/// <summary>
/// Initialise the tile renderer from input, output, and tile sizes
/// </summary>
/// <param name="input">Surface containing the input data (the image to be transformed)</param>
/// <param name="output">Surface containing the output image</param>
/// <param name="tileSize">Width and height of a tile</param>
/// <param name="margin">Outer margin of tiles in percent [0..1]</param>
public TiledRenderer(ISurface <ColorBgra> input, ISurface <ColorBgra> output, int tileSize, float margin)
{
var s = new RangedValue <float>(margin, 0.0f, 1.0f).Value;
TileSize = tileSize;
Margin = (int)(tileSize * s);
Input = input;
Output = output;
}
/// <summary>
/// Return the recommended tile size based on the available RAM
/// </summary>
/// <param name="size">Size of the input in pixels</param>
/// <param name="margin">Tile margin in percent [0, 1.0]</param>
/// <returns>Maximum tile size that can be processed safely</returns>
public static Size GetRecommendedTileSize(Size size, float margin)
{
// the .NET heap *will* allocate much more than 33% of the available RAM
// though the algorithm performs better with less (i.e. bigger) tiles in
// terms of output quality, this will come at the expense of much longer
// calculation time
const int THRESHOLD_PERCENT = 33;
var threshold = (AvailableMemory * THRESHOLD_PERCENT) / 100;
var required = GetEstimatedRequiredMemory(size);
if (required > threshold)
{
var factor = new RangedValue <float>(margin, 0.0f, 1.0f).Value;
var pixels = GetMaximumPixelCount(threshold);
var tileSize = (int)Math.Floor(Math.Sqrt(pixels));
var n = (int)(tileSize / (1.0f + factor));
if (TiledRenderer.GetTiles(size, n).Count > 1)
{
return(new Size(n, n));
}
}
return(size);
}
