Symbian开发笔记(一)

CTest_1AppUi::HandleCommandL(TInt aCommand)
{
switch ( aCommand )
{
case EAknSoftkeyBack:
case EEikCmdExit:
{

_LIT(KQueryDelete,"Are you sure to delete it?");
CAknQueryDialog* dlg = new(ELeave) CAknQueryDialog(const_cast<TDesC&>(KQueryDelete()),CAknQueryDialog::EWarningTone);
dlg->ExecuteLD(R_DIALOG_DELETE_QUERY);
break;
}
case ETest_1CmdAppTest:
{
// Info message shown only in the emulator
iEikonEnv->InfoMsg(_L("test"));

// Load localized message from the resource file
HBufC* message = CEikonEnv::Static()->AllocReadResourceLC(R_MESSAGE_TEXT);

// Show information note dialog
CAknInformationNote* note = new (ELeave) CAknInformationNote;

note->ExecuteLD(message->Des());
CleanupStack::PopAndDestroy(message);
break;
}
// TODO: Add Your command handling code here

default:
break;
}

这里面有几个知识点:

1:_LIT()宏所定义的常量并不是描述符,但可以通过使用一个重载的运算符()将其转换为const TDesC&类型的描述符。

2:CAknQueryDialog的第一个参数需要一个TDesC&类型的参数,所以我们需要把KQueryDelete()强制转换成非const类型的,这需要使用C++中的强制类型转换const_cast<TDesC&>。

3:千万注意要把const_cast<TDesC&>所接的数据加上()。

void CTest_1AppUi::HandleCommandL(TInt aCommand)
{
switch ( aCommand )
{
case EAknSoftkeyBack:
case EEikCmdExit:
{
_LIT(KQueryDelete,"Are you sure to delete it?");
CAknQueryDialog* dlg = new(ELeave) CAknQueryDialog(const_cast<TDesC&>(KQueryDelete()),CAknQueryDialog::EWarningTone);

TInt temp = dlg->ExecuteLD(R_DIALOG_DELETE_QUERY);

_LIT(KReturnValue,"the return value is :");

HBufC* iBuf = HBufC::NewLC(100);
iBuf->Des().Copy(KReturnValue);
iBuf->Des().AppendNum(temp);
CEikonEnv::Static()->InfoMsg(*iBuf);
CleanupStack::PopAndDestroy(iBuf);
break;
}

default:
break;
}
}

从程序执行中我们可以看到,当我们点dlg的NO按钮时,temp的值为一个正数(程序中是3005),而当我们点dlg 的OK的时候,temp的值为0。

所以我们在很多程序中可以看到类似下面的代码:

if(dlg->ExecuteLD(R_DIALOG_DELETE_QUERY))
{
TInt index = iListBox->CurrentItemIndex();
TName name(db.iName);
iUi->iDB->iArrayDB->Delete(index);
iUi->iDB->SaveDBL();
CEikonEnv::Static()->ReadResource(info, R_STR_DELETE_TIPS);
tips.Format(info, &name);
ShowNotify(tips);
if(iUi->iDB->iArrayDB->Count()==0)
{
CEikonEnv::Static()->ReadResource(info, R_STR_NO_CD_TIPS);
ShowNotify(info);
CreateFunctionListBoxL();
}
else
{
CreateRecordListBoxL();
}
}

也就是判断我们是否点击了Dialog的OK按钮。

RESOURCE LOCALISABLE_APP_INFO r_httpenginetest_localisable_app_info
{
short_caption = "HttpEngine";
caption_and_icon =
CAPTION_AND_ICON_INFO
{
caption = "HttpEngineTest";
number_of_icons = 2;
icon_file = "\\resource\\apps\\HttpEngineTestaif.mbm";
};
}

RESOURCE RSS_SIGNATURE {}

RESOURCE TBUF { buf=""; }

RESOURCE EIK_APP_INFO
{
menubar = r_httpenginetest_menubar;
cba = R_AVKON_SOFTKEYS_OPTIONS_BACK;
}

这样写会报告“系统错误”并看不到应用程序的icon，看来签名、文档名缓冲还是要放前面，如下：

RESOURCE RSS_SIGNATURE {}

RESOURCE TBUF { buf=""; }

RESOURCE LOCALISABLE_APP_INFO r_httpenginetest_localisable_app_info
{
short_caption = "HttpEngine";
caption_and_icon =
CAPTION_AND_ICON_INFO
{
caption = "HttpEngineTest";
number_of_icons = 2;
icon_file = "\\resource\\apps\\HttpEngineTestaif.mbm";
};
}

RESOURCE EIK_APP_INFO
{
menubar = r_httpenginetest_menubar;
cba = R_AVKON_SOFTKEYS_OPTIONS_BACK;
}

其实上面这样改，在程序运行到BaseConstructL(EAknEnableSkin)时会报告“User 23”系统错误，原因是我们把LOCALISABLE_APP_INFO放到了EIK_APP_INFO前面去了，应该像下面这样改：

NAME MHWA

#include <eikon.rh>
#include <avkon.rsg>
#include <avkon.rh>
#include <avkon.mbg>
#include <appinfo.rh>

RESOURCE RSS_SIGNATURE {}

RESOURCE TBUF r_default_document_name
{
buf="";
}

RESOURCE EIK_APP_INFO
{
menubar = r_httpenginetest_menubar;
cba = R_AVKON_SOFTKEYS_OPTIONS_BACK;
}

RESOURCE LOCALISABLE_APP_INFO r_httpenginetest_localisable_app_info
{
short_caption = "HttpEngine";
caption_and_icon =
CAPTION_AND_ICON_INFO
{
caption = "HttpEngineTest";
number_of_icons = 2;
icon_file = "\\resource\\apps\\HttpEngineTestaif.mbm";
};
}