C# 语法小记
## 保持窗体最前
```cs
this.TopMost = true;
```
## 将字符串S转化为Keys.S
```cs
Keys s = (Keys)Enum.Parse(typeof(Keys), "S");
```
## picBox 上标签透明（窗体设计器）
```cs
this.Controls.Add(this.pictureBox1);
pictureBox1.Controls.Add(label1);
label1.BackColor = Color.Transparent;
```
## 毛玻璃窗体
```cs
[StructLayout(LayoutKind.Sequential)]
public struct MARGINS
{
public int Left;
public int Right;
public int Top;
public int Bottom;
}
[DllImport("dwmapi.dll", PreserveSig = false)]
static extern void DwmExtendFrameIntoClientArea(IntPtr hwnd, ref MARGINS margins);
[DllImport("dwmapi.dll", PreserveSig = false)]
static extern bool DwmIsCompositionEnabled();
protected override void OnLoad(EventArgs e)
{
if (DwmIsCompositionEnabled())
{
MARGINS m = new MARGINS();
m.Right = m.Left = m.Top = this.Width + this.Height;
DwmExtendFrameIntoClientArea(this.Handle, ref m);
}
base.OnLoad(e);
}
protected override void OnPaintBackground(PaintEventArgs e)
{
base.OnPaintBackground(e);
if (DwmIsCompositionEnabled())
{
e.Graphics.Clear(Color.Black);
}
}
```
## 窗体侧边栏隐藏
```cs
private void timerShowHide_Tick(object sender, EventArgs e)
{
if (this.WindowState == FormWindowState.Normal)
{
Point cursorPoint;
cursorPoint = new Point(Cursor.Position.X, Cursor.Position.Y - 5); //获取鼠标在屏幕的坐标点
if (this.Left == -3 - this.Width)//当窗体在左面隐藏时
cursorPoint = new Point(Cursor.Position.X - 5, Cursor.Position.Y - 5);
Rectangle Rects = new Rectangle(this.Left - 8, this.Top - 8, this.Left + this.Width, this.Top + this.Height);//存储当前窗体在屏幕的所在区域
bool prInRect = PtInRect(ref Rects, cursorPoint);
if (prInRect)
{//当鼠标在当前窗体内
if (this.Top < 0)//窗体的Top属性小于0
this.Top = 0;
else if (this.Left < 0)//窗体的Left属性小于0
this.Left = 0;
else if (this.Right > Screen.PrimaryScreen.WorkingArea.Width)//窗体的Right属性大于屏幕宽度
this.Left = Screen.PrimaryScreen.WorkingArea.Width - this.Width;
}
else
{
if (this.Top < 5) //当窗体的上边框与屏幕的顶端的距离小于5时
this.Top = -3 - this.Height; //将窗体隐藏到屏幕的顶端
else if (this.Left < 5) //当窗体的左边框与屏幕的左端的距离小于5时
this.Left = -3 - this.Width; //将窗体隐藏到屏幕的左端
else if (this.Right > Screen.PrimaryScreen.WorkingArea.Width - 5)//当窗体的右边框与屏幕的右端的距离小于5时
this.Left = Screen.PrimaryScreen.WorkingArea.Width + 3;//将窗体隐藏到屏幕的右端
}
}
}
```
## 进程唯一
```cs
private void RunAProcessAtOnce()
{
System.Diagnostics.Process[] pProcesses = System.Diagnostics.Process.GetProcessesByName(
System.Diagnostics.Process.GetCurrentProcess().ProcessName);
if (pProcesses.Length > 1)
{
Application.Exit();
return;
}
}
```
## 鼠标拖动
```cs
//全局变量
Point oldPoint = new Point(0, 0);
bool mouseDown = false;
//鼠标事件
void Form1_MouseMove(object sender, MouseEventArgs e)
{
if (mouseDown)
{
this.Left += (e.X - oldPoint.X);
this.Top += (e.Y - oldPoint.Y);
left = this.Left;
top = this.Top;
}
}
void Form1_MouseDown(object sender, MouseEventArgs e)
{
oldPoint = e.Location;
mouseDown = true;
}
void Form1_MouseUp(object sender, MouseEventArgs e)
{
mouseDown = false;
}
```
## Form1窗体初始化不可见
```cs
WindowState : Minimized;
ShowInTaskbar : false;
Load 事件 ：this.visable = false;
```
## datagridview 某列不允许为空
```cs
if (this.ShowHostKey.CurrentCell.OwningColumn.HeaderText != "名称")
{
if (this.ShowHostKey.Rows[e.RowIndex].Cells["name"].Value == null)
{
MessageBox.Show("名称不允许为空！");
e.Cancel = true;
}
}
```
## 判断是不是文件（夹）/文件（夹）是否存在
```cs
if(!Directory.Exists("c:\hh"))//如果是文件夹的话
Directory.CreateDirectory("c:\hh");
if(!File.Exists("c:\hh"))//如果是文件的话
File.Create("c:\hh\1.txt");
```
## 通过注册表判定是否是第一次运行程序 并添加启动项
```cs
//引用
using System;
using System.Diagnostics;
using System.Windows.Forms;
using Microsoft.Win32;
///
/// 添加到注册表
///
/// 执行序号
public void Register(int id)
{
Path = Process.GetCurrentProcess().MainModule.FileName;//获取程序路径
String xpath = Path.Substring(0, Path.LastIndexOf(@"\"));//XStart 路径
RegistryKey hklm = Registry.LocalMachine;//注册表Machine 列表下
RegistryKey hksoft = Registry.CurrentUser;//注册表User 列表下
RegistryKey run = hklm.CreateSubKey(@"SOFTWARE\Microsoft\Windows\CurrentVersion\Run");//访问Run
RegistryKey xStart = hksoft.CreateSubKey(@"SOFTWARE\XStart");//新建 XStart 项
switch (id)
{
case 1: //添加开机启动
if (run != null) run.SetValue("XStart", Path);
break;
case 2: //删除开机启动 会产生不存在XStart键值异常
try { if (run != null) run.DeleteValue("XStart"); }
catch { MessageBox.Show("未设置开机启动！"); }
break;
case 3:
//通过查看是否含有XStart注册表项判断是否是第一次启动,如果是 设置启动项并添加注册表
//当然你也可以进行许多其他的操作 不过，这种方式如果手动删除注册表会让程序认为是第一次启动
//但是相对来说还是比较安全的方式，毕竟大多数人不会自己去操作注册表
if (xStart.GetValue("Path") == null)
{
Register(1);
xStart.SetValue("Path", xpath);
}
else
{ //如果更换程序位置
String path = xStart.GetValue("Path").ToString();
if (!(path.Equals(xpath)))
{
//如果已存在启动项，更新注册表
if(run.GetValue("XStart") != null)
Register(1);
xStart.SetValue("Path", xpath); //更新XStart 注册表
}
}
//判断是否开机启动
if (run != null && run.GetValue("XStart") != null)
{
String R = run.GetValue("XStart").ToString();
if (R.Equals(Process.GetCurrentProcess().MainModule.FileName))
//ischecked = true;
//这里是判断是否开机启动 可以用于“设置”里面的“开机启动”属性是否打钩，或者其余用途
}
break;
}
hklm.Close();
hksoft.Close();
if (run != null) run.Close();
if (xStart != null) xStart.Close();
}
```