* PictureLoader: Replace downloadedPics cache with QNetworkCache
Currently when the "Download card pictures on the fly" option is
enabled, Cockatrice stores downloaded pictures into a downloadedPics
sub-folder, keyed on set and card name. If a picture is found in that
folder, we never try to download a picture for that card ever again
(until it is reprinted in a more recent set, I guess).
This has the unfortunate consequence that if you change the URLs for
downloading card images, the changes are not applied to cards that
already have their picture downloaded. In particular, if you use
localized card pictures (through !sflang!), you get a mix of cards in
different languages depending on the currently configured language at
the time each card was downloaded.
This patch removes that mechanism in favor of setting a
QNetworkDiskCache on the QNetworkAccessManager used by the PictureLoader
to download pictures. The QNetworkDiskCache caches the picture keyed on
their URL: if the URL changes, a new request will be made. In
particular, if you use picture URLs with !sflang! and change the
language, pictures for the current language will be downloaded even for
cards that already have a picture. The QNetworkDiskCache is configured
with a maximum size of 4GB, which should be enough to hold one
high-quality JPEG for each M:TG card in existence.
Note that this does not affect the existing mechanism for defining
custom card art, either through the CUSTOM directory or the set-based
one. Cockatrice will still read existing cards in the downloadedPics
directory as before, it will just no longer write into that directory
(since pictures are cached by the QNetworkDiskCache instead). To fully
switch to the new cache, users should use the "Delete Downloaded Images"
button in the settings: it will clear the QNetworkDiskCache but also
remove the downloadedPics directory.
* Do not use system cache dir for portable installs
* Add settings for network cache size
* Delete corrupted cache entries
* Use old-style connect() syntax (Qt5 build failure)
* Add setNetworkCacheSizeInMB to test mocks
* setTransferTimeout was added in Qt 5.15
* Improve logging messages
We now have the following messages
- "Trying to download picture from url: URL" before loading a picture
when picture download is enabled
- "Trying to load picture from cache: URL" before loading a picture
when picture download is disabled (i.e. cache-only offline mode)
- "Removing corrupted cache file for url URL and retrying (ERR)" when
when we fail to load a picture from the cache. Usually, this should
be due to the timeout, in which case ERR will be "Operation
Canceled".
- "Download failed for url URL (ERR)" when there was an error
downloading a picture from the network (ERR is the error message)
- "Following redirect to URL" and "Following cached redirect to URL"
when following a redirect (from network/from cache)
- "Image successfully downloaded from URL" and "Image successfully
loaded from cached url at URL" on success
- "Possible cached/downloaded picture at URL could not be loaded" on
ImageReader error
* Clarify that network cache is on disk
Also migrate "Delete Downloaded Image" to a "Clear" button right next to
the network cache size.
* Remove qPrintable
* Move pixmap cache settings to card sources
* qDebug().nospace()
* some formatting on debug messages
* format
* inverted condition
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Co-authored-by: ebbit1q <ebbit1q@gmail.com>
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