ftc_snode_compare( FTC_Node ftcsnode,
FT_Pointer ftcgquery,
FTC_Cache cache )
{
FTC_SNode snode = (FTC_SNode)ftcsnode;
FTC_GQuery gquery = (FTC_GQuery)ftcgquery;
FTC_GNode gnode = FTC_GNODE( snode );
FT_UInt gindex = gquery->gindex;
FT_Bool result;
result = FT_BOOL( gnode->family == gquery->family &&
(FT_UInt)( gindex - gnode->gindex ) < snode->count );
if ( result )
{
/* check if we need to load the glyph bitmap now */
FTC_SBit sbit = snode->sbits + ( gindex - gnode->gindex );
if ( sbit->buffer == NULL && sbit->width != 255 )
{
FT_ULong size;
if ( !ftc_snode_load( snode, cache->manager,
gindex, &size ) )
{
cache->manager->cur_weight += size;
}
}
}
return result;
}
FTC_SNode_New( FTC_SNode *psnode,
FTC_GQuery gquery,
FTC_Cache cache )
{
FT_Memory memory = cache->memory;
FT_Error error;
FTC_SNode snode = NULL;
FT_UInt gindex = gquery->gindex;
FTC_Family family = gquery->family;
FTC_SFamilyClass clazz = FTC_CACHE_SFAMILY_CLASS( cache );
FT_UInt total;
FT_UInt node_count;
total = clazz->family_get_count( family, cache->manager );
if ( total == 0 || gindex >= total )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
if ( !FT_NEW( snode ) )
{
FT_UInt count, start;
start = gindex - ( gindex % FTC_SBIT_ITEMS_PER_NODE );
count = total - start;
if ( count > FTC_SBIT_ITEMS_PER_NODE )
count = FTC_SBIT_ITEMS_PER_NODE;
FTC_GNode_Init( FTC_GNODE( snode ), start, family );
snode->count = count;
for ( node_count = 0; node_count < count; node_count++ )
{
snode->sbits[node_count].width = 255;
}
error = ftc_snode_load( snode,
cache->manager,
gindex,
NULL );
if ( error )
{
FTC_SNode_Free( snode, cache );
snode = NULL;
}
}
Exit:
*psnode = snode;
return error;
}
ftc_snode_compare( FTC_Node ftcsnode,
FT_Pointer ftcgquery,
FTC_Cache cache,
FT_Bool* list_changed )
{
FTC_SNode snode = (FTC_SNode)ftcsnode;
FTC_GQuery gquery = (FTC_GQuery)ftcgquery;
FTC_GNode gnode = FTC_GNODE( snode );
FT_UInt gindex = gquery->gindex;
FT_Bool result;
if (list_changed)
*list_changed = FALSE;
result = FT_BOOL( gnode->family == gquery->family &&
(FT_UInt)( gindex - gnode->gindex ) < snode->count );
if ( result )
{
/* check if we need to load the glyph bitmap now */
FTC_SBit sbit = snode->sbits + ( gindex - gnode->gindex );
/*
* The following code illustrates what to do when you want to
* perform operations that may fail within a lookup function.
*
* Here, we want to load a small bitmap on-demand; we thus
* need to call the `ftc_snode_load' function which may return
* a non-zero error code only when we are out of memory (OOM).
*
* The correct thing to do is to use @FTC_CACHE_TRYLOOP and
* @FTC_CACHE_TRYLOOP_END in order to implement a retry loop
* that is capable of flushing the cache incrementally when
* an OOM errors occur.
*
* However, we need to `lock' the node before this operation to
* prevent it from being flushed within the loop.
*
* When we exit the loop, we unlock the node, then check the `error'
* variable. If it is non-zero, this means that the cache was
* completely flushed and that no usable memory was found to load
* the bitmap.
*
* We then prefer to return a value of 0 (i.e., NO MATCH). This
* ensures that the caller will try to allocate a new node.
* This operation consequently _fail_ and the lookup function
* returns the appropriate OOM error code.
*
* Note that `buffer == NULL && width == 255' is a hack used to
* tag `unavailable' bitmaps in the array. We should never try
* to load these.
*
*/
if ( sbit->buffer == NULL && sbit->width == 255 )
{
FT_ULong size;
FT_Error error;
ftcsnode->ref_count++; /* lock node to prevent flushing */
/* in retry loop */
FTC_CACHE_TRYLOOP( cache )
{
error = ftc_snode_load( snode, cache->manager, gindex, &size );
}
FTC_CACHE_TRYLOOP_END( list_changed );
ftcsnode->ref_count--; /* unlock the node */
if ( error )
result = 0;
else
cache->manager->cur_weight += size;
}
}
