engine/inc/ImageHandler.h
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     1 /*
       
     2 * Copyright (c) 2007-2010 Sebastian Brannstrom, Lars Persson, EmbedDev AB
       
     3 *
       
     4 * All rights reserved.
       
     5 * This component and the accompanying materials are made available
       
     6 * under the terms of the License "Eclipse Public License v1.0"
       
     7 * which accompanies this distribution, and is available
       
     8 * at the URL "http://www.eclipse.org/legal/epl-v10.html".
       
     9 *
       
    10 * Initial Contributors:
       
    11 * EmbedDev AB - initial contribution.
       
    12 *
       
    13 * Contributors:
       
    14 * Example code from OcrExample Copyright (c) 2006 Nokia Corporation.
       
    15 * Description:
       
    16 *
       
    17 */
       
    18 
       
    19 #ifndef IMAGEHANDLER_H
       
    20 #define IMAGEHANDLER_H
       
    21 
       
    22 #include <f32file.h>
       
    23 #include <ImageConversion.h>
       
    24 #include <BitmapTransforms.h>
       
    25 
       
    26 /**
       
    27  * Listener interface that can be used to listen for image loading operation
       
    28  * completion events from CImageHandler.
       
    29  *
       
    30  * The class is intended to be implemented by a client class that observes the
       
    31  * loading operation of image handler. The methods in this class
       
    32  * are called by the image handler (class CImageHandler) when it loads
       
    33  * an image.
       
    34  *
       
    35  * Reference to implementations of this listener interface can be passed as
       
    36  * a parameter to the constructor of the image handler (class CImageHandler).
       
    37  */
       
    38 class MImageHandlerCallback
       
    39     {
       
    40 public:
       
    41    /**
       
    42     * Called by CImageHandler when an image has been loaded.
       
    43     * @param aError Error code given by the CImageHandler or 0 (zero) if the
       
    44     *   image was loaded successfully.
       
    45     */
       
    46     virtual void ImageOperationCompleteL(TInt aError) = 0;
       
    47     };
       
    48 
       
    49 // ============================================================================
       
    50 class TImageStruct
       
    51 	{
       
    52 public:
       
    53 	CFbsBitmap* iScaledImage;
       
    54 	TSize iScaledSize;
       
    55 	MImageHandlerCallback* iCallBack;
       
    56 	TFileName iFileName;
       
    57 	};
       
    58 /**
       
    59 *  CImageHandler
       
    60 *  Image loader and scaler class.
       
    61 */
       
    62 class CImageHandler : public CActive
       
    63     {
       
    64     public: // Constructors and destructor
       
    65        /**
       
    66         * Factory method that constructs a CImageHandler by using the NewLC method
       
    67         * and then cleans the cleanup stack.
       
    68         * @param aBitmap Bitmap where the image data is loaded to.
       
    69         * @param aScaledBitmap Bitmap where the scaled image data is loaded to.
       
    70         * @param aFs File server reference that is used to load the image data.
       
    71         * @param aCallback Listener interface implementation that is notified
       
    72         *  when an image has been loaded.
       
    73         * @return pointer to created CImageHandler-object
       
    74         */
       
    75         IMPORT_C static CImageHandler* NewL(RFs& aFs);
       
    76 
       
    77        /**
       
    78         * Factory method that constructs a CImageHandler and leaves it to the
       
    79         * cleanup stack.
       
    80         * @param aBitmap Bitmap where the image data is loaded to.
       
    81         * @param aScaledBitmap Bitmap where the scaled image data is loaded to.
       
    82         * @param aFs File server reference that is used to load the image data.
       
    83         * @param aCallback Listener interface implementation that is notified
       
    84         *  when an image has been loaded.
       
    85         * @return pointer to created CImageHandler-object
       
    86         */
       
    87         IMPORT_C static CImageHandler* NewLC(RFs& aFs);
       
    88        /**
       
    89         * Desctructor. Destroys the CImageDecoder used by the image handler.
       
