class TextLineItem(QAbstractGraphicsShapeItem):
"""A one-line text item.
Default origin point is at the left side of the baseline. This can change if setAlignMode is called. TextLineItem
also supports drawing text background. Its brush can be set using setBackgroundBrush(). Text must not contain
newline characters.
"""
def __init__(self, text=None, parent=None):
super().__init__(parent)
self._text = text or ""
self._elided_text = text or ""
self._elide_mode = Qt.ElideRight
self._align_mode = Qt.AlignLeft
self._max_width = None
self._font = QFont()
self._bounding_rect = QRectF()
"""Bounding and drawing rectangle. Determined automatically."""
self.background = QGraphicsRectItem(self)
self.background.setPen(Qt.NoPen)
self.background.setFlag(QGraphicsItem.ItemStacksBehindParent)
self.adjust()
def setText(self, text: str, /) -> None:
if '\n' in text:
raise ValueError("text must not contain newline characters")
self.prepareGeometryChange()
self._text = text
self.adjust()
def setElideMode(self, mode: int, /) -> None:
"""Elide mode specifies where the ellipsis should be located when the text is elided. Default value is
Qt.ElideRight.
"""
self.prepareGeometryChange()
self._elide_mode = mode
self.adjust()
def setAlignMode(self, mode: int, /) -> None:
"""Align mode specifies text alignment.
Text alignment changes the origin point x position:
- If mode is Qt.AlignLeft, the origin point is on the left of the baseline.
- If mode is Qt.AlignHCenter, the origin point is in the center of the baseline.
- If mode is Qt.AlignRight, the origin point is on the right of the baseline.
Vertical alignment has no meaning for one line of text and should not be set. Default value is Qt.AlignLeft.
"""
self.prepareGeometryChange()
self._align_mode = mode
self.adjust()
def setMaximumWidth(self, width, /):
"""Set the maximum width the text is allowed to be. `None` represents unlimited width."""
self.prepareGeometryChange()
self._max_width = width
self.adjust()
def setFont(self, font: QFont, /) -> None:
self.prepareGeometryChange()
self._font = font
self.adjust()
def setBackgroundBrush(self, brush: QBrush, /):
self.background.setBrush(brush)
def text(self) -> str:
return self._text
def elidedText(self) -> str:
return self._elided_text
def elideMode(self) -> int:
return self._elide_mode
def alignMode(self) -> int:
return self._align_mode
def maximumWidth(self):
"""Maximum width the text is allowed to be. `None` represents unlimited width."""
return self._max_width
def font(self) -> QFont:
return self._font
def backgroundBrush(self):
return self.background.brush()
def adjust(self):
"""Adjust the item's geometry in response to changes."""
metrics = QFontMetricsF(self.font())
# Get bounding rectangle for full text
self._bounding_rect = metrics.boundingRect(self.text())
# Constrain by maximum width
if self.maximumWidth() is not None:
self._bounding_rect.setWidth(self.maximumWidth())
# Compute elided text
self._elided_text = metrics.elidedText(self.text(), self.elideMode(),
self.boundingRect().width())
# Get bounding rectangle for elided text
self._bounding_rect = metrics.boundingRect(self.elidedText())
# It seems that for small characters like "..." the bounding rect returned is too small. Adjust it by a small
# value.
metrics_correction = px(1 / 72)
self._bounding_rect.adjust(-metrics_correction, 0, metrics_correction,
0)
# Move origin point according to the alignment
if self.alignMode() & Qt.AlignLeft:
self._bounding_rect.moveLeft(0)
elif self.alignMode() & Qt.AlignRight:
self._bounding_rect.moveRight(0)
else:
self._bounding_rect.moveLeft(-self._bounding_rect.width() / 2)
# Set background rect
self.background.setRect(self.boundingRect())
def boundingRect(self) -> QRectF:
return self._bounding_rect
def paint(self, painter: QPainter, option, widget=...) -> None:
painter.setBrush(self.brush())
painter.setPen(self.pen())
painter.setFont(self.font())
painter.drawText(self.boundingRect(), self.alignMode(),
self.elidedText())
