public partial class Form4 : Form
{
public Form4()
{
InitializeComponent();
}
#region 用户变量
private Point DownPoint = Point.Empty;//记录鼠标按下座标，用来确定绘图起点
private bool CatchFinished = false;//用来表示是否截图完成
private bool CatchStart = false;//表示截图开始
private Bitmap originBmp;//用来保存原始图像
private Rectangle CatchRect;//用来保存截图的矩形
#endregion
private void Form4_Load(object sender, EventArgs e)
{
this.SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true);
this.UpdateStyles();
//以上两句是为了设置控件样式为双缓冲，这可以有效减少图片闪烁的问题，关于这个大家可以自己去搜索下
originBmp = new Bitmap(this.BackgroundImage);//BackgroundImage为全屏图片，我们另用变量来保存全屏图片
}
private void Form4_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
if (!CatchStart)
{//如果捕捉没有开始
CatchStart = true;
DownPoint = new Point(e.X, e.Y);//保存鼠标按下座标
}
}
}
private void Form4_MouseClick(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Right)
{
this.DialogResult = DialogResult.OK;
this.Close();
}
}
private void Form4_MouseMove(object sender, MouseEventArgs e)
{
if (CatchStart)
{//如果捕捉开始
Bitmap destBmp = (Bitmap)originBmp.Clone();//新建一个图片对象，并让它与原始图片相同
Point newPoint = new Point(DownPoint.X, DownPoint.Y);//获取鼠标的座标
Graphics g = Graphics.FromImage(destBmp);//在刚才新建的图片上新建一个画板
Pen p = new Pen(Color.Blue, 1);
int width = Math.Abs(e.X - DownPoint.X), height = Math.Abs(e.Y - DownPoint.Y);//获取矩形的长和宽
if (e.X < DownPoint.X)
{
newPoint.X = e.X;
}
if (e.Y < DownPoint.Y)
{
newPoint.Y = e.Y;
}
CatchRect = new Rectangle(newPoint, new Size(width, height));//保存矩形
g.DrawRectangle(p, CatchRect);//将矩形画在这个画板上
g.Dispose();//释放目前的这个画板
p.Dispose();
Graphics g1 = this.CreateGraphics();//重新新建一个Graphics类
//如果之前那个画板不释放，而直接g=this.CreateGraphics()这样的话无法释放掉第一次创建的g,因为只是把地址转到新的g了．如同string一样
g1 = this.CreateGraphics();//在整个全屏窗体上新建画板
g1.DrawImage(destBmp, new Point(0, 0));//将刚才所画的图片画到这个窗体上
//这个也可以属于二次缓冲技术，如果直接将矩形画在窗体上，会造成图片抖动并且会有无数个矩形．
g1.Dispose();
destBmp.Dispose();//要及时释放，不然内存将会被大量消耗
}
}
private void Form4_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
if (CatchStart)
{
CatchStart = false;
CatchFinished = true;
}
}
}
private void Form4_MouseDoubleClick(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left && CatchFinished)
{
if (CatchRect.Contains(new Point(e.X, e.Y)))
{
Bitmap CatchedBmp = new Bitmap(CatchRect.Width, CatchRect.Height);//新建一个于矩形等大的空白图片
Graphics g = Graphics.FromImage(CatchedBmp);
g.DrawImage(originBmp, new Rectangle(0, 0, CatchRect.Width, CatchRect.Height), CatchRect, GraphicsUnit.Pixel);
//把orginBmp中的指定部分按照指定大小画在画板上
Clipboard.SetImage(CatchedBmp);//将图片保存到剪贴板
g.Dispose();
CatchFinished = false;
this.BackgroundImage = originBmp;
CatchedBmp.Dispose();
this.DialogResult = DialogResult.OK;
this.Close();
}
}
}
}
//以下是聊天窗体的点击事件
private void button2_Click(object sender, EventArgs e)
{
this.Hide();//隐藏当前窗体
Thread.Sleep(50);//让线程睡眠一段时间，窗体消失需要一点时间
Form4 CatchForm = new Form4();
Bitmap CatchBmp = new Bitmap(Screen.AllScreens[0].Bounds.Width, Screen.AllScreens[0].Bounds.Height);//新建一个和屏幕大小相同的图片
Graphics g = Graphics.FromImage(CatchBmp);
g.CopyFromScreen(new Point(0, 0), new Point(0, 0), new Size(Screen.AllScreens[0].Bounds.Width, Screen.AllScreens[0].Bounds.Height));//保存全屏图片
CatchForm.BackgroundImage = CatchBmp;//将Catch窗体的背景设为全屏时的图片
if (CatchForm.ShowDialog() == DialogResult.OK)
{//如果Catch窗体结束,就将剪贴板中的图片放到信息发送框中
IDataObject iData = Clipboard.GetDataObject();
DataFormats.Format myFormat = DataFormats.GetFormat(DataFormats.Bitmap);
if (iData.GetDataPresent(DataFormats.Bitmap))
{
richTextBox1.Paste(myFormat);
//richtextbox1.Paste(myFormat);
Clipboard.Clear();//清除剪贴板中的对象
}
this.Show();//重新显示窗体
}
}