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 * for the specific language governing rights and limitations under the
 * License.
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 * The Original Code is mozilla.org code.
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 *
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#include "nsRegionPool.h"


NS_EXPORT nsNativeRegionPool sNativeRegionPool;

//------------------------------------------------------------------------

nsNativeRegionPool::nsNativeRegionPool()
{
	mRegionSlots = nsnull;
	mEmptySlots = nsnull;
}

//------------------------------------------------------------------------

nsNativeRegionPool::~nsNativeRegionPool()
{
	// Release all of the regions.
	if (mRegionSlots != nsnull) {
		nsRegionSlot* slot = mRegionSlots;
		while (slot != nsnull) {
			::DisposeRgn(slot->mRegion);
			nsRegionSlot* next = slot->mNext;
			delete slot;
			slot = next;
		}
	}
	
	// Release all empty slots.
	if (mEmptySlots != nsnull) {
		nsRegionSlot* slot = mEmptySlots;
		while (slot != nsnull) {
			nsRegionSlot* next = slot->mNext;
			delete slot;
			slot = next;
		}
	}
}

//------------------------------------------------------------------------

RgnHandle nsNativeRegionPool::GetNewRegion()
{
	nsRegionSlot* slot = mRegionSlots;
	if (slot != nsnull) {
		RgnHandle region = slot->mRegion;

		// remove this slot from the free list.
		mRegionSlots = slot->mNext;
		
		// transfer this slot to the empty slot list for reuse.
		slot->mRegion = nsnull;
		slot->mNext = mEmptySlots;
		mEmptySlots = slot;
		
		// initialize the region. 
		::SetEmptyRgn(region);
		return region;
	}
	
	// return a fresh new region. a slot will be created to hold it
	// if and when the region is released.
	return (::NewRgn());
}

//------------------------------------------------------------------------

void nsNativeRegionPool::ReleaseRegion(RgnHandle aRgnHandle)
{
	nsRegionSlot* slot = mEmptySlots;
	if (slot != nsnull)
		mEmptySlots = slot->mNext;
	else
		slot = new nsRegionSlot;
	
	if (slot != nsnull) {
		// put this region on the region list.
		slot->mRegion = aRgnHandle;
		slot->mNext = mRegionSlots;
		mRegionSlots = slot;
	} else {
		// couldn't allocate a slot, toss the region.
		::DisposeRgn(aRgnHandle);
	}
}