python - QStyledItemDelegate 绘制刷新问题

Question

我目前正在尝试研究模型 View 方法并编写缩略图查看器应用程序。

在此示例中，我只是尝试绘制 20 个框，但我得到的似乎是随机选择，该选择会随着鼠标移动而更新。滚动使事情变得更糟，并且绘制有时只有框等。而且文本似乎根本没有渲染。

对我来说，这看起来像是paint方法的刷新/更新问题。我在这里遗漏了什么吗？

最终我需要显示很多项目。所有这些都包含一些标签和一个需要在运行时更新的像素图。所以我认为画它们将是最快的解决方案。或者，我尝试使用 Paint 方法渲染我的小部件:

customWidget.render(painter, QtCore.QPoint(0,0), renderFlags=QtGui.QWidget.DrawChildren)

这似乎更慢，但至少可以工作。

这是一个最小的工作示例来说明我的问题:

import sys
from PySide import QtCore
from PySide import QtGui

elements = range(20)

class ElementListModel(QtCore.QAbstractListModel):
    def __init__(self, elements = [], parent = None):
        super(ElementListModel, self).__init__()
        self.__elements = elements

    def rowCount(self, parent):
        return len(self.__elements)

    def data(self, index, role):
        if role == QtCore.Qt.DisplayRole:
            return str(self.__elements[index.row()])

class ElementThumbDelegate(QtGui.QStyledItemDelegate):
    def __init__(self, view, parent=None):
        super(ElementThumbDelegate, self).__init__(parent)

    def paint(self, painter, options, index):

        width = options.rect.width()
        height = options.rect.height()

        painter.setRenderHint(QtGui.QPainter.Antialiasing)
        painter.setPen(QtGui.QColor(255, 255, 255))
        painter.setBrush(QtGui.QColor(10, 10, 10))
        painter.drawRect(0, 0, width, height)
        painter.drawText(options.rect, QtCore.Qt.AlignHCenter | QtCore.Qt.AlignVCenter, str(index.data()))
        painter.translate(options.rect.topLeft())

    def sizeHint(self, options, index):
        return QtCore.QSize(50, 50)

def main():
    app = QtGui.QApplication(sys.argv)
    viewer = QtGui.QListView()

    viewModel = ElementListModel(elements)
    viewer.setModel(viewModel)
    viewer.setViewMode(QtGui.QListView.IconMode)
    viewer.setItemDelegate(ElementThumbDelegate(viewer))

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

if __name__ == '__main__':
    main()

提前致谢。任何帮助或下一步寻找方向的指示将不胜感激!

Answer 1

事实证明，painter.translate() 与在查看器原点 (0,0) 处绘制框相结合，与自动定位发生冲突并导致了问题。

委托(delegate)到适当位置的转换由 View 本身处理 - 无需手动执行。

工作代码:

import sys
from PySide import QtCore
from PySide import QtGui

elements = range(20)

class ElementListModel(QtCore.QAbstractListModel):
    def __init__(self, elements = [], parent = None):
        super(ElementListModel, self).__init__()
        self.__elements = elements

    def rowCount(self, parent):
        return len(self.__elements)

    def data(self, index, role):
        if role == QtCore.Qt.DisplayRole:
            return str(self.__elements[index.row()])

class ElementThumbDelegate(QtGui.QStyledItemDelegate):
    def __init__(self, view, parent=None):
        super(ElementThumbDelegate, self).__init__(parent)

    def paint(self, painter, options, index):
        painter.setRenderHint(QtGui.QPainter.Antialiasing)
        painter.setPen(QtGui.QColor(255, 255, 255))
        painter.setBrush(QtGui.QColor(10, 10, 10))
        painter.drawRect(options.rect)
        painter.drawText(options.rect, QtCore.Qt.AlignHCenter | QtCore.Qt.AlignVCenter, str(index.data()))

    def sizeHint(self, options, index):
        return QtCore.QSize(50, 50)

def main():
    app = QtGui.QApplication(sys.argv)
    viewer = QtGui.QListView()

    viewModel = ElementListModel(elements)
    viewer.setModel(viewModel)
    viewer.setViewMode(QtGui.QListView.IconMode)
    viewer.setItemDelegate(ElementThumbDelegate(viewer))

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

if __name__ == '__main__':
    main()