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Formatting with Styles

The last topic I want to cover about the DataGridView is how to handle custom formatting of cells. As mentioned earlier, the grid supports a rich formatting model. The styles in the grid work in a layered model, which lets you set styles at a more macro level, then refine it at a more micro level. For example, you might set a default cell style that applies to all cells in the grid, but then have one entire column that has a different cell formatting, and have selected cells within that column have yet a different cell formatting. You do this by setting a series of default cell style properties that are exposed on the grid, which you can then refine by setting cell styles at the individual cell level.

As can be seen in Figure 6.11, the lowest layer in the model is the DefaultCellStyle property. This style will be used by default for any cells in the grid that haven’t had their style set to something else by one of the other style layers. The next layer up contains the RowHeadersDefaultCellStyle and ColumnHeadersDefaultCellStyle, which affect the way the header cells are presented. Above that layer sits the DataGridViewColumn.DefaultCellStyle property, followed by the DataGridViewRow.DefaultCellStyle property, representing the default styles on a column-by-column or row-by-row basis. The grid also supports an alternating row cell style that is set through the AlternatingRowsDefaultCellStyle property on the grid. Finally, the top-level layer that will override the settings of any of the lower layers if set is the DataGridViewCell.CellStyle property.

06fig11.jpg

Figure 6.11 Cell Style Layering

You can set these properties programmatically by accessing the appropriate property member on the instance of the grid, column, row, or cell. All of these properties are of type DataGridViewCellStyle, which exposes properties for setting fonts, colors, alignment, padding, and formatting of values. You can also configure the cell styles through the designer. Whenever you access one of the cell style properties on the grid or a column through the Properties window or Smart Tag property editors in the designer, you will see the CellStyle Builder dialog shown in Figure 6.12.

06fig12.jpg

Figure 6.12 CellStyle Builder Dialog

Using the property fields in this dialog, you can set fine-grained options for how the cell will display its content, and you can even see what it is going to look like in the Preview pane at the bottom of the dialog.

You can also set border styles for cells using the grid’s CellBorderStyle, ColumnHeadersBorderStyle, and RowHeadersBorderStyle properties. Using these styles, you can achieve some fairly sophisticated grid appearances, as seen in Figure 6.13. In this sample, default cell styles were set at the column and row level, and then the filling in of the shape was done through individual cell selection.

06fig13.jpg

Figure 6.13 Cell and Border Styles Applied

However, you will still hit some limitations in using cell styles. For example, a natural next step for the grid shown in Figure 6.13 would be to set the border colors on the cells that have been colored in to show a black border. However, there is really no way to accomplish this just through cell styles, since the border styles available are only 3D effects and are applied at the grid level for entire cells, not for individual sides of a cell. But, as always, you can almost always accomplish what you need through custom painting or custom cell type definition.

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