如何提高 QGraphicsView 在具有许多项目的 2D 静态场景中的性能？（没有办法解决吗？）

发布于 2024-10-13 15:29:25 字数 2453 浏览 4 评论 0 原文

如果理解正确，QGraphicsView 应该能够有效地处理数百万个项目。

在我的应用程序中，我只有几千个，性能已经很糟糕了。当视图显示整个场景时，缩放、hoverEnvents 和任何其他东西都变得不可能。

我尝试在项目之间创建父子关系以及不同的优化标志，但结果仍然相同。我真的希望我犯了一些愚蠢的错误，但是经过几天寻找解决问题的方法，我没有找到任何解决方案。

我真的很感激任何帮助！

这重现了我的问题：

import sys
import random
from PyQt4.QtGui import * 

NO_INDEX = False
OPTIMIZE = False
ITEM_COORD_CACHE = False
ITEM_DEVICE_CACHE = False
NESTED_ITEMS = False


class TestItem(QGraphicsEllipseItem):
    def paint(self, painter, option, index):
        return QGraphicsEllipseItem.paint(self, painter, option, index)

    def hoverEnterEvent (self, e):
        self.setBrush(QBrush(QColor("orange")))

    def hoverLeaveEvent(self,e):
        self.setBrush(QBrush(None))

if __name__ == '__main__':
    n = int(sys.argv[1]) # Number of items. With 5000 I already
                           # have performance problems
    app = QApplication(sys.argv)
    scene = QGraphicsScene()

    # Populates scene
    prev = None
    for i in xrange(n):
        # Random geometry and position
        r1 = random.randint(10, 100)
        r2 = random.randint(10, 100)
        x = random.randint(0, 500)
        y = random.randint(0, 500)

        item = TestItem(x, y, r1*2, r2*2)
        item.setAcceptsHoverEvents(True)

        if NESTED_ITEMS: 
            # Creates a parent child structure among items
            if not prev:
                scene.addItem(item)
            else:
                item.setParentItem(prev)
            prev = item
        else:
            scene.addItem(item)

        if ITEM_COORD_CACHE:
            item.setCacheMode(QGraphicsItem.ItemCoordinateCache)
        elif ITEM_DEVICE_CACHE:
            item.setCacheMode(QGraphicsItem.DeviceCoordinateCache)

    # Creates View
    view = QGraphicsView(scene)
    # Sets basic Flags for nice rendering 
    view.setRenderHints(QPainter.Antialiasing or QPainter.SmoothPixmapTransform)

    if NO_INDEX:
        view.setItemIndexMethod(QGraphicsScene.NoIndex);

    if OPTIMIZE:
        view.setOptimizationFlags(QGraphicsView.DontAdjustForAntialiasing
                                  or QGraphicsView.DontClipPainter
                                  or QGraphicsView.DontSavePainterState)

    view.show()
    sys.exit(app.exec_())

Intel(R) Xeon(R) CPU E5410 @ 2.33GHz
nVidia Corporation G84 [Quadro FX 1700]
Ubuntu 9.04 64 位
qt4 4.5.3
python-qt4 4.6

原文

If understood correctly, QGraphicsView is supposed to handle million items efficiently.

In my application, I only have some few thousand and the performance is already very bad. When the View is showing the whole scene, zooming, hoverEnvents and any other stuff becomes impossible.

I have tried to create a parent-child relationship among items, and different optimization flags, but still the same result. I really hope that I'm making some stupid mistake, but after several days looking for a way to solve the problem, I did not find any solution.

I would really appreciate any help!

This reproduces my problem:

import sys
import random
from PyQt4.QtGui import * 

NO_INDEX = False
OPTIMIZE = False
ITEM_COORD_CACHE = False
ITEM_DEVICE_CACHE = False
NESTED_ITEMS = False


class TestItem(QGraphicsEllipseItem):
    def paint(self, painter, option, index):
        return QGraphicsEllipseItem.paint(self, painter, option, index)

    def hoverEnterEvent (self, e):
        self.setBrush(QBrush(QColor("orange")))

    def hoverLeaveEvent(self,e):
        self.setBrush(QBrush(None))

if __name__ == '__main__':
    n = int(sys.argv[1]) # Number of items. With 5000 I already
                           # have performance problems
    app = QApplication(sys.argv)
    scene = QGraphicsScene()

    # Populates scene
    prev = None
    for i in xrange(n):
        # Random geometry and position
        r1 = random.randint(10, 100)
        r2 = random.randint(10, 100)
        x = random.randint(0, 500)
        y = random.randint(0, 500)

        item = TestItem(x, y, r1*2, r2*2)
        item.setAcceptsHoverEvents(True)

        if NESTED_ITEMS: 
            # Creates a parent child structure among items
            if not prev:
                scene.addItem(item)
            else:
                item.setParentItem(prev)
            prev = item
        else:
            scene.addItem(item)

        if ITEM_COORD_CACHE:
            item.setCacheMode(QGraphicsItem.ItemCoordinateCache)
        elif ITEM_DEVICE_CACHE:
            item.setCacheMode(QGraphicsItem.DeviceCoordinateCache)

    # Creates View
    view = QGraphicsView(scene)
    # Sets basic Flags for nice rendering 
    view.setRenderHints(QPainter.Antialiasing or QPainter.SmoothPixmapTransform)

    if NO_INDEX:
        view.setItemIndexMethod(QGraphicsScene.NoIndex);

    if OPTIMIZE:
        view.setOptimizationFlags(QGraphicsView.DontAdjustForAntialiasing
                                  or QGraphicsView.DontClipPainter
                                  or QGraphicsView.DontSavePainterState)

    view.show()
    sys.exit(app.exec_())

Intel(R) Xeon(R) CPU E5410 @ 2.33GHz
nVidia Corporation G84 [Quadro FX 1700]
Ubuntu 9.04 64 bits
qt4 4.5.3
python-qt4 4.6

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奶茶白久 2024-10-20 15:29:26

基本上，您可以使用的是缓存模式和更新模式，还有场景的 bsp 树的大小。此外，DevDays 2010 的这篇演讲还提供了一些提示和技巧：http://qt.nokia.com/developer/learning/online/talks/developerdays2010/tech-talks/qt-graphics-view-in-deep 。