DBTabie Vie\N - Oriented Software

Inherits From: ScrollView : View : Responder: Object Declared In: dbkitIDBTable View.h

Class Description

DBTabie View is a class that displays data in a table. It's similar to the Matrix class, but with two important differences: First, the data resides not in the DBTabie View instance but in an external data source (usually a DBRecordList). Second, the table's rows and columns can be individually resized and repositioned by the user.

A DB Table View object consists of up to three different views: A row title view, a column title view, and a content view. The content view can be made scrollable, horizontally, vertically, or both. The row and column title views display title information; the titles automatically scroll with their contents. Either or both the title views may be hidden.

Rows and Columns

Although the appearance of the DB Table View is completely configurable, the usual arrangement is to have a fixed number of properties (fields) arranged as columns. Columns are therefore said to be the table's static axis. The rows, representing records, vary dynamically with the data source or with the qualifier used to select records. In that case, rows are said to be the table's dynamic axis. Usually such a DB Table View has column titles but no row titles. (If you ask for titles on a dynamic axis, the display shows consecutive integers, reporting the record's position in the data source.)

When a new DB Table View is initialized, it has no rows and no columris, and neither rows nor columns are static. Sending it the first addColumn:withTitle: message both adds a column and makes columns static rather than dynamic. Similarly, sending it an

addRow: ... message would do the same thing for rows. A few applications may want to have both rows and columns static. In the common case (that is, static columns, dynamic rows), you call addColumn: ... for each column, and then hook up a data source to provide the data. The rows will then be determined lazily at display time through the data source's getValueFor:at:into: method. Like a very lazy browser, the DBTableView doesn't cache data.

There are two ways to refer to a static vector: by its row or column number, or by the property that it represents. Most of the methods that manipulate specific rows or columns refer to them by row number or column number. These numbers are like indexes to an array: if the user or the application moves a vectors to a new position, or deletes or inserts a vector, the row or column numbers change accordingly.

Formatting

To format the display of its content view, a DB Table View uses subclasses of the abstract superclass DB Formatter (see the specifications of DB Formatter, DBTextFormatter, DBEditableFormatter, and DBImageFormatter). A formatter is responsible for taking the data from a particular row/column intersection within the DB Table View's grid and displaying it in a particular rectangle on the screen. That row/column intersection is in some ways like a Cell within a Matrix object, but there are important differences. Whereas a Cell actually stores its data, a formatter does not; a DB Table View must always refer to its data source to get the values it displays.

Although a formatter displays the field at a single row/column intersection, its formatting rule applies to any of the fields having the same property. That is, in the usual case (with static columns), it applies to all the fields in a particular column. When rows are static, it applies to all the fields in a particular row. Since the formatter can apply either to a row or to a column, it is said to apply to a vector-that is, to one axis of the table (be it row or column). The DBVectors protocol provides methods for specifying the format of fields within a vector.

Response to User Action

Although DB Table View is not a subclass of Control, it does implement the target/action paradigm, so that the target to be notified and the action to be performed can be selected in Interface Builder's Conection Inspector. Whenever the user double clicks, or selects a new row or column, whether by mouse action or by pressing the arrow keys, notification is sent to the delegate.

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Instance Variables

The object notified of a double click or change of selection

The DBAssociation linking this view to its data Row layout information

Column layout information Heading of the selected row Heading of the selected column Clip view for the row headings Clip view for the column headings The actual data view

The list of selected rows The list of selected columns

View in the upper left comer of the DB Table View The object that receives target/action messages Selector of the action of a target/action message Selector of the action of a double-click message

Method Types

Initializing and freeing - initFrame:

-free

Setting up the DB Table View - setDataSource:

- dataSource Setting and reporting formatting

- formatterAt::

- dynamicRows - dynamicColumns - isRowHeadingVisible - isColumnHeading Visible - setIntercell:

- getIntercell:

- setGridVisible:

- isGridVisible - acceptArrowKeys:

- doesAcceptArrow Keys - allowVectorReordering:

- doesAllow VectorReordering - allowVectorResizing:

- doesAllow VectorResizing Notifying the DBTabie View of change

- reloadData:

