C#软件开发实例.私人订制自己的屏幕截图工具（四）基本截图功能实现

本实例全部文章目录

（一）功能概览

（二）创建项目、注册热键、显示截图主窗口

（三）托盘图标及菜单的实现

（四）基本截图功能实现

（五）针对拖拽时闪烁卡顿现象的优化

（六）添加配置管理功能

（七）添加放大镜的功能

（八）添加键盘操作截图的功能

（九）使用自定义光标，QQ截图时的光标

（十）在截图中包含鼠标指针形状

实现原理

基本截图的功能主要靠响应主窗体的鼠标按下、鼠标移动、鼠标抬起几个事件的功能来实现的。截取的图片区域使用“Label”组件来显示，需要重新实现“Label”组件的“Paint”方法。

左键单击开始截图，右键单击取消截图，双击鼠标左键完成截图，将截取的图片保存到Windows剪贴板中。

添加“Label”组件

工具箱》公共组件》双击“Label”组件，修改组件属性：

Name=lbl_CutImage，

AutoSize=False，

BackColor=Transparent，

Text = “”

“Form1_Load”事件添加代码：

this.lbl_CutImage.Hide();

定义截图功能依赖的基本变量

#region 截图基本变量
/// <summary>
/// 用于判断是否已经开始截图，控制信息框是否显示。
/// </summary>
private bool isCuting;
/// <summary>
/// 鼠标按下的点
/// </summary>
private Point beginPoint;
/// <summary>
/// 最终确定的绘图基点
/// </summary>
private Point endPoint;
/// <summary>
/// 用于记录截图显示区域的大小（包括调整块的区域，调整区域边框宽度2px）
/// </summary>
private Rectangle cutImageRect = new Rectangle(0, 0, 5, 5);
#endregion

定义枚举类型：更新UI的模式

/// <summary>
/// 更新UI的模式，用于标记哪些需要显示，哪些需要隐藏；
/// </summary>
[FlagsAttribute]
public enum UpdateUIMode : uint
{
    //值得注意的是，如果要使用组合值，那么就不能用连接的数字表示，必须是几何级增长！
    None = 0,
    ShowTextPro = 1,
    ShowPenStyle = 2,
    ShowToolBox = 4,
    ShowInfoBox = 8,
    ShowZoomBox = 16,
    ShowCutImage = 32,
    HideTextPro = 64,
    HidePenStyle = 128,
    HideToolBox = 256,
    HideInfoBox = 512
}

添加方法：计算并保存截图的区域框的大小

/// <summary>
/// 计算并保存截图的区域框的大小
/// </summary>
private void SaveCutImageSize(Point beginPoint, Point endPoint)
{
    // 保存最终的绘图基点，用于截取选中的区域
    this.endPoint = beginPoint;

    // 计算截取图片的大小
    int imgWidth = Math.Abs(endPoint.X - beginPoint.X) + 1;
    int imgHeight = Math.Abs(endPoint.Y - beginPoint.Y) + 1;
    int lblWidth = imgWidth + 4;
    int lblHeight = imgHeight + 4;

    // 设置截图区域的位置和大小
    this.cutImageRect = new Rectangle(beginPoint.X - 2, beginPoint.Y - 2, lblWidth, lblHeight);
}

添加方法：执行截图,将选定区域的图片保存到剪贴板

/// <summary>
/// 执行截图,将选定区域的图片保存到剪贴板
/// </summary>
/// <param name="saveToDisk">
/// 是否将图片保存到磁盘
/// </param>
private void ExecCutImage(bool saveToDisk, bool uploadImage) //bool saveToDisk = false, bool uploadImage = false
{
    // 如果图片获取区域不可见,则退出保存图片过程
    if (!this.lbl_CutImage.Visible) { return; }
    Rectangle srcRect = new Rectangle();
    srcRect.X = this.lbl_CutImage.Location.X + 2;
    srcRect.Y = this.lbl_CutImage.Location.Y + 2;
    srcRect.Width = this.lbl_CutImage.Width - 4;
    srcRect.Height = this.lbl_CutImage.Height - 4;
    Rectangle destRect = new Rectangle(0, 0, srcRect.Width, srcRect.Height);
    Bitmap bmp = new Bitmap(srcRect.Width, srcRect.Height);
    Graphics g = Graphics.FromImage(bmp);
    g.DrawImage(this.screenImage, destRect, srcRect, GraphicsUnit.Pixel);

    Clipboard.SetImage(bmp);

