Introduction
This is a data grid built using ATL 3.0, STL and Win32 API. The article provides some explanation about the grid’s capabilities. I will not describe in detail the implementation of my grid because there is a lot of code and I do not think that anybody would have enough patience to read something like that. Source code is commented and this should be enough.
Data types
As one can see every column of the grid has an associated data type. This means that every value in the same column will have the same type. Available types are:
// These are the data types
typedef [v1_enum] enum DataType
{
DataType_Empty = 0, // Not specified
DataType_Null = 1, // NULL
DataType_I2 = 2, // 2-byte signed int
DataType_I4 = 3, // 4-byte signed int
DataType_R4 = 4, // 4-byte real
DataType_R8 = 5, // 8-byte real
DataType_Cy = 6, // Currency
DataType_Date = 7, // Date
DataType_BStr = 8, // Binary string
DataType_Dispatch = 9, // IDispatch FAR*
DataType_Error = 10, // Scodes
DataType_Bool = 11, // Boolean; True=-1, False=0
DataType_Variant = 12, // VARIANT FAR*
DataType_Unknown = 13, // IUnknown FAR*
DataType_UI1 = 17, // Unsigned char
// My types
DataType_Option = 0x0100, // Combo box
DataType_StrictOption // Drop down list
} DataType;
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As you can see, these types are in fact almost all VARTYPEs. If the user tries to change the value of a cell with a value whose type is incompatible with the type associated with the column, the value of the cell will not change. I also added some custom types, like Option and Strict Option. Data of this types are edited using combo boxes and drop down lists, as you can see in the next picture.
Range specifications
Every column has a type and a range for values. This means that you can enter in the cells values that have the type associated with the column and are in the specified range. For example you can specify ranges for numeric values:”18,49″ or you can specify options that are available for an Option or StrictOption type: “Male|Female”. For numeric values the posibilities to specify ranges are:
“,nMax” |
nMax |
“nMin,” |
nMax |
“nMin,nMax” |
User operations
Row selection is also available. You can select multiple rows of the grid using right-click. Clicking the upper-left corner of the grid selects all rows in the grid. Double clicking the same area unselects all lines. From VB, for example, you can test if a row is selected or not. Optionally, rows can be numbered on the left header. Pressing enter or F2 enters the grid in edit mode. Depending on type of the data that is in the selected cell, on edit mode opens an edit control, combo box, drop down list or the value is automatically changed ( boolean values ). Sorting is available. If a column’s property
AllowUserToSort |
TRUE |
Static and dynamic resizing is available for top header height, left header width, row height and column width. In the previous image I have marked with red dots the points that can be used for resizing.
Colors are fully customizable. You can choose your favorite combination of colours for grid items, as you can see in the screenshot.
Data sources
You can fill the grid with data from code (VB is the easiest way to manipulate this grid). Also, there are two more ways to enter data into the grid: a previously opened ADO Recordset or a connection string and a SQL SELECT statement. Unfortunately, in this version of the grid the databases are not automaticaly updated when the values of the cells change. This will be done in the next version.
// This are data source types
typedef [v1_enum] enum
{
DataSourceType_None = 0,
DataSourceType_ADORecordset,
DataSourceType_SQLStatement,
} DataSourceType;
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Database connection is not very well implemented yet, so I recommand this grid to be used with
DataSourceType_None |
Grid manipulation
I will describe now the interfaces that can be used to manipulate grid elements.
