dirscraccrenderer.cpp

symbian平台上如何在屏幕上快速的显示图片

/*
* ============================================================================
*  Name     : CDirScrAccRenderer from DirScrAccRenderer.h
*  Part of  : DirScrAcc
*  Created  : 06/11/2003 by Forum Nokia
*  Description:
*     Renderer class creating a flying flag effect.
*  Version  :
*  Copyright: Nokia Corporation
* ============================================================================
*/

#include <fbs.h>                // for CFbsBitmap
#include "DirScrAccRenderer.h"
#include <eikenv.h>             // for CEikonEnv::InfoMsg

static const TUint8 sinTable[256] =
{8,  8,  8,  8,  8,  8,  9,  9,
 9,  9,  9, 10, 10, 10, 10, 10,
11, 11, 11, 11, 11, 11, 12, 12,
12, 12, 12, 12, 13, 13, 13, 13,
13, 13, 13, 14, 14, 14, 14, 14,
14, 14, 14, 14, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 15, 15, 15,
15, 15, 15, 15, 15, 14, 14, 14,
14, 14, 14, 14, 14, 14, 13, 13,
13, 13, 13, 13, 13, 12, 12, 12,
12, 12, 12, 11, 11, 11, 11, 11,
11, 10, 10, 10, 10, 10,  9,  9,
 9,  9,  9,  8,  8,  8,  8,  8,
 8,  8,  8,  8,  8,  8,  7,  7,
 7,  7,  7,  6,  6,  6,  6,  6,
 5,  5,  5,  5,  5,  5,  4,  4,
 4,  4,  4,  4,  3,  3,  3,  3,
 3,  3,  3,  2,  2,  2,  2,  2,
 2,  2,  2,  2,  1,  1,  1,  1,
 1,  1,  1,  1,  1,  1,  1,  1,
 1,  1,  1,  1,  1,  1,  1,  1,
 1,  1,  1,  1,  1,  1,  1,  1,
 1,  1,  1,  1,  1,  1,  1,  1,
 1,  1,  1,  1,  1,  2,  2,  2,
 2,  2,  2,  2,  2,  2,  3,  3,
 3,  3,  3,  3,  3,  4,  4,  4,
 4,  4,  4,  5,  5,  5,  5,  5,
 5,  6,  6,  6,  6,  6,  7,  7,
 7,  7,  7,  8,  8,  8,  8,  8};

#define MAX_OFFSET 15
 
_LIT(KBitmapFilename, "c:\\system\\apps\\DirScrAcc\\imagedata.mbm");
const TUint16 KMMCDriveLetter = 'e';
const TUint16 KROMDriveLetter = 'z';

//
// class CFlagRenderer
//
// ---------------------------------------------------------
// CFlagRenderer::CFlagRenderer()
// Contructor (private)
// --------------------------------------------------------- 
CFlagRenderer::CFlagRenderer(TInt aWidth, TInt aHeight)
: iWidth(aWidth),
  iHeight(aHeight),  
  iFrame(0)
 {
 iLength = aWidth * aHeight;
 iScanLineLen = aWidth * 2;
 }
 
// ---------------------------------------------------------
// CFlagRenderer::NewL()
// static method for instantiating a new CFlagRenderer
// ---------------------------------------------------------
CFlagRenderer* CFlagRenderer::NewL(TInt aWidth, TInt aHeight)
 {
 CFlagRenderer* self = new (ELeave) CFlagRenderer(aWidth, aHeight);
 CleanupStack::PushL(self); 
 self->ConstructL(); 
 CleanupStack::Pop(); 
 return self;
 }

// ---------------------------------------------------------
// CFlagRenderer::ConstructL()
// Symbian 2nd phase constructor (private)
// --------------------------------------------------------- 
void CFlagRenderer::ConstructL()
 {
 // decide if we need to load normal or fullscreen bitmap
 TInt useFullScreen = (iHeight == 208) ? 1 : 0;
 // create a bitmap and load an image into it
 // image color depth must be 12 bit
 iImageFlag = new (ELeave) CFbsBitmap();

 // try 3 locations - application directory in C,E (memory card), and Z drive
 TFileName imageLocation(KBitmapFilename);

 TInt loadErr = iImageFlag->Load(imageLocation,useFullScreen);
 