    ExitCutImage(true);
}

添加方法：退出截图过程

/// <summary>
 /// 退出截图过程
 /// </summary>
 private void ExitCutImage(bool hideWindow) //  = true
 {
     this.lbl_CutImage.Visible = false;
     this.isCuting = false;

     if (hideWindow)
     {
         this.screenImage.Dispose();
         this.Hide();
     }
 }

主窗口鼠标按下事件处理程序

/// <summary>
/// 截图窗口鼠标按下事件处理程序
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Form1_MouseDown(object sender, MouseEventArgs e)
{
    // 左键单击事件
    if (e.Button == MouseButtons.Left && e.Clicks == 1)
    {
        if (!this.lbl_CutImage.Visible)
        {
            this.isCuting = true;
            this.beginPoint = e.Location;
            this.endPoint = e.Location;
            SaveCutImageSize(e.Location, e.Location);

            UpdateCutInfoLabel(UpdateUIMode.ShowCutImage | UpdateUIMode.ShowInfoBox);
        }
    }
    // 左键双击事件
    if (e.Button == MouseButtons.Left && e.Clicks == 2)
    {
        if (this.lbl_CutImage.Visible)
        {
            ExecCutImage(false, false);
        }

    }
    // 右键单击事件
    if (e.Button == MouseButtons.Right)
    {
        ExitCutImage(!this.lbl_CutImage.Visible);
    }

}

主窗口鼠标移动事件处理程序

/// <summary>
/// 截图窗口鼠标移动事件处理程序
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Form1_MouseMove(object sender, MouseEventArgs e)
{
    // 如果截取区域不可见,则退出处理过程
    if (!this.lbl_CutImage.Visible)
    {
        UpdateCutInfoLabel(UpdateUIMode.None);
        return;
    }

    Point pntBgn = this.beginPoint;
    Point pntEnd = e.Location;

    // 如果是反向拖动，重新设置起始点
    if (e.Location.X < this.beginPoint.X && e.Location.Y < this.beginPoint.Y)
    {
        pntBgn = e.Location;
        pntEnd = this.beginPoint;
    }
    else
    {
        if (e.Location.X < this.beginPoint.X)
        {
            pntBgn = new Point(e.Location.X, this.beginPoint.Y);
            pntEnd = new Point(this.beginPoint.X, e.Location.Y);
        }
        else
        {
            if (e.Location.Y < this.beginPoint.Y)
            {
                pntBgn = new Point(this.beginPoint.X, e.Location.Y);
                pntEnd = new Point(e.Location.X, this.beginPoint.Y);
            }
        }
    }

    if (this.isCuting)
    {
        SaveCutImageSize(pntBgn, pntEnd);
    }

    UpdateCutInfoLabel(UpdateUIMode.None);
}

主窗口鼠标抬起事件处理程序

/// <summary>
/// 截图窗口鼠标抬起事件处理程序
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Form1_MouseUp(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        if (this.isCuting)
        {
            this.isCuting = false;

            UpdateCutInfoLabel(UpdateUIMode.None);
        }
    }
}

截取区域图片绘制

/// <summary>
/// 截取区域图片的绘制事件处理程序
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void lbl_CutImage_Paint(object sender, PaintEventArgs e)
{
    int imgWidth = this.lbl_CutImage.Width - 4;
    int imgHeight = this.lbl_CutImage.Height - 4;
    if (imgWidth < 1) { imgWidth = 1; }
    if (imgHeight < 1) { imgHeight = 1; }

    // 创建缓存图像，先将要绘制的内容全部绘制到缓存中，最后再一次性绘制到 Label 上，
    // 这样可以提高性能，并且可以防止屏幕闪烁的问题
    Bitmap bmp_lbl = new Bitmap(this.lbl_CutImage.Width, this.lbl_CutImage.Height);
    Graphics g = Graphics.FromImage(bmp_lbl);

    // 将要截取的部分绘制到缓存
    Rectangle destRect = new Rectangle(2, 2, imgWidth, imgHeight);
    Point srcPoint = this.lbl_CutImage.Location;
    srcPoint.Offset(2, 2);
    Rectangle srcRect = new Rectangle(srcPoint, new System.Drawing.Size(imgWidth, imgHeight));
    g.DrawImage(this.screenImage, destRect, srcRect, GraphicsUnit.Pixel);

    SolidBrush brush = new SolidBrush(Color.FromArgb(10, 124, 202));
    Pen pen = new Pen(brush, 1.0F);

