基于C#实现屏幕取色器的示例详解

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    [DllImport("gdi32.dll")]
    static public extern uint GetPixel(IntPtr hDC, int XPos, int YPos);

    [DllImport("gdi32.dll")]
    static public extern IntPtr CreateDC(string driverName, string deviceName, string output, IntPtr lpinitData);

    [DllImport("gdi32.dll")]
    static public extern bool DeleteDC(IntPtr DC);

    static public byte GetRValue(uint color)
    {
        return (byte) color;
    }

    static public byte GetGValue(uint color)
    {
        return ((byte) (((short) (color)) >> 8));
    }

    static public byte GetBValue(uint color)
    {
        return ((byte) ((color) >> 16));
    }

    static public byte GetAValue(uint color)
    {
        return ((byte) ((color) >> 24));
    }

    public Color GetColor(Point screenPoint)
    {
        IntPtr displayDC = CreateDC("DISPLAY", null, null, IntPtr.Zero);
        uint colorref = GetPixel(displayDC, screenPoint.X, screenPoint.Y);
        DeleteDC(displayDC);
        byte Red = GetRValue(colorref);
        byte Green = GetGValue(colorref);
        byte Blue = GetBValue(colorref);
        return Color.FromArgb(Red, Green, Blue);
    }

    private void Form1_Load(object sender, EventArgs e)
    {
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        Point pt = new Point(Control.MousePosition.X, Control.MousePosition.Y);
        Color cl = GetColor(pt);
        panel1.BackColor = cl;
    }
}

partial class Form1
{
    /// <summary>
    /// 必需的设计器变量。
    /// </summary>
    private System.ComponentModel.IContainer components = null;

    /// <summary>
    /// 清理所有正在使用的资源。
    /// </summary>
    /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>
    protected override void Dispose(bool disposing)
    {
        if (disposing && (components != null))
        {
            components.Dispose();
        }
        base.Dispose(disposing);
    }

    #region Windows 窗体设计器生成的代码

    /// <summary>
    /// 设计器支持所需的方法 - 不要
    /// 使用代码编辑器修改此方法的内容。
    /// </summary>
    private void InitializeComponent()
    {
        this.components = new System.ComponentModel.Container();
        this.timer1 = new System.Windows.Forms.Timer(this.components);
        this.panel1 = new System.Windows.Forms.Panel();
        this.SuspendLayout();
        // 
        // timer1
        // 
        this.timer1.Enabled = true;
        this.timer1.Tick += new System.EventHandler(this.timer1_Tick);
        // 
        // panel1
        // 
        this.panel1.Location = new System.Drawing.Point(12, 12);
        this.panel1.Name = "panel1";
        this.panel1.Size = new System.Drawing.Size(200, 100);
        this.panel1.TabIndex = 0;
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(535, 298);
        this.Controls.Add(this.panel1);
        this.Name = "Form1";
        this.Text = "Form1";
        this.Load += new System.EventHandler(this.Form1_Load);
        this.ResumeLayout(false);

    }

    #endregion

    private System.Windows.Forms.Timer timer1;
    private System.Windows.Forms.Panel panel1;
}