问题
I'm trying to display clickable hyperlinks in my QTreeView.
I was able to do this using QLabels and QTreeView.setIndexWidget per the recommendations from this question.
Hyperlinks in QTreeView
Unfortunately, my QTreeView can be rather large (1000s of items), and creating 1000s of QLabels is slow.
The upside is that I can use a Delegate in my QTreeView to draw text that looks like hyperlinks. This is super fast.
The problem now is that I need them to respond like hyperlinks (i.e. mouseover hand cursor, respond to clicks, etc.), but I'm not sure what the best way to go about that is.
I've been able to sort of fake it by just connecting to the clicked() signal of the QTreeView, but it's not exactly the same, because it responds to the whole cell, and not just the text inside the cell.
回答1:
The easiest way to do that seems to be by subclassing QItemDelegate, because the text is drawn by a separate virtual function, drawDisplay (with QStyledItemDelegate you would almost have to redraw the item from scratch and you would need an additional class deriving from QProxyStyle):
- the HTML text is drawn with
QTextDocumentandQTextDocument.documentLayout().draw(), - when the mouse enters an item, that same item is repainted and
drawDisplayis called, we save the position were we are drawing the text (so the saved position is always the position of the text for the item over which the mouse is), - that position is used in
editorEventto get the relative position of the mouse inside the document and to get the link at that position in the document withQAbstractTextDocumentLayout.anchorAt.
import sys
from PySide.QtCore import *
from PySide.QtGui import *
class LinkItemDelegate(QItemDelegate):
linkActivated = Signal(str)
linkHovered = Signal(str) # to connect to a QStatusBar.showMessage slot
def __init__(self, parentView):
QItemDelegate.__init__(self, parentView)
assert isinstance(parentView, QAbstractItemView), \
"The first argument must be the view"
# We need that to receive mouse move events in editorEvent
parentView.setMouseTracking(True)
# Revert the mouse cursor when the mouse isn't over
# an item but still on the view widget
parentView.viewportEntered.connect(parentView.unsetCursor)
# documents[0] will contain the document for the last hovered item
# documents[1] will be used to draw ordinary (not hovered) items
self.documents = []
for i in range(2):
self.documents.append(QTextDocument(self))
self.documents[i].setDocumentMargin(0)
self.lastTextPos = QPoint(0,0)
def drawDisplay(self, painter, option, rect, text):
# Because the state tells only if the mouse is over the row
# we have to check if it is over the item too
mouseOver = option.state & QStyle.State_MouseOver \
and rect.contains(self.parent().viewport() \
.mapFromGlobal(QCursor.pos())) \
and option.state & QStyle.State_Enabled
if mouseOver:
# Use documents[0] and save the text position for editorEvent
doc = self.documents[0]
self.lastTextPos = rect.topLeft()
doc.setDefaultStyleSheet("")
else:
doc = self.documents[1]
# Links are decorated by default, so disable it
# when the mouse is not over the item
doc.setDefaultStyleSheet("a {text-decoration: none}")
doc.setDefaultFont(option.font)
doc.setHtml(text)
painter.save()
painter.translate(rect.topLeft())
ctx = QAbstractTextDocumentLayout.PaintContext()
ctx.palette = option.palette
doc.documentLayout().draw(painter, ctx)
painter.restore()
def editorEvent(self, event, model, option, index):
if event.type() not in [QEvent.MouseMove, QEvent.MouseButtonRelease] \
or not (option.state & QStyle.State_Enabled):
return False
# Get the link at the mouse position
# (the explicit QPointF conversion is only needed for PyQt)
pos = QPointF(event.pos() - self.lastTextPos)
anchor = self.documents[0].documentLayout().anchorAt(pos)
if anchor == "":
self.parent().unsetCursor()
else:
self.parent().setCursor(Qt.PointingHandCursor)
if event.type() == QEvent.MouseButtonRelease:
self.linkActivated.emit(anchor)
return True
else:
self.linkHovered.emit(anchor)
return False
def sizeHint(self, option, index):
# The original size is calculated from the string with the html tags
# so we need to subtract from it the difference between the width
# of the text with and without the html tags
size = QItemDelegate.sizeHint(self, option, index)
# Use a QTextDocument to strip the tags
doc = self.documents[1]
html = index.data() # must add .toString() for PyQt "API 1"
doc.setHtml(html)
plainText = doc.toPlainText()
fontMetrics = QFontMetrics(option.font)
diff = fontMetrics.width(html) - fontMetrics.width(plainText)
return size - QSize(diff, 0)
As long as you don't enable the automatic column resizing to contents (which would call sizeHint for every items), it doesn't seem to be slower than without the delegate.
With a custom model, it might be possible to speed it up by caching directly some data inside the model (for example, by using and storing QStaticText for non hovered items instead of QTextDocument).
