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Form.ResizeBegin Event

Occurs when a form enters resizing mode.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public event EventHandler ResizeBegin

The ResizeBegin event is raised when the user begins to resize a form, typically by clicking and dragging one of the borders or the sizing grip located on the lower-right corner of the form. This action puts the form into a modal sizing loop until the resize operation is completed. Typically, the following set of events occurs during a resize operation:

  1. A single ResizeBegin event occurs as the form enters resizing mode.

  2. Zero or more pairs of Resize and SizeChanged events occur as the form's Size is modified.

  3. A single ResizeEnd event occurs as the form exits resizing mode.

NoteNote

Just clicking without dragging on a border or resizing grip will generate the ResizeBegin and ResizeEnd events without any intermediate Resize and SizeChanged event pairs.

The ResizeBegin and ResizeEnd pair of events is also raised when the user moves the form, typically by clicking and dragging on the caption bar. These events are not generated by programmatic manipulation of the form, for example by changing the Size or Location properties.

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

The following code example demonstrates the use of this member. In the example, an event handler reports on the occurrence of the ResizeBegin 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 Form named Form1. Then ensure that the event handler is associated with the ResizeBegin event.

private void Form1_ResizeBegin(Object sender, EventArgs e) {

   MessageBox.Show("You are in the Form.ResizeBegin event.");

}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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