How to ensure that the scroll bar background is drawn properly in Symbian C++
S60 3rd Edition, FP1
S60 3rd Edition, FP2
S60 5th Edition
S60 5th Edition
S60 3rd Edition FP2
S60 3rd Edition FP1
S60 3rd Edition (initial release)
When drawing a control (list box, grid, editor, etc.) that uses a scroll bar, the background of the scroll bar may remain white. This happens when a container does not pass the correct object (context-specific skin parameters) to its child controls. Proper skinning for child controls can be enabled by implementing the CCoeControl::MopSupplyObject() method for the container class, and making sure that the object provider chain between controls and their parents is set up correctly. For more information, see SDK documentation on MObjectProvider and CCoeControl::SetMopParent().
To correctly draw scroll bar backgrounds, first add the following member variable to the view class derived from CCoeControl:
In the constructor (ConstructL) of that class:
iSkinContext = CAknsBasicBackgroundControlContext::NewL(
Note: When using KAknsIIDQsnBgAreaMainAppsGrid skin ID, provide the application (full screen) rect as above.
Then, implement MopSupplyObject() as follows:
TTypeUid::Ptr CMyCustomGridAppView::MopSupplyObject( TTypeUid aId )
if( iSkinContext && aId.iUid == MAknsControlContext::ETypeId )
return MAknsControlContext::SupplyMopObject( aId, iSkinContext );
return CCoeControl::MopSupplyObject( aId );
To ensure UI scalability, remember to update also the background context's size in CCoeControl::SizeChanged().
TRect rect = Rect();
- S60 Platform: Descriptor Example for an example implementation of a scroll bar-using control with proper background drawing.