Since higher level charting and fsp management need access to the
new `Flume` indexing apis this adjusts some func sigs to pass through
(and/or create) flume instances:
- `LinkedSplits.add_plot()` and dependents.
- `ChartPlotWidget.draw_curve()` and deps, and it now returns a `Flow`.
- `.ui._fsp.open_fsp_admin()` and `FspAdmin.open_fsp_ui()` related
methods => now we wrap the destination fsp shm in a flume on the admin
side and is returned from `.start_engine_method()`.
Drop a bunch of (unused) chart widget methods including some already
moved to flume methods: `.get_index()`, `.in_view()`,
`.last_bar_in_view()`, `.is_valid_index()`.
Move to expect and process new by-tick-event frames where the display
loop can now just iterate the most recent tick events by type instead of
the entire tick history sequence - thus we reduce iterations inside the
update loop.
Also, go back to use using the detected display's refresh rate (minus 6)
as the default feed requested throttle rate since we can now handle
much more bursty-ness in display updates thanks to the new framing
format B)
Factor out the chart widget creation since it's only executed once
during rendering of the first feed/flow whilst keeping plotitem overlay
creation inside the (flume oriented) init loop. Only create one vlm and
FSP chart/chain for now until we figure out if we want FSPs overlayed by
default or selected based on the "front" symbol in use. Add a default
color-palette set using shades of gray when plotting overlays. Presume
that the display loop's quote throttle rate should be uniformly
distributed over all input symbol-feeds for now. Restore feed pausing on
mouse interaction.
Initial support for real-time multi-symbol overlay charts using an
aggregate feed delivered by `Feed.open_multi_stream()`.
The setup steps for constructing the overlayed plot items is still very
very rough and will likely provide incentive for better refactoring high
level "charting APIs". For each fqsn passed into `display_symbol_data()`
we now synchronously,
- create a single call to `LinkedSplits.plot_ohlc_main() -> `ChartPlotWidget`
where we cache the chart in scope and for all other "sibling" fqsns
we,
- make a call to `ChartPlotWidget.overlay_plotitem()` -> `PlotItem`, hide its axes,
make another call with this plotitem input to
`ChartPlotWidget.draw_curve()`, set a sym-specific view box auto-yrange maxmin callback,
register the plotitem in a global `pis: dict[str, list[pgo.PlotItem, pgo.PlotItem]] = {}`
Once all plots have been created we then asynchronously for each symbol,
- maybe create a volume chart and register it in a similar task-global
table: `vlms: dict[str, ChartPlotWidget] = {}`
- start fsp displays for each symbol
Then common entrypoints are entered once for all symbols:
- a single `graphics_update_loop()` loop-task is started wherein
real-time graphics update components for each symbol are created,
* `L1Labels`
* y-axis last clearing price stickies
* `maxmin()` auto-ranger
* `DisplayState` (stored in a table `dss: dict[str, DisplayState] = {}`)
* an `increment_history_view()` task
and a single call to `Feed.open_multi_stream()` is used to create
a symbol-multiplexed quote stream which drives a single loop over all
symbols wherein for each quote the appropriate components are looked
up and passed to `graphics_update_cycle()`.
- a single call to `open_order_mode()` is made with the first symbol
provided as input, though eventually we want to support passing in the
entire list.
Further internal implementation details:
- special tweaks to the `pg.LinearRegionItem` setup wherein the region
is added with a zero opacity and *after* all plotitem overlays to
avoid and issue where overlays weren't being shown within the region
area in the history chart.
- all symbol-specific graphics oriented update calls are adjusted to
pass in the fqsn:
* `update_fsp_chart()`
* `ChartView._set_yrange()`
* ChartPlotWidget.update_graphics_from_flow()`
- avoid a double increment on sample step updates by not calling the
increment on any vlm chart since it seems the vlm-ohlc chart linking
already takes care of this now?
- use global counters for the last epoch time step to avoid incrementing
all views more then once per new time step given underlying shm array
buffers may be on different array-index values from one another.
This is to prep for multi-symbol feeds and charts so we accept
a sequence of fqsns to the top level entrypoints as well as the
`.data.feed.open_feed()` API (though we're not actually supporting true
multiplexed feeds nor shm lookups per fqsn yet).
Factor the multi-sample-rate region UI connecting into a new helper
`link_views_with_region()` which reads in the shm buffer offsets from
the `Feed` and appropriately connects the fast and slow chart handlers
for the linear region graphics. Add detailed comments writeup for the
inter-sampling transform algebra.
- Every time a symbol is switched on chart we need to wait until the
search bar sidepane has been added beside the slow chart before
determining the offset for the pp line's arrow/labels; trigger this in
`GodWidget.load_symbol()` -> required monkeypatching on a
`.mode: OrderMode` to the `.rt_linked` for now..
- Drop the search pane widget removal from the current linked chart,
seems faster?
- On the slow chart override the `LevelMarker.scene_x()` callback to
adjust for the case where no L1 labels are shown beside the y-axis.
Also adds a `GodWidget.resize_all()` helper method which resizes all
sub-widgets and charts to their default ratios and/or parent-widget
dependent defaults using the detected available space on screen. This is
a "default layout" config method that eventually we'll probably want
allow users to customize.
It ended up being what'd you expect, races on the accessing shm buffer
data by the UI during the whole "mega-async-startup-everything" phase XD
So we add the following list of ad-hoc startup steps:
- do `.default_view()` on the slow chart after the fast chart is mostly
fully spawned with the intention being to capture the state where the
historical buffer is mostly loaded before sizing the view to the
graphical form of the data.
- resize slow chart sidepanes from the fast chart just before sleeping
forever (and after order mode has booted).
The slow (history) chart requires it's own y-range checker logic which
needs to be run in 2 cases:
- the last datum is in view and goes outside the previous mx/mn in view
- the chart is incremented a step
Since we need this duplicate logic this patch also factors the incremental
graphics update info "reading" into a new `DisplayState.incr_info()`
method that can be configured to a chart and input state and returns all
relevant "graphics update measure" in a tuple (for now).
Use this method throughout the rest of the display loop for both fast
and slow chart checks and in the `increment_history_view()` slow chart
task.
Use the new `Feed.get_ds_info()` method in a poll loop to definitively
get the inter-chart sampling info and avoid races with shm buffer
backfilling.
Also, factor the history increment closure-task into
`graphics_update_loop()` which will make it clearer how to factor
all the "should we update" logic into some `DisplayState` API.
Add an update call to the display loop to consistently update the last
datum in the history view chart. Compute the inter-chart sampling ratio
and use it to sync the linear region.
Add a first draft of a working `pyqtgraph.LinearRegionItem` link between
a history view chart (+ data set) and the normal real-time "HFT" chart
set.
Add the history view (aka more downsampled data view) chart set to the
rt/hft set's splitter as it's "first widget". Hook up linear region
callbacks to enable syncing between charts including compenstating for
the downsampling rate ration (in this case hardcoded 60 since 1s to 1M,
but we'll actually compute it going forward obvs).
More to come dawgys..
This was introduced in #302 but after thorough testing was clear to be
not working XD. Adjust the display loop to update the last graphics
segment on both the OHLC and vlm charts (as well as all deriving fsp
flows) whenever the uppx >= 1 and there is no current path append
taking place (since more datums are needed to span an x-pixel in view).
Summary of tweaks:
- move vlm chart update code to be at the end of the cycle routine and
have that block include the tests for a "interpolated last datum in
view" line.
- make `do_append: bool` compare with a floor of the uppx value (i.e.
appends should happen when we're just fractionally over a pixel of
x units).
- never update the "volume" chart.
When using m4, we downsample to the max and min of each
pixel-column's-worth of data thus preserving range / dispersion details
whilst not drawing more graphics then can be displayed by the available
amount of horizontal pixels.
Take and apply this exact same concept to the "last datum" graphics
elements for any `Flow` that is reported as being in a downsampled
state:
- take the xy output from the `Curve.draw_last_datum()`,
- slice out all data that fits in the last pixel's worth of x-range
by using the uppx,
- compute the highest and lowest value from that data,
- draw a singe line segment which spans this yrange thus creating
a simple vertical set of pixels which are "filled in" and show the
entire y-range for the most recent data "contained with that pixel".
The basic logic is now this:
- when zooming out, uppx (units per pixel in x) can be >= 1
- if the uppx is `n` then the next pixel in view becomes occupied by
a new datum-x-coordinate-value when the diff between the last
datum step (since the last such update) is greater then the
current uppx -> `datums_diff >= n`
- if we're less then some constant uppx we just always update (because
it's not costly enough and we're not downsampling.
More or less this just avoids unnecessary real-time updates to flow
graphics until they would actually be noticeable via the next pixel
column on screen.
Tyler Goodlet