C# form load event

C# form load event DEFAULT

Order of Events in Windows Forms

  • 2 minutes to read

The order in which events are raised in Windows Forms applications is of particular interest to developers concerned with handling each of these events in turn. When a situation calls for meticulous handling of events, such as when you are redrawing parts of the form, an awareness of the precise order in which events are raised at run time is necessary. This topic provides some details on the order of events during several important stages in the lifetime of applications and controls. For specific details about the order of mouse input events, see Mouse Events in Windows Forms. For an overview of events in Windows Forms, see Events Overview. For details about the makeup of event handlers, see Event Handlers Overview.

Application Startup and Shutdown Events

The Form and Control classes expose a set of events related to application startup and shutdown. When a Windows Forms application starts, the startup events of the main form are raised in the following order:

When an application closes, the shutdown events of the main form are raised in the following order:

The ApplicationExit event of the Application class is raised after the shutdown events of the main form.

Focus and Validation Events

When you change the focus by using the keyboard (TAB, SHIFT+TAB, and so on), by calling the Select or SelectNextControl methods, or by setting the ActiveControl property to the current form, focus events of the Control class occur in the following order:

When you change the focus by using the mouse or by calling the Focus method, focus events of the Control class occur in the following order:

See also

Sours: https://docs.microsoft.com/en-us/dotnet/desktop/winforms/order-of-events-in-windows-forms

UserControl.Load Event

Occurs before the control becomes visible for the first time.

Event Type

EventHandler

Examples

The following code example demonstrates the use of this member. In the example, an event handler reports on the occurrence of the Load event. This report helps you to learn when the event occurs and can assist you in debugging. To report on multiple events or on events that occur frequently, consider replacing MessageBox.Show with Console.WriteLine or appending the message to a multiline TextBox.

To run the example code, paste it into a project that contains an instance of type UserControl named . Then ensure that the event handler is associated with the Load event.

Remarks

You can use this event to perform tasks such as allocating resources used by the control.

Note

If the UserControl is part of an MDI child form, the Load event will occur each time the child form is shown. In this case, you should put any one-time initialization code in the UserControl instead of a Load event handler.

Caution

The Load event occurs when the handle for the UserControl is created. In some circumstances, this can cause the Load event to occur more than one time. For example, the Load event occurs when the UserControl is loaded, and again if the handle is recreated. (One way that a handle is recreated is by calling the RecreateHandle method.) To account for the Load event occurring more than one time, you should put any one time initialization code in the UserControl constructor instead of a Load event handler. In addition, you should not add data bindings to the UserControl in a Load event handler.

For more information about handling events, see Handling and Raising Events.

Applies to

See also

Sours: https://docs.microsoft.com/en-us/dotnet/api/system.windows.forms.usercontrol.load
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C# Form: Event HandlersUse the Form type, and event handlers like FormClosing, in Windows Forms.

Form. Every Windows Forms program will use the Form class. In many programs, the Load, FormClosing and FormClosed event handlers provide needed functionality. We look closer at Form. We demonstrate several event handlers on the Form class.

Load.To start, create a new Windows Forms program. Next, we add the Load event handler. In Visual Studio, double-click somewhere on the visible Form. In Form1_Load, you can set things like the title text (Text property) or the Window position.

Tip This is also a good place to put some initialization code. These run before the form is displayed.

FormClosing Here you can use logic to see if the program should stay open. Perhaps some data was not saved to the database.

Cancel Set the Cancel property on the FormClosingEventArgs to true and the Form will remain open. A dialog box might be helpful.

MessageBox

FormClosed Here you know the Form has been closed. You can't cancel it at this point. This is a good place to write settings to the disk.

Settings.settings

Base.The form class is an important one. It is the base class for all custom windows (such as Form1) that you might develop. You can reference all these derived types from the base type Form.

However If you are handling child forms, it is probably best to reference them through the most derived type.

C# program that uses Load, FormClosing, FormClosed

using System; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { // You can set properties in the Load event handler.this.Text = DateTime.Now.DayOfWeek.ToString(); this.Top = 60; this.Left = 60; } private void Form1_FormClosing(object sender, FormClosingEventArgs e) { // You can cancel the Form from closing.if ((DateTime.Now.Minute % 2) == 1) { this.Text = "Can't close on odd minute"; e.Cancel = true; } } private void Form1_FormClosed(object sender, FormClosedEventArgs e) { // You can write to a file to store settings here.} } }
Using.The clearest way to create a new Form is to add the using statement to your code and then call Show or ShowDialog. To start, you can add a button_Click event handler to your button in Windows Forms by double-clicking on it in the Designer.

And This will create the following method, which we have also added the using statement to.

Info We see the Click event handler for button4, which is just a regular Button control in Windows Forms.

Parameters The 2 parameters, "object sender" and "EventArgs e" are not specific to this example and you can ignore them.

Button

Method that demonstrates using keyword on Form: C#

private void button4_Click(object sender, EventArgs e) { using (Form2 form2 = new Form2()) { form2.ShowDialog(); } }
Using statement.Let's look carefully at how the using statement contains the assignment of a new instance of the Form2 form. The new Form2() constructor is inside the using condition.

Constructor

Also ShowDialog is called on the new Form instance. This will show the dialog in the form. You can assign its result to a DialogResult.

DialogResult

Version that passes argument to Form: C#

private void button1_Click(object sender, EventArgs e) { using (Form3 form3 = new Form3(new object())) // <-- Parameter{ DialogResult result = form3.ShowDialog(); if (result == DialogResult.OK) // <-- Checks DialogResult{ } } }
IDisposable.Form types implement the IDisposable interface, which is a special interface that is called when you have the "using" statement. Windows Forms use system resources that must be cleaned up after you are done with them.

So No matter what happens in ShowDialog, the Form instance will be properly disposed.

Using

Parameter. Here we see a short example of how you can use DialogResult and ShowDialog together. We also pass a parameter to the Form3 constructor. It is useful to pass parameters to Form constructors. You will need to modify the constructor manually.

Summary. The Form type presents several important event handlers as well as properties. The Load, FormClosing, and FormClosed event handlers are of particular interest. Most of the properties and other event handlers are not covered here.

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Sours: https://www.dotnetperls.com/form
C# Forms load \u0026 click event

What is form load event?

The Form Load Event in VB . An important event you'll want to write code for is the Form Load event. You might want to, for example, set the Enabled property of a control to False when a form loads. Or maybe blank out an item on your menu. You can do all this from the Form Load event.

Click to see full answer.


Similarly, it is asked, what is load event?

The load event occurs when a specified element has been loaded. This event works with elements associated with a URL (image, script, frame, iframe), and the window object. Depending on the browser, the load event may not trigger if the image is cached (Firefox and IE).

Subsequently, question is, what is meant by Dom? The Document Object Model (DOM) is a programming API for HTML and XML documents. It defines the logical structure of documents and the way a document is accessed and manipulated. Nevertheless, XML presents this data as documents, and the DOM may be used to manage this data.

In this way, what is Dom content?

The Document Object Model (DOM) is a programming interface for HTML and XML documents. It represents the page so that programs can change the document structure, style, and content. The DOM represents the document as nodes and objects. That way, programming languages can connect to the page.

What is Dom load time?

Dom Load Time represents the time from page initialization to the DomContentLoaded event or, for older Internet Explorer browsers, to the time the DOM is "interactive".

Sours: https://askinglot.com/what-is-form-load-event

Form load event c#

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The Form Load Event

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