Writing +a MIME Recognizer

diff -r 000000000000 -r 89d6a7a84779 Symbian3/SDK/Source/GUID-1AAA88BB-19AD-5B8E-993C-11F4B7CD90EB.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Symbian3/SDK/Source/GUID-1AAA88BB-19AD-5B8E-993C-11F4B7CD90EB.dita Thu Jan 21 18:18:20 2010 +0000 @@ -0,0 +1,179 @@ + + + + + +Writing +a MIME Recognizer

The Mime Recognizers provide the implementation for data type +(MIME Type) recognition using the MIME recognition framework.

Each +MIME recognizer specifies the MIME type it supports along with the priority +and confidence of recognition. A MIME recognizer reads a small piece of data +and identifies the data type. Once the data type is identified, it is passed +to the Application +Architecture (AppArc). AppArc launches the application +that best handles the identified data type.

Symbian OS v9.1 +and onwards, MIME recognizers are ECOM plug-ins. +They are located in \sys\bin\.

Each MIME recognizer is loaded +by the Application +Architecture (AppArc) during the startup sequence.

+ + +Create a project file (.mmp) for the MIME recognizer +and ensure the following parameters are set. + + + + +

Variable Name

Value

Description

+ + +

TargetType

plugin

Specifies the type of binary.

+ + +

Resource

Use the block start resource ... end

The variable Resource is set to the registration +resource file (.rss))of the MIME recognizer.

+ + +

UID

0x10009D8D and the DLL UID

The variable UID requires two values. The first +value is 0x10009D8D and is constant for all MIME recognizers. The second value +is the UID of the DLL.

+ + +

Capability

Protserv

The AppArc server has protserv capability.The MIME +recognizers are loaded by the AppArc server on requirement. The MIME recognizers +must have protserv capability to be loaded by the AppArc +server.

+ + + +

+For more details, refer Creating +a Project File. +The code below shows a sample .mmp file with the +above parameters set. +target exampleRecognizer.dll + +capability Protserv +targettype plugin +uid 0x10009d8d 0x1d1f75ed +vendorid 0x70000001 + +sourcepath . +source exampleRecognizer.cpp +systeminclude \EPOC32\INCLUDE +systeminclude \EPOC32\INCLUDE\ECOM + +library EUSER.LIB APMIME.LIB + +start resource 1d1f75ed.rss +target exampleRecognizer.rsc +end + + +Export the factory code function of the MIME recognizer as shown below. +This is required to create an instance of the MIME recognizer. +The class CExampleRecognizer is derived from CApaDataRecognizerType. +const TInt KImplementationUID = 0x101F7DA1; + +CApaDataRecognizerType* CExampleRecognizer::CreateRecognizerL() + { + return new (ELeave) CExampleRecognizer; + } + +const TImplementationProxy ImplementationTable[] = + { + IMPLEMENTATION_PROXY_ENTRY(KImplementationUID,CExampleRecognizer::CreateRecognizerL); + } + +EXPORT_C const TImplementationProxy* ImplementationGroupProxy(TInt& aTableCount) + { + aTableCount = sizeof(ImplementationTable) / sizeof(TImplementationProxy); + return ImplementationTable; + } + +For more details refer Exporting +Implementation Factories. + + +Implement CApaDataRecognizerType polymorphic interface. + + +The code below shows a sample constructor implementation. +const TUid KExampleUid = {0x1d1f75ed}; + +const TInt KNumDataTypes = 1; + +CExampleRecognizer::CExampleRecognizer() : CApaDataRecognizerType(KExampleUid,CApaDataRecognizerType::EHigh) + + { + iCountDataTypes = KNumDataTypes; + + } + + +Specify a UID (the DLL UID as specified in the plug-in +project definition file) and a priority in +the constructor. +The iCountDataTypes variable, represents the number +of data types supported by the recognizer can also be set in the constructor. +The value set for this variable should match the implementation of CApaDataRecognizerType::SupportedDataTypeL(). + + +Implement the pure virtual function CApaDataRecognizerType::SupportedDataTypeL(). +It returns the MIME types that the recognizer is capable of recognizing. +The code below shows a sample implementation of SupportedDataTypeL() for +supporting MIME type/ subtype "text/example". + +_LIT8(KExampleTextMimeType, "text/example"); + + +TDataType CExampleRecognizer::SupportedDataTypeL(TInt aIndex) const + + { + return TDataType(KExampleTextMimeType); + + } + + +Implement CApaDataRecognizerType::DoRecognizeL(). +This function executes data type recognition. +The code below shows a sample implementation of DoRecognizeL() for +recognizing the MIME type "/text/example" contained in files +with .example extension with maximum confidence. +void CExampleRecognizer::DoRecognizeL(const TDesC& aName, const TDesC8& aBuffer) + { + _LIT8(KExampleData, "example"); + _LIT(KDotExample, ".Example"); + + TParse parse; + parse.Set(aName,NULL,NULL); + TPtrC ext=parse.Ext(); // extract the extension from the filename + + if (ext.CompareF(KDotExample)==0 && aBuffer.FindF(KExampleData)!=KErrNotFound) + { + iConfidence=ECertain; + iDataType=TDataType(KExampleTextMimeType); + } + } + + + + + \ No newline at end of file