 // not found on C, try E & Z
 if(loadErr != KErrNone)
        {
        imageLocation[0] = KMMCDriveLetter;    
        loadErr = iImageFlag->Load(imageLocation,useFullScreen);
        if(loadErr != KErrNone)
            {
            imageLocation[0] = KROMDriveLetter; // in emulator, apps usually reside on z
            loadErr = iImageFlag->Load(imageLocation,useFullScreen);
            }
        }    

 // not found, display error message and leave
 if(loadErr != KErrNone)
    {
    // InfoMsg only has effect in emulator
    CEikonEnv::Static()->InfoMsg(_L("imagedata.mbm not found"));
    // wait a while for the msg to show, then leave
    User::After(1000000);
    User::Leave(loadErr); 
    }
 }

// ---------------------------------------------------------
// CFlagRenderer::~CFlagRenderer()
// Destructor
// ---------------------------------------------------------  
CFlagRenderer::~CFlagRenderer()
 { 
 delete iImageFlag;
 iImageFlag = 0;
 }

// ---------------------------------------------------------
// CFlagRenderer::RenderNextFrameL()
// Renders the next frame of the waving flag to a buffer
// specified by aBitmapAddr parameter
//
// Return value: TInt - index of the last rendered frame
// ---------------------------------------------------------
TInt CFlagRenderer::RenderNextFrameL(TUint8* aBitmapAddr)
 {
 // fetch an address for our flag image data
 iFlagDataAddr = (TUint8*)iImageFlag->DataAddress();

 // clear the target buffer
 Mem::FillZ(aBitmapAddr, iLength << 1);
  
 TInt angle = iFrame;

 // horizontal scan: move scanlines to new locations according to sinTable
 // MAX_OFFSET number of bottom scanlines are reserved for vertical shift, skip these
 for(TInt s = 0; s < iHeight-MAX_OFFSET-1; s++)
  {
  Mem::Copy(aBitmapAddr + (s * iScanLineLen) + sinTable[angle % 256] * 2,
            iFlagDataAddr + (s * iScanLineLen), iScanLineLen);
            
  // store the offset for each scanline (to 4 bits not used for RGB data)  
  *(aBitmapAddr + (s * iScanLineLen) + 1) = static_cast<TUint8>((sinTable[angle % 256]) << 4);

  // calculate a new speed for scanning through sinTable
  angle += WaveSpeed(iFrame + s);
  }

  // vertical scan: move each pixel to new location according to sinTable
  // and adjust pixel brightness 
  for(TInt i = 1; i < iWidth-1; i++)
    {    
    for(TInt j = iHeight-MAX_OFFSET-2; j ; j--)
        {
        TUint16* orgLocation = (TUint16*)aBitmapAddr + j*iWidth + i;
        TUint16* movLocation = orgLocation + (sinTable[angle % 256] * iWidth);

        // get the offset stored in horizontal scan phase and calculate an average of hz/vt offsets        
        TUint8 hzOffset = static_cast<TUint8>(*(aBitmapAddr + ((j * iScanLineLen) + 1)) >> 4);        
        TInt avgOffset = ((sinTable[angle % 256] + hzOffset) >> 2);

        if(orgLocation != movLocation)
            {            
            // use the avg. offset to dim the pixels                        
            TInt8 r = static_cast<TInt8>((*orgLocation  & 0x00f) - avgOffset);
            TInt8 g = static_cast<TInt8>(((*orgLocation & 0x0f0) >> 4) - avgOffset);
            TInt8 b = static_cast<TInt8>(((*orgLocation & 0xf00) >> 8) - avgOffset);

            // copy the pixel data to a new location
            (r < 0) ? *movLocation  = 0     : *movLocation  = r;
            (g < 0) ? *movLocation &= 0xf0f : *movLocation |= g << 4;
            (b < 0) ? *movLocation &= 0x0ff : *movLocation |= b << 8;
        
            // zero the original pixel
            *orgLocation = 0;
            }
        }

    // calculate a new speed for scanning through sinTable
    angle += WaveSpeed(iFrame + i + 70);
    }
 
 return iFrame++;
 }

inline TInt CFlagRenderer::WaveSpeed(TInt aIndex)
    {    
    TInt waveSpeed = (aIndex & 0xe0) >> 5;
    return (waveSpeed > 4) ? 9 - waveSpeed : waveSpeed + 1;        
    }