Merge Table Cells

Sometimes certain rows in a table require a heading or large blocks of text that take up the full width of the table. For proper design of the table, the user can merge several table cells into one. Aspose.Words supports merged cells when working with all input formats, including importing HTML content.

How to Merge Table Cells

In Aspose.Words, merged cells are represented by the following properties of the CellFormat class:

• horizontalMerge which describes if the cell is a part of a horizontal merge of cells
• verticalMerge which describes if the cell is a part of a vertical merge of cells

The values of these properties determine the merge behavior of cells:

• The first cell in a sequence of merged cells will have CellMerge.First
• Any subsequently merged cells will have CellMerge.Previous
• A cell that is not merged will have CellMerge.None

Sometimes, when loading existing document cells in a table, they will appear merged. However, it can actually be one long cell – sometimes Microsoft Word exports merged cells this way. This can be confusing when attempting to work with individual cells, but there doesn’t seem to be any particular pattern as to when this happens.

Check if Cell is Merged

To check if a cell is part of a sequence of merged cells, we simply check the HorizontalMerge and VerticalMerge properties.

The following code example shows how to print the horizontal and vertical cell merge type:

You can download the sample file of this example from Aspose.Words GitHub.

Merge Table Cells When Using DocumentBuilder

To merge cells in a table created with the DocumentBuilder, you need to set the appropriate merge type for each cell where the merge is expected – first CellMerge.First and then CellMerge.Previous.

Also, you must remember to clear the merge setting for those cells where no merge is required – this can be done by setting the first non-merge cell to CellMerge.None. If this is not done, all cells in the table will be merged.

The following code example shows how to create a table with two rows where the cells in the first row are merged horizontally:

The following code example shows how to create a two-column table where the cells in the first column are vertically merged:

Merge Table Cells in Other Cases

In other situations where the DocumentBuilder is not used, such as in an existing table, merging cells in the previous way may not be as easy. Instead, we can wrap the basic operations involved in applying merge properties to cells in a method that makes the task much easier. This method is similar to the Merge automation method, which is called to merge a range of cells in a table.

The code below will merge the table cells in the specified range, starting at the given cell and ending at the end cell. In this case, the range can span multiple rows or columns:

The following code example shows how to merge a range of cells between two specified cells:

You can download the sample file of this example from Aspose.Words GitHub.

Depending on the version of the Framework you are using, you may want to refine this method by turning it into an extension method. In this case, you can call this method directly on a cell to merge a range of cells, such as cell1.Merge(cell2).

Convert to Horizontally Merged Cells

Sometimes it is not possible to detect which cells are merged because some newer versions of Microsoft Word no longer use the merge flags when cells are merged horizontally. But for situations where cells are merged into a cell horizontally by their width using merge flags, Aspose.Words provides the ConvertToHorizontallyMergedCells method to convert cells. This method simply transforms the table and adds new cells as needed.

The following code example shows the above method in operation:

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FAQ

1. Q: How can I determine if a table cell is part of a merged range?
   A: Check the cell’s CellFormat.HorizontalMerge and CellFormat.VerticalMerge properties. If they return CellMerge.First, the cell starts a merged range; CellMerge.Previous indicates it continues a previous merge; CellMerge.None means the cell is not merged.

2. Q: What steps are required to merge cells horizontally using DocumentBuilder?
   A: Create the table with DocumentBuilder, then set cell.getCellFormat().setHorizontalMerge(CellMerge.First) for the first cell in the merge and CellMerge.Previous for each subsequent cell. Finally, set CellMerge.None on the cell that follows the merged block to stop the merge.

3. Q: How do I merge cells vertically in a table?
   A: Use the CellFormat.VerticalMerge property in the same way as horizontal merging: assign CellMerge.First to the top cell of the vertical range and CellMerge.Previous to the cells below it. Reset to CellMerge.None after the merged block.

4. Q: Is there a way to merge a rectangular range of cells with a single call?
   A: Yes. Implement a helper method that receives the start and end cells and sets the appropriate HorizontalMerge and VerticalMerge values for all cells in the rectangle. The sample merge-cell-range.js demonstrates this approach.

5. Q: What does the ConvertToHorizontallyMergedCells method do?
   A: It analyzes a table where cells appear merged only by width (without merge flags) and converts them into proper merged cells by inserting new cells and setting the correct HorizontalMerge flags, making subsequent programmatic manipulation reliable.