A header control typically has several header items that define the columns of the control. To add an item to a header control, send the HDM_INSERTITEM message to the control. The message includes the address of an HDITEM structure. This structure defines the properties of the header item. The following code example shows the HDITEM syntax.
typedef struct _HD_ITEM { hdiUINTmask;intcxy; LPSTRpszText; HBITMAPhbm; intcchTextMax; intfmt; LPARAMlParam; } HD_ITEM;
The fmt member of an item's HDITEM structure can include either the HDF_STRING or HDF_BITMAP flag to indicate whether the control displays the item's string or bitmap. If you want to display both a string and a bitmap, create an owner-drawn item by setting the fmt member to include the HDF_OWNERDRAW flag. You can combine a string and an image from an image list by combining the HDF_IMAGE and HDF_STRING flags.
The HDITEM structure also specifies formatting flags that tell the control whether to center, left-align, or right-align the string or bitmap in the item's rectangle.
HDM_INSERTITEM returns the index of the newly added item. You can use the index in other messages to set properties or retrieve data about the item. To delete an item, use the HDM_DELETEITEM message, which specifies the index of the item to delete.
The HDM_SETITEM message sets the properties of an existing header item and the HDM_GETITEM message retrieves the current properties of an item. To retrieve a count of the items in a header control, use the HDM_GETITEMCOUNT message.
You can define individual items of a header control to be owner-drawn items. Using this technique gives you more control than you would otherwise have over the appearance of a header item.
Use the HDM_INSERTITEM message to insert a new owner-drawn item into a header control or the HDM_SETITEM message to change an existing item to an owner-drawn item. Both messages include the address of an HDITEM structure, which should have the fmt member set to the HDF_OWNERDRAW value.