Articles → LIGHT SWITCH 2011 → Screen Lost Focus Event In Lightswitch 2011

Screen Lost Focus Event In Lightswitch 2011

In this article I will explain how to invoke screen’s lost focus event in lightswitch 2011.

Software Requirement

Before you start reading this tutorial you should make sure that

Visual studio 2010 is installed on your machine.
Visual Studio 2010 service pack 1 is installed on your machine.
Microsoft Visual Studio Light switch 2011 is installed on your machine.

Prerequisite Knowledge

Before you go ahead, it is required that you should know

Basics about lightswitch.
How to create screens in lightswitch?
How to create lightswitch project using visual studio?
What are screens event?

Steps Of Execution

In this tutorial I will execute certain steps for the demonstration of lost focus event of screen in lightswitch application. These steps are

Create a new project
Add 2 screens
Add code for screen’s lost focus

Let us execute each step

Create A New Project

First of all create a new lightswitch project. See the screen shot below for project’s structure

Picture showing the project structure of the lightswitch application in the solution explorer

Click to Enlarge

Add 2 Screens

Add 2 screens of type ‘Editable Grid Screen’. See the screen shot below for project structure after adding screens

Picture showing the 2 screens added in the lightswitch application

Click to Enlarge

Add Code For Screen’S Lost Focus

Add following code in screen’s activated event

using Microsoft.VisualStudio.ExtensibilityHosting;
using Microsoft.LightSwitch.Presentation.Extensions;
using Microsoft.LightSwitch.Sdk.Proxy;

namespace LightSwitchApplication {
  public partial class Screen_one {
    partial void Screen_one_Activated() {
      IServiceProxy proxy = VsExportProviderService.GetExportedValue < IServiceProxy > ();
      VsExportProviderService.GetExportedValue < IServiceProxy > ().ActiveScreensViewModel.PropertyChanged += ActiveScreensViewModel_PropertyChanged;
    }

    void ActiveScreensViewModel_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e) {
      this.Details.Dispatcher.BeginInvoke(() => {
        VsExportProviderService.GetExportedValue < IServiceProxy > ().ActiveScreensViewModel.PropertyChanged -= ActiveScreensViewModel_PropertyChanged;
        this.ShowMessageBox("Screen deactivated event fired");
      });
    }
  }
}

Output

Run the application and open both screens

Picture showing the screen one loaded when the application runs for the first time

Click to Enlarge

Click on ‘Screen Two’ tab and come back to ‘Screen One’

Picture showing the message box appeared when focus on lost from screen 1 to screen 2

Click to Enlarge

Posted By -	Karan Gupta

Posted On -	Saturday, June 1, 2013

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