/// <summary>
/// Returns image from visible tiles with scale factor > 1
/// </summary>
/// <param name="tiles"></param>
/// <param name="leftTopPointOfView"></param>
/// <param name="screenSize"></param>
/// <returns></returns>
private IEnumerable<TileRawWrapper> ScaleUp(Tile[] tiles, Point leftTopPointOfView, Size screenSize)
{
int scaledScreenX = (int)Math.Ceiling(screenSize.Width / Scaler.ScaleFactor);
int scaledScreenY = (int)Math.Ceiling(screenSize.Height / Scaler.ScaleFactor);
var visibleTiles = tiles.Where(x => x.CheckVisibility(leftTopPointOfView,
scaledScreenX, scaledScreenY)).ToArray();
BlockingCollection<TileRawWrapper> tileImgWrappers = new BlockingCollection<TileRawWrapper>();
Size cropS = new Size();
Tile leftTopTile = default(Tile);
foreach(var tile in visibleTiles)
{
//stores relative offset by X for visible part from the beginning of the current tile
int shiftTileX = (int)(leftTopPointOfView.X - tile.LeftTopCoord.X);
shiftTileX = shiftTileX < 0 ? 0 : shiftTileX;
//stores relative offset by Y for visible part from the beginning of the current tile
int shiftTileY = (int)(leftTopPointOfView.Y - tile.LeftTopCoord.Y);
shiftTileY = shiftTileY < 0 ? 0 : shiftTileY;
//if not all scaled tile is visible we only take the visible part.
int croppedWidth = tile.Size.Width - shiftTileX >= scaledScreenX ? scaledScreenX : tile.Size.Width - shiftTileX;
int croppedHeight = tile.Size.Height - shiftTileY >= scaledScreenY ? scaledScreenY : tile.Size.Height - shiftTileY;
var resizedW = (int)(croppedWidth * Scaler.ScaleFactor);
var resizedH = (int)(croppedHeight * Scaler.ScaleFactor);
var padding = (resizedW % 4);
resizedW = resizedW + (padding == 0 ? 0 : 4 - padding);//bmp stride should be multiple of 4
//determines resized canvas size
Size resizedCanvasSize = new Size((int)(croppedWidth * Scaler.ScaleFactor), (int)(croppedHeight * Scaler.ScaleFactor));
//take lefttop visible tile to measure offset for other tiles
if (tile.Equals(visibleTiles.First()))
{
leftTopTile = tile;
cropS = resizedCanvasSize;
}
//see pointToDraw description
int x = tile.LeftTopCoord.X <= leftTopPointOfView.X ? 0 : cropS.Width +
((tile.LeftTopCoord.X - leftTopTile.LeftTopCoord.X) / tile.Size.Width - 1) * tile.Size.Width * (int)Scaler.ScaleFactor;
int y = tile.LeftTopCoord.Y <= leftTopPointOfView.Y ? 0 : cropS.Height +
((tile.LeftTopCoord.Y - leftTopTile.LeftTopCoord.Y) / tile.Size.Height - 1) * tile.Size.Height * (int)Scaler.ScaleFactor;
byte[] imgData = tile.ReadData();
byte[] cropped = DrawingHelper.Crop(imgData, tile.Size.Width, shiftTileX, shiftTileY, croppedWidth, croppedHeight);
byte[] resized = DrawingHelper.Resize(cropped, croppedWidth, resizedW, resizedH, Scaler.ScaleFactor);
tileImgWrappers.Add(new TileRawWrapper(resized, x, y,
resizedCanvasSize.Width, resizedCanvasSize.Height));
}
return tileImgWrappers;
}
/// <summary>
/// Returns image from visible tiles with 1:1 scale
/// </summary>
/// <param name="tiles"></param>
/// <param name="leftTopPointOfView"></param>
/// <param name="screenSize"></param>
/// <returns></returns>
private IEnumerable<TileRawWrapper> ScaleNormal(Tile[] tiles, Point leftTopPointOfView, Size screenSize)
{
var visibleTiles = tiles.Where(x => x.CheckVisibility(leftTopPointOfView,
screenSize.Width, screenSize.Height));
var tileImgWrappers = new List<TileRawWrapper>();
foreach(var tile in visibleTiles)
{
var tileBytes = tile.ReadData();
int xToScreen = tile.LeftTopCoord.X - leftTopPointOfView.X;
int yToScreen = tile.LeftTopCoord.Y - leftTopPointOfView.Y;
tileImgWrappers.Add(new TileRawWrapper(tileBytes, xToScreen, yToScreen, tile.Size.Width, tile.Size.Height));
}
return tileImgWrappers;
}
/// <summary>
/// Returns image from visible tiles with scale factor < 1
/// </summary>
/// <param name="tiles"></param>
/// <param name="leftTopPointOfView"></param>
/// <param name="screenSize"></param>
/// <param name="highRes">Determines if algorithm uses averaging to get downscaled image (true if it uses)</param>
/// <returns></returns>
private IEnumerable<TileRawWrapper> ScaleDown(Tile[] tiles, Point leftTopPointOfView, Size screenSize, bool highRes)
{
int scaledScreenX = (int)Math.Ceiling(screenSize.Width / Scaler.ScaleFactor);
int scaledScreenY = (int)Math.Ceiling(screenSize.Height / Scaler.ScaleFactor);
var visibleTiles = tiles.Where(x => x.CheckVisibility(leftTopPointOfView,
scaledScreenX, scaledScreenY));
int scale = (int)(1 / Scaler.ScaleFactor);
int scalePower = (int)Math.Log(scale, 2);
BlockingCollection<TileRawWrapper> tileImgWrappers = new BlockingCollection<TileRawWrapper>();
//var tileImgWrappers = new List<TileImageWrapper>(visibleTiles.Count());
Parallel.ForEach(visibleTiles, tile =>
{
byte[] imgData = tile.ReadData();
byte[] sievedImage = new byte[imgData.Length >> scalePower >> scalePower];
//scale by averaging nearby pixels
int index = 0;
for (int i = 0; i < tile.Size.Height * tile.Size.Width - tile.Size.Width; i += scale * tile.Size.Width)
{
for (int j = i; j < i + tile.Size.Width; j += scale)
{
if (highRes)
{
int cumulative = 0;
for (int k = j; k < j + scale; k++)
{
cumulative += imgData[k];
}
sievedImage[index] = (byte)(cumulative >> scalePower);
}
else
{
sievedImage[index] = imgData[j];
}
index++;
}
}
var tw = new TileRawWrapper(sievedImage,
(int)((tile.LeftTopCoord.X - leftTopPointOfView.X) >> scalePower),
(int)((tile.LeftTopCoord.Y - leftTopPointOfView.Y) >> scalePower),
tile.Size.Width >> scalePower, tile.Size.Height >> scalePower);
tileImgWrappers.Add(tw);
});
return tileImgWrappers;
}