Hi Mathias,
Very appreciate for the elaborate explanation. Now I know what is
whichID. But OOo IS a very big chunk for me, I have to digest it little
by little. If I have further questions, I will consult you again. Thank
you in advance.
Best regards,
Lihua
在 2009-09-10四的 09:55 +0200，Mathias Bauer写道：
> Zhu Lihua wrote:
>
> >> "Modules" here means the application module. While slotids mark a
> >> functionality in the UI, whichids mark the corresponding attribute in
> >> the document core of the application.
> > Does it mean WhichID is a root ID of the corresponding SlotIDs?
> > I guess, common functionality in different module have different SlotID,
> > but they have the same WhichID which match this functionality. So we
> > convert it to WhichID, and the program know which functionality is it.
> > Right?
>
> A whichid is only valid in the code of a particular application module.
> Even slotids that are common to all modules have different whichids
> assigned in the applications).
>
> >> The slotid is a universal ID, it is understood in all modules. In the
> >> code of each application module there is a conversion table that
> >> converts the slot ids into the matching whichids.
> > Where is this table? I believe it helps to me to understand the
> > relationship of the SlotID and WhichID. Does it exist as a file? or Is
> > it a dynamic array in the run time?
>
> This mapping table is constructed as part of the module's pool. In
> Writer this e.g. happens in sw/source/core/bastyp/init.cxx, in Calc it's
> sc/source/core/data/docpool.cxx.
>
> You will find an array of SlotIds there, and the the whichid belonging
> to each slotid just is the position in this array plus an offset that is
> specified when the pool is created. In Calc you can see:
>
> static SfxItemInfo __READONLY_DATA aItemInfos[] =
> {
> { SID_ATTR_CHAR_FONT, SFX_ITEM_POOLABLE }, // ATTR_FONT
> { SID_ATTR_CHAR_FONTHEIGHT, SFX_ITEM_POOLABLE }, // ATTR_FONT_HEIGHT
> { SID_ATTR_CHAR_WEIGHT, SFX_ITEM_POOLABLE }, // ATTR_FONT_WEIGHT
> .....
> };
>
> where the index of the slotid SID_ATTR_CHAR_FONT is 0.
>
> When the ctor of the ScDocumentPool initializes its base class
> SfxItemPool it hands over this array and an offset:
>
> ScDocumentPool::ScDocumentPool(
> SfxItemPool* pSecPool, BOOL bLoadRefCounts )
> :SfxItemPool (
> String::CreateFromAscii(RTL_CONSTASCII_STRINGPARAM("ScDocumentPool")),
> ATTR_STARTINDEX, ATTR_ENDINDEX,
> aItemInfos, NULL, bLoadRefCounts ),
> pSecondary ( pSecPool )
> {
> ......
> }
>
> This offset is ATTR_STARTINDEX (=100 as defined in sc/inc/scitems.hxx).
> So now the pool knows that the whichid 100 is assigned to the slotid
> SID_ATTR_CHAR_FONT, 101 is assigned to SID_ATTR_CHAR_FONTHEIGHT etc.
>
> If you look at the definition of aItemInfos, you will find some array
> members with slotid 0:
>
> { SID_ATTR_CHAR_RELIEF, SFX_ITEM_POOLABLE }, //
> ATTR_FONT_RELIEF { SID_ATTR_ALIGN_HYPHENATION,
> SFX_ITEM_POOLABLE },//
> ATTR_HYPHENATE
> { 0, SFX_ITEM_POOLABLE }, // ATTR_SCRIPTSPACE
>
>
> These whichids don't have a slotid assigned. A whichid whose attribute
> is not manipulated by dispatch calls or generic dialogs (see below)
> doesn't need a slotid as this is the only place in the code where
> slotids are needed. To handle the attribute in the document core code
> the whichid is sufficient.
>
> OTOH many slotids don't have a whichid assigned in a particular pool.
> Only core attributes (as the Font attributes shown above) have it, but
> e.g. an SfxDocumentInfoItem doesn't.
>
> If an SfxItemSet is created, it must get an SfxItemPool. If an item is
> put into the SfxItemSet that matches the specified "WhichRanges" (an
> unfortunate name as it can contain whichids as well as slotids) of the
> SfxItemSet, the SfxItemSet checks whether the id is a slotid or a
> whichid ( this is simple: slotids are >= 5000, whichids are < 5000). The
> SfxItemSet can convert the slotid to the assigned whichid by using the
> table of the pool. If no whichid for the slotid is found in the pool,
> the item keeps its slotid. Getting this item back from the pool must be
> aware of that and use whichids where necessary.
>
> This procedure is needed in two scenarios: UI controls (e.g. toolbar
> controls) and generic (application independent) dialogs. Both UI
> elements may pass information as SfxPoolItems in an SfxItemSet. As they
> don't know in which application they are used, they use the globally
> unique slotids to identify items. OTOH the document that finally
> receives the call wants to work with its own whichids. So the SfxItemSet
> and its SfxItemPool together work as a "translator" from "slot language"
> to "which language". In case of generic dialogs the SfxItemSet is passed
> to them when the dialog is constructed, in case of dispatch calls from
> UI controls the SfxItemSet is retrieved from the document by the
> framework code that receives the SfxPoolItems from the control and puts
> it into an SfxItemSet that the document code receives as part of an
> SfxRequest object.
>
> HTH,
> Mathias
>
>
--
Lihua
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