How to convert a RectangleF to PointF[] for drawing?

Question

I'm not sure if the question is too trivial but, I need to use the following overload of the method Graphics.DrawImage:

public void DrawImage(
    Image image,
    PointF[] destPoints,
    RectangleF srcRect,
    GraphicsUnit srcUnit,
    ImageAttributes imageAttr
)

I have a RectangleF as destination rectangle, so I need to convert the RectangleF to PointF[] but the example in the MSDN confused me a little bit because it only uses three points to define a parallelogram.

How could I do it?

Thanks in advance

The reason they use three points is the `DrawImage` method calculates the fourth point based on the other three points to ensure a valid paralellagram. — Hand-E-Food, Feb 22 '12 at 21:52

score 3 · Accepted Answer · answered Feb 23 '12 at 13:30

Ok, I found it in the MSDN:

The destPoints parameter specifies three points of a parallelogram. The three PointF structures represent the upper-left, upper-right, and lower-left corners of the parallelogram. The fourth point is extrapolated from the first three to form a parallelogram.

So you can construct your point array in the following way:

    private PointF[] GetPoints(RectangleF rectangle)
    {
        return new PointF[3]
        { 
            new PointF(rectangle.Left, rectangle.Top),
            new PointF(rectangle.Right, rectangle.Top),
            new PointF(rectangle.Left, rectangle.Bottom)
        };
    }

score 2 · Answer 2 · answered Feb 22 '12 at 20:19

2

Couldn't you create it by just constructing the array?

(From memory) Where d is the destination RectangleF:

destPoints[] = new PointF[4] { new PointF(d.Left, d.Top), new PointF(d.Right, d.Top), new PointF(d.Right, d.Bottom), new PointF(d.Left, d.Bottom) };

answered Feb 22 '12 at 20:19

Ann L.

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Wow, didn't even notice the Top, Bottom, Left, Right properties. That should do the trick. – Dave Feb 22 '12 at 20:21
3

If you need to do it often, I'd write a `ToPoints` extension method for RectangleF to easily reuse it. – Avner Shahar-Kashtan Feb 22 '12 at 20:32

How to convert a RectangleF to PointF[] for drawing?

2 Answers2