using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Diagnostics; namespace Mapper { /// <summary> /// This type of canvas places rectangles as far to the left as possible (lowest X). /// If there is a choice between locations with the same X, it will pick the one with the /// lowest Y. /// </summary> public class Canvas : ICanvas { public struct CanvasCell { public bool occupied; public CanvasCell(bool occupied) { this.occupied = occupied; } public override string ToString() { return occupied ? "x" : "."; } } private DynamicTwoDimensionalArray<CanvasCell> _canvasCells = new DynamicTwoDimensionalArray<CanvasCell>(); // Make _canvasCells available to canvas classes derived from this class. protected DynamicTwoDimensionalArray<CanvasCell> CanvasCells { get { return _canvasCells; } } private int _nbrRectangleAddAttempts = 0; public int NbrRectangleAddAttempts { get { return _nbrRectangleAddAttempts; } } private int _canvasWidth = 0; private int _canvasHeight = 0; // Lowest free height deficit found since the last call to SetCanvasDimension private int _lowestFreeHeightDeficitSinceLastRedim = Int32.MaxValue; private int _nbrCellsGenerated = 0; public Canvas() { } /// <summary> /// See ICanvas /// </summary> public int UnlimitedSize { get { return short.MaxValue; } } /// <summary> /// See ICanvas /// </summary> public virtual void SetCanvasDimensions(int canvasWidth, int canvasHeight) { // Right now, it is unknown how many rectangles need to be placed. // So guess that a 100 by 100 capacity will be enough. const int initialCapacityX = 100; const int initialCapacityY = 100; // Initially, there is one free cell, which covers the entire canvas. _canvasCells.Initialize(initialCapacityX, initialCapacityY, canvasWidth, canvasHeight, new CanvasCell(false)); _nbrCellsGenerated = 0; _nbrRectangleAddAttempts = 0; _lowestFreeHeightDeficitSinceLastRedim = Int32.MaxValue; _canvasWidth = canvasWidth; _canvasHeight = canvasHeight; } /// <summary> /// See ICanvas. /// </summary> public virtual bool AddRectangle( int rectangleWidth, int rectangleHeight, out int rectangleXOffset, out int rectangleYOffset, out int lowestFreeHeightDeficit) { rectangleXOffset = 0; rectangleYOffset = 0; lowestFreeHeightDeficit = Int32.MaxValue; int requiredWidth = rectangleWidth; int requiredHeight = rectangleHeight; _nbrRectangleAddAttempts++; int x = 0; int y = 0; int offsetX = 0; int offsetY = 0; bool rectangleWasPlaced = false; int nbrRows = _canvasCells.NbrRows; do { int nbrRequiredCellsHorizontally; int nbrRequiredCellsVertically; int leftOverWidth; int leftOverHeight; // First move upwards until we find an unoccupied cell. // If we're already at an unoccupied cell, no need to do anything. // Important to clear all occupied cells to get // the lowest free height deficit. This must be taken from the top of the highest // occupied cell. while ((y < nbrRows) && (_canvasCells.Item(x, y).occupied)) { offsetY += _canvasCells.RowHeight(y); y += 1; } // If we found an unoccupied cell, than see if we can place a rectangle there. // If not, than y popped out of the top of the canvas. if ((y < nbrRows) && (FreeHeightDeficit(_canvasHeight, offsetY, requiredHeight) <= 0)) { if (IsAvailable( x, y, requiredWidth, requiredHeight, out nbrRequiredCellsHorizontally, out nbrRequiredCellsVertically, out leftOverWidth, out leftOverHeight)) { PlaceRectangle( x, y, requiredWidth, requiredHeight, nbrRequiredCellsHorizontally, nbrRequiredCellsVertically, leftOverWidth, leftOverHeight); rectangleXOffset = offsetX; rectangleYOffset = offsetY; rectangleWasPlaced = true; break; } // Go to the next cell offsetY += _canvasCells.RowHeight(y); y += 1; } // If we've come so close to the top of the canvas that there is no space for the // rectangle, go to the next column. This automatically also checks whether we've popped out of the top // of the canvas (in that case, _canvasHeight == offsetY). int freeHeightDeficit = FreeHeightDeficit(_canvasHeight, offsetY, requiredHeight); if (freeHeightDeficit > 0) { offsetY = 0; y = 0; offsetX += _canvasCells.ColumnWidth(x); x += 1; // This update is far from perfect, because if the rectangle could not be placed at this column // because of insufficient horizontal space, than this update should not be made (because it may lower // _lowestFreeHeightDeficitSinceLastRedim while in raising the height of the canvas by this lowered amount // may not result in the rectangle being placed here after all. // // However, checking for sufficient horizontal width takes a lot of CPU ticks. Tests have shown that this // far outstrips the gains through having fewer failed sprite generations. if (_lowestFreeHeightDeficitSinceLastRedim > freeHeightDeficit) { _lowestFreeHeightDeficitSinceLastRedim = freeHeightDeficit; } } // If we've come so close to the right edge of the canvas that there is no space for // the rectangle, return false now. if ((_canvasWidth - offsetX) < requiredWidth) { rectangleWasPlaced = false; break; } } while (true); lowestFreeHeightDeficit = _lowestFreeHeightDeficitSinceLastRedim; return