C# 4 and .NET 4

Measuring Coordinates and areas ❘ OC11
}
Console.WriteLine("bottomRight = " + bottomRight);
Console.WriteLine("Size = " + rectangleSize);
code download PointsAndSizes.sln
This code, running as a simple console application called PointsAndSizes, produces the output shown in
Figure 48-4.
figure 48-4
Note that this output also shows how the ToString() method has been overridden in both Point and Size
to display the value in {X,Y} format.
It is also possible to subtract a Size from a Point struct to produce a Point struct, and you can add two
Size structs together, producing another Size. It is not possible, however, to add a Point struct to another
Point. Microsoft decided that adding Point structs does not conceptually make sense, and so it chose not
to supply any overload to the + operator that would have allowed that.
You can also explicitly cast a Point to a Size struct and vice versa:
Point topLeft = new Point(10,10);
Size s1 = (Size)topLeft;
Point p1 = (Point)s1;
With this cast, s1.Width is assigned the value topLeft.X, and s1.Height is assigned the value topLeft.Y.
Hence, s1 contains (10,10). p1 will end up storing the same values as topLeft.
Fectangle and rectanglef
These structures represent a rectangular region (usually of the screen). Just as with Point and Size, only
the Rectangle struct is considered here. RectangleF is basically identical except that the properties that
represent dimensions all use float, whereas those of Rectangle use int.
A Rectangle struct can be thought of as composed of a point, representing the top-left corner of the
rectangle, and a Size struct, representing how large it is. One of its constructors actually takes a Point
struct and a Size struct as its parameters. You can see this by rewriting the earlier code from the
DrawShapes sample that draws a rectangle:
Graphics dc = e.Graphics;
Pen bluePen = new Pen(Color.Blue, 3);
Point topLeft = new Point(0,0);
Size howBig = new Size(50,50);
Rectangle rectangleArea = new Rectangle(topLeft, howBig);
dc.DrawRectangle(bluePen, rectangleArea);
This code also uses an alternative override of Graphics.DrawRectangle(), which takes a Pen and a
Rectangle struct as its parameters.
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