C# KeyEventArgs.Modifiers属性代码示例

private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Determine whether the key entered is the F1 key. If it is, display Help.
    if(e.KeyCode == Keys.F1 && (e.Alt || e.Control || e.Shift))
    {
        // Display a pop-up Help topic to assist the user.
        Help.ShowPopup(textBox1, "Enter your name.", new Point(textBox1.Bottom, textBox1.Right));
    }
    else if(e.KeyCode == Keys.F2 && e.Modifiers == Keys.Alt)
    {
        // Display a pop-up Help topic to provide additional assistance to the user.
        Help.ShowPopup(textBox1, "Enter your first name followed by your last name. Middle name is optional.",
            new Point(textBox1.Top, this.textBox1.Left));
    }
}

//引入命名空间
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

public class Form1 : Form
{
   [DllImport("User32.dll")]
   private static extern short GetAsyncKeyState( System.Windows.Forms.Keys vKey); 
  private System.Windows.Forms.TextBox textBox1;
  private System.Windows.Forms.Label lbl;
  private System.Windows.Forms.Button cmdAsyncState;

  public Form1() {
        InitializeComponent();
  }

  private void Form1_KeyPress(object sender, KeyPressEventArgs e)
  {
    e.Handled = true;
  }

  private void Form1_KeyDown(object sender, KeyEventArgs e)
  {
    lbl.Text = "Key Down: " + e.KeyValue.ToString();
    lbl.Text += "\nKey Code: " + e.KeyCode.ToString();
    lbl.Text += "\nKey Data: " + e.KeyData.ToString();

    if ((e.Modifiers & Keys.Shift) == Keys.Shift)
    {
      lbl.Text += "\n" + "Shift was held down.";
    }

    if ((e.Modifiers & Keys.Control) == Keys.Control)
    {
      lbl.Text += "\n" + "Control was held down.";
    }
    if (e.Alt)
    {
      lbl.Text += "\n" + "Alt was held down.";
    }
  }

  private void cmdAsyncState_Click(object sender, EventArgs e)
  {
    int state = Convert.ToInt32(GetAsyncKeyState(Keys.A).ToString());
    switch (state)
    {
      case 0:
        lbl.Text = "A has not been pressed since the last call.";
        break;
      case 1:
        lbl.Text = "A is not currently pressed, but has been pressed since the last call.";
          break;
      case -32767:
        lbl.Text = "A is currently pressed.";
        break;
    }
  }

  private void InitializeComponent()
  {
    this.textBox1 = new System.Windows.Forms.TextBox();
    this.lbl = new System.Windows.Forms.Label();
    this.cmdAsyncState = new System.Windows.Forms.Button();
    this.SuspendLayout();
    // 
    // textBox1
    // 
    this.textBox1.Location = new System.Drawing.Point(36, 36);
    this.textBox1.Name = "textBox1";
    this.textBox1.Size = new System.Drawing.Size(205, 21);
    this.textBox1.TabIndex = 0;
    this.textBox1.Text = "<Text will never appear here>";
    // 
    // lbl
    // 
    this.lbl.AutoSize = true;
    this.lbl.Location = new System.Drawing.Point(35, 77);
    this.lbl.Name = "lbl";
    this.lbl.Size = new System.Drawing.Size(0, 0);
    this.lbl.TabIndex = 1;
    // 
    // cmdAsyncState
    // 
    this.cmdAsyncState.Location = new System.Drawing.Point(36, 202);
    this.cmdAsyncState.Name = "cmdAsyncState";
    this.cmdAsyncState.Size = new System.Drawing.Size(141, 24);
    this.cmdAsyncState.TabIndex = 2;
    this.cmdAsyncState.Text = "GetAsyncState() for \"A\"";
    this.cmdAsyncState.Click += new System.EventHandler(this.cmdAsyncState_Click);
    // 
    // Form1
    // 
    this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
    this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
    this.ClientSize = new System.Drawing.Size(292, 266);
    this.Controls.Add(this.cmdAsyncState);
    this.Controls.Add(this.lbl);
    this.Controls.Add(this.textBox1);
    this.Font = new System.Drawing.Font("Tahoma", 8.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
    this.KeyPreview = true;
    this.Name = "Form1";
    this.Text = "KeyTest";
    this.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.Form1_KeyPress);
    this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Form1_KeyDown);
    this.ResumeLayout(false);
    this.PerformLayout();

  }


  [STAThread]
  static void Main()
  {
    Application.EnableVisualStyles();
    Application.Run(new Form1());
  }

}