private static PassableDirections GetPassableDirections(MaskedMaze maze, Cell cell)
{
var position = maze.GetPositionOfCell(cell);
var neighborPositions = cell.CellWalls
.Where(x => x.IsPassable)
.Select(x => maze.GetPositionOfCell(x.GetOtherCell(cell)))
.ToArray();
var northPassable = neighborPositions.Any(x => x.row == position.row - 1);
var southPassable = neighborPositions.Any(x => x.row == position.row + 1);
var eastPassable = neighborPositions.Any(x => x.column == position.column + 1);
var westPassable = neighborPositions.Any(x => x.column == position.column - 1);
return(new PassableDirections(northPassable, southPassable, eastPassable, westPassable));
}
public static SKImage RenderWithSkia(this MaskedMaze maze,
RenderOptions renderOptions,
DistanceInfo distanceInfo,
ShortestPathInfo shortestPathInfo)
{
if (maze == null)
{
throw new ArgumentNullException(nameof(maze));
}
renderOptions = renderOptions ?? new RenderOptions();
var imageWidth = (CellSize * maze.ColumnCount) + (Margin * 2);
var imageHeight = (CellSize * maze.RowCount) + (Margin * 2);
var imageInfo = new SKImageInfo(imageWidth, imageHeight, SKColorType.Rgba8888, SKAlphaType.Premul);
using (var surface = SKSurface.Create(imageInfo))
{
surface.Canvas.Clear(SKColors.Black);
var whitePaint = new SKPaint {
Color = SKColors.White, StrokeWidth = CellLineWidth
};
var startPaint = new SKPaint {
Color = SKColors.Green, StrokeWidth = CellLineWidth
};
var finishPaint = new SKPaint {
Color = SKColors.Red, StrokeWidth = CellLineWidth
};
var pathPaint = new SKPaint {
Color = SKColors.Yellow, StrokeWidth = CellLineWidth
};
foreach (var cell in maze.AllCells)
{
var(row, column) = maze.GetPositionOfCell(cell);
var leftX = (column * CellSize) + Margin;
var rightX = leftX + CellSize;
var topY = (row * CellSize) + Margin;
var bottomY = topY + CellSize;
var isNorthFacingExit = (maze.FinishingCell == cell || maze.StartingCell == cell) && row == 0 && column > 1;
var isSouthFacingExit = (maze.FinishingCell == cell || maze.StartingCell == cell) && row == maze.RowCount - 1 && column > 1;
var isEastFacingExit = (maze.FinishingCell == cell || maze.StartingCell == cell) && column == maze.ColumnCount - 1;
var isWestFacingExit = (maze.FinishingCell == cell || maze.StartingCell == cell) && column == 0;
var passableDirections = GetPassableDirections(maze, cell);
if (!passableDirections.North && !isNorthFacingExit)
{
surface.Canvas.DrawLine(leftX, topY, rightX, topY, whitePaint);
}
if (!passableDirections.South && !isSouthFacingExit)
{
surface.Canvas.DrawLine(leftX, bottomY, rightX, bottomY, whitePaint);
}
if (!passableDirections.East && !isEastFacingExit)
{
surface.Canvas.DrawLine(rightX, topY, rightX, bottomY, whitePaint);
}
if (!passableDirections.West && !isWestFacingExit)
{
surface.Canvas.DrawLine(leftX, topY, leftX, bottomY, whitePaint);
}
if (renderOptions.ShowGradientOfDistanceFromStart)
{
const int shadingMargin = 2;
var finishingCellDistance = distanceInfo.DistanceFromStartMap[distanceInfo.FarthestCell];
var currentCellDistance = distanceInfo.DistanceFromStartMap[cell];
var intensity = (byte)(255 * (currentCellDistance / (decimal)finishingCellDistance));
var color = new SKColor(0, 0, intensity);
var paint = new SKPaint {
Color = color
};
var shadeWidth = rightX - leftX - (shadingMargin * 2);
var shadeHeight = bottomY - topY - (shadingMargin * 2);
surface.Canvas.DrawRect(leftX + shadingMargin, topY + shadingMargin, shadeWidth, shadeHeight, paint);
}
if (renderOptions.HighlightShortestPath && shortestPathInfo.IsCellInPath(cell))
{
var paint = cell == maze.StartingCell ? startPaint
: cell == maze.FinishingCell ? finishPaint
: pathPaint;
var distance = distanceInfo.DistanceFromStartMap[cell];
surface.Canvas.DrawText(distance.ToString(), leftX + LabelMarginX, topY + LabelMarginY, paint);
}
else if (renderOptions.ShowAllDistances && distanceInfo.DistanceFromStartMap.ContainsKey(cell))
{
var distance = distanceInfo.DistanceFromStartMap[cell];
surface.Canvas.DrawText(distance.ToString(), leftX + LabelMarginX, topY + LabelMarginY, whitePaint);
}
else if (cell == maze.StartingCell)
{
surface.Canvas.DrawText("S", leftX + LabelMarginX, topY + LabelMarginY, startPaint);
}
else if (cell == maze.FinishingCell)
{
surface.Canvas.DrawText("E", leftX + LabelMarginX, topY + LabelMarginY, finishPaint);
}
}
return(surface.Snapshot());
}
}
