table_cell.md
In rswipl: Embed 'SWI'-'Prolog'

class table_cell {#class-table_cell}

Cell in a table. It plays a similar role to class node, controlling graphical images in a hierarchical layout.

Normally, a table_cell object is created as a side effect of table ->append, appending a graphical to a table.

The table_cell object stores layout information on this particular cell (spanning, alignment, etc.), as well as information required by the table object for fast manipulation of the cells. Important attributes:

| ->cell_padding | Space around the <-image          |
| ->col_span     | # columns spanned                 |
| ->row_span     | # rows spanned                    |
| ->halign       | Horizontal alignment of the image |
| ->valign       | Vertical alignment of the image   |
| ->selected     | Select the cell.                  |
| <-column       | 1-based column index (read)       |
| <-row          | 1-based row index (read)          |

table_cell<-cell_padding: [size] Size around contents of the cell. If @default, this is read from the <-table.
table_cell<-col_span: 1.. Number of columns spanned. The default is 1. Extending the ->col_span will destroy cells in the spanned area, while contracting the span will created holes in the table. See also ->row_span.
table_cell<-column: int* X-location in table environment. Updated by the table object. @nil if the cell is not part of a table. See also table <-column
table_cell-halign: [{left,center,right,reference,stretch}] Horizontal alignment of <-image in cell. Values:
- @default Use value from the table_column object.
- left Left align the area of the <-image in the box.
- center Center the area of the <-image in the box
- right Right align the <-image in the box
- reference Fetch the graphical <-reference of all cells in this column having this alignment, and place the graphicals such that the references are horizontally aligned. For example, one could define a subclass of class text that returns the X-location of a decimal dot as the X-value of the reference, for proper alignment of a column holding numerical data.
- stretch The image will be made as big as the cell.
See also table_column ->halign and ->valign.
table_cell<-note_mark: image* If present, this image is painted in the top-right corner of the table_cell object. It is intended for marking cells, for example for indicating the presence of an annotation to this cell.

The image is part of the background of the cell. See also ->background.
table_cell<-row: int* Y-location in table environment. Updated by the table object. @nil if the cell is not part of a table. See also table <-row.
table_cell<-row_span: 1.. Number of rows spanned. Symetric to ->col_span.
table_cell<-selected: bool Is cell selected? The selection is used by table->_redraw_area to draw a box around the selected cells. See also table <->selection.
table_cell-valign: [{top,center,bottom,reference,stretch}] Vertical alignment of <-image in cell. Symetric to ->halign.

table_cell->background: [colour|pixmap] Backround colour for the cell. In addition to a colour or image, backgrounds can also be modified using the ->note_mark.
table_cell->initialise: graphical Create a default table_cell object from the graphical object. The graphical becomes the <-image of the cell. Normally, table_cell objects are created implicitely by <-convert.
table_cell->unlink Informs the <-table and removes the <-image from its device.

table_cell<-area: -> area Area of the cell (including table <-cell_padding) in the coordinate system of the device to which the table object is connected. See also table<-cell_from_position, graphical<-area and graphical->in_event_area.
table_cell<-convert: graphical -> table_cell Converts a graphical object into a table_cell by creating a default table_cell and associating the graphical as the <-image.

This method ensures graphicals can be appended directly to a table.
table_cell<-table: -> table Same as <-layout_manager, but fails of the cell is not part of a table, instead of returning @nil.