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C# 绘制窗体客户非客户区要用WM_PAINT和WM_NCPAINT

2024-07-09 00:31:35   219人阅读

窗体分为两部分：客户区(Client area)和非客户区(Non-Client area) 
WM_PAINT消息、OnPaint()方法、GetDC()API函数都是处理窗体客户区绘制的 
  
而标题栏处于非客户区中，所以WM_PAINT消息、OnPaint()方法、GetDC()API函数都用不上 
  
GetWindowDC()是获得整个窗体的画布句柄(Device Context翻译为：设备清单，我习惯称为画布句柄)，包括非客户区 
  
GDI的绘制都离不开DC，因为操作系统必须知道你要在什么地方绘制图形 
  
当其他窗体遮挡或者移开，系统都会重新绘制窗体。这时就会发出WM_PAINT和WM_NCPAINT消息通知窗体重绘界面。 
  
收到WM_NCPAINT消息(非客户区绘制消息)说明非客户区正需要重新绘制 
  
重载WndProc()方法(窗体消息处理过程)，处理WM_NCPAINT等消息即可.... 
  
“基本的步骤” 就是：截获WM_NCPAINT消息、得到窗体完整画布句柄、在完整画布上绘制图形。 
    WM_NCPAINT WM_NCCALCSIZE WM_NCACTIVATE WM_NCHITTEST
建议楼主搜索关键词：“C# WM_NCPAINT WndProc Graphics”得到更多的参考资料 
贴

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[DllImport   ( "User32.dll ")]   private   static   extern   IntPtr   GetWindowDC(IntPtr   hwnd);   [DllImport   ( "User32.dll ")]   private   static   extern   int   ReleaseDC(IntPtr   hwnd,   IntPtr   hdc);   [DllImport   ( "Kernel32.dll ")]   private   static   extern   int   GetLastError();   //标题栏按钮的矩形区域。   Rectangle   m_rect   =   new   Rectangle(205,   6,   20,   20);   protected   override   void   WndProc(ref   Message   m)   {   base.WndProc(ref   m);   switch(m.Msg)   {   case   0x86://WM_NCACTIVATE   goto   case   0x85;   case   0x85://WM_NCPAINT   {   IntPtr   hDC   =   GetWindowDC(m.HWnd);   //把DC转换为.NET的Graphics就可以很方便地使用Framework提供的绘图功能了   Graphics   gs   =   Graphics.FromHdc(hDC);   gs.FillRectangle(new   LinearGradientBrush(m_rect,   Color.Pink,   Color.Purple,   LinearGradientMode.BackwardDiagonal),   m_rect);   StringFormat   strFmt   =   new   StringFormat();   strFmt.Alignment   =   StringAlignment.Center;   strFmt.LineAlignment   =   StringAlignment.Center;   gs.DrawString( "√ ",   this.Font,   Brushes.BlanchedAlmond,   m_rect,   strFmt);   gs.Dispose();   //释放GDI资源   ReleaseDC(m.HWnd,   hDC);   break;   }   case   0xA1://WM_NCLBUTTONDOWN   {   Point   mousePoint   =   new   Point((int)m.LParam);   mousePoint.Offset(-this.Left,   -this.Top);   if(m_rect.Contains(mousePoint))   {   MessageBox.Show( "hello ");   }   break;   }   }   }   //在窗口大小改变时及时更新按钮的区域。   private   void   Form1_SizeChanged(object   sender,   System.EventArgs   e)   {   m_rect.X   =   this.Bounds.Width   -   95;   m_rect.Y   =   6;   m_rect.Width   =   m_rect.Height   =   20;   }   }   }

　　


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