NetAdvantage 笔记

1.UltraControlBase Class Members

　　1.BeginUpdate Method

　　　　Sets the IsUpdating flag to true which prevents painting.

　　　　This is used to optimize performanance while setting a number of properties or adding a number of items (e.g. nodes in a tree control) so that all paint messages are ignored until EndUpdate is called.

　　2.EndUpdate() Method

　　　　Resets the IsUpdating flag to false and invalidates the control

　　　　This method must be called after BeginUpdate. If BeginUpdate was called without a subsequent call to EndUpdate the control will not draw itself.

　　3.EndUpdate(Boolean) Method

　　　　Resets the IsUpdating flag to false and optionally invalidates the control.

　　　　True to invalidate the control and dirty the child elements; otherwise false.

　　　　Calling this method passing in false should only be done when it is known that the changes made between the BeginUpdate and EndUpdate calls did not require invalidation or dirtying of the elements or when the invalidation is being handled by the programmer.

　　4.Update Method

　　　　Causes the control to redraw the invalidated regions.

2.UltraGrid Class Members

　　1.UpdateData Method

　　　　Updates (commits) any modified information.

　　　　The UpdateData method updates any modified information in the grid, sending it to the data provider. When the update is complete, any rows that were marked as having modified data will have that mark cleared. The DataChanged property will be set to False.

　　　　Normally, the grid handles the updating of data automatically based on the UpdateMode property, so there will be few situations in which you will need to invoke this method. The major exception is when you want to update the data in response to an event that does not cause the grid to lose focus. For example, clicking on a toolbar button. Since toolbars do not typically take focus, the grid will not send any data to the data provider until you invoke the UpdateData method.

　　　　Note that if a cell in the grid is currently in edit mode, this method will not commit the changes to that cell. To handle this, you may want to call the PerformAction method and specify the ExitEditMode action. This allows you to attempt to take the cell out of edit mode and check to make sure this process is successful before calling UpdateData.

　　2.Refresh Method

　　　　Overridden. Forces the control to invalidate its client area and immediately redraw itself and any child controls.

　　　　Refresh method re-draws the control. Typically calling this method is not necessary since UltraGrid will redraw itself automatically whenever data or settings change that affect the UltraGrid display. This is useful when for example the data source doesn't support change notifications and as a result when the data changes the UltraGrid doesn't redraw the display. In such a scenario this method can be called to redraw the UltraGrid.

　　3.PerformAction Method

　　　　Simulates user interaction with the control.　　　

　　　　Invoke this method to simulate an action the user can perform.

　　　　Many actions are only appropriate in certain situations; if an action is inappropriate, it will not be performed. For example, attempting to delete rows by performing the DeleteRows action (37 - KeyActionDeleteRows) will have no effect if no rows are selected. Similarly, an attempt to toggle a cell's dropdown list by performing a droptown toggle action (14 - KeyActionToggleDropdown) will also be ignored if the column does not have a dropdown list associated with it.

　　　　You can use the CurrentState property to determine the state of the control when the action is about to be performed.

3.DataTable

　　1.AcceptChanges 方法

　　　　提交自上次调用 AcceptChanges 以来对该表进行的所有更改。

　　　　调用 AcceptChanges 时，任何仍处于编辑模式的 DataRow 对象将成功结束其编辑。 DataRowState 也发生更改：所有 Added 和 Modified 行都变为 Unchanged，Deleted 行则被移除。

　　　　在您尝试使用 DbDataAdapter.Update 方法更新 DataSet 之后，通常会对 DataTable 调用 AcceptChanges 方法。

4.UltraGridCell Class Members

　　1.Text Property

　　　　Returns the text of the cell. If the cell is in edit mode, it returns the text in the editor being used for editing the cell.

　　2.Value Property

　　　　Returns or sets the underlying data value of a cell. This property is not available at design-time.

　　　　Use this property to retrieve or modify a cell's value. When the value of a cell is changed, the BeforeCellUpdate and the AfterCellUpdate events are generated and the cell's DataChanged property is set to True. Note that the cell's new value is not necessarily committed to the data source when this property is set, however, since various factors such as the type of record locking employed by the data source, as well as the value of the UpdateMode property, can affect when the actual update occurs.

　　　　The OriginalValue property of the cell can be used to determine the cell's value before it was changed.

　　　　The GetText method can be invoked to return the formatted value of a cell.

5.UltraGridRow Class Members

　　1.GetCellText Method

　　　　Retruns the text that's displayed in the cell.

　　2.GetCellValue Method

　　　　Returns the data value for a cell from the database

	// UltraGridCell.Text property returns the same text as returned by GetCellText below
	// except when the cell is in edit mode in which case the UltraGridCell.Text returns the
	// current text that the user has entered in the cell while UltraGridColumn.GetCellText
	// returns the cell's value that's in the bound list converted to text. NOTE: The same
	// doesn't hold true for UltraGridCell.Value and UltraGridColumn.GetCellValue where both
	// return the values from the bound list regardless of whether the cell is in edit mode and
	// the user has modified the cell's value.

6.UltraGridColumn Class Members

　　1.Format Property

　　　　Returns or sets a string used to control the formatting of displayed text.

　　　　The Format property is similar to the Visual Basic Format function, and supports all of the named arguments and literal strings supported by that function when the UltraGrid is being used in Visual Basic. In other host environments, the Format property provides a subset of theFormat function's capabilites, including the use of named arguments.

　　　　The Format property applies only to cells that are not in edit mode.

　　　　The underlying .NET formatting mechanism is used to format the value. See .NET help for more information regarding list of the named formats that are supported.