python - 如何绘制可拖动的多边形

Question

关于this matplotlib 示例绘制可拖动矩形我尝试对多边形执行相同的操作。

到目前为止，我能够绘制一个多边形并将其拖动到 Canvas 上的某个位置。如果我释放鼠标按钮，我将无法再次移动多边形，这就是我的问题。我想通过每次按下鼠标来拖放多边形，只要我愿意。

我还注意到，移动多边形后，我仍然可以单击多边形原来所在的位置并再次拖动它。因此，初始的几何图形必须保存在某个地方，但我想它应该被覆盖。

编辑:按照下面的评论中的建议，我将添加一个补丁而不是一个集合，因为我只会绘制一个多边形(请参阅注释掉的旧代码)。此外，我关闭了多边形，以演示您只能通过单击多边形内部来拖动面片，而不能通过单击其边缘来拖动面片。

如果我想再次拖动多边形，它会自动跳回其初始位置。

import matplotlib.pyplot as plt
from matplotlib.patches import Polygon
#from matplotlib.collections import PatchCollection

class DraggablePolygon:
    lock = None
    def __init__(self, polygon):
        self.poly = polygon
        self.press = None

    def connect(self):
        'connect to all the events we need'
        self.cidpress = self.poly.figure.canvas.mpl_connect(
            'button_press_event', self.on_press)
        self.cidrelease = self.poly.figure.canvas.mpl_connect(
            'button_release_event', self.on_release)
        self.cidmotion = self.poly.figure.canvas.mpl_connect(
            'motion_notify_event', self.on_motion)

    def on_press(self, event):
        'on button press we will see if the mouse is over us and store some data'
        if event.inaxes != self.poly.axes: return
        if DraggablePolygon.lock is not None: return
        contains, attrd = self.poly.contains(event)
        if not contains: return
        x0, y0 = geometry[0]
        self.press = x0, y0, event.xdata, event.ydata
        DraggablePolygon.lock = self

    def on_motion(self, event):
        'on motion we will move the rect if the mouse is over us'
        if DraggablePolygon.lock is not self:
            return
        if event.inaxes != self.poly.axes: return
        x0, y0, xpress, ypress = self.press
        dx = event.xdata - xpress
        dy = event.ydata - ypress
        xdx = [i+dx for i,_ in geometry]
        ydy = [i+dy for _,i in geometry]
        self.newGeometry = [[a, b] for a, b in zip(xdx, ydy)]
        #polygon = Polygon(self.newGeometry, closed=False, fill=False, linewidth=3, color='#F97306')
        #patches = []
        #patches.append(polygon)
        #plt.cla()
        #p = PatchCollection(patches, match_original=True)
        #ax.add_collection(p)

        self.poly.set_xy(newGeometry)  # this will set the vertices of the polygon

        self.poly.figure.canvas.draw()

    def on_release(self, event):
        'on release we reset the press data'
        if DraggablePolygon.lock is not self:
            return

        self.press = None
        DraggablePolygon.lock = None

    def disconnect(self):
        'disconnect all the stored connection ids'
        self.poly.figure.canvas.mpl_disconnect(self.cidpress)
        self.poly.figure.canvas.mpl_disconnect(self.cidrelease)
        self.poly.figure.canvas.mpl_disconnect(self.cidmotion)


fig = plt.figure()
ax = fig.add_subplot(111)

geometry = [[0.0,0.0],[0.1,0.05],[0.2,0.15],[0.3,0.20],[0.4,0.25],[0.5,0.30],
        [0.6,0.25],[0.7,0.15],[0.8,0.05],[0.9,0.025],[1.0,0.0]]

patches = []
polygon = plt.Polygon(geometry, closed=True, fill=False, linewidth=3, color='#F97306')
#patches.append(polygon)
#p = PatchCollection(patches, match_original=True)
#ax.add_collection(p)

ax.add_patch(polygon)

dp = DraggablePolygon(polygon)
dp.connect()

plt.show()

我认为geometry和newGeometry的定义必须位于代码内的不同位置，但经过几次尝试后我找不到可行的解决方案。有人发现我犯的错误吗？

Answer 1

问题下面的评论有助于最终找到工作代码。也许这不是最好的、最Pythonic的方式，但它做到了我想要的。

import matplotlib.pyplot as plt
from matplotlib.patches import Polygon

class DraggablePolygon:
    lock = None
    def __init__(self):
        print('__init__')
        self.press = None

        fig = plt.figure()
        ax = fig.add_subplot(111)

        self.geometry = [[0.0,0.0],[0.1,0.05],[0.2,0.15],[0.3,0.20],[0.4,0.25],[0.5,0.30],
                    [0.6,0.25],[0.7,0.15],[0.8,0.05],[0.9,0.025],[1.0,0.0]]
        self.newGeometry = []
        poly = plt.Polygon(self.geometry, closed=True, fill=False, linewidth=3, color='#F97306')
        ax.add_patch(poly)
        self.poly = poly

    def connect(self):
        'connect to all the events we need'
        print('connect')
        self.cidpress = self.poly.figure.canvas.mpl_connect(
        'button_press_event', self.on_press)
        self.cidrelease = self.poly.figure.canvas.mpl_connect(
        'button_release_event', self.on_release)
        self.cidmotion = self.poly.figure.canvas.mpl_connect(
        'motion_notify_event', self.on_motion)

    def on_press(self, event):
        'on button press we will see if the mouse is over us and store some data'
        print('on_press')
        if event.inaxes != self.poly.axes: return
        if DraggablePolygon.lock is not None: return
        contains, attrd = self.poly.contains(event)
        if not contains: return

        if not self.newGeometry:
            x0, y0 = self.geometry[0]
        else:
            x0, y0 = self.newGeometry[0]

        self.press = x0, y0, event.xdata, event.ydata
        DraggablePolygon.lock = self

    def on_motion(self, event):
        'on motion we will move the rect if the mouse is over us'
        if DraggablePolygon.lock is not self:
            return
        if event.inaxes != self.poly.axes: return
        x0, y0, xpress, ypress = self.press
        dx = event.xdata - xpress
        dy = event.ydata - ypress

        xdx = [i+dx for i,_ in self.geometry]
        ydy = [i+dy for _,i in self.geometry]
        self.newGeometry = [[a, b] for a, b in zip(xdx, ydy)]
        self.poly.set_xy(self.newGeometry)
        self.poly.figure.canvas.draw()

    def on_release(self, event):
        'on release we reset the press data'
        print('on_release')
        if DraggablePolygon.lock is not self:
            return

        self.press = None
        DraggablePolygon.lock = None
        self.geometry = self.newGeometry


    def disconnect(self):
        'disconnect all the stored connection ids'
        print('disconnect')
        self.poly.figure.canvas.mpl_disconnect(self.cidpress)
        self.poly.figure.canvas.mpl_disconnect(self.cidrelease)
        self.poly.figure.canvas.mpl_disconnect(self.cidmotion)


dp = DraggablePolygon()
dp.connect()

plt.show()