I have followed this tutorial in order to create a rounded panel. The code in the tutorial is in vb but I was able to convert it to C# so here is my code:
public class SPanel : Panel
{
Pen pen;
float penWidth = 2.0f;
int _edge = 20;
Color _borderColor = Color.White;
public int Edge
{
get
{
return _edge;
}
set
{
_edge = value;
Invalidate();
}
}
public Color BorderColor
{
get
{
return _borderColor;
}
set
{
_borderColor = value;
pen = new Pen(_borderColor, penWidth);
Invalidate();
}
}
public SPanel()
{
pen = new Pen(_borderColor, penWidth);
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
ExtendedDraw(e);
//DrawBorder(e.Graphics);
}
private void ExtendedDraw(PaintEventArgs e)
{
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
GraphicsPath path = new GraphicsPath();
path.StartFigure();
path.StartFigure();
path.AddArc(GetLeftUpper(Edge), 180, 90);
path.AddLine(Edge, 0, Width - Edge, 0);
path.AddArc(GetRightUpper(Edge), 270, 90);
path.AddLine(Width, Edge, Width, Height - Edge);
path.AddArc(GetRightLower(Edge), 0, 90);
path.AddLine(Width - Edge, Height, Edge, Height);
path.AddArc(GetLeftLower(Edge), 90, 90);
path.AddLine(0, Height - Edge, 0, Edge);
path.CloseFigure();
Region = new Region(path);
}
Rectangle GetLeftUpper(int e)
{
return new Rectangle(0, 0, e, e);
}
Rectangle GetRightUpper(int e)
{
return new Rectangle(Width - e, 0, e, e);
}
Rectangle GetRightLower(int e)
{
return new Rectangle(Width - e, Height - e, e, e);
}
Rectangle GetLeftLower(int e)
{
return new Rectangle(0, Height - e, e, e);
}
void DrawSingleBorder(Graphics graphics)
{
graphics.DrawArc(pen, new Rectangle(0, 0, Edge, Edge), 180, 90);
graphics.DrawArc(pen, new Rectangle(Width - Edge -1, -1, Edge, Edge), 270, 90);
graphics.DrawArc(pen, new Rectangle(Width - Edge - 1, Height - Edge - 1, Edge, Edge), 0, 90);
graphics.DrawArc(pen, new Rectangle(0, Height - Edge - 1, Edge, Edge), 90, 90);
graphics.DrawRectangle(pen, 0.0F, 0.0F, Width - 1, Height - 1);
}
void DrawBorder(Graphics graphics)
{
DrawSingleBorder(graphics);
}
}
I did not use the border however the result is the same. Here is a ss:
I thought smoothing with anti alias would do the trick but I guess i was wrong. The question is how can I smooth the edges?
I was able to solve this by following this link. I just downloaded the sample project and created a new panel. Copied what he had on Form's onpaint to new panel's onpaint and now I have smooth edges.
public class SPanel : Panel
{
protected override void OnPaint(PaintEventArgs e)
{
Graphics g = e.Graphics;
g.SmoothingMode = SmoothingMode.AntiAlias;
g.FillRoundedRectangle(new SolidBrush(Color.White), 10, 10, this.Width - 40, this.Height - 60, 10);
SolidBrush brush = new SolidBrush(
Color.White
);
g.FillRoundedRectangle(brush, 12, 12, this.Width - 44, this.Height - 64, 10);
g.DrawRoundedRectangle(new Pen(ControlPaint.Light(Color.White, 0.00f)), 12, 12, this.Width - 44, this.Height - 64, 10);
g.FillRoundedRectangle(new SolidBrush(Color.White), 12, 12 + ((this.Height - 64) / 2), this.Width - 44, (this.Height - 64)/2, 10);
}
}
Here is his GraphicsExtension class if link ever get broken.
static class GraphicsExtension
{
private static GraphicsPath GenerateRoundedRectangle(
this Graphics graphics,
RectangleF rectangle,
float radius)
{
float diameter;
GraphicsPath path = new GraphicsPath();
if (radius <= 0.0F)
{
path.AddRectangle(rectangle);
path.CloseFigure();
return path;
}
else
{
if (radius >= (Math.Min(rectangle.Width, rectangle.Height)) / 2.0)
return graphics.GenerateCapsule(rectangle);
diameter = radius * 2.0F;
SizeF sizeF = new SizeF(diameter, diameter);
RectangleF arc = new RectangleF(rectangle.Location, sizeF);
path.AddArc(arc, 180, 90);
arc.X = rectangle.Right - diameter;
path.AddArc(arc, 270, 90);
arc.Y = rectangle.Bottom - diameter;
path.AddArc(arc, 0, 90);
arc.X = rectangle.Left;
path.AddArc(arc, 90, 90);
path.CloseFigure();
}
return path;
}
private static GraphicsPath GenerateCapsule(
this Graphics graphics,
RectangleF baseRect)
{
float diameter;
RectangleF arc;
GraphicsPath path = new GraphicsPath();
try
{
if (baseRect.Width > baseRect.Height)
{
diameter = baseRect.Height;
SizeF sizeF = new SizeF(diameter, diameter);
arc = new RectangleF(baseRect.Location, sizeF);
path.AddArc(arc, 90, 180);
arc.X = baseRect.Right - diameter;
path.AddArc(arc, 270, 180);
}
else if (baseRect.Width < baseRect.Height)
{
diameter = baseRect.Width;
SizeF sizeF = new SizeF(diameter, diameter);
arc = new RectangleF(baseRect.Location, sizeF);
path.AddArc(arc, 180, 180);
arc.Y = baseRect.Bottom - diameter;
path.AddArc(arc, 0, 180);
}
else path.AddEllipse(baseRect);
}
catch { path.AddEllipse(baseRect); }
finally { path.CloseFigure(); }
return path;
}
/// <summary>
/// Draws a rounded rectangle specified by a pair of coordinates, a width, a height and the radius
/// for the arcs that make the rounded edges.
