How to select and show a landmark
Article Metadata
Standard Dialogs
Landmarks UI Selector API contains several classes that allow you to select landmarks as well as landmark categories.
Headers required:
#include <clmklandmarkselectordlg.h> //CLmkLandmarkSelectorDlg
#include <clmkcategoryselectordlg.h> //CLmkCategorySelectorDlg
#include <clmkeditordlg.h> // CLmkEditorDlg
Library needed:
LIBRARY LmkCommonUi.lib //CLmkLandmarkSelectorDlg , CLmkCategorySelectorDlg
Required Capabilities:
Capabilities LocalServices Location NetworkServices ReadUserData WriteUserData
The following code snippet demonstrates how to select one landmark
TLmkItemIdDbCombiInfo item;
CLmkLandmarkSelectorDlg* selectLandmarkDlg = CLmkLandmarkSelectorDlg :: NewL();
selectLandmarkDlg->SetMopParent( this );
// select one landmark
if( selectLandmarkDlg->ExecuteLD( item ) != 0 ) // dlg is deleted automatically
{
// get item ID
TPosLmItemId itemId = item.GetItemId();
// your code here
delete item.GetLmDb(); // fixing memory leak
}
And next code snippet demonstrates how to select multiple landmarks:
CLmkLandmarkSelectorDlg* selectLandmarkDlg = CLmkLandmarkSelectorDlg::NewL();
selectLandmarkDlg->SetMopParent( this );
RArray< TLmkItemIdDbCombiInfo > arrItems;
CleanupClosePushL( arrItems );
// select list of active landmarks
if( selectLandmarkDlg->ExecuteLD( arrItems ) != 0 )
{
// your code here
delete arrItems[0].GetLmDb(); // fixing memory leak
}
CleanupStack::PopAndDestroy(); // arrItems
You can use class CLmkCategorySelectorDlg for selecting one or more categories in the same manner (include clmkcategoryselectordlg.h).
Landmarks UI Add/Edit API allows to use standart dialog for view/edit the specified landmark. API contains one class CLmkEditorDlg ( include clmkeditordlg.h ).
The following code snippet demonstrates how to edit specified landmark:
// Opens the default landmark database
CPosLandmarkDatabase* db = CPosLandmarkDatabase :: OpenL( );
CleanupStack::PushL( db );
CLmkEditorDlg::TLmkEditorParams editParams;
// all attributes of the landmark will be presented
editParams.iAttributes = CLmkEditorDlg::ELmkAll;
// user can change values of the attributes
editParams.iEditorMode = CLmkEditorDlg::ELmkEditor;
// lmItem - ID of the specified landmark
CLmkEditorDlg *dlg = CLmkEditorDlg::NewL(*db, lmItem, editParams);
dlg->ExecuteLD();
CleanupStack :: PopAndDestroy(); // db
Custom Dialogs
This example demostrates:
- how to select landmark from database
- how to read landmark data (latitude, longitude...)
- how to present landmark data
There are used following header files:
#include <clmklandmarkselectordlg.h>
#include <tlmkitemiddbcombiinfo.h>
#include <epos_cposlandmarkdatabase.h>
#include <e32cmn.h> //Abs
MMP-file must include following libraries:
LIBRARY lmkcommonui.lib
LIBRARY eposlandmarks.lib
LIBRARY lbs.lib
// for dialog
LIBRARY eikdlg.lib
LIBRARY eikctl.lib
It is necessary to note, that the values of coordinates of each landmark from the database are presented in decimal system - it is good for calculations. In pratice, for demonstrating latitude and longitude, there are used deg, minutes and seconds. Geographical latitudes of landmarks, located in the North Hemisphere are considered positive, and the latitude of landmarks in the South Hemisphere are considered negative. Geographical longtitude of marks, located west of Greenwich meridian are considered positive, and the longtitude of marks located east of Greenwich are considered negative.
