# CLVColumn

Derived from: public BInvoker /*Not currently*/

Declared in: CLVColumn.h

Library: none

## Overview

A CLVColumn is an object that can cooperate with a ColumnListView to display one column as a header for one column of items in a list.

## Constructor and Destructor

### CLVColumn()

          CLVColumn(const char* label, float width = 20.0, uint32 flags = 0,
                float min_width = 20.0);

          CLVColumn(BMessage *archive)    /*Not implemented*/

Initializes the new CLVColumn. The label will appear in the column heading.

The flags can be:

`CLV_SORT_KEYABLE` | The user can select this column to be the key column for sorting the items in the list
`CLV_NOT_MOVABLE` | The user can't drag this column to move it
`CLV_NOT_RESIZABLE` | The user can't drag the resize handle to change the size of this column
`CLV_LOCK_AT_BEGINNING` | This column is locked at the beginning for display purposes
`CLV_LOCK_AT_END` | This column is locked at the end for display purposes
`CLV_HIDDEN` | This column is initially hidden from the user
`CLV_MERGE_WITH_RIGHT` | This column is merged with the column to the right of it. It will not show a border / resize handle between the two items
`CLV_LOCK_WITH_RIGHT` | This column is locked to the column to the right of it. If either column is dragged to a new position, the partner will be dragged with it. Any number of columns may be locked together
`CLV_EXPANDER` | This column should display an expander. You may only use one expander in a ColumnListView, and an expander may not be added to a non-hierarchal ColumnListView. It may not have a label. Its width is automatically set to 20.0. The only flags that affect it are `CLV_NOT_MOVABLE`, `CLV_LOCK_AT_BEGINNING`, `CLV_NOT_SHOWN` and `CLV_LOCK_WITH_RIGHT`. The others are set for you: `CLV_NOT_RESIZABLE` | `CLV_MERGE_WITH_RIGHT`. If the user uses the arrow in an expander to display the items underneath it, the subitems will be indented, and will push the contents of the next column to the right by an appropriate amount
`CLV_PUSH_PASS` | Allows the column, if pushed by an expander, to "pass on" that push and push the next column over as well. Typically, this is used in an icon column following an expander, so that the name (or whatever) column that follows it will be pushed by the expander as well.
`CLV_HEADER_TRUNCATE` | Causes the text in the column label to be truncated with an ellipsis if it doesn't fit in the width of the column header.
`CLV_TELL_ITEMS_WIDTH` | Causes this column to call ColumnWidthChanged for all items when the width of this column changes. This is necessary for columns with string truncation using CLVEasyItem.

See also: `ColumnListView::AddColumn()`

### ~CLVColumn()

          virtual ~CLVColumn()

If the column has been added to a ColumnListView, removes it then deletes the column.

## Member Functions

### Archive()

          virtual status_t Archive(BMessage *archive, bool deep = true) const

Currently not implemented. It isn't high on my priorities, since archival is not something I'm making use of. If someone needs this functionality and fills it in, please send me the modified code so that others can benefit from it.

See also: `BArchivable::Archive()`, `Instantiate()` static function

### DrawColumnHeader()

          virtual void DrawColumnHeader(BView* view, BRect header_rect, bool sort_key,
                bool focus, float font_ascent)

Can be overridden to implement your own column header drawing. It should be rendered in view, in the header_rect provided. If sort_key is `true`, it should be underlined. If focus is `true`, it is being dragged or clicked on and should be rendered in `BeFocusBlue`. font_ascent is the ascent of the font selected for the ColumnListView to use for the header.

- The background will already be filled with and LowColor set to BeBackgroundGrey
- The highlight and shadow edges will already be drawn
- The header_rect does not include the one-pixel border for the highlight and shadow edges
- The view font will already be set to the font specified when the ColumnListView was constructed, and should not be changed
- If text is being rendered, it should be rendered at BPoint text_point(header_rect.left+8.0,header_rect.top+1.0+font_ascent)
- If sort_key is true, the text should be underlined, with the underline being drawn from BPoint(text_point.x-1,text_point.y+2.0) to BPoint(text_point.x-1+label_width,text_point.y+2.0)
- If focus is true, the text and underline should be in BeFocusBlue, otherwise in Black.

See also: `CLVColumn()`

###

Flags()

          uint32 void Flags() const

Returns the flags for this column.

See also: `CLVColumn()`

### GetHeaderView()

          BView* GetHeaderView() const

Returns the header view which contains this column.

### GetLabel()

          const char* GetLabel() const

Returns the label for this column.

### GetParent()

          ColumnListView* GetParent() const

Returns the ColumnListView which owns this column.

### SetShown(), IsShown()

          virtual void SetShown(bool shown)

          bool IsShown() const

Sets or returns whether the column is currently shown. `IsShown()` returns `true` if the column is currently shown (though not necessarily visible as it may be outside the ColumnListView's rectangle, in which case it is accessible using the horizontal scroll bar if the ColumnListView has one). Returns `false` otherwise.

### SetWidth(), Width()

          virtual void SetWidth(float width)

          float Width() const

Sets or returns the width of the column. To detect changes in the width of the column, override `ColumnListView::ColumnWidthChanged()`.

### SetSortMode(), SortMode()

          virtual void SetSortMode(CLVSortMode mode)

          CLVSortMode SortMode() const

Sets or returns the sort mode of the column. Sort modes may be `Ascending`, `Descending` or `NoSort`. A mode other than ascending or descending does not necessarily make it used for sorting, as it also needs to be selected as a sort key. To detect user changes in the sort mode of the column, override `ColumnListView::SetSortMode()`.

See also: `ColumnListView::SetSortKey(), ColumnListView::AddSortKey()`

## Utility Functions

### GetTruncatedString()

          void GetTruncatedString(const char* full_string, char* truncated, float width) const

Truncates a full_string to fit in the space provided, placing the results in a buffer which must be provided in truncated. The buffer must be strlen(full_string) + 3 bytes long.

By Brian Tietz

Copyright 1997

Bug reports (including documentation errors) and feature requests can be sent to briant@digaudio.com.