- layoutChanged:

- rowsChangedFrom:to:

- columnsChangedFrom:to:

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Handling rows and columns - columnCount

Editing support - editFieldAt::

- setEditable:

- isEditable - endEditing Handling the selection - setMode:

-mode

- selectRow: by Extension:

- selectColumn:byExtension:

Setting DBTabie View components

Adjusting the view - drawSelf::

- scrollClip:to: Transmitting action - setAction:

- action Appointing a delegate - setDelegate:

- delegate

Instance Methods

acceptArrowKeys:

- acceptArrowKeys:(BOOL)jlag

Enables or disables the arrow keys for keystrokes the user makes within the DB Table View, asjlag is YES or NO. The default when a DBTableView is initialized is YES. Returns self.

When at least one row is selected,

l'

moves the selection to the row below the highest selected row, and

-t

to the row above it (if necessary, scrolling to make the newly selected row visible);

the horizontal arrows do nothing. Similarly, when at least one column is selected, ~ moves

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the selection to the column to the left of the leftmost selected column, and ~ to the column to the right of it (if necessary, scrolling to make the newly selected column visible); the vertical arrows do nothing. In either case, arrows don't wrap around; if the selection is the first or last vector, pressing the arrow that points to the edge does nothing.

See also: - doesAcceptArrowKeys

acceptsFirstResponder

- (BOOL )acceptsFirstResponder

Returns YES if the DBTableView accepts the role of first responder for its Window.

action

- (SEL)action

Returns the selector for the action method that will be sent to the DBTableView's target when a target/action event occurs in the DBTableView. Usually, this is the action you selected in Interface Builder's Connections Inspector.

addColumn:at:

- addColumn:identifier at:(unsigned int)aPosition

Inserts a new static column into the DB Table View. The data for the new column will come from the DBRecordList's attribute identified by identifier. The new column will be inserted so that it precedes the column whose column-number (before the insertion) was aPosition.

No title is assigned to the new column; its formatting will be handled by a default formatter.

Return self.

addColumn:withFormatter:andlitle:at:

- addColumn:identifier

withFormatter:formatter andTitle:( const char *)title at:(unsigned int)aPosition

Inserts a new static column into the DB Table View. The data for the new column will come from the DBRecordList's attribute identified by identifier. Text for the new column's title will be taken from title. The column's formatting will be handled by formatter. The new column will be inserted so that it precedes the column whose column-number (before the insertion) was aPosition.

addColumn :with litle:

- addColumn:identifier withTitle:(const char *)title

Appends a new static column following the last existing column in the DB Table View. The data for the new column will come from the DBRecordList's attribute identified by identifier. Text for the new column's title will be taken from title. The new column has its own default DBTextFormatter. Returns self.

addRow:at:

- addRow:identifier at:(unsigned int)aPosition

Inserts a new static row into the DBTable View. The data for the new row will come from the DBRecordList's attribute identified by identifier. The new row will be inserted so that it precedes the row whose row-number (before the insertion) was aPosition. No title is assigned to the new row; its formatting will be handled by a default formatter. Returns self.

addRow:withFormatter:andlitle:at:

- addRow:identifier

withFormatter:formatter andTitle:(const char *)title at: (unsigned int )aP osition

Inserts a new static row into the DBTableView. The data for the new row will come from the DBRecordList's attribute identified by identifier. Text for the new row's title will be taken from title. The row's formatting will be handled by formatter. The new row will be inserted so that it precedes the row whose row-number (before the insertion) was aPosition.

Returns self.

addRow:with litle:

- addRow:identifier withTitle:(const char *)title

Appends a new static row following the last existing row in the DBTableView. The data for the new row will come from the DBRecordList's attribute identified by identifier. Text for the new row's title will be taken from title. The new row gets it its own

DB TextFormatter. If the DB Table View previously had no rows, adding a row makes rows static. Returns self.

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allowEmptySel:

- a1lowEmptySel:(BOOL)flag

Permits the user to deselect a vector (with shift-click) when that would leave nothing selected (or prohibits it, when flag is NO). The default is NO. Returns self.