PyQt5_ Pyqtgraph mouse draws line segments on the line graph

Catalog

effect ：

Code ：

Use ：

---

effect ：

When using broken line to analyze data , It is often necessary to use line segments to draw trend lines on curves , Check here to realize the function of drawing line segments on the line chart .

 

Code ：

Need to use the package import

import sys
from PyQt5 import QtCore,QtGui,QtWidgets
from PyQt5.QtCore import Qt
from typing import Dict,Any,List
import pyqtgraph as pg
pg.setConfigOption('background','w')
pg.setConfigOption('foreground','k')

  Abscissa of string , Used to display date

class RotateAxisItem(pg.AxisItem):
    def drawPicture(self, p, axisSpec, tickSpecs, textSpecs):
        p.setRenderHint(p.Antialiasing,False)
        p.setRenderHint(p.TextAntialiasing,True)

        ## draw long line along axis
        pen,p1,p2 = axisSpec
        p.setPen(pen)
        p.drawLine(p1,p2)
        p.translate(0.5,0)  ## resolves some damn pixel ambiguity

        ## draw ticks
        for pen,p1,p2 in tickSpecs:
            p.setPen(pen)
            p.drawLine(p1,p2)

        ## draw all text
        # if self.tickFont is not None:
        #     p.setFont(self.tickFont)
        p.setPen(self.pen())
        for rect,flags,text in textSpecs:
            # this is the important part
            p.save()
            p.translate(rect.x(),rect.y())
            p.rotate(-30)
            p.drawText(-rect.width(),rect.height(),rect.width(),rect.height(),flags,text)
            # restoring the painter is *required*!!!
            p.restore()

Brush attribute box ： Draw a line segment to set the line segment color 、 Line segment thickness  、 Undo the previous line segment

class DrawLineSegmentWidget(QtWidgets.QWidget):
    sinout_signal = QtCore.pyqtSignal(object)
    def __init__(self):
        super().__init__()
        self.default_color: str = '#ff557f'
        self.init_ui()
        pass
    def init_ui(self):
        self.setWindowFlags(Qt.WindowStaysOnTopHint | Qt.WindowCloseButtonHint)
        self.setWindowTitle(' Draw a trend line ')
        self.setMinimumHeight(400)
        self.setMinimumWidth(100)

        self.current_color_label = QtWidgets.QLabel(' Current color ')
        self.current_color_label.setAlignment(Qt.AlignCenter)
        self.current_color_label.setStyleSheet('QLabel{font-size:16px;color:'+self.default_color+';font-weight:bold}')
        change_color_btn = QtWidgets.QPushButton(' Line color ')
        change_color_btn.clicked.connect(self.change_color_btn_clicked)
        layout_color = QtWidgets.QVBoxLayout()
        layout_color.addWidget(self.current_color_label)
        layout_color.addWidget(change_color_btn)
        layout_color.addStretch(1)

        tip_linewidth_label = QtWidgets.QLabel(' Line segment thickness ')
        self.linewidth_spin = QtWidgets.QSpinBox()
        self.linewidth_spin.setValue(4)
        linewidth_check_btn = QtWidgets.QPushButton(' determine ')
        linewidth_check_btn.clicked.connect(self.linewidth_check_btn_clicked)
        layout_linewidth = QtWidgets.QHBoxLayout()
        layout_linewidth.addWidget(self.linewidth_spin)
        layout_linewidth.addWidget(linewidth_check_btn)
        layout_linewidth_00 = QtWidgets.QVBoxLayout()
        layout_linewidth_00.addWidget(tip_linewidth_label)
        layout_linewidth_00.addLayout(layout_linewidth)
        layout_linewidth_00.addStretch(1)

        previous_step_btn = QtWidgets.QPushButton(' revoke ')
        previous_step_btn.clicked.connect(self.previous_step_btn_clicked)

        layout = QtWidgets.QVBoxLayout()
        layout.addLayout(layout_color)
        layout.addLayout(layout_linewidth_00)
        layout.addWidget(previous_step_btn)
        self.setLayout(layout)
        pass
    def change_color_btn_clicked(self):
        col = QtWidgets.QColorDialog.getColor()
        if col.isValid():
            pal = self.current_color_label.palette()
            pal.setColor(QtGui.QPalette.WindowText,col)
            self.current_color_label.setPalette(pal)
            pre_map = {
                'change_type':'color',
                'data':col.name()
            }
            self.sinout_signal.emit(pre_map)
        pass
    def previous_step_btn_clicked(self):
        pre_map = {
            'change_type': 'pre_step',
            'data': None
        }
        self.sinout_signal.emit(pre_map)
        pass
    def linewidth_check_btn_clicked(self):
        line_width = self.linewidth_spin.value()
        if int(line_width)<=0:
            QtWidgets.QMessageBox.information(
                self,
                ' Tips ',
                ' The line thickness must be greater than 0',
                QtWidgets.QMessageBox.Yes
            )
            return
        # linewidth
        pre_map = {
            'change_type':'linewidth',
            'data':int(line_width)
        }
        self.sinout_signal.emit(pre_map)
        pass

