C#取屏幕顏色

 C#取屏幕顏色

1.原理
調用API取得屏幕上一個象素大小的位圖,這個位圖的底色就是鼠標所在點的屏幕顏色.

2.實現
--1.先聲明API 

       [DllImport("gdi32.dll")]
        private static extern bool BitBlt(
            IntPtr hdcDest,  //  目標設備的句柄  
            int nXDest,  //  目標對像的左上角的X坐標  
            int nYDest,  //  目標對像的左上角的X坐標  
            int nWidth,  //  目標對像的矩形的寬度  
            int nHeight,  //  目標對像的矩形的長度  
            IntPtr hdcSrc,  //  源設備的句柄  
            int nXSrc,  //  源對像的左上角的X坐標  
            int nYSrc,  //  源對像的左上角的X坐標  
            int dwRop  //  光柵的操作值  
            );

        [DllImport("gdi32.dll")]
        private static extern IntPtr CreateDC(
            string lpszDriver,  //  驅動名稱  
            string lpszDevice,  //  設備名稱  
            string lpszOutput,  //  無用，可以設定位"NULL"  
            IntPtr lpInitData  //  任意的打印機數據  
            );

--2.編寫取色函數

        private Color GetArgb()
        {
            Color rtnColor;
            //  創建顯示器的DC  
            IntPtr hdlDisplay = CreateDC("DISPLAY", null, null, IntPtr.Zero);
            //  從指定設備的句柄創建新的  Graphics  對像  
            Graphics gfxDisplay = Graphics.FromHdc(hdlDisplay);
            //  創建隻有一個像素大小的  Bitmap  對像  
            Bitmap bmp = new Bitmap(1, 1, gfxDisplay);
            //  從指定  Image  對像創建新的  Graphics  對像  
            Graphics gfxBmp = Graphics.FromImage(bmp);
            //  獲得屏幕的句柄  
            IntPtr hdlScreen = gfxDisplay.GetHdc();
            //  獲得位圖的句柄  
            IntPtr hdlBmp = gfxBmp.GetHdc();
            //  把當前屏幕中鼠標指針所在位置的一個像素拷貝到位圖中  
            BitBlt(hdlBmp, 0, 0, 1, 1, hdlScreen, MousePosition.X, MousePosition.Y, 13369376);
            //  釋放屏幕句柄  
            gfxDisplay.ReleaseHdc(hdlScreen);
            //  釋放位圖句柄  
            gfxBmp.ReleaseHdc(hdlBmp);
            rtnColor = bmp.GetPixel(0, 0);  //  獲取像素的顏色  
            bmp.Dispose();  //  釋放  bmp  所使用的資源  
            return rtnColor;
        }

3.触發事件
這里采用時間触發方式.
Bug:我認為采用鼠標移動時触發更合适.

this.tmr.Tick += new System.EventHandler(this.tmr_Tick);
 private void tmr_Tick(object sender, EventArgs e)
        {
            lblColor.BackColor=GetArgb();
            txtArgb.Text = lblColor.BackColor.R.ToString() + "," + lblColor.BackColor.G.ToString() + "," + lblColor.BackColor.B.ToString();

        }

4.調整顯示窗体
當鼠標移到當前窗体時,窗体需要移開.
先聲明變量:

        //  桌面工作區的尺寸  
        Size workingArea;
        //  Form  的初始位置和在左下角，右下角的位置  
        Point formLoc, ptLeftBottom, ptRightBottom;

初始化變量:

            Rectangle rect = SystemInformation.WorkingArea;
            workingArea = new Size(rect.Width, rect.Height);
            ptLeftBottom = new Point(0, workingArea.Height - this.Height);
            ptRightBottom = new Point(workingArea.Width - this.Width, workingArea.Height - this.Height);

