Method StartBackgroundImageLoad

neo/renderer/Image_init.cpp:1810–1872

================== idImage::StartBackgroundImageLoad ================== */

==================
*/
void idImage::StartBackgroundImageLoad() {
	if ( imageManager.numActiveBackgroundImageLoads >= idImageManager::MAX_BACKGROUND_IMAGE_LOADS ) {
		return;
	}
	if ( globalImages->image_showBackgroundLoads.GetBool() ) {
		common->Printf( "idImage::StartBackgroundImageLoad: %s\n", imgName.c_str() );
	}
	backgroundLoadInProgress = true;

	if ( !precompressedFile ) {
		common->Warning( "idImageManager::StartBackgroundImageLoad: %s wasn't a precompressed file", imgName.c_str() );
		return;
	}

	bglNext = globalImages->backgroundImageLoads;
	globalImages->backgroundImageLoads = this;

	char	filename[MAX_IMAGE_NAME];
	ImageProgramStringToCompressedFileName( imgName, filename );

	bgl.completed = false;
	bgl.f = fileSystem->OpenFileRead( filename );
	if ( !bgl.f ) {
		common->Warning( "idImageManager::StartBackgroundImageLoad: Couldn't load %s", imgName.c_str() );
		return;
	}
	bgl.file.position = 0;
	bgl.file.length = bgl.f->Length();
	if ( bgl.file.length < sizeof( ddsFileHeader_t ) ) {
		common->Warning( "idImageManager::StartBackgroundImageLoad: %s had a bad file length", imgName.c_str() );
		return;
	}

	bgl.file.buffer = R_StaticAlloc( bgl.file.length );

	fileSystem->BackgroundDownload( &bgl );

	imageManager.numActiveBackgroundImageLoads++;

	// purge some images if necessary
	int		totalSize = 0;
	for ( idImage *check = globalImages->cacheLRU.cacheUsageNext ; check != &globalImages->cacheLRU ; check = check->cacheUsageNext ) {
		totalSize += check->StorageSize();
	}
	int	needed = this->StorageSize();

	while ( ( totalSize + needed ) > globalImages->image_cacheMegs.GetFloat() * 1024 * 1024 ) {
		// purge the least recently used
		idImage	*check = globalImages->cacheLRU.cacheUsagePrev;
		if ( check->texnum != TEXTURE_NOT_LOADED ) {
			totalSize -= check->StorageSize();
			if ( globalImages->image_showBackgroundLoads.GetBool() ) {
				common->Printf( "purging %s\n", check->imgName.c_str() );
			}
			check->PurgeImage();
		}
		// remove it from the cached list
		check->cacheUsageNext->cacheUsagePrev = check->cacheUsagePrev;