Line chart control

class PyQtGraphLineWidget(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        self.init_data()
        self.init_ui()

    def init_data(self):
        self.draw_line_yeah: bool = False
        self.segment_list: List = []
        self.draw_widget: QtWidgets.QWidget = None
        self.draw_line_color: str = '#ff557f'
        self.draw_line_width: int = 4
        #  Color value  https://www.sioe.cn/yingyong/yanse-rgb-16/
        self.color_one = (30, 144, 255)
        pass

    def init_ui(self):
        self.title_label = QtWidgets.QLabel(' Broken line diagram ')
        self.title_label.setAlignment(Qt.AlignCenter)
        self.title_label.setStyleSheet('QLabel{font-size:18px;font-weight:bold;}')

        self.tip_label = QtWidgets.QLabel(' Left boundary ~ Right border ')
        self.draw_lines_checkbox = QtWidgets.QCheckBox(' drawing ')
        self.draw_lines_checkbox.clicked.connect(self.draw_lines_checkbox_clicked)
        layout_control = QtWidgets.QHBoxLayout()
        layout_control.addWidget(self.tip_label)
        layout_control.addStretch(1)
        layout_control.addWidget(self.draw_lines_checkbox)

        xax = RotateAxisItem(orientation='bottom')
        xax.setHeight(h=80)
        self.pw = pg.PlotWidget(axisItems={'bottom': xax})
        self.pw.setMouseEnabled(x=True, y=False)
        # self.pw.enableAutoRange(x=False,y=True)
        self.pw.setAutoVisible(x=False, y=True)
        layout = QtWidgets.QVBoxLayout()
        layout.addWidget(self.title_label)
        layout.addLayout(layout_control)
        layout.addWidget(self.pw)
        self.setLayout(layout)
        pass

    def set_data(self,data:Dict[str,Any]):
        self.set_data_1(data)
        self.proxy_clicked = pg.SignalProxy(self.pw.scene().sigMouseClicked, rateLimit=60, slot=self.mouseClicked)

    def set_data_1(self, data: Dict[str, Any]):
        ''' Single root y Axis '''
        if data is None:
            self.pw.clear()
            return
        #  Empty the last view 
        self.pw.clear()
        self.pw.addLegend()
        title_str = data['title_str']
        self.title_label.setText(title_str)
        xTick = [data['xTick00']]
        x = data['x']
        y = data['y']
        whole_data = data['whole_data']
        self.y_datas = y
        self.x_data = xTick
        self.x_Tick = data['xTick']
        self.whole_data = whole_data
        self.tip_label.setText(f"{xTick[0][0][1]}~{xTick[0][-1][1]}")

        xax = self.pw.getAxis('bottom')
        xax.setTicks(xTick)

        self.pw.plot(x, y, connect='finite', pen=pg.mkPen({'color': self.color_one, 'width': 4}))

        self.vLine = pg.InfiniteLine(angle=90, movable=False)
        self.hLine = pg.InfiniteLine(angle=0, movable=False)
        self.label = pg.TextItem()

        self.pw.addItem(self.vLine, ignoreBounds=True)
        self.pw.addItem(self.hLine, ignoreBounds=True)
        self.pw.addItem(self.label, ignoreBounds=True)
        self.vb = self.pw.getViewBox()
        self.proxy = pg.SignalProxy(self.pw.scene().sigMouseMoved, rateLimit=60, slot=self.mouseMoved)
        #  Display the whole line chart 
        self.pw.enableAutoRange()
        pass
    def mouseMoved(self, evt):
        pos = evt[0]
        if self.pw.sceneBoundingRect().contains(pos):
            mousePoint = self.vb.mapSceneToView(pos)
            index = int(mousePoint.x())
            if index>=0 and index<len(self.whole_data):
                cur_data = self.whole_data[index]
                html_str = ''
                for k,v in cur_data.items():
                    html_str += '<p style="color:black;">'+k+':'+str(v)+'</p>'
                self.label.setHtml(html_str)
                self.label.setPos(mousePoint.x(), mousePoint.y())
                pass
            self.vLine.setPos(mousePoint.x())
            self.hLine.setPos(mousePoint.y())
        pass
    def mouseClicked(self,evt):
        if not self.draw_line_yeah:
            pass
        else:
            pos = evt[0].pos()
            if self.pw.sceneBoundingRect().contains(pos):
                #  Get the current lower left corner 
                pos_pre = pg.Point(pos[0]-10,pos[1]-10)
                mousePoint_pre = self.vb.mapSceneToView(pos_pre)
                pos_x_pre = mousePoint_pre.x()
                pos_y_pre = mousePoint_pre.y()
                mousePoint = self.vb.mapSceneToView(pos)
                pos_x = int(mousePoint.x())
                pos_y = int(mousePoint.y())