    90         */
       
    91         IMPORT_C virtual ~CImageHandler();
       
    92         IMPORT_C CFbsBitmap* ScaledBitmap();
       
    93     public: // New functions      
       
    94 
       
    95         /**
       
    96          * Loads a the given frame from the given file and scale it to the
       
    97          * specified size
       
    98          * @param aFileName Filename wherefrom the bitmap data is loaded.
       
    99          * @param aSize the target size for the scaling
       
   100          * @param aSelectedFrame A single frame index in a multi-frame file.
       
   101          *  If not given the first frame is loaded.
       
   102          */
       
   103     	IMPORT_C void LoadFileAndScaleL(CFbsBitmap* aScaledBitmap, 
       
   104 							   const TFileName& aFileName,
       
   105                                const TSize &aSize,
       
   106                                MImageHandlerCallback& aCallback,
       
   107                                TInt aSelectedFrame = 0);
       
   108 
       
   109         /**
       
   110          * Returns the current frame information.
       
   111          * @return Current frame information.
       
   112          */
       
   113         const TFrameInfo& FrameInfo() const;     
       
   114     private:
       
   115         /**
       
   116          * Loads a the given frame from the given file.
       
   117          * @param aFileName Filename wherefrom the bitmap data is loaded.
       
   118          * @param aSelectedFrame A single frame index in a multi-frame file. If not given the first frame is loaded.
       
   119          */
       
   120         void LoadFileL(const TFileName& aFileName, TInt aSelectedFrame = 0);
       
   121 
       
   122        /**
       
   123         * Scales a loaded image
       
   124         * Scales a loaded image to the target size (given in LoadFileAndScaleL or
       
   125         * FitToScreenL). The scaled image is stored into iScaledBitmap.
       
   126         */
       
   127         void ScaleL();
       
   128 
       
   129     private: // Functions from base classes
       
   130 
       
   131         /**
       
   132          * CActive::RunL() implementation. Called on image load success/failure.
       
   133          */
       
   134         void RunL();
       
   135         /**
       
   136          * CActive::Cancel() implementation. Stops decoding.
       
   137          */
       
   138         void DoCancel();
       
   139 
       
   140     protected:
       
   141         /**
       
   142          * C++ default constructor. Just stores the given parameters to
       
   143          * corresponding attributes.      
       
   144          * @param aScaledBitmap Bitmap where the scaled image data is loaded to.
       
   145          * @param aFs File server reference that is used to load the image data.
       
   146          * @param aCallback Listener interface implementation that is notified
       
   147          *  when an image has been loaded.
       
   148          */
       
   149         CImageHandler(RFs& aFs);
       
   150         /**
       
   151          * 2nd phase constructor. Adds this object to the active scheduler.
       
   152          */
       
   153         void ConstructL();
       
   154 
       
   155     private: // Data
       
   156         /** Image decoder that is used to load the image data from file. */
       
   157         CImageDecoder           *iDecoder;
       
   158 
       
   159         /** Image scaler that is used to scale the image */
       
   160         CBitmapScaler           *iScaler;
       
   161 
       
   162         /** Listener that is notified when an image has been loaded. */
       
   163         MImageHandlerCallback *  iCallback;
       
   164 
       
   165         /** Bitmap (owned by the user of this class) where the loaded image is put */
       
   166         CFbsBitmap              *iBitmap;
       
   167 
       
   168         /** Bitmap (owned by the user of this class) where the SCALED image is put */
       
   169         CFbsBitmap              *iScaledBitmap;
       
   170 
       
   171         /** File server session (owned by the user of this class) */
       
   172         RFs                     &iFs;
       
   173 
       
   174         /** Current image frame information. */
       
   175         TFrameInfo              iFrameInfo;
       
   176 
       
   177         /** target size for scaled image */
       
   178         TSize                   iSize;
       
   179         RArray<TImageStruct> iCallbackQue;      
       
   180     };
       
   181 
       
   182 #endif
       
   183