[Qgis-user] Accessing temporal controller stuff via the python console
Cory Albrecht
maps at hanfastolfe.com
Tue Jan 25 13:30:05 PST 2022
Thanks.
While I no longer got a whole bunch of similar images, instead I got a
series of partially rendered canvases in triplets. First the static,
non-temporal-data layers and a few features of one of the temporal layers.
Second is all the layers but no labels. Third is with the labels (including
the date of the frame). Each triplet appears to be from the same time frame
selected with setCurrentFrameNumber(), but the third image of the triplet
shows a date that is is three items in the list after the previous one.
I ended up with the following as the only way to make sure that all
temporal controller and map canvas events were properly consumed before
taking the snapshot to image:
listOfDates ['1815-06-09', …]
navigator = iface.mapCanvas().temporalController()
dt = QDateTime.fromString(listOfDates[0], 'yyyy-MM-dd')
f = navigator.findBestFrameNumberForFrameStart(dt)
navigator.setCurrentFrameNumber(f)
QCoreApplication.processEvents(QEventLoop.AllEvents, 10000)
time.sleep(1)
QCoreApplication.processEvents(QEventLoop.WaitForMoreEvents, 10000)
time.sleep(1)
i = 1
for d in listOfDates:
dt = QDateTime.fromString(d, 'yyyy-MM-dd')
f = navigator.findBestFrameNumberForFrameStart(dt)
navigator.setCurrentFrameNumber(f)
fn = '/home/cory/Downloads/image-{:06d}.png'.format(i)
print(d)
print(f)
i = i + 1
QCoreApplication.processEvents(QEventLoop.AllEvents, 10000)
time.sleep(1)
QCoreApplication.processEvents(QEventLoop.AllEvents, 10000)
time.sleep(1)
QCoreApplication.processEvents(QEventLoop.AllEvents, 10000)
time.sleep(1)
QCoreApplication.processEvents(QEventLoop.AllEvents, 10000)
time.sleep(1)
QCoreApplication.processEvents(QEventLoop.AllEvents, 10000)
iface.mapCanvas().saveAsImage(fn)
print(fn)
print("\n")
print('Done!')
Longer waits in processEvents() or time.sleep() after setting the frame
didn't seem to matter, the key was sleeping and processing events multiple
times and 5 seems to be the minimum. I also had to do the set frame to the
first date before the loop, as for some reason inside the loop it required
more than 5 times when jumping backwards from the final date to the
beginning and would thus result in a bunch of incompletely drawn images and
a few skipped dates.
Next I need to find if there is a way to change the size of the output
image to different than the map canvas, but I suspect that will require
playing with the pyqgis stuff that controlls the Print Layout stuff, and
that is probably beyond my nonexistent python skills.
On Mon, Jan 24, 2022 at 6:27 PM Nyall Dawson <nyall.dawson at gmail.com> wrote:
> On Tue, 25 Jan 2022 at 04:39, Cory Albrecht <maps at hanfastolfe.com> wrote:
> >
> > But the `navigator.setCurrentFrameNumber(f)` doesn't change the canvas'
> temporal frame.
> >
> > If I do `f=54003` manually in the console and then
> `navigator.setCurrentFrameNumber(f)` manually as well, the frame changes.
> I've used time.sleep() with values up to 5 seconds to see if setting the
> frame was just a background task that returns early before actually
> completed, but that didn;t make any difference.
> >
>
> Try QCoreApplication.processEvents() instead of time.sleep
>
> > Why does it not change the frame in the middle of the for loop?
>
> it's a bit technical, but you need to let the Qt "event loop" process
> in order for any GUI widgets to update. time.sleep doesn't do this --
> it just blocks the caller for the requested time, and doesn't let Qt
> do it's thing and update the screen.
>
> But a huge warning is needed here: processEvents() is very dangerous
> to call in certain circumstances. Here it's ok to do, but definitely
> use with caution!! (You'll know you're using it wrong if you get
> crashes...)
>
> Nyall
>
>
>
> >
> > On Tue, Jan 18, 2022 at 2:32 PM Cory Albrecht <maps at hanfastolfe.com>
> wrote:
> >>
> >> Thanks, I'll check it out.
> >>
> >> On Sun, Jan 16, 2022 at 8:04 PM Nyall Dawson <nyall.dawson at gmail.com>
> wrote:
> >>>
> >>> On Mon, 17 Jan 2022 at 10:46, Cory Albrecht <maps at hanfastolfe.com>
> wrote:
> >>> >
> >>> > Thanks for the pointer, but unfortunately it is incomplete. It tells
> me this:
> >>> >
> >>> > # get the current responsible for the mapCanvas behaviour and
> Temporal Controller gui
> >>> > navigator = iface.mapCanvas().temporalController()
> >>> >
> >>> > And a few other methods for that object, but it's all about
> mimicking the "Save Animation" button with no explanation how to choose a
> specific frame or even anything as simple as going forward or backward by a
> single frame. Is there no list anywhere of all that temporal controller
> object's methods?
> >>>
> >>> Yes, in the usual place (the PyQGIS API reference):
> >>>
> >>> https://qgis.org/pyqgis/master/core/QgsTemporalNavigationObject.html
> >>>
> >>> Nyall
> >>>
> >>> >
> >>> >
> >>> >
> >>> > On Sun, Jan 16, 2022 at 3:40 PM Delaz J <delazj at gmail.com> wrote:
> >>> >>
> >>> >> Hi Cory,
> >>> >>
> >>> >> I don't know if it's still compatible with API and of any help, but
> there's that stale pull request in the docs by Richard (
> https://github.com/qgis/QGIS-Documentation/pull/5521) you might want to
> look at.
> >>> >>
> >>> >> Regards,
> >>> >>
> >>> >> Harrissou
> >>> >>
> >>> >> Le 16/01/2022 à 18:34, Cory Albrecht a écrit :
> >>> >>
> >>> >> Hello,
> >>> >>
> >>> >> Is there a way I can access and change/set stuff for the dynamic
> temporal controller programmatically in python? I'm looking to make a
> simple script that I can just cut and paste into the python console that
> will change the current frame of the DTC to a given timestamp, export the
> canvas to a PNG, and repeat for all the timestamps in an array.
> >>> >>
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