The qtmultimedia-based qrreader has the concept of "strong_count":
before the scanner returns a decoded qr code result, it waits until
it has seen at least "strong_count" (e.g. 10) frames in which the qr code was seen and successfully decoded.
I think the idea might have been to reduce false positives, mis-decoding qr codes from bad frames.
However in practice it makes scanning even moderately sized qr codes really difficult for the user:
it takes several seconds (at least on my laptop cam) to obtain enough "clear" frames that count into the strong_count.
So I am lowering the strong_count to 2, down from CAMERA_FPS/3,
which makes it easier to scan, and I still haven't seen false positives even with this value.
- without this, in send tab paytoedit, try_payment_identifier will get called and it will error
df1b9a223c/electrum/gui/qt/paytoedit.py (L153)
- also, in all text fields this used to result in clearing the current text (but now it is kept instead)
A new config API is introduced, and ~all of the codebase is adapted to it.
The old API is kept but mainly only for dynamic usage where its extra flexibility is needed.
Using examples, the old config API looked this:
```
>>> config.get("request_expiry", 86400)
604800
>>> config.set_key("request_expiry", 86400)
>>>
```
The new config API instead:
```
>>> config.WALLET_PAYREQ_EXPIRY_SECONDS
604800
>>> config.WALLET_PAYREQ_EXPIRY_SECONDS = 86400
>>>
```
The old API operated on arbitrary string keys, the new one uses
a static ~enum-like list of variables.
With the new API:
- there is a single centralised list of config variables, as opposed to
these being scattered all over
- no more duplication of default values (in the getters)
- there is now some (minimal for now) type-validation/conversion for
the config values
closes https://github.com/spesmilo/electrum/pull/5640
closes https://github.com/spesmilo/electrum/pull/5649
Note: there is yet a third API added here, for certain niche/abstract use-cases,
where we need a reference to the config variable itself.
It should only be used when needed:
```
>>> var = config.cv.WALLET_PAYREQ_EXPIRY_SECONDS
>>> var
<ConfigVarWithConfig key='request_expiry'>
>>> var.get()
604800
>>> var.set(3600)
>>> var.get_default_value()
86400
>>> var.is_set()
True
>>> var.is_modifiable()
True
```
This commit ports the work of EchterAgo and cculianu from Electron-Cash,
to implement a new toolchain to scan qr codes.
Previously, on Linux and Win, we have been using zbar to access the camera
and read qrcodes; and on macOS we used CalinsQRReader (an objective-C
project by cculianu).
The new toolchain added here can use QtMultimedia to access the camera,
and then feed that image into zbar. When used this way, zbar needs
fewer dependencies and is easier to compile, in particular it can be
compiled for macOS.
The new toolchain works on all three platforms, with some caveats
(see code comments in related commits) -- so we also keep the end-to-end
zbar toolchain; but at least we can drop CalinsQRReader.
The related changes in Electron-Cash are spread over 50+ commits (several PRs and direct
pushes to master), but see in particular:
https://github.com/Electron-Cash/Electron-Cash/pull/1376
some other interesting links:
b2b737001c163224cf1f3b31e0fcb1eda015908ehttps://github.com/Electron-Cash/Electron-Cash/pull/1545052aa06c23
