1 // Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).
2 // All rights reserved.
3 // This component and the accompanying materials are made available
4 // under the terms of "Eclipse Public License v1.0"
5 // which accompanies this distribution, and is available
6 // at the URL "http://www.eclipse.org/legal/epl-v10.html".
8 // Initial Contributors:
9 // Nokia Corporation - initial contribution.
22 #ifndef FBSRASTERIZER_H
23 #define FBSRASTERIZER_H
28 /** CFbsRasterizer represents the system's rasterizer that has the ability to generate
29 standard pixel data from data stored in proprietary formats.
31 Multiple formats of proprietary data may be supported by the rasterizer. Formats are
32 identified by UID. Support for formats is platform-specific and controlled
33 by the platform vendor. The OS does not mandate that the system's rasterizer must
34 support any specific data formats.
36 CFbsRasterizer is used solely by the Font & Bitmap Server component to simulate pixel
37 access to extended bitmaps, i.e. bitmaps created using CFbsBitmap::CreateExtendedBitmap().
38 CFbsRasterizer is not intended for use by applications.
40 CFbsRasterizer is intended to be implemented by licensees through derivation from the
41 abstract base class. If a licensee wishes to provide a rasterizer implementation, they
42 should create a rasterizer dll that is exported as "fbsrasterizer.dll" and include it in
43 their ROM. Note that a stub rasterizer is exported to "fbsrasterizer.dll" and is loaded
44 by the Font & Bitmap server by default to prevent a rogue dll being loaded in the rasterizer's
45 place from the C:\ drive or removable media. Licensees can override this by using the
46 following build option:
47 -DFBSRASTERIZER_DLL <rasterizer_dll_name>
48 where <rasterizer_dll_name> is the name of the licensee rasterizer dll.
50 CFbsRasterizer will be instantiated in client threads that use the Font & Bitmap Server,
51 including the Window Server's main thread. Therefore the implementation of the rasterizer
52 must be robust. Rasterizer functions should never lead to process termination, even
53 when invalid proprietary data is passed in. Instances of CFbsRasterizer are not intended
54 to be shared between threads.
56 The CFbsRasterizer interface has been designed to allow the implementation to optimise
57 certain access patterns for performance. For example, the implementation might prepare
58 for sequential access to a region by rasterizing the entire region inside a private scratch
59 buffer. A further opportunity would be to take advantage of the immutability of extended
60 bitmaps by maintaining rasterized scratch buffers for the most recently used bitmaps.
62 class CFbsRasterizer : public CBase
65 /** Helper class for storing information about a bitmap that is being registered
71 /** The width and height in pixels to rasterize into. */
73 /** The display mode to rasterize into. */
74 TDisplayMode iDispMode;
75 /** The UID identifying the proprietary data format. */
77 /** A pointer to the proprietary data. */
79 /** The size in bytes of the proprietary data. */
84 /** Create a new rasterizer.
86 IMPORT_C static CFbsRasterizer* New();
88 /** Registers an extended bitmap so that scanline access requests can be made on
89 the bitmap. The same bitmap may be registered multiple times. The rasterizer instance
90 must be able to maintain at least 3 registrations simultaneously. This is to support
91 BitGDI drawing operations that make use of 3 source bitmaps.
96 @param aBitmapId A unique identifier for the bitmap that is being registered. This
97 identifier is never reused for other bitmaps.
98 @param aBitmapDesc A full description of the bitmap including the proprietary data.
99 The description and proprietary data associated with a particular value of aBitmapId
100 never changes. This allows the implementation to cache this information even after a
101 bitmap has been unregistered.
102 @param aRegionOfInterest The region within which scanline access requests will be made,
103 if known. A value of NULL implies that the user does not have any useful information
104 to contribute and the implementation must be prepared to accept scanline requests
105 anywhere inside the bitmap. If the rasterizer uses the region of interest after the
106 call to BeginBitmap() then it must make a copy of it, since the region pointed to by
107 aRegionOfInterest is valid only during the call to BeginBitmap().
109 @post The rasterizer is able to satisfy scanline requests for the bitmap identified by aBitmapId.
111 virtual void BeginBitmap(TInt64 aBitmapId,
112 const TBitmapDesc& aBitmapDesc,
113 const TRegion* aRegionOfInterest) = 0;
115 /** Unregisters a bitmap previously registered using BeginBitmap().
116 The rasterizer should access the proprietary data of a bitmap only between
117 calls to BeginBitmap() and EndBitmap(), since a bitmap can be destroyed
118 without notifying the rasterizer after the call to EndBitmap().
123 @param aBitmapId A unique identifier for the bitmap that is being unregistered.
125 @pre aBitmapId is registered with this rasterizer.
126 @post aBitmapId is unregistered once from this rasterizer. If all registrations for
127 aBitmapId have been removed, scanline access for aBitmapId is no longer supported
128 and any scanline pointers previously returned by ScanLine() become invalid.
130 virtual void EndBitmap(TInt64 aBitmapId) = 0;
132 /** Requests a pointer to a scanline containing pixel data for a specified bitmap.
137 @param aBitmapId The unique identifier of the bitmap to extract the scanline from.
138 @param aPixel An co-ordinate within the bitmap of the first pixel to retrieve.
139 @param aLength The number of pixels to retrieve.
141 @return Returns a pointer to a valid scanline, or NULL if the rasterizer can not allocate
142 enough memory to return the scanline. Note that the scanline returned is always the
143 length of a full scanline, where the first pixel returned represents x-coordinate zero
144 (not aPixel.iX), however the only pixels that are guaranteed to be valid in the returned
145 scanline are from x-coordinate aPixel.iX to x-coordinate aPixel.iX+aLength-1.
147 @pre aBitmapId must be registered with this rasterizer. The sequence of pixels identified
148 by aPixel and aLength must lie entirely inside the conceptual width and height of
149 the bitmap, i.e. the bounds specified by the bitmap's TBitmapDesc::iSizeInPixels.
150 @post Any scanline address previously returned by this rasterizer is not guaranteed to be
151 valid. If successful, the returned pointer references the start of a scanline buffer,
152 the full length of which can hold an entire row of pixels. The pixel range within
153 the scanline buffer specified by the user (aPixel.iX...aPixel.iX+aLength) will contain
154 accurate pixel values.
156 virtual const TUint32* ScanLine(TInt64 aBitmapId,
157 const TPoint& aPixel,
160 /** Returns a pointer to an extension interface. Allows extension of the CFbsRasterizer
161 interface without breaking compatibility with existing implementations.
163 @param aInterfaceId A UID defined by the OS identifying a specific extension interface.
164 @param aInterface A pointer that will be set to the extension interface.
166 @return KErrNone is returned if aInterface has been set correctly to the extension interface.
167 KErrExtensionNotSupported is returned if the rasterizer does not support the extension
168 interface specified by aExtensionId.
169 KErrNoMemory is returned if the rasterizer supports the extension interface but
170 there is not enough memory to use it.
172 @post If successful, KErrNone is returned and aInterface can be cast into a pointer to
173 the M-class associated with the specified extension UID.
175 virtual TInt GetInterface(TUid aInterfaceId, TAny*& aInterface) = 0;
178 /** The UID3 value in the compound identifier of the extended bitmap rasterizer DLL.
180 const TUid KFbsRasterizerLibraryUid = {0x10285EAE};
182 #endif // FBSRASTERIZER_H