# -*- 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(QObject): def __init__(self): QObject.__init__(self) self.attributes = 0 self.hasClipping = False self.seriesItem = None # QwtPlotSeriesItem self.clipRegion = QRegion() self.painter = QPainter() self.from_ = None self.to = None 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() 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() 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 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 def hasClipping(self): """ :return: Return true, when clipping is enabled .. seealso:: :py:meth:`setClipping()`, :py:meth:`clipRegion()`, :py:meth:`setClipRegion()` """ return self.__data.hasClipping 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 def clipRegion(self): """ :return: Return Currently set clip region. .. seealso:: :py:meth:`hasClipping()`, :py:meth:`setClipping()`, :py:meth:`setClipRegion()` """ return self.__data.clipRegion 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 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() 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