下面的代码仅显示计算机驱动器的树状视图。每次选择新文件/文件夹时,视图都会滚动以使此新选择可见。
问题 1 :在此过程中,启动应用程序后的初始选择不会触发滚动。为什么?
问题 2 :如果说明:
self.my_view.scrollTo(index, QAbstractItemView.EnsureVisible)
self.my_view.resizeColumnToContents(0)
倒置:
self.my_view.resizeColumnToContents(0)
self.my_view.scrollTo(index, QAbstractItemView.EnsureVisible)
第一列大小在初始显示中都不会调整,只有在之后才会调整。为什么?
import sys
from PyQt5.QtCore import Qt, QModelIndex, QDir
from PyQt5.QtWidgets import QApplication, QTreeView, QMainWindow, QFileSystemModel, QAbstractItemView
class MyWindow(QMainWindow):
def __init__(self):
super().__init__()
# Instance variables
self.my_view = QTreeView()
self.my_model = QFileSystemModel()
# Init FS model to show all computer drives
model_root_path = str(self.my_model.myComputer())
self.my_model.setRootPath(model_root_path)
# Init tree view
self.my_view.setModel(self.my_model)
self.my_view.setRootIndex(self.my_model.index(model_root_path))
self.my_view.setSelectionMode(QAbstractItemView.SingleSelection)
self.my_view.setSelectionBehavior(QAbstractItemView.SelectRows)
# Connect selection change events to custom slot
select_model = self.my_view.selectionModel()
select_model.currentRowChanged.connect(self.current_row_changed)
# Main window
self.setCentralWidget(self.my_view)
self.setGeometry(200, 200, 800, 600)
# Select initial row on view
focus_path = QDir.currentPath()
focus_index = self.my_model.index(focus_path)
self.my_view.setCurrentIndex(focus_index)
def current_row_changed(self):
"""Current row of the model has changed"""
# Scroll view to new row
index = self.my_view.selectionModel().currentIndex()
self.my_view.scrollTo(index, QAbstractItemView.EnsureVisible)
self.my_view.resizeColumnToContents(0)
# Show path of current row in window title
absolute_path = self.my_model.filePath(index)
self.setWindowTitle(absolute_path)
def main():
a = QApplication(sys.argv)
mw = MyWindow()
mw.show()
sys.exit(a.exec_())
if __name__ == '__main__':
main()
`
编辑:使用@ekhumoro提供的良好解决方案后,我上面的示例代码成功了。但是,另一段代码仍然没有:
import os
import sys
from PyQt5.QtCore import pyqtSignal, QTimer, QDir, Qt
from PyQt5.QtWidgets import QMainWindow, QGridLayout, QWidget, QTreeView, QAbstractItemView, QFileSystemModel, \
QApplication
class AppWindow(QMainWindow):
default_folder_path = "."
def __init__(self):
super().__init__()
self.folder_view = FolderTreeView()
self.folder_view.folder_has_changed.connect(self.folder_changed)
self.build_ui()
self.show()
# Select initial folder
self.select_initial_folder()
def build_ui(self):
main_widget = QWidget()
layout = QGridLayout(main_widget)
layout.addWidget(self.folder_view)
self.setCentralWidget(main_widget)
self.setGeometry(200, 100, 800, 600)
def select_initial_folder(self):
folder_index = self.folder_view.get_index(AppWindow.default_folder_path)
if folder_index.isValid():
self.folder_view.select_folder(folder_index)
def folder_changed(self, folder_path):
if not os.path.isdir(folder_path):
print("Non existing folder:", folder_path)
return
class FolderTreeView(QTreeView):
folder_has_changed = pyqtSignal(str)
def __init__(self):
super().__init__()
self.folder_tree_model = FolderTreeModel()
self.setModel(self.folder_tree_model)
self.setSelectionMode(QAbstractItemView.SingleSelection)
self.setSelectionBehavior(QAbstractItemView.SelectRows)
def select_folder(self, folder_index):
self.setCurrentIndex(folder_index)
def currentChanged(self, current, previous):
super(FolderTreeView, self).currentChanged(current, previous)
# Scroll the view to current item and resize folder name column
QTimer.singleShot(50, lambda: self.delayed_scroll(current))
# Emit signal for other uses
self.folder_has_changed.emit(self.folder_tree_model.filePath(current))
def delayed_scroll(self, index):
self.scrollTo(index, QAbstractItemView.EnsureVisible)
self.resizeColumnToContents(0)
def get_index(self, folder_path):
return self.folder_tree_model.index(folder_path)
class FolderTreeModel(QFileSystemModel):
def __init__(self):
super().__init__()
self.setFilter(QDir.AllDirs | QDir.NoDotAndDotDot)
self.setRootPath("")
def main():
app = QApplication(sys.argv)
window = AppWindow()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
答案 0 :(得分:2)
默认情况下,如果模型将其当前索引初始化到当前目录,则可能导致第一个问题。这意味着如果再次将其设置为相同的索引,则不会发出行更改信号(因为没有任何更改)。可以通过直接调用行更改处理程序来解决此问题:
class MyWindow(QMainWindow):
def __init__(self):
super().__init__()
...
focus_path = QDir.currentPath()
focus_index = self.my_model.index(focus_path)
self.my_view.setCurrentIndex(focus_index)
self.current_row_changed()
def current_row_changed(self):
index = self.my_view.currentIndex()
self.my_view.scrollTo(index, QAbstractItemView.EnsureVisible)
self.my_view.resizeColumnToContents(0)
...
关于第二个问题:调用scrollTo
时,可能必须扩展几个目录才能选择所需的索引。显然,这可能会更改第一列的宽度,因此,应始终调用resizeColumnToContents
,以获取正确的宽度。
更新:
我认为还有另一个由计时问题引起的问题。 QFileSystemModel
必须在某种程度上异步工作,因为它必须从操作系统请求资源,然后等待响应。而且,在获得响应之前,它无法事先确切知道要接收多少数据,因为文件系统可能在等待时已被更新。响应可能包括来自巨大目录的数据,其中包含数千个文件。因此,为了使GUI保持响应状态,将批量处理数据,这些数据的大小足以填充当前视图。如果在显示窗口之前将当前索引设置为,并且其所有小部件都已完全布置,则不能保证该视图将能够正确调整其列的大小。
可以通过单触发计时器以较小的延迟显式地重新调用行更改处理程序来解决此问题。这应该允许视图正确地重新计算其列宽:
...
focus_path = QDir.currentPath()
focus_index = self.my_model.index(focus_path)
self.my_view.setCurrentIndex(focus_index)
QTimer.singleShot(50, self.current_row_changed)
def current_row_changed(self):
index = self.my_view.currentIndex()
self.my_view.scrollTo(index, QAbstractItemView.EnsureVisible)
self.my_view.resizeColumnToContents(0)