/// <summary>
/// 鼠标抬起，结束截图
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Cutter_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
if (Is_CatchStart)
{
Is_CatchStart = false;
if (CatchRectangle.Width == 0 || CatchRectangle.Height == 0)
{
return;
}
Bitmap CatchedBmp = new Bitmap(CatchRectangle.Width, CatchRectangle.Height);
Graphics g = Graphics.FromImage(CatchedBmp);
// 把originBmp中指定部分按照指定大小画到空白图片上
// CatchRectangle指定originBmp中指定部分
// 第二个参数指定绘制到空白图片的位置和大小
// 画完后CatchedBmp不再是空白图片了，而是具有与截取的图片一样的内容
g.DrawImage(WinBmp, new Rectangle(0, 0, CatchRectangle.Width, CatchRectangle.Height), CatchRectangle, GraphicsUnit.Pixel);
// 将图片保存到剪切板中
Clipboard.Clear();
Clipboard.SetImage(CatchedBmp);
g.Dispose();
retBitmap = CatchedBmp;
WinBmp.Dispose();
CatchedBmp.Dispose();
this.CanRead = true;
this.Close();
}
}
}
/// <summary>
/// 按下左键后移动鼠标，标记截图区域
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Cutter_MouseMove(object sender, MouseEventArgs e)
{
// 确保截图开始
if (Is_CatchStart)
{
// 新建一个图片对象，让它与屏幕图片相同
Bitmap copyBmp = (Bitmap)WinBmp.Clone();
// 获取鼠标按下的坐标
Point newPoint = new Point(DownPonint.X, DownPonint.Y);
// 新建画板和画笔
Graphics g = Graphics.FromImage(copyBmp);
Pen p = new Pen(Color.Red, 1);
// 获取矩形的长宽
int width = Math.Abs(e.X - DownPonint.X);
int height = Math.Abs(e.Y - DownPonint.Y);
if (e.X < DownPonint.X)
{
newPoint.X = e.X;
}
if (e.Y < DownPonint.Y)
{
newPoint.Y = e.Y;
}
CatchRectangle = new Rectangle(newPoint, new Size(width, height));
// 将矩形画在画板上
g.DrawRectangle(p, CatchRectangle);
// 释放目前的画板
g.Dispose();
p.Dispose();
// 从当前窗体创建新的画板
Graphics g1 = this.CreateGraphics();
// 将刚才所画的图片画到截图窗体上
// 为什么不直接在当前窗体画图呢？
// 如果自己解决将矩形画在窗体上，会造成图片抖动并且有无数个矩形
// 这样实现也属于二次缓冲技术
g1.DrawImage(copyBmp, new Point(0, 0));
g1.Dispose();
// 释放拷贝图片，防止内存被大量消耗
copyBmp.Dispose();
}
}
