在Windows窗体应用程序中绘制形状

Question

I am trying to draw a shape with 4 corners. The corner details are given in X and Y co-ordinate (as shown in the Picture below). I tried a method as given by this link: Drawing Colors in a picturebox? . But the issue is it only for rectangles.

Could any one propose something. I need it basically to generate a swept path (area taken by a car while driving) of the car. So, I get center of the Car in X and Y and the Orientation in degrees. From that I determine the Corner Points of the car in X and Y space. Now I need to show it Visualize it. Please help.

Answer 1

You can use the Graphics.DrawPolygon (or Graphics.FillPolygon ) method in the OnDraw method of your Form/Control, as follows:

protected override void OnPaint(PaintEventArgs e)
{
   // If there is an image and it has a location, 
   // paint it when the Form is repainted.
   base.OnPaint(e);
   PointF[] rotatedVertices = // Your rotated rectangle vertices
   e.Graphics.DrawPolygon(yourPen, rotatedVertices);
   // OR
   e.Graphics.FillPolygon(new SolidBrush(Color.Red), rotatedVertices);
}

Answer 2

Since you know the rotation degree, you can use Graphics.RotateTransform for that. This way you don't need to calculate the corners yourself (guess this implementation is faster).

protected override void OnPaint(PaintEventArgs e)
{
    base.OnPaint(e);
    e.Graphics.RotateTransform(45 /* your degrees here */);
    e.Graphics.FillRectangle(Brushes.Red, 10, 10, 200, 100);
}

Note that it rotates around (0;0) , so you may need to translate it (using Graphics.TranslateTransform ), too.

Answer 3

You can use the Rectangle class along with the Matrix class to create a rectangle and then rotate it by your orientation like so:

Graphics g = new Graphics()
Rectangle car = new Rectangle(200, 200, 100, 50)
Matrix m = new Matrix()
m.RotateAt(orientation, new PointF(car.Left + (car.Width / 2), car.Top + (car.Height / 2)));
g.Transform = m
g.FillRectangle(Pens.Red, car)