                # [(pos_x_00, pos_y_00), (pos_x, pos_y)]
                r = pg.LineSegmentROI([(pos_x_pre, pos_y_pre), (pos_x, pos_y)],
                                      pen={'color': self.draw_line_color, 'width': self.draw_line_width},
                                      movable=True,
                                      hoverPen={'color': (255, 255, 0), 'width': 8})
                self.segment_list.append(r)
                self.pw.addItem(r)
        pass
    def draw_lines_checkbox_clicked(self):
        if self.draw_lines_checkbox.isChecked():
            self.draw_line_yeah = True
            if self.draw_widget is None:
                self.draw_widget = DrawLineSegmentWidget()
                self.draw_widget.sinout_signal.connect(self.draw_widget_sinout_signal_emit)
            self.draw_widget.show()
            pass
        else:
            self.draw_line_yeah = False
            for item in self.segment_list:
                self.pw.removeItem(item)
            self.segment_list.clear()
            if self.draw_widget:
                self.draw_widget.close()
            pass
        pass
    def draw_widget_sinout_signal_emit(self,data:Dict[str,Any]):
        change_type = data['change_type']
        if change_type == 'color':
            self.draw_line_color = data['data']
        elif change_type == 'linewidth':
            self.draw_line_width = data['data']
        elif change_type == 'pre_step':
            if len(self.segment_list)>=1:
                last_item = self.segment_list[-1]
                self.pw.removeItem(last_item)
                self.segment_list.pop()
        pass
    pass

Use ：

call ：

if __name__ == '__main__':
    temp_map = {}
    temp_map['xTick'] = [(0, '2021-01-01'),
                         (1, '2021-02-0'),
                         (2, '2021-03-01'),
                         (3, '2021-04-01'),
                         (4, '2021-05-01'),
                         (5, '2021-06-01'),
                         (6, '2021-07-01'),
                         (7, '2021-08-01'),
                         (8, '2021-09-01'),
                         (9, '2021-10-01'),
                         (10, '2021-11-01'),
                         (11, '2021-12-01'),
                         (12, '2022-01-01'),
                         (13, '2022-02-01'),
                         ]
    temp_map['xTick00'] = temp_map['xTick']
    temp_map['x'] = [0, 1, 2, 3, 4, 5, 6,7,8,9,10,11,12,13]
    temp_map['y'] = [1, 8, 0, 5, 1, -6, 3,-9, 12, 6, 0, 8, -2,3]
    temp_map['title_str'] = ' Brush function use '
    temp_map['whole_data'] = [{' date ':'2021-01-01',' value ':1},
{' date ':'2021-02-01',' value ':8},
{' date ':'2021-03-01',' value ':0},
{' date ':'2021-04-01',' value ':5},
{' date ':'2021-05-01',' value ':1},
{' date ':'2021-06-01',' value ':-6},
{' date ':'2021-07-01',' value ':3},
{' date ':'2021-08-01',' value ':-9},
{' date ':'2021-09-01',' value ':12},
{' date ':'2021-10-01',' value ':6},
{' date ':'2021-11-01',' value ':0},
{' date ':'2021-12-01',' value ':8},
{' date ':'2022-01-01',' value ':-2},
{' date ':'2022-02-01',' value ':3}]

    QtCore.QCoreApplication.setAttribute(QtCore.Qt.HighDpiScaleFactorRoundingPolicy.PassThrough)
    app = QtWidgets.QApplication(sys.argv)
    temp_widget = PyQtGraphLineWidget()
    temp_widget.set_data(temp_map)
    temp_widget.show()
    sys.exit(app.exec_())
    pass

function ：

When you want to draw a line segment , Check the draw check box in the upper right corner

The pop-up form can be understood as “ Brush attribute box ”, Click in the curve , A line segment will be generated , The two endpoints of the line segment can drive the line segment to rotate , The whole line segment can be translated as a whole .

Click the draw check box here , When the check box is not selected , The drawing function is off , And clear the drawn line segment