symbian半透明效果

概述

本文描述了如何在支持EColor16MA显示模式的设备上创建半透明窗口。

前提条件

设备必须支持EColor16MA显示模式。使用以下代码可以检查设备支持的显示模式。

if(CCoeEnv::Static()->ScreenDevice()->DisplayMode()==EColor16MA)
{
// 支持EColor16MA
}

方案

本方案最初由william.edwards在UIQ论坛的"半透明窗口"系列文章中阐明 (UIQ论坛已经关闭，但仍然可以使用Google搜索"Semi-Transparent Windows #1"和"Semi-Transparent Windows #2"，然后查看缓存的网页).

void CControlOnTopCtrl::ConstructL(const TRect& aRect, RWindowGroup* aWindowGroup)
{
  TRect rc(aRect);
  TInt w = rc.Width();
  TInt h = rc.Height();
 
  CreateWindowL(aWindowGroup);
for (TInt i = 0; i < 2; i++)
{
	w /= 2;
	h /= 2;
}
 
  SetUniqueHandle(EMyCueControl);
 
  TRect rc_new(w, h, w+15, h+15);
  SetRect(rc_new);
// begin by chen, code from William's post
// we need to set the display mode to ensure that it has an
// alpha-component specified.  However, the system may instead return
// another display mode.  We don't have to pay much attention, as the
// call to SetTransparencyAlphaChannel will check wether the Window
// Server and the window's display mode support this kind of
// transparency
	Window().SetRequiredDisplayMode(EColor16MA);
	TRgb backgroundColour = KRgbWhite; // for example
if(KErrNone == Window().SetTransparencyAlphaChannel())
{
// we now have a semi-transparent window,
// so we have to not clear the window region in an
// opaque colour before drawing it each time;
// 0 alpha is completely transparent,
// 255 alpha is completely opaque
		backgroundColour.SetAlpha(0);
}
	Window().SetBackgroundColor(backgroundColour);
// end by chen
  ActivateL();
}

该代码已经在S60第五版仿真器和一台支持EColor16MA显示模式的设备上验证通过, 以下是仿真器屏幕截图 (透明窗口上的红点):

 

 

 

传入相应的图片,就会把图片变成半透明效果并显示在程序界面上.

　　void CMegajoyContainer::ConvertToAlpha(CWindowGc& gc,CFbsBitmap *imgToBrighten) const

　　{

　　CFbsBitmap* iEmptyBitmap = new ( ELeave ) CFbsBitmap();

　　CleanupStack::PushL( iEmptyBitmap );

　　User::LeaveIfError( iEmptyBitmap->Create( imgToBrighten->SizeInPixels(), CEikonEnv::Static()->DefaultDisplayMode() ) );

　　CFbsBitmapDevice *iGD = CFbsBitmapDevice::NewL( iEmptyBitmap );

　　CleanupStack::PushL( iGD );

　　CFbsBitGc *iGC;

　　User::LeaveIfError( iGD->CreateContext( iGC ) );

　　iGC->SetPenStyle( CGraphicsContext::ENullPen );

　　iGC->SetBrushColor( KRgbWhite );

　　iGC->SetBrushStyle( CGraphicsContext::ESolidBrush );

　　iGC->DrawRect( TRect(TPoint(0,0), iEmptyBitmap->SizeInPixels()) );

　　iGC->SetBrushStyle( CGraphicsContext::ENullBrush );

　　delete iGC;

　　CleanupStack::PopAndDestroy( iGD );

　　CFbsBitmap* iEmptyBitmapMask = new ( ELeave ) CFbsBitmap();

　　CleanupStack::PushL( iEmptyBitmapMask );

　　User::LeaveIfError( iEmptyBitmapMask->Create( imgToBrighten->SizeInPixels(), EGray256 ) );

　　iGD = CFbsBitmapDevice::NewL( iEmptyBitmapMask );

　　CleanupStack::PushL( iGD );

　　User::LeaveIfError( iGD->CreateContext( iGC ) );

　　iGC->SetPenStyle( CGraphicsContext::ENullPen );

　　iGC->SetBrushColor( KRgbGray );

　　iGC->SetBrushStyle( CGraphicsContext::ESolidBrush );

　　iGC->DrawRect( TRect(TPoint(0,0), iEmptyBitmap->SizeInPixels()) );

　　iGC->SetBrushStyle( CGraphicsContext::ENullBrush );

　　delete iGC;

　　CleanupStack::PopAndDestroy( iGD );

　　gc.BitBltMasked(TPoint(0,0),iEmptyBitmap,TRect(TPoint(0,0),iEmptyBitmapMask->SizeInPixels()),iEmptyBitmapMask,EFalse);

　　CleanupStack::PopAndDestroy(iEmptyBitmapMask);

　　CleanupStack::PopAndDestroy( iEmptyBitmap );

　　}

　　注意要在.mmp文件中加入库文件

　　LIBRARY bitgdi.lib

　　LIBRARY ws32.lib

　　LIBRARY fbscli.lib