private void SwapCacheAndClear()
{
ImageCache temp;
temp = _verticalCache;
_verticalCache = _backupVerticalCache;
_backupVerticalCache = temp;
temp.Clear();
temp = _horizontalCache;
_horizontalCache = _backupHorizontalCache;
_backupHorizontalCache = temp;
temp.Clear();
}
public async Task FillRegionAsync(int x, int y, Image <Rgb24> region, CancellationToken cancellationToken)
{
int layer = _ripper._layers.Length - 1;
int tileYIndex = y / _deepZoomTileSize;
int tileYOffset = tileYIndex * _deepZoomTileSize;
int tileYCount = (y - tileYOffset + region.Height + _deepZoomTileSize - 1) / _deepZoomTileSize;
tileYCount = Math.Min(tileYCount, _deepZoomTileRowCount - tileYIndex);
int tileXIndex = x / _deepZoomTileSize;
int tileXOffset = tileXIndex * _deepZoomTileSize;
int tileXCount = (x - tileXOffset + region.Width + _deepZoomTileSize - 1) / _deepZoomTileSize;
tileXCount = Math.Min(tileXCount, _deepZoomTileColCount - tileXIndex);
ImageCache nextVerticalCache = _backupVerticalCache;
ImageCache nextHorizontalCache = _backupHorizontalCache;
for (int i = 0; i < tileXCount; i++)
{
int tileCol = tileXIndex + i;
for (int j = 0; j < tileYCount; j++)
{
int tileRow = tileYIndex + j;
int tilePointX = tileXOffset + i * _deepZoomTileSize;
int tilePointY = tileYOffset + j * _deepZoomTileSize;
int drawPointX = tilePointX - x - _deepZoomTileOverlap;
int drawPointY = tilePointY - y - _deepZoomTileOverlap;
cancellationToken.ThrowIfCancellationRequested();
Image <Rgb24> tile = null;
bool cachedOnce = false;
try
{
// First column
if (i == 0)
{
if (_verticalCache.TryFind(tilePointX, tilePointY, out Image <Rgb24> cachedImage))
{
_verticalCache.RemoveEntry(tilePointX, tilePointY);
tile = cachedImage;
}
}
// First row
if (tile == null && j == 0)
{
if (_horizontalCache.TryFind(tilePointX, tilePointY, out Image <Rgb24> cachedImage))
{
_horizontalCache.RemoveEntry(tilePointX, tilePointY);
tile = cachedImage;
}
}
// Not found in the cache
if (tile == null)
{
tile = await _ripper.ReadTileImageAsync(layer, tileCol, tileRow, cancellationToken).ConfigureAwait(false);
}
// Draw on the canvas
region.Mutate(ctx =>
{
ctx.DrawImage(tile, new Point(drawPointX, drawPointY), GraphicsOptions.Default);
});
// Last column
if (tilePointX + _deepZoomTileSize > x + region.Width)
{
nextVerticalCache.SetEntry(tilePointX, tilePointY, tile);
cachedOnce = true;
}
// Lat row
if (tilePointY + _deepZoomTileSize > y + region.Height)
{
nextHorizontalCache.SetEntry(tilePointX, tilePointY, cachedOnce ? tile.Clone() : tile);
cachedOnce = true;
}
if (cachedOnce)
{
tile = null;
}
}
finally
{
tile?.Dispose();
}
}
}
SwapCacheAndClear();
}
