public static Stream GenerateMosaicFromTiles(
Stream sourceImage,
string tileBucket, string tileDirectory,
int tilePixels,
ILogger logger)
{
using (var tileProvider = new QuadrantMatchingTileProvider()) {
// override default tile width and height if specified
if (tilePixels != 0)
{
MosaicBuilder.TileWidth = MosaicBuilder.TileHeight = tilePixels;
}
MosaicBuilder.DitheringRadius = -1;
MosaicBuilder.ScaleMultiplier = 1;
List <byte[]> tileImages = GetTileImages(tileBucket, tileDirectory, logger);
tileProvider.SetSourceStream(sourceImage);
tileProvider.ProcessInputImageColors(MosaicBuilder.TileWidth, MosaicBuilder.TileHeight);
tileProvider.ProcessTileColors(tileImages);
logger.LogInformation("Generating mosaic...");
var start = DateTime.Now;
return(GenerateMosaic(tileProvider, sourceImage, tileImages));
}
}
private static Stream GenerateMosaic(
QuadrantMatchingTileProvider tileProvider, Stream inputStream,
List <byte[]> tileImages)
{
SKBitmap[,] mosaicTileGrid;
inputStream.Seek(0, SeekOrigin.Begin);
using (var skStream = new SKManagedStream(inputStream))
using (var bitmap = SKBitmap.Decode(skStream)) {
// use transparency for the source image overlay
var srcImagePaint = new SKPaint()
{
Color = SKColors.White.WithAlpha(200)
};
int xTileCount = bitmap.Width / MosaicBuilder.TileWidth;
int yTileCount = bitmap.Height / MosaicBuilder.TileHeight;
int tileCount = xTileCount * yTileCount;
mosaicTileGrid = new SKBitmap[xTileCount, yTileCount];
int finalTileWidth = MosaicBuilder.TileWidth * MosaicBuilder.ScaleMultiplier;
int finalTileHeight = MosaicBuilder.TileHeight * MosaicBuilder.ScaleMultiplier;
int targetWidth = xTileCount * finalTileWidth;
int targetHeight = yTileCount * finalTileHeight;
var tileList = new List <(int, int)>();
// add coordinates for the left corner of each tile
for (int x = 0; x < xTileCount; x++)
{
for (int y = 0; y < yTileCount; y++)
{
tileList.Add((x, y));
}
}
// create output surface
var surface = SKSurface.Create(targetWidth, targetHeight, SKImageInfo.PlatformColorType, SKAlphaType.Premul);
surface.Canvas.DrawColor(SKColors.White); // clear the canvas / fill with white
surface.Canvas.DrawBitmap(bitmap, 0, 0, srcImagePaint);
// using the Darken blend mode causes colors from the source image to come through
var tilePaint = new SKPaint()
{
BlendMode = SKBlendMode.Darken
};
surface.Canvas.SaveLayer(tilePaint); // save layer so blend mode is applied
var random = new Random();
while (tileList.Count > 0)
{
// choose a new tile at random
int nextIndex = random.Next(tileList.Count);
var tileInfo = tileList[nextIndex];
tileList.RemoveAt(nextIndex);
// get the tile image for this point
var tileBitmap = tileProvider.GetImageForTile(tileInfo.Item1, tileInfo.Item2);
mosaicTileGrid[tileInfo.Item1, tileInfo.Item2] = tileBitmap;
// draw the tile on the surface at the coordinates
SKRect tileRect = SKRect.Create(tileInfo.Item1 * TileWidth, tileInfo.Item2 * TileHeight, finalTileWidth, finalTileHeight);
surface.Canvas.DrawBitmap(tileBitmap, tileRect);
}
surface.Canvas.Restore(); // merge layers
surface.Canvas.Flush();
var imageBytes = surface.Snapshot().Encode(SKEncodedImageFormat.Jpeg, 80);
return(new MemoryStream(imageBytes.ToArray()));
}
}