触發事件:

        this.MouseEnter += new System.EventHandler(this.Form1_MouseEnter);
        private void Form1_MouseEnter(object sender, EventArgs e)
        {
            if (this.Location == ptLeftBottom)  //窗體在左下角  
            {
                this.Location = ptRightBottom;
            }
            else if (this.Location == ptRightBottom)  //  窗體在右下角  
            {
                this.Location = ptLeftBottom;
            }
        }

 

3.全部源碼,可運行

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

namespace PrintDemo
{
    ///  <summary>  
    ///  Form1  的摘要說明。  
    ///  </summary>  
    public class Form1 : System.Windows.Forms.Form
    {
        //  桌面工作區的尺寸  
        Size workingArea;
        //  Form  的初始位置和在左下角，右下角的位置  
        Point formLoc, ptLeftBottom, ptRightBottom;

        private System.Windows.Forms.Label lblColor;
        private System.Windows.Forms.TextBox txtArgb;
        private System.Windows.Forms.Timer tmr;
        private System.Windows.Forms.ToolTip tip;
        private System.ComponentModel.IContainer components;

        public Form1()
        {
            InitializeComponent();

            this.FormBorderStyle = FormBorderStyle.FixedToolWindow;
            this.StartPosition = FormStartPosition.CenterScreen;

            Rectangle rect = SystemInformation.WorkingArea;
            workingArea = new Size(rect.Width, rect.Height);
            ptLeftBottom = new Point(0, workingArea.Height - this.Height);
            ptRightBottom = new Point(workingArea.Width - this.Width,
                workingArea.Height - this.Height);

            String tipMsg = "在窗體空白處雙擊鼠標左鍵開始取色，按ESC鍵確定顏色";
            tip.SetToolTip(this, tipMsg);
            tip.SetToolTip(lblColor, tipMsg);
            tip.SetToolTip(txtArgb, tipMsg);
        }

        ///  <summary>  
        ///  清理所有正在使用的資源。  
        ///  </summary>  
        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (components != null)
                {
                    components.Dispose();
                }
            }
            base.Dispose(disposing);
        }

        #region  Windows  Form  Designer  generated  code
        ///  <summary>  
        ///  設計器支持所需的方法  -  不要使用代碼編輯器修改  
        ///  此方法的內容。  
        ///  </summary>  
        private void InitializeComponent()
        {
            this.components = new System.ComponentModel.Container();
            this.lblColor = new System.Windows.Forms.Label();
            this.tmr = new System.Windows.Forms.Timer(this.components);
            this.txtArgb = new System.Windows.Forms.TextBox();
            this.tip = new System.Windows.Forms.ToolTip(this.components);
            this.SuspendLayout();
            // 
            // lblColor
            // 
            this.lblColor.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
            this.lblColor.Location = new System.Drawing.Point(8, 8);
            this.lblColor.Name = "lblColor";
            this.lblColor.Size = new System.Drawing.Size(120, 23);
            this.lblColor.TabIndex = 0;
            // 
            // tmr
            // 
            this.tmr.Tick += new System.EventHandler(this.tmr_Tick);
            // 
            // txtArgb
            // 
            this.txtArgb.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
            this.txtArgb.Font = new System.Drawing.Font("Arial", 10.5F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((System.Byte)(0)));
            this.txtArgb.Location = new System.Drawing.Point(8, 40);
            this.txtArgb.Name = "txtArgb";
            this.txtArgb.Size = new System.Drawing.Size(120, 24);
            this.txtArgb.TabIndex = 1;
            this.txtArgb.Text = "";
            this.txtArgb.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.txtArgb_KeyPress);
            // 
            // Form1
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
            this.ClientSize = new System.Drawing.Size(136, 69);
            this.Controls.Add(this.txtArgb);
            this.Controls.Add(this.lblColor);
            this.Name = "Form1";
            this.Text = "屏幕取色(upto)";
            this.DoubleClick += new System.EventHandler(this.Form1_DoubleClick);
            this.MouseEnter += new System.EventHandler(this.Form1_MouseEnter);
            this.ResumeLayout(false);

