Bitmap/Midpoint circle algorithm: Difference between revisions

== {{header|C#}} ==

This extension method extends GenericImage which is very similar to [http://rosettacode.org/wiki/Bitmap#C.23 Bitmap] but instead of using a SetPixel method it uses a "Color this[int x, int y] { get; set; }" property to get and set pixels.

<lang csharp>

/// <summary>

/// Draws a circle.

/// </summary>

/// <param name="image">

/// The destination image.

/// </param>

/// <param name="centerX">

/// The x center position of the circle.

/// </param>

/// <param name="centerY">

/// The y center position of the circle.

/// </param>

/// <param name="radius">

/// The radius of the circle.

/// </param>

/// <param name="color">

/// The color to use.

/// </param>

public static void DrawCircle(this GenericImage image, int centerX, int centerY, int radius, Color color)

{

int d = (5 - radius * 4) / 4;

int x = 0;

int y = radius;

do

{

// ensure index is in range before setting (depends on your image implementation)

// in this case we check if the pixel location is within the bounds of the image before setting the pixel

if (centerX + x >= 0 && centerX + x <= image.Width - 1 && centerY + y >= 0 && centerY + y <= image.Height - 1) image[centerX + x, centerY + y] = color;

if (centerX + x >= 0 && centerX + x <= image.Width - 1 && centerY - y >= 0 && centerY - y <= image.Height - 1) image[centerX + x, centerY - y] = color;

if (centerX - x >= 0 && centerX - x <= image.Width - 1 && centerY + y >= 0 && centerY + y <= image.Height - 1) image[centerX - x, centerY + y] = color;

if (centerX - x >= 0 && centerX - x <= image.Width - 1 && centerY - y >= 0 && centerY - y <= image.Height - 1) image[centerX - x, centerY - y] = color;

if (centerX + y >= 0 && centerX + y <= image.Width - 1 && centerY + x >= 0 && centerY + x <= image.Height - 1) image[centerX + y, centerY + x] = color;

if (centerX + y >= 0 && centerX + y <= image.Width - 1 && centerY - x >= 0 && centerY - x <= image.Height - 1) image[centerX + y, centerY - x] = color;

if (centerX - y >= 0 && centerX - y <= image.Width - 1 && centerY + x >= 0 && centerY + x <= image.Height - 1) image[centerX - y, centerY + x] = color;

if (centerX - y >= 0 && centerX - y <= image.Width - 1 && centerY - x >= 0 && centerY - x <= image.Height - 1) image[centerX - y, centerY - x] = color;

if (d < 0)

{

d += 2 * x + 1;

}

else

{

d += 2 * (x - y) + 1;

y--;

}

x++;

} while (x <= y);

}

</lang>