|
Step 9: PE_RESULT Message
The PE_RESULT message arrives only if the application has specified an HRC object in step 6, rather than an HPENDATA or other object. The message signals the target window that recognition
results are ready. This message differs slightly from the others in that its lParam holds the HRC handle and not a pointer to a TARGET structure. If DefWindowProc handles PE_RESULT, it converts the recognizer's best guess to a string of
characters and sends them to the target window as WM_CHAR messages. Gestures are
also converted to appropriate messages, such as WM_COPY or WM_PASTE.
If the application handles the message, it must not destroy the HRC for the default system recognizer. Because DoDefaultPenInput created the default HRC, it expects to destroy it as well. The application must not destroy objects
it did not create.
At this point, an application can process any of the results itself. For
example, it might check for a recognized gesture such as the lasso or cut gesture.
The procedure for examining gestures at this point involves three steps:
- Retrieve any recognized gesture symbols from the HRCRESULT object by calling the GetResultsHRC function with the GRH_GESTURE argument.
- If this call indicates the recognizer has found a gesture, the application
then calls the GetSymbolsHRCRESULT function to see if the gesture is a lasso or X mark.
- If the gesture is a lasso or X mark, the application should examine the data further to determine the size
of the gesture, as outlined in the following example.
If the first or second test fails, indicating the recognizer has found no
lasso or X mark, the application should pass the PE_RESULT message to DefWindowProc for text processing. Note that the lasso and cut gestures cannot exist with
other gestures; therefore, the following code allocates only one HRCRESULT object because it examines at most a single gesture:
HRCRESULT hresult; // Look at only the first gesture
HPENDATA hpendata; // Points that comprise the gesture
HRGN hrgn; // Screen region of the gesture
SYV syv; // Symbol value of the gesture
UINT uRgnType; // Region type: X or LASSO
int cGest; // Count of gestures in results
.
.
.
switch ( wParam ) // Handle WM_PENEVENT messages
{
case PE_RESULT:
// Check for gesture
cGest = GetResultsHRC( (HRC) lParam, // HRC handle
GRH_GESTURE, // Gestures only
(LPHRCRESULT)&hresult, // Buffer
1 ); // Get one result
// If one gesture available, get its symbol
if (cGest == 1)
{
GetSymbolsHRCRESULT( hresult, // HRCRESULT handle
0, // Index to 1st syv
(LPSYV) &syv, // Symbol buffer
1 ); // Get 1 symbol
//
// If the gesture is lasso or x, collect the
// points that make up the gesture
//
if (syv == SYV_LASSO || syv == SYV_CUT)
{
hpendata = GetPenDataHRC( (HRC) lParam );
if (hpendata)
{
// Step 1: Get region of the gesture
uRgnType = (syv==SYV_LASSO) ? CPDR_LASSO : CPDR_BOX;
hrgn = CreatePenDataRegion( hpendata, uRngType );
// Step 2: Determine what text lies within the
// region. If the gesture covers more than one
// letter of a word but not the entire word, assume
// it's meant for entire word.
.
.
.
// Step 3: Either select . . .
if (syv == SYV_LASSO)
{
. // Select the text
.
.
}
// . . . or delete the text
else
{
. // Delete the text
.
.
}
DeleteObject( hrgn );
DestroyHPENDATA( hpendata );
}
}
}
break;
default:
DefWindowProc( hwnd, message, wParam, lParam );
}
As the previous code shows, applying a gesture to text requires three steps:
- Call the CreatePenDataRegion function to find the region covered by the gesture.
- Determine the text that lies within the gesture's region using the Windows GetTextExtentPoint32 function or some other method.
- Select or cut the text, according to the gesture.
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