# -*- coding: utf-8 -*-
#
# Licensed under the terms of the Qwt License
# Copyright (c) 2002 Uwe Rathmann, for the original C++ code
# Copyright (c) 2015 Pierre Raybaut, for the Python translation/optimization
# (see LICENSE file for more details)
"""
QwtPlotDirectPainter
--------------------
.. autoclass:: QwtPlotDirectPainter
:members:
"""
from qtpy.QtCore import QEvent, QObject, Qt
from qtpy.QtGui import QPainter, QRegion
from qwt.plot import QwtPlotItem
from qwt.plot_canvas import QwtPlotCanvas
def qwtRenderItem(painter, canvasRect, seriesItem, from_, to):
# TODO: A minor performance improvement is possible with caching the maps
plot = seriesItem.plot()
xMap = plot.canvasMap(seriesItem.xAxis())
yMap = plot.canvasMap(seriesItem.yAxis())
painter.setRenderHint(
QPainter.Antialiasing, seriesItem.testRenderHint(QwtPlotItem.RenderAntialiased)
)
seriesItem.drawSeries(painter, xMap, yMap, canvasRect, from_, to)
def qwtHasBackingStore(canvas):
return (
canvas.testPaintAttribute(QwtPlotCanvas.BackingStore)
and canvas.backingStore() is not None
and not canvas.backingStore().isNull()
)
class QwtPlotDirectPainter_PrivateData(object):
def __init__(self):
self.attributes = 0
self.hasClipping = False
self.seriesItem = None # QwtPlotSeriesItem
self.clipRegion = QRegion()
self.painter = QPainter()
self.from_ = None
self.to = None
[docs]
class QwtPlotDirectPainter(QObject):
"""
Painter object trying to paint incrementally
Often applications want to display samples while they are
collected. When there are too many samples complete replots
will be expensive to be processed in a collection cycle.
`QwtPlotDirectPainter` offers an API to paint
subsets (f.e all additions points) without erasing/repainting
the plot canvas.
On certain environments it might be important to calculate a proper
clip region before painting. F.e. for Qt Embedded only the clipped part
of the backing store will be copied to a (maybe unaccelerated)
frame buffer.
.. warning::
Incremental painting will only help when no replot is triggered
by another operation (like changing scales) and nothing needs
to be erased.
Paint attributes:
* `QwtPlotDirectPainter.AtomicPainter`:
Initializing a `QPainter` is an expensive operation.
When `AtomicPainter` is set each call of `drawSeries()` opens/closes
a temporary `QPainter`. Otherwise `QwtPlotDirectPainter` tries to
use the same `QPainter` as long as possible.
* `QwtPlotDirectPainter.FullRepaint`:
When `FullRepaint` is set the plot canvas is explicitly repainted
after the samples have been rendered.
* `QwtPlotDirectPainter.CopyBackingStore`:
When `QwtPlotCanvas.BackingStore` is enabled the painter
has to paint to the backing store and the widget. In certain
situations/environments it might be faster to paint to
the backing store only and then copy the backing store to the canvas.
This flag can also be useful for settings, where Qt fills the
the clip region with the widget background.
"""
# enum Attribute
AtomicPainter = 0x01
FullRepaint = 0x02
CopyBackingStore = 0x04
def __init__(self, parent=None):
QObject.__init__(self, parent)
self.__data = QwtPlotDirectPainter_PrivateData()
[docs]
def setAttribute(self, attribute, on=True):
"""
Change an attribute
:param int attribute: Attribute to change
:param bool on: On/Off
.. seealso::
:py:meth:`testAttribute()`
"""
if self.testAttribute(attribute) != on:
self.__data.attributes |= attribute
else:
self.__data.attributes &= ~attribute
if attribute == self.AtomicPainter and on:
self.reset()
[docs]
def testAttribute(self, attribute):
"""
:param int attribute: Attribute to be tested
:return: True, when attribute is enabled
.. seealso::
:py:meth:`setAttribute()`
"""
return self.__data.attributes & attribute
[docs]
def setClipping(self, enable):
"""
En/Disables clipping
:param bool enable: Enables clipping is true, disable it otherwise
.. seealso::
:py:meth:`hasClipping()`, :py:meth:`clipRegion()`,
:py:meth:`setClipRegion()`
"""
self.__data.hasClipping = enable
[docs]
def hasClipping(self):
"""
:return: Return true, when clipping is enabled
.. seealso::
:py:meth:`setClipping()`, :py:meth:`clipRegion()`,
:py:meth:`setClipRegion()`
"""
return self.__data.hasClipping
[docs]
def setClipRegion(self, region):
"""
Assign a clip region and enable clipping
Depending on the environment setting a proper clip region might
improve the performance heavily. F.e. on Qt embedded only the clipped
part of the backing store will be copied to a (maybe unaccelerated)
frame buffer device.
