如何在Windows Forms中使用VB.NET/C#在运行时创建一个圆角矩形？

Question

我很想在运行时创建一个填充的圆角矩形，并将其指定为Windows窗体中PictureBox（已创建和隐藏）的内容。

你知道我该如何实现它吗？

Answer 1

此方法填充上的图形对象（VB代码）圆角矩形：

Public Sub FillRoundedRectangle(ByVal g As Drawing.Graphics, ByVal r As Rectangle, ByVal d As Integer, ByVal b As Brush) 
    Dim mode As Drawing2D.SmoothingMode = g.SmoothingMode 
    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed 
    g.FillPie(b, r.X, r.Y, d, d, 180, 90) 
    g.FillPie(b, r.X + r.Width - d, r.Y, d, d, 270, 90) 
    g.FillPie(b, r.X, r.Y + r.Height - d, d, d, 90, 90) 
    g.FillPie(b, r.X + r.Width - d, r.Y + r.Height - d, d, d, 0, 90) 
    g.FillRectangle(b, CInt(r.X + d/2), r.Y, r.Width - d, CInt(d/2)) 
    g.FillRectangle(b, r.X, CInt(r.Y + d/2), r.Width, CInt(r.Height - d)) 
    g.FillRectangle(b, CInt(r.X + d/2), CInt(r.Y + r.Height - d/2), CInt(r.Width - d), CInt(d/2)) 
    g.SmoothingMode = mode 
End Sub 

为了调用此函数，处理的PictureBox的绘制事件并通过e.Graphics对象作为第一个参数，如果你想让矩形完全填充你的图片框，那么图片框的界限就是第二个参数。

d参数改变边角的角度，我把它的值为30，你可以尝试不同的价值观......

而且，这里的一些代码来绘制（而不是填充）圆角矩形：

Public Sub DrawRoundedRectangle(ByVal g As Drawing.Graphics, ByVal r As Rectangle, ByVal d As Integer, ByVal p As Pen) 
    g.DrawArc(p, r.X, r.Y, d, d, 180, 90) 
    g.DrawLine(p, CInt(r.X + d/2), r.Y, CInt(r.X + r.Width - d/2), r.Y) 
    g.DrawArc(p, r.X + r.Width - d, r.Y, d, d, 270, 90) 
    g.DrawLine(p, r.X, CInt(r.Y + d/2), r.X, CInt(r.Y + r.Height - d/2)) 
    g.DrawLine(p, CInt(r.X + r.Width), CInt(r.Y + d/2), CInt(r.X + r.Width), CInt(r.Y + r.Height - d/2)) 
    g.DrawLine(p, CInt(r.X + d/2), CInt(r.Y + r.Height), CInt(r.X + r.Width - d/2), CInt(r.Y + r.Height)) 
    g.DrawArc(p, r.X, r.Y + r.Height - d, d, d, 90, 90) 
    g.DrawArc(p, r.X + r.Width - d, r.Y + r.Height - d, d, d, 0, 90) 
End Sub 

Answer 2

最简单的方法是使用Graphics对象即时创建一个Bitmap。 DrawEllipse方法应该足够了。

然后将该位图分配为PictureBox对象的内容。

Answer 3

标记为答案的填充解决方案的问题在于，它不适用于非固体/均匀刷子。这是基于GraphicsPath类至极我认为另外一个更可重复使用：

public static void FillRoundedRectangle(Graphics graphics, Rectangle rectangle, Brush brush, int radius) 
{ 
    if (graphics == null) 
     throw new ArgumentNullException("graphics"); 

    SmoothingMode mode = graphics.SmoothingMode; 
    graphics.SmoothingMode = SmoothingMode.AntiAlias; 

    using (GraphicsPath path = RoundedRectangle(rectangle, radius)) 
    { 
     graphics.FillPath(brush, path); 
    } 
    graphics.SmoothingMode = mode; 
} 

public static GraphicsPath RoundedRectangle(Rectangle r, int radius) 
{ 
    GraphicsPath path = new GraphicsPath(); 
    int d = radius * 2; 

    path.AddLine(r.Left + d, r.Top, r.Right - d, r.Top); 
    path.AddArc(Rectangle.FromLTRB(r.Right - d, r.Top, r.Right, r.Top + d), -90, 90); 
    path.AddLine(r.Right, r.Top + d, r.Right, r.Bottom - d); 
    path.AddArc(Rectangle.FromLTRB(r.Right - d, r.Bottom - d, r.Right, r.Bottom), 0, 90); 
    path.AddLine(r.Right - d, r.Bottom, r.Left + d, r.Bottom); 
    path.AddArc(Rectangle.FromLTRB(r.Left, r.Bottom - d, r.Left + d, r.Bottom), 90, 90); 
    path.AddLine(r.Left, r.Bottom - d, r.Left, r.Top + d); 
    path.AddArc(Rectangle.FromLTRB(r.Left, r.Top, r.Left + d, r.Top + d), 180, 90); 
    path.CloseFigure(); 
    return path; 
} 

，这里是为借鉴，只有（不填）的代码，基于同样的想法：

public static void DrawRoundedRectangle(Graphics graphics, Rectangle rectangle, Pen pen, int radius) 
{ 
    if (graphics == null) 
     throw new ArgumentNullException("graphics"); 

    SmoothingMode mode = graphics.SmoothingMode; 
    graphics.SmoothingMode = SmoothingMode.AntiAlias; 

    using (GraphicsPath path = RoundedRectangle(rectangle, radius)) 
    { 
     graphics.DrawPath(pen, path); 
    } 
    graphics.SmoothingMode = mode; 
}