如何将N97变成罗盘仪

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文章信息

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代码示例

源文件: Media:PhoneCompass.zip

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文章

翻译:

翻译自: How to turn the N97 into a Magnetic Compass

由 hoolee

最后由 hamishwillee 在 22 Dec 2011 编辑

简介

下列代码演示了如何将N97变成一个罗盘。这个程序可以用来根据内建的磁北感应器，用来寻找磁北方向。如果你转动设备，那么罗盘就会转向北方。

磁北感应器

N97以及某些设备有一个内建的磁力仪。这个磁力仪可以用来寻找方向。可以通过位图旋转来改变。

	TInt i = 0;
	CSensrvChannelFinder* finder = CSensrvChannelFinder::NewLC();
	RSensrvChannelInfoList channelList;
	CleanupClosePushL( channelList );
	TSensrvChannelInfo Channelinfo;
	finder->FindChannelsL( channelList, Channelinfo );
 
	for (i = 0; i<channelList.Count(); i++)
		{
	    Channelinfo = channelList[i];
	    switch(Channelinfo.iChannelType)
	        {
	        case KSensrvChannelTypeIdMagneticNorthData:
	        	iBoolMagSupported = ETrue;
	            break;
	        default:
	        	iBoolMagSupported = EFalse;
	            break;
	        }	
	    if(iBoolMagSupported == (TInt)ETrue)
	    	{
	    	break;
	    	}	    
	    }
 
    if(iBoolMagSupported == (TInt)EFalse)
    	{
    	User::Leave(KErrNotSupported);
    	}	
 
    if ( channelList.Count() > 0 )
        {
        Channelinfo = channelList[i];
        iMagneticNorthSensor = CSensrvChannel::NewL( channelList[ i ] );
        iMagneticNorthSensor->OpenChannelL();
        iMagneticNorthSensor->StartDataListeningL( this, 1, 1, 0 );                 
        }
    channelList.Close();
    CleanupStack::Pop( &channelList );
    CleanupStack::PopAndDestroy( finder );

位图旋转

Following code shows how to rotate bitmap.
 
CFbsBitmap *CImageConverterEngine::Bitmap_Rotate(TInt Angle)
{
 
	Angle = 360 -Angle;
    TReal CosA = 0.0;
    TReal SinA = 0.0;
 
	   if(!iOriginalBitmap)
	    	{
	    	return NULL;
	    	}
 
    TBitmapUtil BaseBmpUtil(iOriginalBitmap);
 
    TBitmapUtil RotateBmpUtil(iRotatedBitmap);
 
    BaseBmpUtil.Begin(TPoint(0,0));
 
    RotateBmpUtil.Begin(TPoint(0,0), BaseBmpUtil);
      RotateBmpUtil.Begin(TPoint(0,0));
 
    TReal aAngle = (KPi/180.0)* (TReal)Angle;
 
    TInt ret = Math::Cos(CosA, aAngle);
      if(ret != KErrNone)
    	  {
    	  return NULL;
    	  }
 
     ret = Math::Sin(SinA, aAngle);
      if(ret != KErrNone)
    	  {
    	  return NULL;
    	  }      
 
    TInt xC = iSize.iWidth/2;
    TInt yC = iSize.iHeight/2;
 
    for(TInt new_y=0;new_y<iSize.iHeight;new_y++)
    {   
        for(TInt new_x=0;new_x<iSize.iWidth;new_x++)
        {	
            if( (new_x-xC)*(new_x-xC) + (new_y-yC)*(new_y-yC) <= (xC*yC))
			{
				TInt x = xC + (TInt)(((new_x - xC)*CosA) + ((new_y-yC)*SinA)); //new x pixel bitmap
				TInt y = yC + (TInt)(-((new_x-xC)*SinA) + ((new_y-yC)*CosA)); // new y pixel bitmap
 
				BaseBmpUtil.SetPos(TPoint(x,y));
				RotateBmpUtil.SetPos(TPoint(new_x,new_y));
				RotateBmpUtil.SetPixel(BaseBmpUtil);
			}    
        }
    }
    BaseBmpUtil.End();
    RotateBmpUtil.End();
 
    return iRotatedBitmap;
}

示例程序

这里需要ReadDeviceData能力 示例程序需要在N97上测试，可以在这里下载File:PhoneCompass.zip