For translating latitude/longitude from decimal system You can use the function Decompose2Geographical:
const TInt KMinsPerDegree = 60;
const TInt KSecsPerDegree = 3600;
// decompose latitude/longitude in deg, minutes, seconds
void YourClassName :: Decompose2Geographical( TReal64& aValue, TInt& aDeg,
TInt& aMinutes, TReal& aSeconds )
{
aDeg = ( TInt )aValue;
aMinutes = ( Abs( aValue - aDeg ) ) * KMinsPerDegree;
aSeconds = ( Abs( aValue - aDeg ) ) * KSecsPerDegree - aMinutes * KMinsPerDegree;
}
For presentation latitude/longitude as string, You can use following function:
// append latitude/longitude data in aDes
// i.e. if aValue = -23,3876 then aDes += -23°23'15.36"
void YourClassName :: AppendValueAsGeographical( TReal64& aValue,
TDes& aDes )
{
TInt deg, minutes;
TReal secs;
Decompose2Geographical( aValue, deg, minutes, secs );
aDes.AppendNum( deg );
aDes.Append( 176 ); // degree sign
aDes.AppendNum( minutes );
aDes.Append( '\'' );
TRealFormat format( 5, 2 );
format.iType = KRealFormatFixed | KDoNotUseTriads;
aDes.AppendNum( secs, format );
aDes.Append( '"' );
}
The choice of the landmark from the database and showing of its data are presented in the following snippet of code:
// this dialog allows to select landmark
CLmkLandmarkSelectorDlg* selectLandmarkDlg = CLmkLandmarkSelectorDlg :: NewL();
TLmkItemIdDbCombiInfo selectedItem;
// dlg is deleted automatically
TInt ret = selectLandmarkDlg->ExecuteLD( selectedItem );
if( ret != 0 )
{
// Select or OK was pressed
TPosLmItemId itemId = selectedItem.GetItemId(); // selected item ID
CPosLandmarkDatabase* lmDb = selectedItem.GetLmDb(); // selected item DB
CPosLandmark* lmItemPos = lmDb->ReadLandmarkLC( itemId ); // read item data
// !!! All dialogical strings must be defined in resources.
// In this example (in order not to overflow the code) the strings are declared
// as string literals (macro _LIT).
TBuf<128> lmInfo;
_LIT( KName, "Name: ");
lmInfo.Append( KName );
TPtrC landmarkName;
if( lmItemPos->GetLandmarkName( landmarkName ) == KErrNone )
lmInfo.Append( landmarkName ); // landmark name is defined
lmInfo.Append( '\n' );
TLocality pos;
if( lmItemPos->GetPosition( pos ) == KErrNone )
{
_LIT( KLatitude, "Latitude: " );
lmInfo.Append(KLatitude);
TReal64 latitude = pos.Latitude();
AppendValueAsGeographical( latitude, lmInfo );
lmInfo.Append( '\n' );
_LIT( KLongitude, "Longitude: " );
lmInfo.Append( KLongitude );
TReal64 longitude = pos.Longitude();
AppendValueAsGeographical( longitude, lmInfo );
lmInfo.Append( '\n' );
_LIT( KAltitude, "Altitude: " );
lmInfo.Append( KAltitude );
TRealFormat format( 6, 2 );
lmInfo.AppendNum( pos.Altitude(), format );
lmInfo.Append( '\n' );
_LIT( KHorAcc, "Hor. Acc.: " );
lmInfo.Append( KHorAcc );
lmInfo.AppendNum( pos.HorizontalAccuracy(), format );
}
delete lmDb;
// create and execute dialog
CAknMessageQueryDialog* dlg = CAknMessageQueryDialog :: NewL( lmInfo );
dlg->PrepareLC( R_LANDMARK_DIALOG ); // don't forget to include Your rsg-file
_LIT( KDlgName, "Landmark Info" );
dlg->SetHeaderTextL( KDlgName );
dlg->RunLD();
}
RSS-data for the dialog:
RESOURCE DIALOG r_landmark_dialog
{
flags = EEikDialogFlagNoDrag | EEikDialogFlagCbaButtons | EEikDialogFlagWait;
buttons = R_AVKON_SOFTKEYS_BACK;
items =
{
DLG_LINE
{
type = EAknCtPopupHeadingPane;
id = EAknMessageQueryHeaderId;
control = AVKON_HEADING
{
headinglayout = R_AVKON_LIST_HEADING_PANE_POPUPS;
};
},
DLG_LINE
{
type = EAknCtMessageQuery;
id = EAknMessageQueryContentId;
control = AVKON_MESSAGE_QUERY
{
message="";
};
}
};
}
The snapshot of the dialog:
Internal Links
- How to manage landmark categories
- KIS000784 - Landmarks category selector dialog leaks memory
- Landmarks/web client example using Carbide.c++ and UI designer
- How to use Landmarks API
- How to compact local landmark databases
- How to export landmarks from database to file
- How to import landmarks from file to database
- Execution of landmark operations
- How to obtain and save current location
- Retrieving location information
22 Sep
2009
This article represents code snippests and explaination for mainly three tasks: selecting landmark from database, reading the landmark data and displaying that landmark data through a dialog.
All three tasks are very well performed and explained by this article. The article contains the detailed information about libraries and header files and capabilities required to perform these tasks. Code snippests contains comments and make the code easy to understand for beginners. APIs used for the demostrated example are CLmkLandmarkSelectorDlg , CLmkCategorySelectorDlg.
This article is mainly made for beginners for their further progress.