async void LoadAndStartAnimation()
{
// Show total bitmap storage
TallyBitmapSizes();
// Create progressReporter for async operation
Progress <double> progressReporter =
new Progress <double>((double progress) => progressBar.Progress = progress);
// Create (unused) CancellationTokenSource for async operation
CancellationTokenSource cancelTokenSource = new CancellationTokenSource();
// Loop through all the zoom levels
for (int zoomLevel = 0; zoomLevel < COUNT; zoomLevel++)
{
// If the file exists, load it
if (File.Exists(FilePath(zoomLevel)))
{
statusLabel.Text = $"Loading bitmap for zoom level {zoomLevel}";
using (Stream stream = File.OpenRead(FilePath(zoomLevel)))
{
bitmaps[zoomLevel] = SKBitmap.Decode(stream);
}
}
// Otherwise, create a new bitmap
else
{
statusLabel.Text = $"Creating bitmap for zoom level {zoomLevel}";
CancellationToken cancelToken = cancelTokenSource.Token;
// Do the (generally lengthy) Mandelbrot calculation
BitmapInfo bitmapInfo =
await Mandelbrot.CalculateAsync(center,
4 / Math.Pow(2, zoomLevel),
4 / Math.Pow(2, zoomLevel),
BITMAP_SIZE, BITMAP_SIZE,
(int)Math.Pow(2, 10), progressReporter, cancelToken);
// Create bitmap & get pointer to the pixel bits
SKBitmap bitmap = new SKBitmap(BITMAP_SIZE, BITMAP_SIZE, SKColorType.Rgba8888, SKAlphaType.Opaque);
IntPtr basePtr = bitmap.GetPixels();
// Set pixel bits to color based on iteration count
for (int row = 0; row < bitmap.Width; row++)
{
for (int col = 0; col < bitmap.Height; col++)
{
int iterationCount = bitmapInfo.IterationCounts[row * bitmap.Width + col];
uint pixel = 0xFF000000; // black
if (iterationCount != -1)
{
double proportion = (iterationCount / 32.0) % 1;
byte red = 0, green = 0, blue = 0;
if (proportion < 0.5)
{
red = (byte)(255 * (1 - 2 * proportion));
blue = (byte)(255 * 2 * proportion);
}
else
{
proportion = 2 * (proportion - 0.5);
green = (byte)(255 * proportion);
blue = (byte)(255 * (1 - proportion));
}
pixel = MakePixel(0xFF, red, green, blue);
}
// Calculate pointer to pixel
IntPtr pixelPtr = basePtr + 4 * (row * bitmap.Width + col);
unsafe // requires compiling with unsafe flag
{
*(uint *)pixelPtr.ToPointer() = pixel;
}
}
}
// Save as PNG file
SKData data = SKImage.FromBitmap(bitmap).Encode();
try
{
File.WriteAllBytes(FilePath(zoomLevel), data.ToArray());
}
catch
{
// Probably out of space, but just ignore
}
// Store in array
bitmaps[zoomLevel] = bitmap;
// Show new bitmap sizes
TallyBitmapSizes();
}
// Display the bitmap
bitmapIndex = zoomLevel;
canvasView.InvalidateSurface();
}
// Now do the animation
stopwatch.Start();
int cycle = 6000 * COUNT; // total cycle length in milliseconds
while (true)
{
// Time in milliseconds from 0 to cycle
int time = (int)(stopwatch.ElapsedMilliseconds % cycle);
// Make it sinusoidal, including bitmap index and gradation between bitmaps
double progress = COUNT * 0.5 * (1 + Math.Sin(2 * Math.PI * time / cycle - Math.PI / 2));
// These are the field values that the PaintSurface handler uses
bitmapIndex = (int)progress;
bitmapProgress = progress - bitmapIndex;
// It doesn't often happen that we get up to COUNT, but an exception would be raised
if (bitmapIndex < COUNT)
{
// Show progress in UI
statusLabel.Text = $"Displaying bitmap for zoom level {bitmapIndex}";
progressBar.Progress = bitmapProgress;
// Update the canvas
canvasView.InvalidateSurface();
}
// Wait 16 milliseconds
await Task.Delay(16);
}
}
async void LoadAndStartAnimation()
{
// Show total bitmap storage
TallyBitmapSizes();
// Create progressReporter for async operation
Progress <double> progressReporter =
new Progress <double>((double progress) => progressBar.Progress = progress);
// Create (unused) CancellationTokenSource for async operation
CancellationTokenSource cancelTokenSource = new CancellationTokenSource();
// Loop through all the zoom levels
for (int zoomLevel = 0; zoomLevel < COUNT; zoomLevel++)
{
// If the file exists, load it
if (File.Exists(FilePath(zoomLevel)))
{
statusLabel.Text = $"Loading bitmap for zoom level {zoomLevel}";
using (Stream stream = File.OpenRead(FilePath(zoomLevel)))
{
bitmaps[zoomLevel] = SKBitmap.Decode(stream);
}
}
// Otherwise, create a new bitmap
else
{
statusLabel.Text = $"Creating bitmap for zoom level {zoomLevel}";
CancellationToken cancelToken = cancelTokenSource.Token;
// Do the (generally lengthy) Mandelbrot calculation
BitmapInfo bitmapInfo =
await Mandelbrot.CalculateAsync(center,
4 / Math.Pow(2, zoomLevel),
4 / Math.Pow(2, zoomLevel),
BITMAP_SIZE, BITMAP_SIZE,
(int)Math.Pow(2, 10), progressReporter, cancelToken);
// Create bitmap & get pointer to the pixel bits
SKBitmap bitmap = new SKBitmap(BITMAP_SIZE, BITMAP_SIZE, SKColorType.Rgba8888, SKAlphaType.Opaque);
IntPtr basePtr = bitmap.GetPixels();
// Set pixel bits to color based on iteration count
for (int row = 0; row < bitmap.Width; row++)
{
for (int col = 0; col < bitmap.Height; col++)
{
int iterationCount = bitmapInfo.IterationCounts[row * bitmap.Width + col];
uint pixel = 0xFF000000; // black
if (iterationCount != -1)
{
double proportion = (iterationCount / 32.0) % 1;
byte red = 0, green = 0, blue = 0;
if (proportion < 0.5)
{
red = (byte)(255 * (1 - 2 * proportion));
blue = (byte)(255 * 2 * proportion);
}
else
{
proportion = 2 * (proportion - 0.5);
green = (byte)(255 * proportion);
blue = (byte)(255 * (1 - proportion));
}
pixel = MakePixel(0xFF, red, green, blue);
}
// Calculate pointer to pixel
IntPtr pixelPtr = basePtr + 4 * (row * bitmap.Width + col);
unsafe // requires compiling with unsafe flag
{
*(uint *)pixelPtr.ToPointer() = pixel;
}
}
}
// Save as PNG file
SKData data = SKImage.FromBitmap(bitmap).Encode();
try
{
File.WriteAllBytes(FilePath(zoomLevel), data.ToArray());
}
catch
{
// Probably out of space, but just ignore
}
// Store in array
bitmaps[zoomLevel] = bitmap;
// Show new bitmap sizes
TallyBitmapSizes();
}
// Display the bitmap
bitmapIndex = zoomLevel;
canvasView.InvalidateSurface();
}
// Now start the animation
stopwatch.Start();
Device.StartTimer(TimeSpan.FromMilliseconds(16), OnTimerTick);
}