    //以下部分（边框和调整块）的绘制放在（编辑内容）的后面，是解决绘制编辑内容会覆盖（边框和调整块）的问题

    // 绘制边框外的区域，解决会被编辑内容覆盖的问题
    // 上边
    destRect = new Rectangle(0, 0, this.lbl_CutImage.Width, 2);
    srcPoint = this.lbl_CutImage.Location;
    //srcPoint.Offset(2, 2);
    srcRect = new Rectangle(srcPoint, new System.Drawing.Size(this.lbl_CutImage.Width, 2));
    g.DrawImage(this.BackgroundImage, destRect, srcRect, GraphicsUnit.Pixel);

    // 下边
    destRect = new Rectangle(0, this.lbl_CutImage.Height - 2, this.lbl_CutImage.Width, 2);
    srcPoint = this.lbl_CutImage.Location;
    srcPoint.Offset(0, this.lbl_CutImage.Height - 2);
    srcRect = new Rectangle(srcPoint, new System.Drawing.Size(this.lbl_CutImage.Width, 2));
    g.DrawImage(this.BackgroundImage, destRect, srcRect, GraphicsUnit.Pixel);

    // 左边
    destRect = new Rectangle(0, 2, 2, this.lbl_CutImage.Height - 4);
    srcPoint = this.lbl_CutImage.Location;
    srcPoint.Offset(0, 2);
    srcRect = new Rectangle(srcPoint, new System.Drawing.Size(2, this.lbl_CutImage.Height - 4));
    g.DrawImage(this.BackgroundImage, destRect, srcRect, GraphicsUnit.Pixel);

    // 右边
    destRect = new Rectangle(this.lbl_CutImage.Width - 2, 2, 2, this.lbl_CutImage.Height - 4);
    srcPoint = this.lbl_CutImage.Location;
    srcPoint.Offset(this.lbl_CutImage.Width - 2, 2);
    srcRect = new Rectangle(srcPoint, new System.Drawing.Size(2, this.lbl_CutImage.Height - 4));
    g.DrawImage(this.BackgroundImage, destRect, srcRect, GraphicsUnit.Pixel);

    // 绘制边框
    g.DrawLine(pen, 2, 2, this.lbl_CutImage.Width - 3, 2);
    g.DrawLine(pen, 2, 2, 2, this.lbl_CutImage.Height - 3);
    g.DrawLine(pen, this.lbl_CutImage.Width - 3, 2, this.lbl_CutImage.Width - 3, this.lbl_CutImage.Height - 3);
    g.DrawLine(pen, 2, this.lbl_CutImage.Height - 3, this.lbl_CutImage.Width - 3, this.lbl_CutImage.Height - 3);

    // 绘制四个角的调整块
    g.FillRectangle(brush, 0, 0, 4, 5);
    g.FillRectangle(brush, this.lbl_CutImage.Width - 4, 0, 4, 5);
    g.FillRectangle(brush, 0, this.lbl_CutImage.Height - 5, 4, 5);
    g.FillRectangle(brush, this.lbl_CutImage.Width - 4, this.lbl_CutImage.Height - 5, 4, 5);

    // 绘制中间的四个调整块
    int blockX = this.lbl_CutImage.Width / 2 - 2;
    int blockY = this.lbl_CutImage.Height / 2 - 2;
    g.FillRectangle(brush, blockX, 0, 4, 5);
    g.FillRectangle(brush, 0, blockY, 4, 5);
    g.FillRectangle(brush, blockX, this.lbl_CutImage.Height - 5, 4, 5);
    g.FillRectangle(brush, this.lbl_CutImage.Width - 4, blockY, 4, 5);

    // 绘制到 Label 上
    e.Graphics.DrawImage(bmp_lbl, 0, 0);
    bmp_lbl.Dispose();
}

双击鼠标左键完成截图功能

/// <summary>
/// 截取区域图片的鼠标按下事件处理程序
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void lbl_CutImage_MouseDown(object sender, MouseEventArgs e)
{
    // 左键双击事件
    if (e.Button == MouseButtons.Left && e.Clicks == 2)
    {
        if (this.lbl_CutImage.Visible)
        {
            ExecCutImage(false, false);
        }
    }
}

注意：代码都贴完了，别忘了为窗体或组件绑定事件处理程序；

例如：截取区域图片的鼠标按下事件处理程序“lbl_CutImage_MouseDown”，就是“lbl_CutImage”组件的“MouseDown”事件的处理程序，绑定方法参考下图：

到此，基本截图的功能实现已经实现，赶快去截取一张图片，粘贴到QQ的聊天窗口看看吧。
源码下载：http://download.csdn.net/detail/testcs_dn/7261365