rectangleWasPlaced; } /// <summary> /// Works out the free height deficit when placing a rectangle with a required height at a given offset. /// /// If the free height deficit is 0 or negative, there may be room to place the rectangle (still need to check for blocking /// occupied cells). /// /// If the free height deficit is greater than 0, you're too close to the top edge of the canvas to place the rectangle. /// </summary> /// <param name="canvasHeight"></param> /// <param name="offsetY"></param> /// <param name="requiredHeight"></param> /// <returns></returns> private int FreeHeightDeficit(int canvasHeight, int offsetY, int requiredHeight) { int spaceLeftVertically = canvasHeight - offsetY; int freeHeightDeficit = requiredHeight - spaceLeftVertically; return freeHeightDeficit; } /// <summary> /// Sets the cell at x,y to occupied, and also its top and right neighbours, as needed /// to place a rectangle with the given width and height. /// /// If the rectangle takes only part of a row or column, they are split. /// </summary> /// <param name="x"></param> /// <param name="y"></param> /// <param name="requiredWidth"></param> /// <param name="requiredHeight"></param> /// <param name="nbrRequiredCellsHorizontally"> /// Number of cells that the rectangle requires horizontally /// </param> /// <param name="nbrRequiredCellsVertically"> /// Number of cells that the rectangle requires vertically /// </param> /// <param name="leftOverWidth"> /// The amount of horizontal space left in the right most cells that could be used for the rectangle /// </param> /// <param name="leftOverHeight"> /// The amount of vertical space left in the bottom most cells that could be used for the rectangle /// </param> private void PlaceRectangle( int x, int y, int requiredWidth, int requiredHeight, int nbrRequiredCellsHorizontally, int nbrRequiredCellsVertically, int leftOverWidth, int leftOverHeight) { // Split the far most row and column if needed. if (leftOverWidth > 0) { _nbrCellsGenerated += _canvasCells.NbrRows; int xFarRightColumn = x + nbrRequiredCellsHorizontally - 1; _canvasCells.InsertColumn(xFarRightColumn, leftOverWidth); } if (leftOverHeight > 0) { _nbrCellsGenerated += _canvasCells.NbrColumns; int yFarBottomColumn = y + nbrRequiredCellsVertically - 1; _canvasCells.InsertRow(yFarBottomColumn, leftOverHeight); } for (int i = x + nbrRequiredCellsHorizontally - 1; i >= x; i--) { for (int j = y + nbrRequiredCellsVertically - 1; j >= y; j--) { _canvasCells.SetItem(i, j, new CanvasCell(true)); } } } /// <summary> /// Returns true if a rectangle with the given width and height can be placed /// in the cell with the given x and y, and its right and top neighbours. /// /// This method assumes that x,y is far away enough from the edges of the canvas /// that the rectangle could actually fit. So this method only looks at whether cells /// are occupied or not. /// </summary> /// <param name="x"></param> /// <param name="y"></param> /// <param name="requiredWidth"></param> /// <param name="requiredHeight"></param> /// <param name="nbrRequiredCellsHorizontally"> /// Number of cells that the rectangle requires horizontally /// </param> /// <param name="nbrRequiredCellsVertically"> /// Number of cells that the rectangle requires vertically /// </param> /// <param name="leftOverWidth"> /// The amount of horizontal space left in the right most cells that could be used for the rectangle /// </param> /// <param name="leftOverHeight"> /// The amount of vertical space left in the bottom most cells that could be used for the rectangle /// </param> /// <returns></returns> private bool IsAvailable( int x, int y, int requiredWidth, int requiredHeight, out int nbrRequiredCellsHorizontally, out int nbrRequiredCellsVertically, out int leftOverWidth, out int leftOverHeight) { nbrRequiredCellsHorizontally = 0; nbrRequiredCellsVertically = 0; leftOverWidth = 0; leftOverHeight = 0; int foundWidth = 0; int foundHeight = 0; int trialX = x; int trialY = y; // Check all cells that need to be unoccupied for there to be room for the rectangle. while (foundHeight < requiredHeight) { trialX = x; foundWidth = 0; while (foundWidth < requiredWidth) { if (_canvasCells.Item(trialX, trialY).occupied) { return false; } foundWidth += _canvasCells.ColumnWidth(trialX); trialX++; } foundHeight += _canvasCells.RowHeight(trialY); trialY++; } // Visited all cells that we'll need to place the rectangle, // and none were occupied. So the space is available here. nbrRequiredCellsHorizontally = trialX - x; nbrRequiredCellsVertically = trialY - y; leftOverWidth = (foundWidth - requiredWidth); leftOverHeight = (foundHeight - requiredHeight); return true; } /// <summary> /// See ICanvas /// </summary> /// <param name="canvasStats"></param> public void GetStatistics(ICanvasStats canvasStats) { canvasStats.NbrCellsGenerated = _nbrCellsGenerated; canvasStats.RectangleAddAttempts = _nbrRectangleAddAttempts; canvasStats.LowestFreeHeightDeficit = _lowestFreeHeightDeficitSinceLastRedim; } } }
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