当在系统设置中设置了“实时监控”，此时手机画面的指示面板上应该出现一个图标，表明有程序在后台运行。
本文就是探讨怎样在S60指示面板上画图标。为了在电源面板附近显示图标，你必须要作相应的编码。
我写了一个CIndicatorIcon的类，它继承自CCoeControl。
二次构造函数ConstructL()代码如下：
void CIndicatorIcon::ConstructL()
{
iMyWindowGroup = RWindowGroup(iCoeEnv->WsSession());
User::LeaveIfError(iMyWindowGroup.Construct((TUint32)&iMyWindowGroup));
iMyWindowGroup.SetOrdinalPosition(0, ECoeWinPriorityAlwaysAtFront);
iMyWindowGroup.EnableReceiptOfFocus(EFalse);
CreateWindowL(&iMyWindowGroup);
// by default setting the indicator icon to inactive
SetIndicatorIconL(EIndicatorIconAppActive);
ActivateL();
}
注意，RWindowGroup需要W32std.h头文件，连接时需要添加Ws32.lib。
在构造函数中，调用另外一个函数SetIndicatorIconL()来设置图标：
void CIndicatorIcon::SetIndicatorIconL(TIndicatorIcon aIndicatorIconType, TBool aRedraw)
{
switch(aIndicatorIconType)
{
case EIndicatorIconEmpty:
iIndicator = CEikonEnv::Static()->CreateBitmapL(KSysIconFile, EMbmAvkonQgn_prop_empty);
iIndicatorMask = CEikonEnv::Static()->CreateBitmapL(KSysIconFile, EMbmAvkonQgn_prop_empty_mask);
break;
case EIndicatorIconAppActive:
iIndicator = CEikonEnv::Static()->CreateBitmapL(KSysIconFile, EMbmAvkonQgn_bt_connect_on);
iIndicatorMask = CEikonEnv::Static()->CreateBitmapL(KSysIconFile, EMbmAvkonQgn_bt_connect_on_mask);
break;
case EIndicatorIconAppInactive:
iIndicator = CEikonEnv::Static()->CreateBitmapL(KSysIconFile, EMbmAvkonQgn_prop_bt_audio);
iIndicatorMask = CEikonEnv::Static()->CreateBitmapL(KSysIconFile, EMbmAvkonQgn_prop_bt_audio_mask);
break;
default:
break;
}
SetRect(TRect(TPoint(KIndicatorPosX, KIndicatorPosY),iIndicator->SizeInPixels()));
// if aRedraw == ETrue just draw the canvas again.
if(aRedraw)
{
DrawNow();
}
}
上面把指示面板需要显示的图标设置好了，但是必须要重载CCoeControl的Draw()函数来显示这个图标，Draw()代码如下：
void CIndicatorIcon::Draw(const TRect& aRect) const
{
CWindowGc& gc = SystemGc();
gc.Clear();
gc.SetBrushStyle(CGraphicsContext::ENullBrush);
gc.BitBltMasked(TPoint(aRect.iTl.iX, aRect.iTl.iY),
iIndicator,
TRect(TPoint(0, 0), iIndicator->SizeInPixels()),
iIndicatorMask,
ETrue);
}
最后在AppUi类的构造函数中添加如下两行代码：
iIndicatorIcon = CIndicatorIcon::NewL();
// The next line will set the icon to draw and it'll draw to the screen.
iIndicatorIcon->SetIndicatorIconL(CIndicatorIcon::EIndicatorIconAppInactive, ETrue);
效果图如下：
Indicator icon when application is running in the foreground.
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Indicator icon when application is running in the background..
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Indicator icon when application is running in the background with the task view..
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你可以在这里下载示例程序的源代码：
Sample code for showing icon on the IndicatorPane