How to draw a circular progressbar pie using GraphicsPath in WinForm?

问题

I want my custom circular progress bar in WinForm. But the result doesnt fit to what I think. How can I draw the shape as the same in this picture?. I uploaded two image to be clear in my problem.

My code to do this:

void Form1_Paint(object sender, PaintEventArgs e)
    {
        int angle = 120;

        e.Graphics.SmoothingMode = SmoothingMode.HighQuality;

        Rectangle outerRect = new Rectangle(50, 50, 100, 100);
        Rectangle innerRect = new Rectangle(70, 70, 60, 60);

        int innerRadius = innerRect.Width / 2;
        int outerRadius = outerRect.Width / 2;

        Point innerCenter = new Point(innerRect.X + innerRadius, innerRect.Y + innerRadius);
        Point outerCenter = new Point(outerRect.X + outerRadius, outerRect.Y + outerRadius);

        GraphicsPath outerCircle = new GraphicsPath();
        outerCircle.AddEllipse(outerRect);

        GraphicsPath innerCircle = new GraphicsPath();
        innerCircle.AddEllipse(innerRect);

        GraphicsPath progPath = new GraphicsPath();

        Point p1 = new Point(outerRect.X + outerRadius, outerRect.Y);
        Point p2 = new Point(innerRect.X + innerRadius, innerRect.Y);


        Point inner = new Point((int)(innerRadius * Math.Cos(angle * Math.PI / 180) + innerCenter.X),
                                (int)(innerRadius * Math.Sin(angle * Math.PI / 180) + innerCenter.Y));
        Point outer = new Point((int)(outerRadius * Math.Cos(angle * Math.PI / 180) + outerCenter.X),
                                (int)(outerRadius * Math.Sin(angle * Math.PI / 180) + outerCenter.Y));

        progPath.AddLine(p1, p2);
        progPath.AddArc(innerRect, -90, angle);
        progPath.AddLine(inner, outer);
        progPath.AddArc(outerRect, angle - 90,-angle);

        progPath.Widen(Pens.Black);
        e.Graphics.DrawPath(Pens.Black, progPath);

    }

回答1:

You can create a GraphicsPath, then add 2 arcs to the path using AddArc method:

Outer arc from start angle 270 and sweep angle 120 degree.
Inner arc in opposite direction, from start angle 270 + 120 and sweep angle -120 degree
Then close the path using GraphicsPath.CloseFigure.

This way the you will have a thick arc as path.

You can fill the path, using Graphics.FillPath method. And also you can draw the borders using GraphicsPath.DrawPath method.

Result

Code

private void Form1_Paint(object sender, PaintEventArgs e)
{
    var g = e.Graphics;
    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

    var center = new Point(100, 100);
    var innerR = 30;
    var thickness = 20;
    var startAngle = 270;
    var arcLength = 120;
    var outerR = innerR + thickness;
    var outerRect = new Rectangle
                    (center.X - outerR, center.Y - outerR, 2 * outerR, 2 * outerR);
    var innerRect = new Rectangle
                    (center.X - innerR, center.Y - innerR, 2 * innerR, 2 * innerR);

    using (var p = new GraphicsPath())
    {
        p.AddArc(outerRect, startAngle, arcLength);
        p.AddArc(innerRect, startAngle + arcLength, -arcLength);
        p.CloseFigure();
        e.Graphics.FillPath(Brushes.Green, p);
        e.Graphics.DrawPath(Pens.Black, p);
    }
}

来源：https://stackoverflow.com/questions/36096759/how-to-draw-a-circular-progressbar-pie-using-graphicspath-in-winform

标签

winforms

custom-controls

gdi+