如何将 QChart 坐标映射到 QChartView 点？

Question

我想在QChart中做一个橡皮筋窗口，但是不知道如何将QChart的坐标映射到QChartView。

例如 (0, 0) 是一个QChart 坐标，在QChartView 中可能是(10, 10)，怎么转换呢？ 看到Get mouse coordinates in QChartView's axis system 的回答了

但是好像和我的要求相反。

import sys
from PyQt5.QtChart import QChart, QChartView, QLineSeries
from PyQt5.QtCore import QPointF, QEvent, QPoint, QRect
from PyQt5.QtWidgets import QApplication, QMainWindow, QRubberBand

class ChartView(QChartView):
    def init_rubber_band(self):
        chart = self.chart()

        start1 = chart.mapToPosition(QPointF(0, 0))
        start2 = chart.mapToScene(start1)
        start3 = QPoint()
        start3.setX(int(start2.x()))
        start3.setY(int(start2.y()))

        end = QPoint(200, 200)

        self.rubber = QRubberBand(QRubberBand.Rectangle, self);
        self.rubber.setGeometry(QRect(start3, end))
        self.rubber.show()


app = QApplication(sys.argv)
series0 = QLineSeries()
series1 = QLineSeries()

series0 << QPointF(1, 15) << QPointF(3, 17) << QPointF(7, 16) << QPointF(9, 17) \
        << QPointF(12, 16) << QPointF(16, 17) << QPointF(18, 15)
series1 << QPointF(1, 3) << QPointF(3, 4) << QPointF(7, 3) << QPointF(8, 2) \
        << QPointF(12, 3) << QPointF(16, 4) << QPointF(18, 3)

chart = QChart()
chart.addSeries(series0)
chart.addSeries(series1)
chart.createDefaultAxes()
chartView = ChartView(chart)

chartView.init_rubber_band()

window = QMainWindow()
window.setCentralWidget(chartView)
window.resize(400, 300)
window.show()

sys.exit(app.exec_())

我用mapToPosition获取原点坐标，但是好像不行。

Answer 1

如果你想执行一些计算，你必须在小部件显示后进行，因为QChartView 只是重新计算项目，在下面的示例中，我将创建一个QRubberBand，它位于一个矩形上，其坐标与@987654325 有关@从QPointF(1, 17)到QPointF(18, 2)

class ChartView(QChartView):
    def init_rubber_band(self):
        chart = self.chart()
        start_value = QPointF(1, 17)
        end_value = QPointF(18, 2)
        start = chart.mapToPosition(start_value)
        end = chart.mapToPosition(end_value)

        self.rubber = QRubberBand(QRubberBand.Rectangle, self)
        self.rubber.setGeometry(QRect(start.toPoint(), end.toPoint()))
        self.rubber.show()


app = QApplication(sys.argv)
series0 = QLineSeries()
series1 = QLineSeries()

series0 << QPointF(1, 15) << QPointF(3, 17) << QPointF(7, 16) << QPointF(9, 17) \
        << QPointF(12, 16) << QPointF(16, 17) << QPointF(18, 15)
series1 << QPointF(1, 3) << QPointF(3, 4) << QPointF(7, 3) << QPointF(8, 2) \
        << QPointF(12, 3) << QPointF(16, 4) << QPointF(18, 3)

chart = QChart()
chart.addSeries(series0)
chart.addSeries(series1)
chart.createDefaultAxes()
chartView = ChartView(chart)

window = QMainWindow()
window.setCentralWidget(chartView)
window.resize(400, 300)
window.show()

chartView.init_rubber_band()

sys.exit(app.exec_())

输出：