        }
        #endregion


        [DllImport("gdi32.dll")]
        private static extern bool BitBlt(
            IntPtr hdcDest,  //  目標設備的句柄  
            int nXDest,  //  目標對像的左上角的X坐標  
            int nYDest,  //  目標對像的左上角的X坐標  
            int nWidth,  //  目標對像的矩形的寬度  
            int nHeight,  //  目標對像的矩形的長度  
            IntPtr hdcSrc,  //  源設備的句柄  
            int nXSrc,  //  源對像的左上角的X坐標  
            int nYSrc,  //  源對像的左上角的X坐標  
            int dwRop  //  光柵的操作值  
            );

        [DllImport("gdi32.dll")]
        private static extern IntPtr CreateDC(
            string lpszDriver,  //  驅動名稱  
            string lpszDevice,  //  設備名稱  
            string lpszOutput,  //  無用，可以設定位"NULL"  
            IntPtr lpInitData  //  任意的打印機數據  
            );

        private void Form1_DoubleClick(object sender, EventArgs e)
        {
            formLoc = this.Location;
            this.Location = ptRightBottom;
            this.TopMost = true;
            tmr.Enabled = true;
        }

        private Color GetArgb()
        {
            Color rtnColor;
            //  創建顯示器的DC  
            IntPtr hdlDisplay = CreateDC("DISPLAY", null, null, IntPtr.Zero);
            //  從指定設備的句柄創建新的  Graphics  對像  
            Graphics gfxDisplay = Graphics.FromHdc(hdlDisplay);
            //  創建隻有一個像素大小的  Bitmap  對像  
            Bitmap bmp = new Bitmap(1, 1, gfxDisplay);
            //  從指定  Image  對像創建新的  Graphics  對像  
            Graphics gfxBmp = Graphics.FromImage(bmp);
            //  獲得屏幕的句柄  
            IntPtr hdlScreen = gfxDisplay.GetHdc();
            //  獲得位圖的句柄  
            IntPtr hdlBmp = gfxBmp.GetHdc();
            //  把當前屏幕中鼠標指針所在位置的一個像素拷貝到位圖中  
            BitBlt(hdlBmp, 0, 0, 1, 1, hdlScreen, MousePosition.X, MousePosition.Y, 13369376);
            //  釋放屏幕句柄  
            gfxDisplay.ReleaseHdc(hdlScreen);
            //  釋放位圖句柄  
            gfxBmp.ReleaseHdc(hdlBmp);
            rtnColor = bmp.GetPixel(0, 0);  //  獲取像素的顏色  
            bmp.Dispose();  //  釋放  bmp  所使用的資源  
            return rtnColor;
        }
        private void tmr_Tick(object sender, EventArgs e)
        {
            lblColor.BackColor=GetArgb();
            txtArgb.Text = lblColor.BackColor.R.ToString() + "," + lblColor.BackColor.G.ToString() + "," + lblColor.BackColor.B.ToString();

        }

        private void txtArgb_KeyPress(object sender, KeyPressEventArgs e)
        {
            //  當按下ESC鍵時，確定所取的顏色ARGB值  
            //  Bug：隻有當窗體處於激活狀態時才有效,以後要是能點一下右鍵就可以就好了或者換成熱鍵觸發.
            if (e.KeyChar == (char)Keys.Escape)
            {
                tmr.Enabled = false;
                this.Location = formLoc;
                this.TopMost = false;
                txtArgb.SelectAll();
            }
        }

        private void Form1_MouseEnter(object sender, EventArgs e)
        {
            if (this.Location == ptLeftBottom)  //窗體在左下角  
            {
                this.Location = ptRightBottom;
            }
            else if (this.Location == ptRightBottom)  //  窗體在右下角  
            {
                this.Location = ptLeftBottom;
            }
        }
    }
}