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POCalculating rowspan and colspan for html table (Algorithm)
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copied!<p>I have been working about 18 hours and I became a zombie.. And I can't figure out this problem without your help..</p> <p><em><strong>Project</em></strong></p> <p>I am working on a pdf to epub converter application what converts pdf files to epub format.</p> <p><em><strong>Problem</em></strong></p> <p>Because of EPub limitations, absolute positioning is not allowed on EPub xhtml. So, i decided to use table layout for all elements (text and images) on a page (html). </p> <p>But i can't imagine how i could calculate the rowspan and colspan values of cells..</p> <p><em><strong>What I Did</em></strong></p> <pre><code> class TableItem { public IRenderable Item; public Rectangle Bounds; public int RowSpan, ColSpan; public TableItem(Rectangle bounds, IRenderable item) { this.Bounds = bounds; this.Item = item; } } class Table { Rectangle bounds; List<TableItem> items; public Table(int width, int height) { bounds = new Rectangle(0, 0, width, height); items = new List<TableItem>(); } public void Add(IRenderable item) { Rectangle rect = Rectangle.Intersect(bounds, item.GetBounds()); if (rect.IsEmpty) return; items.Add(new TableItem(rect, item)); } List<TableItem> Slice(List<TableItem> list, int startIndex, int endIndex) { TableItem[] tmp = new TableItem[endIndex - startIndex]; list.CopyTo(startIndex, tmp, 0, tmp.Length); return new List<TableItem>(tmp); } List<TableItem>[] Analyze(out int maxCol) { maxCol = 0; if (items.Count < 1) return new List<TableItem>[0]; /* items.Sort ( delegate(TableItem x, TableItem y) { if (x.Bounds.Y == y.Bounds.Y) return x.Bounds.X - y.Bounds.X; return x.Bounds.Y - y.Bounds.Y; } ); */ List<Rectangle> freeAreas = new List<Rectangle>(); freeAreas.Add(bounds); foreach (TableItem item in items) { for (int i = 0; i < freeAreas.Count; i++) { Rectangle area; if ((area = freeAreas[i]).Contains(item.Bounds)) { freeAreas.RemoveAt(i); freeAreas.InsertRange(i, SplitRect(area, item.Bounds)); } } } foreach (Rectangle rt in freeAreas) items.Add(new TableItem(rt, null)); items.Sort ( delegate(TableItem x, TableItem y) { if (x.Bounds.Y == y.Bounds.Y) return x.Bounds.X - y.Bounds.X; return x.Bounds.Y - y.Bounds.Y; } ); List<List<TableItem>> xlist = new List<List<TableItem>>(); int lasty = items[0].Bounds.Y; int startIndex = 0; for(int i=0;i<items.Count;i++) if (lasty < items[i].Bounds.Y) { lasty = items[i].Bounds.Y; List<TableItem> xl = Slice(items, startIndex, i); xlist.Add(xl); startIndex = i; if (maxCol < xl.Count) maxCol = xl.Count; } if (startIndex < items.Count - 1) { xlist.Add(Slice(items, startIndex, items.Count)); int t = xlist[xlist.Count - 1].Count; if (maxCol < t) t = maxCol; } return xlist.ToArray(); } private Rectangle[] SplitRect(Rectangle a, Rectangle r) { if (a == r) return new Rectangle[0]; if (!Rectangle.Inflate(a, -2, -2).Contains(r)) return new Rectangle[0]; #region MyRegion if (r.X == a.X) { if (r.Height == a.Height) { #region MyRegion return new Rectangle[] { new Rectangle(r.Right, a.Y, a.Width - r.Width, a.Height) }; #endregion } else if (r.Y == a.Y) { #region MyRegion if (r.Width == a.Width) { return new Rectangle[] { new Rectangle(a.X, r.Bottom, a.Width, a.Height - r.Height) }; } return new Rectangle[] { new Rectangle(r.Right, a.Y, a.Width - r.Width, r.Height), new Rectangle(a.X, r.Bottom, a.Width, a.Height - r.Height) }; #endregion } else if (r.Bottom == a.Bottom) { #region MyRegion if (r.Width == a.Width) { return new Rectangle[] { new Rectangle(a.X, a.Y, a.Width, r.Y - a.Y) }; } return new Rectangle[] { new Rectangle(a.X, a.Y, a.Width, r.Y - a.Y), new Rectangle(r.Right, r.Y, a.Width - r.Width, r.Height) }; #endregion } else { #region MyRegion if (a.Width == r.Width) { return new Rectangle[] { new Rectangle(a.X, a.Y, a.Width, a.Height - (r.Y - a.Y)), new Rectangle(a.X, r.Bottom, a.Width, a.Height - (r.Bottom - a.Y)) }; } return new Rectangle[] { new Rectangle(a.X, a.Y, a.Width, a.Height - (r.Y - a.Y)), new Rectangle(r.Right, r.Y, a.Width - r.Right, r.Height), new Rectangle(a.X, r.Bottom, a.Width, a.Height - (r.Bottom - a.Y)) }; #endregion } } else if (r.Y == a.Y) { if (r.Height == a.Height) { #region MyRegion if (r.Right == a.Right) { return new Rectangle[] { new Rectangle(a.X, a.Y, a.Width - r.Width, a.Height) }; } return new Rectangle[] { new Rectangle(a.X, a.Y, r.X - a.X, a.Height), new Rectangle(r.Right, a.Y, a.Right - r.Right, a.Height) }; #endregion } else { #region MyRegion if (r.Right == a.Right) { return new Rectangle[] { new Rectangle(a.X, a.Y, a.Width, r.Y - a.Y), new Rectangle(a.X, r.Y, r.X - a.X, r.Height), new Rectangle(a.X, r.Bottom, a.Width, a.Bottom - r.Bottom) }; } return new Rectangle[] { new Rectangle(a.X, a.Y, r.X - a.X, r.Height), Rectangle.FromLTRB(r.Right, a.Y, a.Right, r.Bottom), Rectangle.FromLTRB(a.X, r.Bottom, a.Right, a.Bottom) }; #endregion } } else if (r.Right == a.Right) { #region MyRegion if (a.Bottom == r.Bottom) { return new Rectangle[] { Rectangle.FromLTRB(a.X, a.Y, a.Right, r.Y), Rectangle.FromLTRB(a.X, r.Y, r.X, r.Bottom) }; } return new Rectangle[] { Rectangle.FromLTRB(a.X, a.Y, a.Right, r.Y), Rectangle.FromLTRB(a.X, r.Y, r.X, r.Bottom), Rectangle.FromLTRB(a.X, r.Bottom, a.Right, a.Bottom) }; #endregion } else if (r.Bottom == a.Bottom) { #region MyRegion return new Rectangle[] { Rectangle.FromLTRB(a.X, a.Y, a.Right, r.Y), Rectangle.FromLTRB(a.X, r.Y, r.X, r.Bottom), Rectangle.FromLTRB(r.Right, r.Y, a.Right, a.Bottom) }; #endregion } #endregion return new Rectangle[] { Rectangle.FromLTRB(a.X, a.Y, a.Right, r.Y), Rectangle.FromLTRB(a.X, r.Y, r.X, r.Bottom), Rectangle.FromLTRB(r.Right, r.Y, a.Right, r.Bottom), Rectangle.FromLTRB(a.X, r.Bottom, a.Right, a.Bottom) }; } public void Compose(EPubWriter writer) { int mc; List<TableItem>[] all = Analyze(out mc); if (all.Length < 1) return; foreach (List<TableItem> item in all) { writer.BeginRow(); for (int i = 0; i < item.Count; i++) { TableItem ti = item[i]; ti.RowSpan = 0; //???? Should Calculate ti.ColSpan = 0; //???? Should Calculate writer.Render(ti.Item, ti.RowSpan, ti.ColSpan); } writer.EndRow(); } } } </code></pre> <p><em><strong>What I Need</em></strong></p> <pre><code> public void Compose(EPubWriter writer) { int mc; // Analyze: Calculates item positions, creates // empty TableItem s if needs, sorts by y ASC,x ASC // Returns array of rows (TR) what contains cells (TD) List<TableItem>[] all = Analyze(out mc); if (all.Length < 1) return; foreach (List<TableItem> item in all) { writer.BeginRow(); for (int i = 0; i < item.Count; i++) { TableItem ti = item[i]; ti.RowSpan = 0; //???? Should Calculate ti.ColSpan = 0; //???? Should Calculate writer.Render(ti.Item, ti.RowSpan, ti.ColSpan); } writer.EndRow(); } } </code></pre> <blockquote> <pre><code> ti.RowSpan = 0; //???? Should Calculate ti.ColSpan = 0; //???? Should Calculate </code></pre> </blockquote> <p>Thank you..</p>

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