標注示例來自 QtCharts 包：https ://doc.qt.io/qt-5/qtcharts-callout-example.html這個（優秀的）示例展示了如何在圖表頂部繪制附加元素（標注）。問題是這個例子是否可以在 python 實現的某個地方找到？
1 回答
蠱毒傳說
TA貢獻1895條經驗 獲得超3個贊
我一直在尋找移植到 PyQt5 (python) 的示例，但沒有找到。所以我自己寫的，想和大家分享一下（只是為了節省你的時間）。它是為 Python 3.8 編寫的，但也適用于舊版本，PyQt 版本是 5.14.1。
與原始的 C++ 實現只有一點點不同。QGraphicsScene必須顯式設置 - 在View構造函數類中，并且每個新Callout對象都必須顯式添加到場景中。坦率地說，我不知道為什么，但我不在乎。C++ 中完全相同的 Qt 庫版本不需要。
import sys
from typing import List
from PyQt5.QtChart import QChart, QLineSeries, QSplineSeries
from PyQt5.QtCore import QPointF, QRect, QRectF, QSizeF, Qt
from PyQt5.QtGui import QColor, QFont, QFontMetrics, QMouseEvent, QPainter, QPainterPath, QResizeEvent
from PyQt5.QtWidgets import QApplication, QGraphicsItem, QGraphicsScene, QGraphicsSceneMouseEvent, \
QGraphicsSimpleTextItem, QGraphicsView, QStyleOptionGraphicsItem, QWidget
class Callout(QGraphicsItem):
def __init__(self, parent: QChart):
super().__init__()
self.m_chart: QChart = parent
self.m_text: str = ''
self.m_anchor: QPointF = QPointF()
self.m_font: QFont = QFont()
self.m_textRect: QRectF = QRectF()
self.m_rect: QRectF = QRectF()
def setText(self, text: str):
self.m_text = text
metrics = QFontMetrics(self.m_font)
self.m_textRect = QRectF(metrics.boundingRect(QRect(0, 0, 150, 150), Qt.AlignLeft, self.m_text))
self.m_textRect.translate(5, 5)
self.prepareGeometryChange()
self.m_rect = QRectF(self.m_textRect.adjusted(-5, -5, 5, 5))
self.updateGeometry()
def updateGeometry(self):
self.prepareGeometryChange()
self.setPos(self.m_chart.mapToPosition(self.m_anchor) + QPointF(10, -50))
def boundingRect(self) -> QRectF:
from_parent = self.mapFromParent(self.m_chart.mapToPosition(self.m_anchor))
anchor = QPointF(from_parent)
rect = QRectF()
rect.setLeft(min(self.m_rect.left(), anchor.x()))
rect.setRight(max(self.m_rect.right(), anchor.x()))
rect.setTop(min(self.m_rect.top(), anchor.y()))
rect.setBottom(max(self.m_rect.bottom(), anchor.y()))
return rect
def paint(self, painter: QPainter, option: QStyleOptionGraphicsItem, widget: QWidget):
path = QPainterPath()
mr = self.m_rect
path.addRoundedRect(mr, 5, 5)
anchor = QPointF(self.mapFromParent(self.m_chart.mapToPosition(self.m_anchor)))
if not mr.contains(anchor):
point1 = QPointF()
point2 = QPointF()
# establish the position of the anchor point in relation to self.m_rect
above = anchor.y() <= mr.top()
above_center = mr.top() < anchor.y() <= mr.center().y()
below_center = mr.center().y() < anchor.y() <= mr.bottom()
below = anchor.y() > mr.bottom()
on_left = anchor.x() <= mr.left()
left_of_center = mr.left() < anchor.x() <= mr.center().x()
right_of_center = mr.center().x() < anchor.x() <= mr.right()
on_right = anchor.x() > mr.right()
