Class TNetworkRequestQueue

Fields

Unit

type TNetworkRequestQueue = class(TObject)

Queuer of network requests. Under the hood uses multiple background threads to execute several blocking requests at the same time.

	`constructor Create(MaxTasksPerThread, MaxThreads: Cardinal; RequestProc: TBlockingNetworkRequestProc; TilesProvider: TTilesProvider);`
	`destructor Destroy; override;`
	`procedure RequestTile(const Tile: TTile);`
	`procedure SetCurrentViewRect(const ViewRect: TRect);`

	`property RequestProps: THttpRequestProps read FRequestProps write FRequestProps;`
	`property DumbQueueOrder: Boolean read FDumbQueueOrder write FDumbQueueOrder;`
	`property OnGotTileBgThr: TGotTileCallbackBgThr read FGotTileCb write FGotTileCb;`

constructor Create(MaxTasksPerThread, MaxThreads: Cardinal; RequestProc: TBlockingNetworkRequestProc; TilesProvider: TTilesProvider);

Constructor

MaxTasksPerThread: - if number of tasks becomes more than MaxTasksPerThread*%currentThreadCount%, add one more thread
MaxThreads: - limit of the number of threads
RequestProc: - implementator of network request
TilesProvider: - object holding properties of current tile provider. Object takes ownership on this object and destroys it on release.

	`destructor Destroy; override;`
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	`procedure RequestTile(const Tile: TTile);`
Add request for an image for `Tile` to the request queue

	`procedure SetCurrentViewRect(const ViewRect: TRect);`
Set current view rect in absolute map coords. If smart ordering facilities are enabled, tiles inside current view have priority when extracted from request queue.

	`property RequestProps: THttpRequestProps read FRequestProps write FRequestProps;`
Common network request props applied to all requests in current queue. Changing the properties won't take effect until queue gets empty. URL field is ignored.

property DumbQueueOrder: Boolean read FDumbQueueOrder write FDumbQueueOrder;

If set: disable all smart ordering facilities. Queue will retrieve all added tiles one by one. If not set (default):

When RequestTile adds a tile, all queued items with another zoom level are cancelled (use case: user quickly zooms in/out by multiple steps - no sense to wait for all of them to download)
If current view area is set via SetCurrentViewRect, the tiles inside this rect are downloaded first (priority of visible area)

	`property OnGotTileBgThr: TGotTileCallbackBgThr read FGotTileCb write FGotTileCb;`
Handler to call when request is completed (executed in the context of background thread!)

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