private void ColorizeHeatMap(Bitmap mask, HeatMapStyle style)
{
// Create new bitmap to act as a work surface for the colorization process
Bitmap coloredImage = new Bitmap(mask.Width, mask.Height, mask.PixelFormat);
// Create a graphics object from our memory bitmap so we can draw on it and clear it's drawing surface
using (var gr = Graphics.FromImage(coloredImage))
{
gr.Clear(Color.Transparent);
// Create new image attributes class to handle the color remappings
// Inject our color map array to instruct the image attributes class how to do the colorization
ImageAttributes remapper = new ImageAttributes();
remapper.SetRemapTable(style.ColorMapCollection);
// Draw our mask onto our memory bitmap work surface using the new color mapping scheme
gr.DrawImage(mask, new Rectangle(0, 0, mask.Width, mask.Height), 0, 0, mask.Width, mask.Height, GraphicsUnit.Pixel, remapper);
}
using (var gr = Graphics.FromImage(mask))
{
gr.Clear(Color.Transparent);
gr.DrawImage(coloredImage, new PointF(0, 0));
}
}
public Task <System.IO.MemoryStream> RenderData(List <PointF> data, HeatMapStyle style, int radiusPx, int width, int height)
{
if (renderTask != null && renderTask.Status == TaskStatus.Running)
{
cancel = true;
renderTask.Wait();
cancel = false;
}
renderTask = Task.Run <System.IO.MemoryStream>(() =>
{
try
{
if (style.ColorMapCollection != null)
{
Bitmap bmp = new Bitmap(width, height);
using (Graphics g = Graphics.FromImage(bmp))
{
g.Clear(Color.Transparent);
g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighSpeed;
g.Clip = new Region(new Rectangle(0, 0, width, height));
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighSpeed;
if (data != null)
{
var s = DateTime.Now;
var rect = new RectangleF(-radiusPx, -radiusPx, width + radiusPx, height + radiusPx);
CreateHeatMask(data, style, radiusPx, rect, g);
ColorizeHeatMap(bmp, style);
if (cancel)
{
g.Clear(Color.Transparent);
}
var e = DateTime.Now;
Console.WriteLine("Render Heat Map - {0}ms", (e - s).TotalMilliseconds);
}
}
var ms = new System.IO.MemoryStream();
bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
return(ms);
}
}
catch (Exception ex)
{
var t = "";
}
return(null);
});
return(renderTask);
}
private void CreateHeatMask(List <PointF> data, HeatMapStyle style, int radiusPx, RectangleF rect, Graphics g)
{
//Calculate angle between radiis
float circleResolution = 360 / _numberOfRadiis;
float[] radianXRadiis = new float[_numberOfRadiis];
float[] radianYRadiis = new float[_numberOfRadiis];
for (int i = 0; i < _numberOfRadiis; i++)
{
radianXRadiis[i] = (float)(radiusPx * Math.Cos((i * circleResolution) * Math.PI / 180));
radianYRadiis[i] = (float)(radiusPx * Math.Sin((i * circleResolution) * Math.PI / 180));
}
// Create an empty array that will be populated with points from the generic list
var circumferencePointsArray = new System.Drawing.PointF[_numberOfRadiis];
// Store scaled and flipped intensity value for use with gradient center location
//0.9 is to make it feather out at the edges all the time.
float fIntensity = (float)Math.Min((1 - style.Intensity / Byte.MaxValue) * 1F, 0.9);
// Create new color blend to tell the PathGradientBrush what colors to use and where to put them
var gradientSpecifications = new ColorBlend(3);
// Define positions of gradient colors, use intesity to adjust the middle color to
// show more mask or less mask
gradientSpecifications.Positions = new float[3] {
0, fIntensity, 1
};
// Define gradient colors and their alpha values, adjust alpha of gradient colors to match intensity
gradientSpecifications.Colors = new Color[3]
{
Color.FromArgb(0, Color.White),
Color.FromArgb((byte)(style.Intensity * 255), Color.Black),
Color.FromArgb((byte)(style.Intensity * 255), Color.Black)
};
foreach (var p in data)
{
if (cancel)
{
break;
}
if (rect.Contains(p))
{
// Loop through all angles of a circle
// Define loop variable as a double to prevent casting in each iteration
// Iterate through loop on 15 degree deltas, this can be changed to improve performance
for (int i = 0; i < _numberOfRadiis; i++)
{
// Plot new point on the circumference of a circle of the defined radius
// Using the point coordinates, radius, and angle
// Calculate the position of this iterations point on the circle
// Add newly plotted circumference point to generic point list
circumferencePointsArray[i] = new System.Drawing.PointF(p.X + radianXRadiis[i], p.Y + radianYRadiis[i]);
}
// Create new PathGradientBrush to create a radial gradient using the circumference points
var gradientShaper = new PathGradientBrush(circumferencePointsArray);
// Pass off color blend to PathGradientBrush to instruct it how to generate the gradient
gradientShaper.InterpolationColors = gradientSpecifications;
// Draw polygon (circle) using our point array and gradient brush
g.FillPolygon(gradientShaper, circumferencePointsArray);
}
}
}