# get the nearest self.m_rect corner.
x = (on_right + right_of_center) * mr.width()
y = (below + below_center) * mr.height()
corner_case = (above and on_left) or (above and on_right) or (below and on_left) or (below and on_right)
vertical = abs(anchor.x() - x) > abs(anchor.y() - y)
horizontal = bool(not vertical)
x1 = x + left_of_center * 10 - right_of_center * 20 + corner_case * horizontal * (
on_left * 10 - on_right * 20)
y1 = y + above_center * 10 - below_center * 20 + corner_case * vertical * (above * 10 - below * 20)
point1.setX(x1)
point1.setY(y1)
x2 = x + left_of_center * 20 - right_of_center * 10 + corner_case * horizontal * (
on_left * 20 - on_right * 10)
y2 = y + above_center * 20 - below_center * 10 + corner_case * vertical * (above * 20 - below * 10)
point2.setX(x2)
point2.setY(y2)
path.moveTo(point1)
path.lineTo(anchor)
path.lineTo(point2)
path = path.simplified()
painter.setPen(QColor(30, 30, 30))
painter.setBrush(QColor(255, 255, 255))
painter.drawPath(path)
painter.drawText(self.m_textRect, self.m_text)
def mousePressEvent(self, event: QGraphicsSceneMouseEvent):
event.setAccepted(True)
def mouseMoveEvent(self, event: QGraphicsSceneMouseEvent):
if event.buttons() & Qt.LeftButton:
self.setPos(self.mapToParent(event.pos() - event.buttonDownPos(Qt.LeftButton)))
event.setAccepted(True)
else:
event.setAccepted(False)
class View(QGraphicsView):
def __init__(self, parent=None):
super().__init__(parent)
self.m_callouts: List[Callout] = []
self.setDragMode(QGraphicsView.NoDrag)
self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
# chart
self.m_chart = QChart(parent)
self.m_chart.setMinimumSize(640, 480)
self.m_chart.setTitle("Hover the line to show callout. Click the line to make it stay")
self.m_chart.legend().hide()
series = QLineSeries()
series.append(1, 3)
series.append(4, 5)
series.append(5, 4.5)
series.append(7, 1)
series.append(11, 2)
self.m_chart.addSeries(series)
series2 = QSplineSeries()
series2.append(1.6, 1.4)
series2.append(2.4, 3.5)
series2.append(3.7, 2.5)
series2.append(7, 4)
series2.append(10, 2)
self.m_chart.addSeries(series2)
self.m_chart.createDefaultAxes()
self.m_chart.setAcceptHoverEvents(True)
self.setRenderHint(QPainter.Antialiasing)
self.setScene(QGraphicsScene())
self.scene().addItem(self.m_chart)
self.m_coordX = QGraphicsSimpleTextItem(self.m_chart)
self.m_coordX.setPos(self.m_chart.size().width() / 2 - 50, self.m_chart.size().height() - 20)
self.m_coordX.setText("X: ")
self.m_coordY = QGraphicsSimpleTextItem(self.m_chart)
self.m_coordY.setPos(self.m_chart.size().width() / 2 + 50, self.m_chart.size().height() - 20)
self.m_coordY.setText("Y: ")
self.m_tooltip = Callout(self.m_chart)
self.scene().addItem(self.m_tooltip)
series.clicked.connect(self.keep_callout)
series.hovered.connect(self.tooltip)
series2.clicked.connect(self.keep_callout)
series2.hovered.connect(self.tooltip)
self.setMouseTracking(True)
def resizeEvent(self, event: QResizeEvent):
if scene := self.scene():
scene.setSceneRect(QRectF(QPointF(0, 0), QSizeF(event.size())))
self.m_chart.resize(QSizeF(event.size()))
self.m_coordX.setPos(self.m_chart.size().width() / 2 - 50, self.m_chart.size().height() - 20)
self.m_coordY.setPos(self.m_chart.size().width() / 2 + 50, self.m_chart.size().height() - 20)
for callout in self.m_callouts:
callout.updateGeometry()
super().resizeEvent(event)
def mouseMoveEvent(self, event: QMouseEvent):
from_chart = self.m_chart.mapToValue(event.pos())
self.m_coordX.setText(f"X: {from_chart.x()}")
self.m_coordX.setText(f"Y: {from_chart.y()}")
super().mouseMoveEvent(event)
def keep_callout(self):
self.m_callouts.append(self.m_tooltip)
self.m_tooltip = Callout(self.m_chart)
self.scene().addItem(self.m_tooltip)
def tooltip(self, point: QPointF, state: bool):
if not self.m_tooltip:
self.m_tooltip = Callout(self.m_chart)
if state:
self.m_tooltip.setText(f"X: {point.x()} \nY: {point.x()} ")
self.m_tooltip.m_anchor = point
self.m_tooltip.setZValue(11)
self.m_tooltip.updateGeometry()
self.m_tooltip.show()
else:
self.m_tooltip.hide()
if __name__ == '__main__':
app = QApplication(sys.argv)
window = View()
window.resize(640, 480)
window.show()
sys.exit(app.exec_())
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