How to Interact with the Current Selection
The user can select text in a rich edit control by using the mouse or the keyboard. The current selection is the range of selected characters, or the position of the insertion point if no characters are selected. An application can get information about the current selection, set it, determine when it changes, and show or hide the selection highlight.
- Windows User Interface Programming
To determine the current selection in a rich edit control, use the EM_EXGETSEL message. To set the current selection, use the EM_EXSETSEL message. The CHARRANGE structure is used with both messages and specifies a range of characters. To retrieve information about the contents of the current selection, you can use the EM_SELECTIONTYPE message.
An application can detect when the current selection changes by processing the EN_SELCHANGE notification code. The notification code specifies a SELCHANGE structure that contains information about the new selection. A rich edit control sends this notification code only if you enable it by using the EM_SETEVENTMASK message.
By default, a rich edit control shows and hides the selection highlight when it gains and loses the focus. You can show or hide the selection highlight at any time by using the EM_HIDESELECTION message. For example, an application might provide a Search dialog box to find text in a rich edit control. The application might select matching text without closing the dialog box, in which case it must use the EM_HIDESELECTION message to highlight the selection.
As with edit controls, you can specify the ES_NOHIDESEL window style to prevent a rich edit control from hiding the selection highlight when it loses the focus.
As an alternative to using the EM_EXGETSEL and EM_EXSETSEL messages, you can retrieve and set the current selection by using the EM_GETSEL and EM_SETSEL edit control messages. The EM_GETSEL message packs two 16-bit character indexes into its 32-bit return value and therefore, works only for selections that fall entirely within the first 64K. However, a rich edit control will never contain more than 32K characters of text, unless you extend this limit by using the EM_LIMITTEXT or EM_EXLIMITTEXT message. For selections that extend beyond the first 64 KB of text, the EM_GETSEL message returns –1. In such a case you can still use the values that are returned in wParam and lParam to find the start and end characters of the selection.