twipToPixel and pixelToTwip are also being used by the new TileBuffer
clsas. Lets move these utility functions to a common header,
tilebuffer.hxx
The variables for DPI and tileSize are also moved to tilebuffer.hxx
Change-Id: I9d0bec7f2aefe412df232040a7a9abc6db3e4ccb
Using vector each tile needs to be allocated memory irrespective of
whether tile is required or not. This approach fails when we zoom in to
a very high level to have thousands of tiles due to lot of memory
required. Using maps instead of vector takes care of this, and only
allocates Tiles when required.
Change-Id: I523f815618451a7f014e28258e0de7b1c0693370
The TileBuffer class now manages all the tiles. The tile rendering calls
to LO core is also managed by this class.
Change-Id: Ic667a93dcf1c097e0601c0496e8a083c4742e8cb
