接上一篇写的截取电脑屏幕，我们在原来的基础上加一个选择区域的功能，实现自定义选择截图。
个人比较懒，上一篇的代码就不重新设计了，就简单改一下呈现方式。
不得不吐槽一下，在windows10系统上设置了放大比例的话，用这种方式来实现截图功能的话需要去计算比例。后面有机会的话，用第三方DLL再实现一次。
实现功能
屏幕选择区域截图
开发环境
开发工具：Visual Studio 2013
.NET Framework版本：4.5
实现代码
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//将上一篇的内容改成以下内容 // pictureBox1.Image = bmp; Form2 frm = new Form2(); frm.BaseImage = bmp; frm.TopMost = true; frm.Show(); |
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/*Form2代码*/ #region Dll引用 [DllImport("User32.dll", EntryPoint = "GetDC")] private extern static IntPtr GetDC(IntPtr hWnd);
[DllImport("User32.dll", EntryPoint = "ReleaseDC")] private extern static int ReleaseDC(IntPtr hWnd, IntPtr hDC);
[DllImport("gdi32.dll")] public static extern int GetDeviceCaps(IntPtr hdc, int nIndex);
[DllImport("User32.dll")] public static extern int GetSystemMetrics(int hWnd);
const int DESKTOPVERTRES = 117; const int DESKTOPHORZRES = 118;
const int SM_CXSCREEN = 0; const int SM_CYSCREEN = 1;
#endregion
//<summary> //获取DPI缩放比例 //</summary> //<param name="dpiscalex"></param> //<param name="dpiscaley"></param> public static void GetDPIScale(ref float dpiscalex, ref float dpiscaley) { int x = GetSystemMetrics(SM_CXSCREEN); int y = GetSystemMetrics(SM_CYSCREEN); IntPtr hdc = GetDC(IntPtr.Zero); int w = GetDeviceCaps(hdc, DESKTOPHORZRES); int h = GetDeviceCaps(hdc, DESKTOPVERTRES); ReleaseDC(IntPtr.Zero, hdc); dpiscalex = (float)w / x; dpiscaley = (float)h / y; }
public Bitmap BaseImage { get; set; }
Graphics picGraphics; //记录鼠标开始截图的位置 int startX = 0, startY = 0; //记录鼠标结束截图的位置 int endX = 0, endY = 0; //记录DPI缩放比例 float x = 0f, y = 0f; public Form2() { InitializeComponent(); } private void Form2_Load(object sender, EventArgs e) { /* 初始化赋值*/
GetDPIScale(ref x, ref y); picGraphics = pictureBox1.CreateGraphics(); }
private void pictureBox1_Paint(object sender, PaintEventArgs e) { DrawRect(endX - startX, endY - startY,e.Graphics); }
private void Form2_KeyPress(object sender, KeyPressEventArgs e) { //按下esc退出 if (e.KeyChar == 27) { this.Close(); } }
//完成截图 private void lbSucess_Click(object sender, EventArgs e) { int clip_w = (int)((endX - startX) * x) - 4, clip_h = (int)((endY - startY) * y) - 4; if (clip_w < 1 || clip_h < 1) { return; } //获取截图 Bitmap clipBmp = new Bitmap(clip_w, clip_h); Graphics g = Graphics.FromImage(clipBmp); g.CopyFromScreen((int)(startX * x) + 2, (int)(startY * y) + 2, 0, 0, new Size(clip_w, clip_h), CopyPixelOperation.SourceCopy); //将截图设置到剪切板 Clipboard.SetImage(clipBmp); g.Dispose(); this.Close(); }
private void pictureBox1_MouseDown(object sender, MouseEventArgs e) { //隐藏操作面板 panel1.Visible = false; //记录鼠标开始截图的位置 if (e.Button == MouseButtons.Left) { startX = e.X; startY = e.Y; endX = 0; endY = 0; } }
private void pictureBox1_MouseMove(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { //绘制截图区域 DrawRect(e.X - startX, e.Y - startY, picGraphics); } }
private void pictureBox1_MouseUp(object sender, MouseEventArgs e) { //截图完成 if (e.Button == MouseButtons.Left) { endX = e.X; endY = e.Y;
DrawRect(endX - startX, endY - startY, picGraphics); if (endX > startX && endY > startY) { //显示操作面板 Thread.Sleep(100); panel1.Location = new Point(e.X - panel1.Width, e.Y + 5); panel1.Visible = true;
} } }
//绘制截图区域 private void DrawRect(int w, int h,Graphics g) { Bitmap img = (Bitmap)BaseImage.Clone();
//双缓冲技术画矩形,防止重影和抖动 Graphics Painter = Graphics.FromImage(img); Painter.DrawRectangle(new Pen(Color.Red), startX * x, startY * y, w * x, h * y); g.DrawImage(img, 0, 0, img.Width / x, img.Height / y);
Painter.Dispose(); img.Dispose(); } |
实现效果
我这边演示代码很少做异常处理（前面也是，后面也是，毕竟不是做项目为主），大家使用的时候根据情况自行处理下即可，亦或者可能会有内存未及时释放的情况。
