Changes between Version 1 and Version 2 of SoCTMSDriver

Timestamp:

Mar 26, 2008, 10:13:00 AM (16 years ago)

Author:

keo

Comment:

--

SoCTMSDriver

@@ -23 +23 @@
 == Work plan ==
 
-The work is divided into several steps. First two are essential, all others
+The work is divided into several steps. First three are essential, all others
 are optional.
 
@@ -36 +36 @@
 to the way the WMS driver works.
 
-Although the tiled map has several zooming levels, only the lowest one will be used. 
-`IReadBlock` requests will be handled by loading data from the files representing 
-the selected area using existing PNG driver.
+`RasterIO` method will determine the appropriate zooming level from which to get the tiles
+so that their number won't be too big (e.g. 9 at most). `GetBlockSize` will report the size
+as the dimensions of one tile and `GetXSize` and `GetYSize` will report the size of the map
+on the lowest zooming level.
 
-=== Write driver ===
+=== Write driver with `CreateCopy` ===
 
-Next on plan is the writing part. The driver will support the
+Next on plan is the writing part. The driver will at first support the
 `CreateCopy` method returning the created dataset as `ReadOnly` (implemented in previous step). 
-This will allow to export existing datasets in tiled format. Creation options will include
-the dimensions of tiles, number of zooming levels and the zooming ratio between them.
+Creation options will include the dimensions of tiles, number of zooming levels and the zooming 
+ratio between them.
 
-Implementing `Create` method and `Update` mode dataset is questionable.
-The PNG driver has this mode controlled by compile time option, so the
-TMS driver would have to do the same. Even then, the PNG driver imposes some 
-restrictions on the calling side: ''"Note: callers must provide blocks in increasing Y order."'', 
-from `pngdataset.cpp`. This would translate to the TMS driver itself and its users too.
-JPEG drivers have `CreateCopy` method only.
+=== Write driver with `Create` ===
+
+In this step the driver will also feature the `Create` method and `Update` mode datasets.
+Upon writing, the `RasterIO` method will load all affected tiles from all zooming levels
+into memory, perform the write operation and then write the tiles back to file system.
+
 
 === Performance tuning ===