides a new instance of the CoronaRuntimeEnvironment class. This instance represents the loaded Lua environment of your project and, using this object, you can listen for and dispatch Corona Runtime events in Lua.
The following example illustrates C# requesting Lua to sum two numbers and return the result back to C#. This is accomplished by having C# dispatch an event to Lua named "requestingSum" with two number properties. This is received by a Lua listener which then returns the sum back to C#.
// [C#]
/// <summary>Constructor. Initializes member variables and the user interface.</summary>
public MainPage()
{
// Initialize this page's components that were set up via the UI designer.
InitializeComponents();
// Set up Corona to automatically start up when the control's Loaded event has been raised.
fCoronaPanel.AutoLaunchEnabled = true;
// Add a Corona event handler which detects when the Corona project has been started.
fCoronaPanel.Runtime.Started += OnCoronaRuntimeStarted;
}
/// <summary>Called when the Corona runtime has started and finished loaded the "main.lua" file.</summary>
/// <param name="sender">The CoronaRuntime object that raised this event.</param>
/// <param name="e">Event arguments providing the CoronaRuntimeEnvironment that has been started.</param>
private void OnCoronaRuntimeStarted(object sender, CoronaLabs.Corona.WinRT.CoronaRuntimeEventArgs e)
{
// Create a custom Corona event named "requestingSum" with the following properties.
// This will be converted into a Lua "event" table once dispatched by Corona.
var eventProperties = CoronaLabs.Corona.WinRT.CoronaLuaEventProperties.CreateWithName("requestingSum");
eventProperties.Set("x", 5);
eventProperties.Set("y", 10);
eventProperties.Set("message", "Hello. Can you add these 2 numbers please?");
// Dispatch the event to Lua.
var eventArgs = new CoronaLabs.Corona.WinRT.CoronaLuaEventArgs(eventProperties);
var result = e.CoronaRuntimeEnvironment.DispatchEvent(eventArgs);
// Check if a number was returned from the Lua listener.
var boxedNumber = result.ReturnedValue as CoronaLabs.Corona.WinRT.CoronaBoxedNumber;
if (boxedNumber != null)
{
// A number was returned from Lua. Fetch it.
double sum = boxedNumber.Value;
}
}
-- [Lua]
-- Called when a Corona event named "requestingSum" has been dispatched
local function onRequestingSum( event )
-- Print event property "message" to Visual Studio's Output Panel
print( event.message )
-- Sum event properties "x" and "y" and return the result back to C#
return event.x + event.y
end
-- Set up the above function to be called when an event named "requestingSum" has been dispatched
Runtime:addEventListener( "requestingSum", onRequestingSum )
The following example illustrates Lua requesting C# to display a native message box by dispatching a "requestingMessageBox" event. The C# side of the app sets up the Corona event listener when the Corona Runtime has been loaded — this is the best time to add Corona Runtime event listeners because the “Loaded” event is raised in C# before main.lua is executed.
// [C#]
/// <summary>Constructor. Initializes member variables and the user interface.</summary>
public MainPage()
{
// Initialize this page's components that were set up via the UI designer.
InitializeComponents();
// Set up Corona to automatically start up when the control's Loaded event has been raised.
fCoronaPanel.AutoLaunchEnabled = true;
// Add a Corona event handler which detects when the Corona project has been loaded, but not started yet.
fCoronaPanel.Runtime.Loaded += OnCoronaRuntimeLoaded;
}
/// <summary>
/// Called when a new CoronaRuntimeEnvironment has been created/loaded,
/// but before the "main.lua" has been executed.
/// </summary>
/// <param name="sender">The CoronaRuntime object that raised this event.</param>
/// <param name="e">Event arguments providing the CoronaRuntimeEnvironment that has been created/loaded.</param>
private void OnCoronaRuntimeLoaded(object sender, CoronaLabs.Corona.WinRT.CoronaRuntimeEventArgs e)
{
// Set up C# method OnRequestingMessageBox() to be invoked when Corona runtime event
// "requestingMessageBox" has been dispatched.
e.CoronaRuntimeEnvironment.AddEventListener("requestingMessageBox", OnRequestingMessageBox);
}
/// <summary>Called when Corona runtime event "requestingMessageBox" has been dispatched.</summary>
/// <param name="sender">The CoronaRuntimeEnvironment that dispatched the event.</param>
/// <param name="e">Provides the Lua event table's fields/properties.</param>
private CoronaLabs.Corona.WinRT.ICoronaBoxedData OnRequestingMessageBox(
CoronaLabs.Corona.WinRT.CoronaRuntimeEnvironment sender,
CoronaLabs.Corona.WinRT.CoronaLuaEventArgs e)
{
// Fetch the "event.message" property.
var boxedMessage = e.Properties.Get("message") as CoronaLabs.Corona.WinRT.CoronaBoxedString;
if (boxedMessage == null)
{
// A "message" property was not provided or it was not of type string.
// Return an error message to Lua describing what went wrong.
return CoronaLabs.Corona.WinRT.CoronaBoxedString.From("'event.message' is a required field.");
}
// Display a native message box with the given string.
System.Windows.MessageBox.Show(boxedMessage.ToString());
// Return a success message to Lua.
return CoronaLabs.Corona.WinRT.CoronaBoxedString.From("Message box was displayed successfully!");
}
-- [Lua]
-- Dispatch an event named "requestingMessageBox" to be received by C#
local requestingMessageBoxEvent =
{
name = "requestingMessageBox",
message = "Hello World!"
}
local result = Runtime:dispatchEvent( requestingMessageBoxEvent )
-- Print the message returned by C#
print( tostring(result) )
Documentation for the Corona .NET/C++/CX class framework can be found here.