圆角矩形不准确 [英] Rounded Rectangle Not Accurate

问题描述

我发现的使用 GDI+ 绘制圆角矩形的每个示例代码都是这样的(从 BobPowell.net 中提取并稍作修改):

Every sample code I've ever found for drawing rounded rectangles using GDI+ goes something like this (lifted and slightly modified from BobPowell.net):

  Private Sub Panel1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs) Handles Panel1.Paint
    e.Graphics.Clear(SystemColors.Window)
    e.Graphics.SmoothingMode = SmoothingMode.None

    Call DrawRoundRect(e.Graphics, Pens.Red, 10, 10, 48, 24, 6)
  End Sub

  Public Sub DrawRoundRect(ByVal g As Graphics, ByVal p As Pen, ByVal x As Single, ByVal y As Single, ByVal width As Single, ByVal height As Single, ByVal radius As Single)
    Using gp As New GraphicsPath()
      gp.StartFigure()
      gp.AddArc(x + width - radius, y, radius * 2, radius * 2, 270, 90)
      gp.AddArc(x + width - radius, y + height - radius, radius * 2, radius * 2, 0, 90)
      gp.AddArc(x, y + height - radius, radius * 2, radius * 2, 90, 90)
      gp.AddArc(x, y, radius * 2, radius * 2, 180, 90)
      gp.CloseFigure()
      g.DrawPath(p, gp)
    End Using
  End Sub

这会生成一个圆角矩形，其中只有左上角是准确的.

This produces a rounded rectangle where only the top left corner is accurate.

AntiAliasing 必须关闭，因为它正在通过远程桌面连接，我不能依赖它可用.此外，我正在寻找一个清晰的圆角矩形.

AntiAliasing has to be turned off because it is going through a remote desktop connection, and I can't depend on it being available. Besides, I am looking for a crisp rounded rectangle.

我尝试过调整其他角的大小并更改笔对齐方式，但似乎无法生成简单、准确的圆角矩形.

I've tried resizing the other corners and changing the pen alignments, but nothing seems to produce a simple, accurate rounded rectangle.

有没有办法在旧的 Winforms 中绘制比这更好的圆角矩形?

Is there a way to draw a better rounded rectangle than this in good old winforms?

推荐答案

我发现最好的解决方案是老式 Windows API:

I have found the best solution to be just old-school Windows API:

Private Sub DrawRoundRect(ByVal g As Graphics, ByVal r As Rectangle)
  Dim hDC As IntPtr = g.GetHdc
  Dim hPen As IntPtr = CreatePen(PS_SOLID, 0, ColorTranslator.ToWin32(Color.Red))
  Dim hOldPen As IntPtr = SelectObject(hDC, hPen)
  SelectObject(hDC, GetStockObject(NULL_BRUSH))
  RoundRect(hDC, r.Left, r.Top, r.Right - 1, r.Bottom - 1, 12, 12)
  SelectObject(hDC, hOldPen)
  DeleteObject(hPen)
  g.ReleaseHdc(hDC)
End Sub

这产生了我一直在寻找的对称圆角矩形:

This produces the symmetrical rounded rectangle I've been looking for:

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