ISmartGrid
// Use this to manipulate grid properties interace ISmartGrid : IDispatch; |
ISmartGrid |
ISmartGrid |
Methods
AddColumn( [in] Name, [in] Type, [in, optional] ReadOnly,
[in, optional] Range, [out, optional] Column )
InsertColumn( [in] Name, [in] Type, [in] Position,
[in, optional] ReadOnly, [in, optional] Range,
[out, optional] Column )
RemoveColumn( [in] Position )
AddRow( [out, optional] Row )
InsertRow( [in] Position, [out, optional] Row )
RemoveRow( [in] Position )
SelectAllRows()
UnselectAllRows()
Requery()
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Properties
// State ActiveColumn ActiveRow NumberOfColumns NumberOfRows ReadOnly UILocked // Data access Column ConnectionString CursorType DataSource DataSourceType LockType Row // User interface ActiveRowColor ContentBkColor ContentForeColor ContentLinesColor DefaultColumnWidth Font HeaderBkCOlor HeaderForeColor HeaderLinesColor LeftHeaderVisible LeftHeaderWidth RowHeight SelectedItemColor TopHeaderHeight TopHeaderVisible |
Using methods from
ISmartGrid |
ICell
[
helpstring("ICell interface is used to access cells"),
uuid(C6462BB2-E639-11d3-8138-0000B49DBD2E),
pointer_default(unique)
]
interface ICell : IUnknown
{
[propget, helpstring("property Value")]
HRESULT Value([out, retval] VARIANT *pVal);
[propput, helpstring("property Value")]
HRESULT Value([in] VARIANT newVal);
};
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As you can see
ICell |
Value |
IRow
[
helpstring("IRow interface used to access rows from grid"),
uuid(E18D7A91-E639-11d3-8138-0000B49DBD2E),
pointer_default(unique)
]
interface IRow : IUnknown
{
[propget, helpstring("Get the specified cell of this row")]
HRESULT Cell(long nIndex, [out, retval] ICell **pVal);
[propget,
helpstring("Returs TRUE if this row is active and false otherwise")]
HRESULT Active([out, retval] BOOL *pVal);
[propput,
helpstring("Put this property TRUE if you wanna activate this row")]
HRESULT Active([in] BOOL newVal);
[propget,
helpstring("TRUE if this row is selected")]
HRESULT Selected([out, retval] BOOL *pVal);
[propput,
helpstring("Put this property on TRUE if you want to select this row")]
HRESULT Selected([in] BOOL newVal);
[propget, helpstring("Returns the index of this row")]
HRESULT Index([out, retval] long *pVal);
};
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IRow |
Active |
Selected |
Index |
IColumn
[
helpstring("IColumn interface used to access columns individually"),
uuid(506580C1-E643-11d3-8138-0000B49DBD2E),
pointer_default(unique)
]
interface IColumn : IUnknown
{
[propget, helpstring("Access a cell from this column")]
HRESULT Cell(long nIndex, [out, retval] ICell** pVal);
[propget, helpstring("Get the width of the column in pixels")]
HRESULT Width([out, retval] long *pVal);
[propput, helpstring("Put the width of the column in pixels")]
HRESULT Width([in] long newVal);
[propget, helpstring("Get the label of the column")]
HRESULT Name([out, retval] BSTR *pVal);
[propput, helpstring("Put the label of the column")]
HRESULT Name([in] BSTR newVal);
[propget, helpstring("Get data type used for this column")]
HRESULT DataType([out, retval] DataType *pVal);
[propget, helpstring("Put the values range")]
HRESULT Range([out, retval] BSTR *pVal);
[propput, helpstring("Get the values range")]
HRESULT Range([in] BSTR newVal);
[propget, helpstring("Get the index of the column")]
HRESULT Index([out, retval] long *pVal);
[propget, helpstring("Get the ReadOnly state of the column")]
HRESULT ReadOnly([out, retval] BOOL *pVal);
[propput, helpstring("Changes the ReadOnly state of the column")]
HRESULT ReadOnly([in] BOOL newVal);
[propget, helpstring("Get SortOrder property of this column")]
HRESULT SortOrder([out, retval] SortOrder *pVal);
[propput, helpstring("Changes the SortOrder property of the column")]
HRESULT SortOrder([in] SortOrder newVal);
[propget, helpstring("Returns AllowUserToSort value")]
HRESULT AllowUserToSort([out, retval] BOOL *pVal);
[propput, helpstring("Sets AllowUserToSort value")]
HRESULT AllowUserToSort([in] BOOL newVal);
[helpstring("Resorts the grid data, by this column content")]
HRESULT Resort();
};
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IColumn |
Cell |
Width |
Name |
DataType |
Index |
ReadyOnly |
Events
There are a few events that the grid raises when certain operations takes place. This events can be seen in the following dispinterface:
[
uuid(855D88AF-C9BD-11D3-A34E-0080AD303A9A),
helpstring("_ISmartGridEvents Interface")
]
dispinterface _ISmartGridEvents
{
properties:
methods:
[id(1), helpstring("Raised when the active row has changed")]
HRESULT RowChanged(long nPrevious, long nNew);
[id(2), helpstring("Raised when the active column has changed")]
HRESULT ColumnChanged(long nPrevious, long nNew);
[id(3), helpstring("Raised when the active cell has changed")]
HRESULT CellChanged(long nPreviousRow, long nPreviousColumn,
long nNewRow, long nNewColumn);
// Cell content changing events
[id(4), helpstring("method BeginCellEdit")]
VARIANT_BOOL BeginCellEdit(long nRow, long nColumn, ICell*);
[id(5), helpstring("method EndCellEdit")]
HRESULT EndCellEdit(long nRow, long nColumn, ICell*);
[id(6), helpstring("method CellUpdated")]
HRESULT CellUpdated(long nRow, long nColumn, ICell*);
};
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I have tested this dll using Microsoft Visual Basic 6.0. The archive contains the VB project that I used to test this ActiveX control.
This control does not depends on MFC.
Version History
- 2000/05/11 – Original Post
- 2000/05/18 – Added a lot of functionality like sorting, combo-boxes, sorting capabilities, event firing and bug fixes.
