to support custom font directory for EPUB documents
Now Koreader could find fonts in the "fonts" directory in the USB root
directory of kindle, Kobo and PocketBook devices, thus no need to copy
fonts to "koreader/fonts" directory.
This is a major overhaul of the hardware abstraction layer.
A few notes:
General platform distinction happens in
frontend/device.lua
which will delegate everything else to
frontend/device/<platform_name>/device.lua
which should extend
frontend/device/generic/device.lua
Screen handling is implemented in
frontend/device/screen.lua
which includes the *functionality* to support device specifics.
Actually setting up the device specific functionality, however,
is done in the device specific setup code in the relevant
device.lua file.
The same goes for input handling.
so that when document is modified the persistent cache will
be invalidated automatically because the cache key will not
be matched. There is no perfermance overhead here at all. We
even don't need to check the modification time of the cache item
on disk, because the name of the on disk cache is a md5sum of the
cacheitem key, now the filename of the cache files contains the
modification time information.
If the document is modified since one rendered page is cached to disk,
the cache key won't match the cache file. And the cache file will
be discarded without the need to open the cache file or to check
the modification time of the cache file itself.
This will use the new API where the Lua/C interface was used before
and also drop usage of mupdfimg wrapper which is now implemented
within the mupdf interface
so that when calling getCoverPageImage in screensaver mode
the document won't be opened again. This should avoid a lot of
problem such as messing up style and options described in #863.
We may have multiple documents opened simultaneously, such as in
screensaver mode the current document is opened twice, it's better
to keep seperate info table for each document.
This should fix#858. When a credocument is opened for screensaver to
get the cover page, the total pages info is set to 1(strangely enough),
before this fix this total pages is shared with the reading document
so the progress bar will get a progress percentage well beyond 100% and
rendering the progress bar out of the boundering box as shown in #858.