回答2:
It is probably possible to avoid the use of QLabels, but it may affect code readability.
There may be no need to fill the entire tree at once. Have you considered generating QLabels as needed? Allocate enough to cover a sub-tree with the expand and expandAll signals. You can expand this by creating a pool of QLabels and changing their text (and where they are used) as needed.
回答3:
Thanks for this code, the better I found on the web. I use your code in my project but I need to use qss style sheet and your code doesn't work. I replace QItemDelegate by QStyledItemDelegate and modify your code (vertical alignment on html link, may be you can find another simpler workaroud), and make computations only when string begins with '
class LinkItemDelegate(QStyledItemDelegate):
linkActivated = pyqtSignal(str)
linkHovered = pyqtSignal(str) # to connect to a QStatusBar.showMessage slot
def __init__(self, parentView):
super(LinkItemDelegate, self).__init__(parentView)
assert isinstance(parentView, QAbstractItemView), \
"The first argument must be the view"
# We need that to receive mouse move events in editorEvent
parentView.setMouseTracking(True)
# Revert the mouse cursor when the mouse isn't over
# an item but still on the view widget
parentView.viewportEntered.connect(parentView.unsetCursor)
# documents[0] will contain the document for the last hovered item
# documents[1] will be used to draw ordinary (not hovered) items
self.documents = []
for i in range(2):
self.documents.append(QTextDocument(self))
self.documents[i].setDocumentMargin(0)
self.lastTextPos = QPoint(0,0)
def drawDisplay(self, painter, option, rect, text):
# Because the state tells only if the mouse is over the row
# we have to check if it is over the item too
mouseOver = option.state & QStyle.State_MouseOver \
and rect.contains(self.parent().viewport() \
.mapFromGlobal(QCursor.pos())) \
and option.state & QStyle.State_Enabled
# Force to be vertically align
fontMetrics = QFontMetrics(option.font)
rect.moveTop(rect.y() + rect.height() / 2 - fontMetrics.height() / 2)
if mouseOver:
# Use documents[0] and save the text position for editorEvent
doc = self.documents[0]
self.lastTextPos = rect.topLeft()
doc.setDefaultStyleSheet("")
else:
doc = self.documents[1]
# Links are decorated by default, so disable it
# when the mouse is not over the item
doc.setDefaultStyleSheet("a {text-decoration: none; }")
doc.setDefaultFont(option.font)
doc.setHtml(text)
painter.save()
painter.translate(rect.topLeft())
ctx = QAbstractTextDocumentLayout.PaintContext()
ctx.palette = option.palette
doc.documentLayout().draw(painter, ctx)
painter.restore()
def editorEvent(self, event, model, option, index):
if event.type() not in [QEvent.MouseMove, QEvent.MouseButtonRelease] \
or not (option.state & QStyle.State_Enabled):
return False
# Get the link at the mouse position
# (the explicit QPointF conversion is only needed for PyQt)
pos = QPointF(event.pos() - self.lastTextPos)
anchor = self.documents[0].documentLayout().anchorAt(pos)
if anchor == "":
self.parent().unsetCursor()
else:
self.parent().setCursor(Qt.PointingHandCursor)
if event.type() == QEvent.MouseButtonRelease:
self.linkActivated.emit(anchor)
return True
else:
self.linkHovered.emit(anchor)
return False
def sizeHint(self, option, index):
# The original size is calculated from the string with the html tags
# so we need to subtract from it the difference between the width
# of the text with and without the html tags
size = super(LinkItemDelegate, self).sizeHint(option, index)
if option.text.startswith('<a'):
# Use a QTextDocument to strip the tags
doc = self.documents[1]
html = index.data() # must add .toString() for PyQt "API 1"
doc.setHtml(html)
plainText = doc.toPlainText()
fontMetrics = QFontMetrics(option.font)
diff = fontMetrics.width(html) - fontMetrics.width(plainText)
size = size - QSize(diff, 0)
return size
def paint(self, painter, option, index):
if (index.isValid()):
text = None
options = QStyleOptionViewItem(option)
self.initStyleOption(options,index)
if options.text.startswith('<a'):
text = options.text
options.text = ""
style = options.widget.style() if options.widget.style() else QApplication.style()
style.drawControl(QStyle.CE_ItemViewItem, options, painter, options.widget)
if text:
textRect = style.subElementRect(QStyle.SE_ItemViewItemText, options, options.widget)
self.drawDisplay(painter, option, textRect, text)
Don't forget to connect item delegate :
linkItemDelegate = LinkItemDelegate(self.my_treeView)
linkItemDelegate.linkActivated.connect(self.onClicLink)
self.my_treeView.setItemDelegate(linkItemDelegate) # Create custom delegate and set model and delegate to the treeview object
And it's work great !
来源：https://stackoverflow.com/questions/7102397/hyperlinks-in-qtreeview-without-qlabel