:param QRegion region: Clip region
.. seealso::
:py:meth:`hasClipping()`, :py:meth:`setClipping()`,
:py:meth:`clipRegion()`
"""
self.__data.clipRegion = region
self.__data.hasClipping = True
[docs]
def clipRegion(self):
"""
:return: Return Currently set clip region.
.. seealso::
:py:meth:`hasClipping()`, :py:meth:`setClipping()`,
:py:meth:`setClipRegion()`
"""
return self.__data.clipRegion
[docs]
def drawSeries(self, seriesItem, from_, to):
"""
Draw a set of points of a seriesItem.
When observing a measurement while it is running, new points have
to be added to an existing seriesItem. drawSeries() can be used to
display them avoiding a complete redraw of the canvas.
Setting `plot().canvas().setAttribute(Qt.WA_PaintOutsidePaintEvent, True)`
will result in faster painting, if the paint engine of the canvas widget
supports this feature.
:param qwt.plot_series.QwtPlotSeriesItem seriesItem: Item to be painted
:param int from_: Index of the first point to be painted
:param int to: Index of the last point to be painted. If to < 0 the series will be painted to its last point.
"""
if seriesItem is None or seriesItem.plot() is None:
return
canvas = seriesItem.plot().canvas()
canvasRect = canvas.contentsRect()
if canvas and qwtHasBackingStore(canvas):
painter = QPainter(canvas.backingStore())
if self.__data.hasClipping:
painter.setClipRegion(self.__data.clipRegion)
qwtRenderItem(painter, canvasRect, seriesItem, from_, to)
painter.end()
if self.testAttribute(self.FullRepaint):
canvas.repaint()
return
if canvas.testAttribute(Qt.WA_WState_InPaintEvent):
if not self.__data.painter.isActive():
self.reset()
self.__data.painter.begin(canvas)
canvas.installEventFilter(self)
if self.__data.hasClipping:
self.__data.painter.setClipRegion(
QRegion(canvasRect) & self.__data.clipRegion
)
elif not self.__data.painter.hasClipping():
self.__data.painter.setClipRect(canvasRect)
qwtRenderItem(self.__data.painter, canvasRect, seriesItem, from_, to)
if self.__data.attributes & self.AtomicPainter:
self.reset()
elif self.__data.hasClipping:
self.__data.painter.setClipping(False)
else:
self.reset()
self.__data.seriesItem = seriesItem
self.__data.from_ = from_
self.__data.to = to
clipRegion = QRegion(canvasRect)
if self.__data.hasClipping:
clipRegion &= self.__data.clipRegion
canvas.installEventFilter(self)
canvas.repaint(clipRegion)
canvas.removeEventFilter(self)
self.__data.seriesItem = None
[docs]
def reset(self):
"""Close the internal QPainter"""
if self.__data.painter.isActive():
w = self.__data.painter.device() # XXX: cast to QWidget
if w:
w.removeEventFilter(self)
self.__data.painter.end()
[docs]
def eventFilter(self, obj_, event):
if event.type() == QEvent.Paint:
self.reset()
if self.__data.seriesItem:
pe = event # XXX: cast to QPaintEvent
canvas = self.__data.seriesItem.plot().canvas()
painter = QPainter(canvas)
painter.setClipRegion(pe.region())
doCopyCache = self.testAttribute(self.CopyBackingStore)
if doCopyCache:
plotCanvas = canvas # XXX: cast to QwtPlotCanvas
if plotCanvas:
doCopyCache = qwtHasBackingStore(plotCanvas)
if doCopyCache:
painter.drawPixmap(
plotCanvas.rect().topLeft(), plotCanvas.backingStore()
)
if not doCopyCache:
qwtRenderItem(
painter,
canvas.contentsRect(),
self.__data.seriesItem,
self.__data.from_,
self.__data.to,
)
return True
return False
