ESRI.ArcGIS.Client.Toolkit.DataSources.PngEncoder.SetPixelAtRowStart C# (CSharp) Method

        public void SetPixelAtRowStart(int col, int rowStart, byte red, byte green, byte blue, byte alpha)
        {
            int start = rowStart + (col << 2);

            _buffer[start] = red;
            _buffer[start + 1] = green;
            _buffer[start + 2] = blue;
            _buffer[start + 3] = alpha;
        }

        /// <summary>
        /// Handles the DoWork event of the renderThread control. This is where we
        /// render the heatmap outside the UI thread.
        /// </summary>
        /// <param name="sender">The source of the event.</param>
        /// <param name="e">The <see cref="System.ComponentModel.DoWorkEventArgs"/> instance
        /// containing the event data.</param>
        private void renderThread_DoWork(object sender, DoWorkEventArgs e)
        {
            BackgroundWorker worker = (BackgroundWorker)sender;

            object[] args   = (object[])e.Argument;
            Envelope extent = (Envelope)args[0];
            int      width  = (int)args[1];
            int      height = (int)args[2];
            int      size   = (int)args[3];
            List <ThreadSafeGradientStop> stops = (List <ThreadSafeGradientStop>)args[4];
            List <HeatPoint> points             = (List <HeatPoint>)args[5];
            OnImageComplete  onComplete         = (OnImageComplete)args[6];

            size = size * 2 + 1;
            ushort[] matrix = CreateDistanceMatrix(size);
            int[]    output = new int[width * height];
            foreach (HeatPoint p in points)
            {
                AddPoint(matrix, size, p.X, p.Y, output, width);
                if (worker.CancellationPending)
                {
                    e.Cancel = true;
                    e.Result = null;
                    return;
                }
            }
            matrix = null;
            int max = 0;

            foreach (int val in output)             //find max - used for scaling the intensity
            {
                if (max < val)
                {
                    max = val;
                }
            }

            //If we only have single points in the view, don't show them with too much intensity.
            if (max < 2)
            {
                max = 2;
            }
#if SILVERLIGHT
            PngEncoder ei = new PngEncoder(width, height);
#else
            int[] pixels = new int[height * width];
#endif
            for (int idx = 0; idx < height; idx++)                  // Height (y)
            {
#if SILVERLIGHT
                int rowstart = ei.GetRowStart(idx);
#endif
                for (int jdx = 0; jdx < width; jdx++)                     // Width (x)
                {
                    Color c = InterpolateColor(output[idx * width + jdx] / (float)max, stops);
#if SILVERLIGHT
                    ei.SetPixelAtRowStart(jdx, rowstart, c.R, c.G, c.B, c.A);
#else
                    int color = (c.A << 24) + (c.R << 16) + (c.G << 8) + c.B;
                    pixels[idx * width + jdx] = color;
#endif
                }
                if (worker.CancellationPending)
                {
                    e.Cancel = true;
                    e.Result = null;
                    output   = null;
#if SILVERLIGHT
                    ei = null;
#else
                    pixels = null;
#endif
                    return;
                }
                //Raise the progress event for each line rendered
                worker.ReportProgress((idx + 1) * 100 / height);
            }
            stops.Clear();
            output = null;

            // Get stream and set image source
#if SILVERLIGHT
            e.Result = new object[] { ei, width, height, extent, onComplete };
#else
            e.Result = new object[] { pixels, width, height, extent, onComplete };
#endif
        }