Add initial pixel buffer caching usage
Leverages `QGraphicsItem.cacheMode` to speed up interactivity via less `.paint()` calls (on mouse interaction) and redraws of the underlying path when there are no transformations (other then a shift). In order to keep the "flat bar on new time period" UX, a couple special methods have to be triggered to get a redraw of the pixel buffer when appending new data. Use `QPainterPath.controlPointRect()` over `.boundingRect()` since supposedly it's a lot faster. Drop all use of `QPicture` (since it seems to conflict with the pixel buffer stuff?) and it doesn't give any measurable speedup when drawing the "last bar" lines. Oh, and add some profiling for now.chart_trader
Tyler Goodlet
parent
6166e5900e
commit
cac797a7fc
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@ -27,7 +27,7 @@ from numba import jit, float64, int64 # , optional
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from PyQt5 import QtCore, QtGui
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from PyQt5.QtCore import QLineF, QPointF
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from .._profile import timeit
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# from .._profile import timeit
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# from ..data._source import numba_ohlc_dtype
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from ._style import (
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_xaxis_at,
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@ -355,7 +355,7 @@ class CrossHair(pg.GraphicsObject):
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# update all subscribed curve dots
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# first = plot._ohlc[0]['index']
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for cursor in opts.get('cursors', ()):
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cursor.setIndex(ix) # - first)
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cursor.setIndex(ix)
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# update the label on the bottom of the crosshair
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self.xaxis_label.update_label(
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@ -495,10 +495,16 @@ def gen_qpath(
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w,
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) -> QtGui.QPainterPath:
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profiler = pg.debug.Profiler(disabled=False)
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x, y, c = path_arrays_from_ohlc(data, start, bar_gap=w)
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profiler("generate stream with numba")
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# TODO: numba the internals of this!
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return pg.functions.arrayToQPath(x, y, connect=c)
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path = pg.functions.arrayToQPath(x, y, connect=c)
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profiler("generate path with arrayToQPath")
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return path
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class BarItems(pg.GraphicsObject):
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@ -520,10 +526,21 @@ class BarItems(pg.GraphicsObject):
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) -> None:
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super().__init__()
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self.last_bar = QtGui.QPicture()
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# NOTE: this prevents redraws on mouse interaction which is
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# a huge boon for avg interaction latency.
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# TODO: one question still remaining is if this makes trasform
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# interactions slower (such as zooming) and if so maybe if/when
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# we implement a "history" mode for the view we disable this in
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# that mode?
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self.setCacheMode(QtGui.QGraphicsItem.DeviceCoordinateCache)
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# not sure if this is actually impoving anything but figured it
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# was worth a shot:
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# self.path.reserve(int(100e3 * 6))
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# self.last_bar = QtGui.QPicture()
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self.path = QtGui.QPainterPath()
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# self._h_path = QtGui.QGraphicsPathItem(self.path)
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self._pi = plotitem
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@ -570,7 +587,7 @@ class BarItems(pg.GraphicsObject):
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# create pics
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# self.draw_history()
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self.draw_last_bar()
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# self.draw_last_bar()
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# trigger render
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# https://doc.qt.io/qt-5/qgraphicsitem.html#update
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@ -587,17 +604,16 @@ class BarItems(pg.GraphicsObject):
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# ) -> None:
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# ...
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# def draw_last_bar(self) -> None:
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# """Currently this draws lines to a cached ``QPicture`` which
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# is supposed to speed things up on ``.paint()`` calls (which
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# is a call to ``QPainter.drawPicture()`` but I'm not so sure.
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def draw_last_bar(self) -> None:
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"""Currently this draws lines to a cached ``QPicture`` which
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is supposed to speed things up on ``.paint()`` calls (which
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is a call to ``QPainter.drawPicture()`` but I'm not so sure.
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"""
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p = QtGui.QPainter(self.last_bar)
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p.setPen(self.bars_pen)
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p.drawLines(*tuple(filter(bool, self._last_bar_lines)))
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p.end()
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# """
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# p = QtGui.QPainter(self.last_bar)
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# # p.setPen(self.bars_pen)
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# p.drawLines(*tuple(filter(bool, self._last_bar_lines)))
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# p.end()
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# @timeit
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def update_from_array(
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@ -642,12 +658,19 @@ class BarItems(pg.GraphicsObject):
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# update path
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old_path = self.path
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self.path = prepend_path
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# self.path.reserve(int(100e3 * 6))
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self.path.addPath(old_path)
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# trigger redraw despite caching
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self.prepareGeometryChange()
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if append_length:
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# generate new lines objects for updatable "current bar"
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self._last_bar_lines = lines_from_ohlc(array[-1], self.w)
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self.draw_last_bar()
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# self.draw_last_bar()
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# self.update()
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# generate new graphics to match provided array
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# path appending logic:
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@ -659,11 +682,14 @@ class BarItems(pg.GraphicsObject):
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self.path.moveTo(float(istop - self.w), float(new_bars[0]['open']))
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self.path.addPath(append_path)
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# trigger redraw despite caching
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self.prepareGeometryChange()
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self._xrange = first_index, last_index
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if just_history:
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self.update()
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return
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# if just_history:
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# self.update()
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# return
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# last bar update
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i, o, h, l, last, v = array[-1][
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@ -696,20 +722,21 @@ class BarItems(pg.GraphicsObject):
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# else:
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# # XXX: h == l -> remove any HL line to avoid render bug
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# if body is not None:
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# body = self.lines[index - 1][0] = None
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# self._last_bar_lines = (None, larm, rarm)
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# # body = self.lines[index - 1][0] = None
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self.draw_last_bar()
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# self.draw_last_bar()
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self.resetTransform()
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self.setTransform(self.transform())
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self.update()
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# @timeit
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def paint(self, p, opt, widget):
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# profiler = pg.debug.Profiler(disabled=False, delayed=False)
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# TODO: use to avoid drawing artefacts?
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# self.prepareGeometryChange()
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profiler = pg.debug.Profiler(disabled=False) #, delayed=False)
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# p.setCompositionMode(0)
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p.setPen(self.bars_pen)
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# TODO: one thing we could try here is pictures being drawn of
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# a fixed count of bars such that based on the viewbox indices we
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@ -717,10 +744,12 @@ class BarItems(pg.GraphicsObject):
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# as is necesarry for what's in "view". Not sure if this will
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# lead to any perf gains other then when zoomed in to less bars
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# in view.
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p.drawPicture(0, 0, self.last_bar)
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# p.drawPicture(0, 0, self.last_bar)
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p.drawLines(*tuple(filter(bool, self._last_bar_lines)))
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profiler('draw last bar')
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p.setPen(self.bars_pen)
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p.drawPath(self.path)
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profiler('draw history path')
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# @timeit
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def boundingRect(self):
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@ -738,16 +767,31 @@ class BarItems(pg.GraphicsObject):
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# bounding rect for us).
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# compute aggregate bounding rectangle
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lb = self.last_bar.boundingRect()
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hb = self.path.boundingRect()
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# lb = self.last_bar.boundingRect()
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# hb = self.path.boundingRect()
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# apparently this a lot faster says the docs?
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# https://doc.qt.io/qt-5/qpainterpath.html#controlPointRect
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hb = self.path.controlPointRect()
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hb_size = hb.size()
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# print(f'hb_size: {hb_size}')
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w = hb_size.width() + 1
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h = hb_size.height() + 1
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br = QtCore.QRectF(
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return QtCore.QRectF(
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# top left
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QtCore.QPointF(hb.topLeft()),
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# total size
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QtCore.QSizeF(QtCore.QSizeF(lb.size()) + hb.size())
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# QtCore.QSizeF(QtCore.QSizeF(lb.size()) + hb.size())
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QtCore.QSizeF(w, h)
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# QtCore.QSizeF(lb.size() + hb.size())
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)
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# print(f'bounding rect: {br}')
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return br
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# XXX: when we get back to enabling tina mode for xb
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