Question

我正在尝试为我的文本框创建自定义onPaint，它正在运行... it is working但是当我尝试输入内容时，a textbox is rendering above the textbox。

这是我的构造函数：

public TextBox()
{
  Font = new Font("Segoe UI", 11F, FontStyle.Regular, GraphicsUnit.Point, ((byte)(0)));
  BackColor = Color.White;
  BorderColor = Color.Gray;
  BorderStyle = BorderStyle.None;
  SetStyle(ControlStyles.UserPaint, true);
}

onPaint：

protected override void OnPaint(PaintEventArgs e)
{
  Graphics g = e.Graphics;
  g.FillRectangle(backgroundBrush, 0, 0, this.Width, this.Height);

  SizeF fontSize = g.MeasureString(Text, Font);
  g.DrawString(Text, Font, new SolidBrush(ForeColor), new PointF(5, 5), cFormat);

  g.DrawRectangle(borderPen, borderPen.Width / 2, borderPen.Width / 2,
                  this.Width - borderPen.Width, this.Height - borderPen.Width);
}

Answer 1

如果您只想要一个带有自定义边框（宽度和颜色）的自定义TextBox，我在这里有2个解决方案：

使用ControlPaint，这将允许您绘制一些样式和颜色的边框，但不能使用Brush进行更多的绘制（如HatchBrush可以做的）：

public class CustomTextBox : TextBox
{
    [DllImport("user32")]
    private static extern IntPtr GetWindowDC(IntPtr hwnd);
    struct RECT
    {
      public int left, top, right, bottom;
    }
    struct NCCALSIZE_PARAMS
    {
      public RECT newWindow;
      public RECT oldWindow;
      public RECT clientWindow;
      IntPtr windowPos;
    }            
    float clientPadding = 2;  
    float actualBorderWidth = 4;
    Color borderColor = Color.Red;      
    protected override void WndProc(ref Message m)
    {
      //We have to change the clientsize to make room for borders
      //if not, the border is limited in how thick it is.
      if (m.Msg == 0x83) //WM_NCCALCSIZE   
      {
        if (m.WParam == IntPtr.Zero)
        {
            RECT rect = (RECT)Marshal.PtrToStructure(m.LParam, typeof(RECT));
            rect.left += clientPadding;
            rect.right -= clientPadding;
            rect.top += clientPadding;
            rect.bottom -= clientPadding;
            Marshal.StructureToPtr(rect, m.LParam, false);
        }
        else
        {
            NCCALSIZE_PARAMS rects = (NCCALSIZE_PARAMS)Marshal.PtrToStructure(m.LParam, typeof(NCCALSIZE_PARAMS));
            rects.newWindow.left += clientPadding;
            rects.newWindow.right -= clientPadding;
            rects.newWindow.top += clientPadding;
            rects.newWindow.bottom -= clientPadding;
            Marshal.StructureToPtr(rects, m.LParam, false);
        }
      }
      if (m.Msg == 0x85) //WM_NCPAINT    
      {         
         IntPtr wDC = GetWindowDC(Handle);
         using(Graphics g = Graphics.FromHdc(wDC)){                                                      
           ControlPaint.DrawBorder(g, new Rectangle(0,0,Size.Width, Size.Height), borderColor, actualBorderWidth, ButtonBorderStyle.Solid,
         borderColor, actualBorderWidth, ButtonBorderStyle.Solid, borderColor, actualBorderWidth, ButtonBorderStyle.Solid,
         borderColor, actualBorderWidth, ButtonBorderStyle.Solid); 
         }   
         return;          
      }
      base.WndProc(ref m);
    }
}

这是文本框快照：

使用FillRegion的{{1}}方法绘制各种Graphics的边框，在这里我使用Brush：
```
HatchBrush
```
这是文本框快照：

文本框自定义onPaint

1 个答案: