Control.ProcessKeyPreview Method (System.Windows.Forms)

.NET Framework Class Library

Control..::.ProcessKeyPreview Method

Previews a keyboard message.

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

<SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags := SecurityPermissionFlag.UnmanagedCode)> _
<SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags := SecurityPermissionFlag.UnmanagedCode)> _
Protected Overridable Function ProcessKeyPreview ( _
	ByRef m As Message _
) As Boolean

[SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
protected virtual bool ProcessKeyPreview(
	ref Message m
)

[SecurityPermissionAttribute(SecurityAction::InheritanceDemand, Flags = SecurityPermissionFlag::UnmanagedCode)]
[SecurityPermissionAttribute(SecurityAction::LinkDemand, Flags = SecurityPermissionFlag::UnmanagedCode)]
protected:
virtual bool ProcessKeyPreview(
	Message% m
)

[<SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags = SecurityPermissionFlag.UnmanagedCode)>]
[<SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)>]
abstract ProcessKeyPreview : 
        m:Message byref -> bool 
[<SecurityPermissionAttribute(SecurityAction.InheritanceDemand, Flags = SecurityPermissionFlag.UnmanagedCode)>]
[<SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)>]
override ProcessKeyPreview : 
        m:Message byref -> bool

Parameters

m: Type: System.Windows.Forms..::.Message%
A Message, passed by reference, that represents the window message to process.

Return Value

Type: System..::.Boolean
true if the message was processed by the control; otherwise, false.

Remarks

This method is called by a child control when the child control receives a keyboard message. The child control calls this method before generating any keyboard events for the message. If this method returns true, the child control considers the message processed and does not generate any keyboard events. The m parameter contains the window message to preview. Possible values for the Message..::.Msg property are WM_CHAR, WM_KEYDOWN, WM_SYSKEYDOWN, WM_KEYUP, and WM_SYSKEYUP. The ProcessKeyPreview method simply sends the character to the parent's ProcessKeyPreview method, or returns false if the control has no parent. The Form class overrides this method to perform actual processing of dialog keys.

Notes to Inheritors

When overriding the ProcessKeyPreview method in a derived class, a control should return true to indicate that it has processed the key. For keys that are not processed by the control, the result of calling the base class's ProcessKeyPreview method should be returned.

Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET Framework Security

UIPermission
for all windows for inheriting classes to call this method. Associated enumeration: AllWindows value of UIPermissionWindow.
SecurityPermission
for the immediate caller to call unmanaged code. Associated enumeration: UnmanagedCode

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Reference

Control Class

System.Windows.Forms Namespace