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* Migrate inprogress winforms contnet from docs * Fix preview note * Fix vb code * Minor fixes to keyboard articles * Minor adjustment to overview * Test redirects for 4.0 -> 5.0 * adjust links * Add mouse input section winforms (#81) * Update projects to .NET 5 * Update keyboard desc * Finish mouse events * Add remaining mouse articles;code * finish mouse input * minor fixes * Remove branch restriction (#82) * Update build-validation.yml (#84) * Update build-validation.yml (#85) * Fix vb proj * Add WinForms tutorial (#91) * redirect between overview * New create an app tutorial * Fix markdown * Fix preserve view setting * Add forms articles (#93) * Add forms articles * Fix warnings * Winforms publish (#95) * Prep TOC for publish * Updated date * Automatic how-to topic type * Update desc/headers * Fix links * Fix build errors * Add preview note * Update toc landing page * Convert old style project files * update download links * Apply suggestions from code review Co-authored-by: Genevieve Warren <[email protected]> * Adjust number key * Update dotnet-desktop-guide/net/winforms/overview/index.md * Try toc position task via bookmark * Improve images * Remove sentence * File redirects Co-authored-by: Genevieve Warren <[email protected]>
63 lines
4.1 KiB
Markdown
63 lines
4.1 KiB
Markdown
---
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title: "Check which modifier key is pressed"
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description: Learn how to detect when the SHIFT, ALT, or CTRL keys are pressed in Windows Forms for .NET.
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ms.date: 10/26/2020
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dev_langs:
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- "csharp"
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- "vb"
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helpviewer_keywords:
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- "keyboard input"
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- "shift keys"
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- "events [Windows Forms], mouse"
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- "Keys.ControlKey enumeration member"
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- "keys [Windows Forms], control keys"
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- "user input [Windows Forms], checking for keyboard"
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- "keys [Windows Forms], determining last pressed"
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- "keys [Windows Forms], shift keys"
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- "keys [Windows Forms], modifier keys"
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- "control keys"
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- "keys [Windows Forms], alt keys"
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- "alt keys"
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- "Keys.Shift enumeration member"
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- "events [Windows Forms], keyboard"
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- "keyboards [Windows Forms], keyboard input"
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- "Keys.Alt enumeration member"
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- "modifier keys"
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---
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# How to check for modifier key presses (Windows Forms .NET)
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As the user types keys into your application, you can monitor for pressed modifier keys such as the <kbd>SHIFT</kbd>, <kbd>ALT</kbd>, and <kbd>CTRL</kbd>. When a modifier key is pressed in combination with other keys or even a mouse click, your application can respond appropriately. For example, pressing the <kbd>S</kbd> key may cause an "s" to appear on the screen. If the keys <kbd>CTRL+S</kbd> are pressed, instead, the current document may be saved.
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[!INCLUDE [desktop guide under construction](../../includes/desktop-guide-preview-note.md)]
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If you handle the <xref:System.Windows.Forms.Control.KeyDown> event, the <xref:System.Windows.Forms.KeyEventArgs.Modifiers?displayProperty=nameWithType> property received by the event handler specifies which modifier keys are pressed. Also, the <xref:System.Windows.Forms.KeyEventArgs.KeyData?displayProperty=nameWithType> property specifies the character that was pressed along with any modifier keys combined with a bitwise OR.
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If you're handling the <xref:System.Windows.Forms.Control.KeyPress> event or a mouse event, the event handler doesn't receive this information. Use the <xref:System.Windows.Forms.Control.ModifierKeys%2A> property of the <xref:System.Windows.Forms.Control> class to detect a key modifier. In either case, you must perform a bitwise AND of the appropriate <xref:System.Windows.Forms.Keys> value and the value you're testing. The <xref:System.Windows.Forms.Keys> enumeration offers variations of each modifier key, so it's important that you do the bitwise AND check with the correct value.
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For example, the <kbd>SHIFT</kbd> key is represented by the following key values:
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- <xref:System.Windows.Forms.Keys.Shift?displayProperty=nameWithType>
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- <xref:System.Windows.Forms.Keys.ShiftKey?displayProperty=nameWithType>
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- <xref:System.Windows.Forms.Keys.RShiftKey?displayProperty=nameWithType>
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- <xref:System.Windows.Forms.Keys.LShiftKey?displayProperty=nameWithType>
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The correct value to test <kbd>SHIFT</kbd> as a modifier key is <xref:System.Windows.Forms.Keys.Shift?displayProperty=nameWithType>. Similarly, to test for <kbd>CTRL</kbd> and <kbd>ALT</kbd> as modifiers you should use the <xref:System.Windows.Forms.Keys.Control?displayProperty=nameWithType> and <xref:System.Windows.Forms.Keys.Alt?displayProperty=nameWithType> values, respectively.
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## Detect modifier key
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Detect if a modifier key is pressed by comparing the <xref:System.Windows.Forms.Control.ModifierKeys%2A> property and the <xref:System.Windows.Forms.Keys> enumeration value with a bitwise AND operator.
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The following code example shows how to determine whether the <kbd>SHIFT</kbd> key is pressed within the <xref:System.Windows.Forms.Control.KeyPress> and <xref:System.Windows.Forms.Control.KeyDown> event handlers.
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:::code language="csharp" source="snippets/how-to-check-modifier-key/csharp/Form1.cs" id="DetectModifier":::
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:::code language="vb" source="snippets/how-to-check-modifier-key/vb/Form1.vb" id="DetectModifier":::
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## See also
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- [Overview of using the keyboard (Windows Forms .NET)](overview.md)
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- [Using keyboard events (Windows Forms .NET)](events.md)
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- <xref:System.Windows.Forms.Keys>
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- <xref:System.Windows.Forms.Control.ModifierKeys>
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- <xref:System.Windows.Forms.Control.KeyDown>
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- <xref:System.Windows.Forms.Control.KeyPress>
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