2 * Copyright (c) 1997-2009 Nokia Corporation and/or its subsidiary(-ies).
4 * This component and the accompanying materials are made available
5 * under the terms of "Eclipse Public License v1.0"
6 * which accompanies this distribution, and is available
7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".
9 * Initial Contributors:
10 * Nokia Corporation - initial contribution.
28 class MTextFieldFactory;
33 class CTextField : public CBase
35 Abstract class: derive from this to instantiate a particular type of field (eg date etc)
36 Abstract base class for all field types.
38 A field contains information which relates to a text object and can be automatically
39 updated, e.g. page number or current date and time. Fields must implement
40 the pure virtual functions defined in this class, including Value() which
41 should calculate and return the field's new value, and Type() which returns
42 the field's type UID. The type UID identifies the field type to the field
43 factory (see class MTextFieldFactory).
49 IMPORT_C virtual TStreamId StoreL(CStreamStore& aStore)const; // calls ExternalizeL()
50 IMPORT_C virtual void RestoreL(const CStreamStore& aStore,TStreamId aId); // calls InternalizeL()
52 // Should be replaced by concrete derived classes.
53 IMPORT_C virtual void ExternalizeL(RWriteStream& aStream)const; // Externalize state info for the field
54 /** Internalises the field data. Called by RestoreL().
56 @param aStream Stream from which the field data should be internalised. */
57 virtual void InternalizeL(RReadStream& aStream)=0;
59 /** Sets aValueText to the current field value if the buffer is large enough. If
60 not, aValueText is not changed, and the function returns the length which
61 is required to hold the field's value.
63 @param aValueText Descriptor which on return contains the field's updated
65 @return Zero on success, otherwise, the length of the buffer which is required
66 to hold the field's updated value. */
67 virtual TInt Value(TPtr& aValueText)=0;
69 /** Returns the field's type UID.
71 @return The field's type UID. */
72 virtual TUid Type()const=0;
78 class MTextFieldFactory
80 Abstract class that should be derived from by any application that wishes to support fields
81 Abstract base class for field factories.
83 To use fields in editable text,
85 1) Define a field factory class (derived from MTextFieldFactory) that implements
88 2) Create an instance of the field factory and set this to be the editable
89 text object's field factory (see CPlainText::SetFieldFactory(), or you can
90 specify a field factory in the text object 's NewL()).
92 3) Create a new field (CPlainText::NewTextFieldL()), specifying the field
93 type UID (the built in field type UID values are defined in flddef.h). This
94 calls the factory's NewFieldL() function.
96 4) Insert the field into the text object (CPlainText::InsertFieldL()).
98 5) Evaluate the field (CPlainText::UpdateFieldL()) and then re-evaluate when
106 /** Implementations of this function should create a field of the type specified,
107 returning NULL if the field type is not recognised or supported.
109 @param aFieldType The field's type UID.
110 @return Pointer to the new text field, or NULL if the factory does not recognise
111 or support the field type. */
112 virtual CTextField* NewFieldL(TUid aFieldType)=0;
113 // Creates a field of the type specified
114 // Returns NULL if it does not recognise/support the field type