Symbian中卡拉OK字幕实现_symbian播放器字幕-优快云博客

在Symbian环境下实现卡拉OK字幕功能，包括双缓冲位图资源的创建、释放及重画，使用特定字体颜色在两张位图上显示文字信息，并通过BitBlt函数将这两张图拼接实现字幕效果。实现过程涉及窗口、位图、字体、颜色和坐标等概念。

Symbian中卡拉OK字幕实现

纯属个人娱乐，代码贴出，有什么问题和建议可以留言。

实现步骤如下：

在.h文件中

private:
/**
* CreateBackBufferL.
* 用于创建双缓冲位图资源的函数.
*/
void CreateBackBufferL();
/**
* ReleaseBackBuffer.
* 用于释放双缓冲位图资源的函数.
*/
void ReleaseBackBuffer();

void DrawToBackBuffer();

//双缓冲用到的私有成员
private:
CFbsBitmap*                     iBackBuffer; //双缓冲中用到的位图
CFbsBitmapDevice*               iBackBufferDevice; //用于得到Gc
CFbsBitGc*                      iBackBufferContext; //双缓冲位图Gc

CFbsBitmap*                     iBackBuffer_2; //双缓冲中用到的位图
CFbsBitmapDevice*               iBackBufferDevice_2; //用于得到Gc
CFbsBitGc*                      iBackBufferContext_2; //双缓冲位图Gc

在。cpp中函数的实现

void CAuditionContainer::CreateBackBufferL()
{
// Create back buffer bitmap
iBackBuffer = new (ELeave) CFbsBitmap;

User::LeaveIfError( iBackBuffer->Create(TSize(240,30),
iEikonEnv->DefaultDisplayMode()));

// Create back buffer graphics context
iBackBufferDevice = CFbsBitmapDevice::NewL(iBackBuffer);
User::LeaveIfError(iBackBufferDevice->CreateContext(iBackBufferContext));
iBackBufferContext->SetPenStyle(CGraphicsContext::ESolidPen);

iBackBuffer_2 = new (ELeave) CFbsBitmap;

User::LeaveIfError( iBackBuffer_2->Create(TSize(240,30),
iEikonEnv->DefaultDisplayMode()));

// Create back buffer graphics context
iBackBufferDevice_2 = CFbsBitmapDevice::NewL(iBackBuffer_2);
User::LeaveIfError(iBackBufferDevice_2->CreateContext(iBackBufferContext_2));
iBackBufferContext_2->SetPenStyle(CGraphicsContext::ESolidPen);
}

void CAuditionContainer::ReleaseBackBuffer()
{
// Release double buffering classes
if (iBackBufferContext)
{
  delete iBackBufferContext;
  iBackBufferContext = NULL;
}
if (iBackBufferDevice)
{
  delete iBackBufferDevice;
  iBackBufferDevice = NULL;
}
if (iBackBuffer)
{
  delete iBackBuffer;
  iBackBuffer = NULL;
}
if (iBackBufferContext_2)
{
  delete iBackBufferContext_2;
  iBackBufferContext_2 = NULL;
}
if (iBackBufferDevice_2)
{
  delete iBackBufferDevice_2;
  iBackBufferDevice_2 = NULL;
}
if (iBackBuffer_2)
{
  delete iBackBuffer_2;
  iBackBuffer_2 = NULL;
}
}

void CAuditionContainer::DrawToBackBuffer()
{
const CFont *Font = CEikonEnv::Static()->DenseFont();
iBackBufferContext->UseFont(Font);
// _LIT(KText,"hello world");

TBuf8<20> msg8 ;
TBuf<20> KText ;
msg8.Format(_L8(" 谢谢您的使用")) ;
ConvGbk2Uni(msg8, KText) ;

iBackBufferContext->SetPenColor(KRgbGreen);
iBackBufferContext->DrawText(KText,TPoint(0,Font->HeightInPixels()));

iBackBufferContext_2->UseFont(Font);
// _LIT(KText,"hello world");
iBackBufferContext_2->SetPenColor(KRgbRed);
iBackBufferContext_2->DrawText(KText,TPoint(0,Font->HeightInPixels()));
}

void CAuditionContainer::Draw( const TRect& /*aRect*/ ) const
{
CWindowGc& gc = SystemGc();
gc.Clear();
gc.BitBlt(TPoint(0,100),iBackBuffer,TRect(TPoint(0,0),TSize(iBackBuffer->SizeInPixels().iWidth/5,iBackBuffer->SizeInPixels().iHeight)));
gc.BitBlt(TPoint(iBackBuffer_2->SizeInPixels().iWidth/5,100),iBackBuffer_2,TRect(TPoint(iBackBuffer_2->SizeInPixels().iWidth/5,0),TSize(iBackBuffer_2->SizeInPixels().iWidth*4/5,iBackBuffer_2->SizeInPixels().iHeight)));

}

使用步骤

第一步：初始化

在container的SetRect之前添加如下代码：

      iBackBuffer = NULL;
     iBackBufferDevice = NULL;
     iBackBufferContext = NULL;

     iBackBuffer_2 = NULL;
      iBackBufferDevice_2 = NULL;
      iBackBufferContext_2 = NULL;

第二步：在sizechange中添加代码

      ReleaseBackBuffer(); //释放双缓冲位图资源
      CreateBackBufferL(); //创建双缓冲位图资源
      DrawToBackBuffer(); //重画双缓冲位图资源

第三步：编译运行即可。

图片没发上传，看不到效果了。

实现的基本思路：将 “谢谢您的使用”这句话分别用两种字体颜色写在两张位图上，在Draw函数中通过BitBlt函数将两张图拼接，即可实现一个字，两种颜色。如需要实现卡拉OK中的移动效果，只需要通过一个循环定时器，改变BitBlt函数中的TPoint和TRect即可。还算是比较方便的。

抱歉贴掉了一个函数，在这里补上

void ConvGbk2Uni(TDesC8& original, TDes& res)
{
//RFs aFileServerSession = CEikonEnv::Static()->FsSession();
RFs aFileServerSession;
aFileServerSession.Connect();
// CleanupStack::Pop();
CCnvCharacterSetConverter* converter=CCnvCharacterSetConverter::NewLC();

if(converter->PrepareToConvertToOrFromL(KCharacterSetIdentifierGbk,aFileServerSession)!=CCnvCharacterSetConverter::EAvailable)
User::Leave(KErrNotSupported);

TInt state=CCnvCharacterSetConverter::KStateDefault;

TPtrC8 str( original );
HBufC* iInfoText = HBufC::NewL( str.Length() );

TPtr16 ptr = iInfoText->Des();

if(CCnvCharacterSetConverter::EErrorIllFormedInput == converter->ConvertToUnicode(ptr, str, state))
User::Leave(KErrArgument);

res.Zero() ;
res.Copy(ptr) ;
aFileServerSession.Close();
CleanupStack::PopAndDestroy();
delete iInfoText;
}