// TODO: Make this obey blending rules properly
public unsafe void DrawPieChart(uint* pxls, int width, int height,
PieChartSection[] sections, uint color)
{
if (0 == sections.Length)
{
throw new ArgumentException("Pie chart sections array cannot be empty");
}
// We need at least a 5x5 image
if (width < 5 || height < 5)
{
return;
}
// If the image is not square, we want non-zero starting points
int ystart = 0;
int yend = height - 1; // Inclusive upper bound
if (height > width)
{
ystart = (height - width) / 2;
yend = height - ystart;
}
float xcenter = (float)width / 2.0f;
float ycenter = (float)height / 2.0f;
double radius = Math.Min(xcenter, ycenter) - 2.0;
// Make a circle object for the pie chart area
Circle2D circle = new Circle2D(xcenter, ycenter, (float)radius);
// Compute the sum of all values in the pie sections
double sum = 0.0;
foreach (PieChartSection pcs in sections)
{
sum += pcs.Value;
}
// Make an angle table. This table stores the ending angle of each category. Also
// make a color table.
double[] angles = new double[sections.Length];
uint[] clrLookup = new uint[sections.Length];
int i = 0;
double angle = 0.0;
foreach (PieChartSection pcs in sections)
{
clrLookup[i] = pcs.Color;
angles[i] = pcs.Value / sum * (Math.PI * 2.0) + angle;
angle = pcs.Value / sum * (Math.PI * 2.0) + angle;
i++;
}
while (ystart <= yend)
{
// Compute the intersections of the scan line with the pie chart
float minx, maxx;
circle.HLineIntersection((float)ystart, out minx, out maxx);
// Clear the row if there isn't an intersection
if (float.IsNaN(minx) || float.IsNaN(maxx))
{
DrawHorizontalLine(0, width - 1, ystart, 0, pxls, width, height, BlendMode.None);
ystart++;
continue;
}
int xstart = (int)Math.Floor(minx);
int xend = (int)Math.Min(Math.Ceiling(maxx), (float)(width - 1));
uint* row = &pxls[ystart * width + xstart];
for (int x = xstart; x <= xend; x++)
{
// For each pixel, we want to start by computing the distance from the center
Vector2D pos = new Vector2D((float)x - xcenter, ycenter - (float)ystart);
double dist = pos.Length;
// Set the pixel to 0 if we're outside of the pie chart area
if (dist >= radius)
{
*row++ = 0;
continue;
}
// Compute the angle so we know what category of the pie we're in
angle = pos.GetCCWAngle();
i = 0;
while (angle > angles[i])
{
i++;
}
// Advance to the next pixel
*row++ = clrLookup[i];
}
ystart++;
}
// Draw lines between sections
if (sections.Length > 1)
{
List<Stadium> stadiums = new List<Stadium>();
foreach (double tempAngle in angles)
{
stadiums.Add(new Stadium(circle.Center,
new Vector2D(xcenter + (float)(radius * Math.Cos(tempAngle)),
ycenter - (float)(radius * Math.Sin(tempAngle))), 1.75f));
}
FillStadiums(new SimpleImage(width, height, pxls), color, stadiums.ToArray(), 2f);
}
// Draw a circular border around the pie chart
FrameCircle_Composite(circle, 3.5f, color, pxls, width, height);
}