/// </summary>
/// <param name="brush">System.Drawing.Pen that determines the color, width and style of the rectangle.</param>
/// <param name="x">The x-coordinate of the upper-left corner of the rectangle to draw.</param>
/// <param name="y">The y-coordinate of the upper-left corner of the rectangle to draw.</param>
/// <param name="width">Width of the rectangle to draw.</param>
/// <param name="height">Height of the rectangle to draw.</param>
/// <param name="radius">The radius of the arc used for the rounded edges.</param>
public static void DrawRoundedRectangle(
this Graphics graphics,
Pen pen,
float x,
float y,
float width,
float height,
float radius)
{
RectangleF rectangle = new RectangleF(x, y, width, height);
GraphicsPath path = graphics.GenerateRoundedRectangle(rectangle, radius);
SmoothingMode old = graphics.SmoothingMode;
graphics.SmoothingMode = SmoothingMode.AntiAlias;
graphics.DrawPath(pen, path);
graphics.SmoothingMode = old;
}
/// <summary>
/// Draws a rounded rectangle specified by a pair of coordinates, a width, a height and the radius
/// for the arcs that make the rounded edges.
/// </summary>
/// <param name="brush">System.Drawing.Pen that determines the color, width and style of the rectangle.</param>
/// <param name="x">The x-coordinate of the upper-left corner of the rectangle to draw.</param>
/// <param name="y">The y-coordinate of the upper-left corner of the rectangle to draw.</param>
/// <param name="width">Width of the rectangle to draw.</param>
/// <param name="height">Height of the rectangle to draw.</param>
/// <param name="radius">The radius of the arc used for the rounded edges.</param>
public static void DrawRoundedRectangle(
this Graphics graphics,
Pen pen,
int x,
int y,
int width,
int height,
int radius)
{
graphics.DrawRoundedRectangle(
pen,
Convert.ToSingle(x),
Convert.ToSingle(y),
Convert.ToSingle(width),
Convert.ToSingle(height),
Convert.ToSingle(radius));
}
/// <summary>
/// Fills the interior of a rounded rectangle specified by a pair of coordinates, a width, a height
/// and the radius for the arcs that make the rounded edges.
/// </summary>
/// <param name="brush">System.Drawing.Brush that determines the characteristics of the fill.</param>
/// <param name="x">The x-coordinate of the upper-left corner of the rectangle to fill.</param>
/// <param name="y">The y-coordinate of the upper-left corner of the rectangle to fill.</param>
/// <param name="width">Width of the rectangle to fill.</param>
/// <param name="height">Height of the rectangle to fill.</param>
/// <param name="radius">The radius of the arc used for the rounded edges.</param>
public static void FillRoundedRectangle(
this Graphics graphics,
Brush brush,
float x,
float y,
float width,
float height,
float radius)
{
RectangleF rectangle = new RectangleF(x, y, width, height);
GraphicsPath path = graphics.GenerateRoundedRectangle(rectangle, radius);
SmoothingMode old = graphics.SmoothingMode;
graphics.SmoothingMode = SmoothingMode.AntiAlias;
graphics.FillPath(brush, path);
graphics.SmoothingMode = old;
}
/// <summary>
/// Fills the interior of a rounded rectangle specified by a pair of coordinates, a width, a height
/// and the radius for the arcs that make the rounded edges.
/// </summary>
/// <param name="brush">System.Drawing.Brush that determines the characteristics of the fill.</param>
/// <param name="x">The x-coordinate of the upper-left corner of the rectangle to fill.</param>
/// <param name="y">The y-coordinate of the upper-left corner of the rectangle to fill.</param>
/// <param name="width">Width of the rectangle to fill.</param>
/// <param name="height">Height of the rectangle to fill.</param>
/// <param name="radius">The radius of the arc used for the rounded edges.</param>
public static void FillRoundedRectangle(
this Graphics graphics,
Brush brush,
int x,
int y,
int width,
int height,
int radius)
{
graphics.FillRoundedRectangle(
brush,
Convert.ToSingle(x),
Convert.ToSingle(y),
Convert.ToSingle(width),
Convert.ToSingle(height),
Convert.ToSingle(radius));
}
}
In your code:
private void ExtendedDraw(PaintEventArgs e)
{
e.Graphics.InterpolationMode = InterpolationMode.HighQualityBilinear;
e.Graphics.CompositingQuality = CompositingQuality.HighQuality;
e.Graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
LinearGradientBrush brush = new LinearGradientBrush(ClientRectangle, Color.White, Color.White, 90); //here you need your target rectangle
GraphicsPath path = new GraphicsPath();
path.StartFigure();
path.StartFigure();
path.AddArc(GetLeftUpper(Edge), 180, 90);
path.AddLine(Edge, 0, Width - Edge, 0);
path.AddArc(GetRightUpper(Edge), 270, 90);
path.AddLine(Width, Edge, Width, Height - Edge);
path.AddArc(GetRightLower(Edge), 0, 90);
path.AddLine(Width - Edge, Height, Edge, Height);
path.AddArc(GetLeftLower(Edge), 90, 90);
path.AddLine(0, Height - Edge, 0, Edge);
path.CloseFigure();
e.Graphics.FillPath(brush, path);
}
来源：https://stackoverflow.com/questions/38632035/winforms-smooth-the-rounded-edges-for-panel