如何在軸外使用 matplotlib blit artist？

Question

https://matplotlib.org/stable/gallery/event_handling/cursor_demo.html

我試圖在右軸上制作一個帶有注釋的十字線光標來顯示 Y 值

一切正常，除非藝術家/注釋繪制在軸外

繼續繪制圖形會起作用，但我的圖表有很多數據，每次繪制會導致 0.5 - 0.7 秒，這對於游標函數 self.ax.figure.canvas.draw() 來說非常滯后

我的猜測是當我保存背景時，“self.ax.bbox”只是為軸內的東西保存圖像，這就是為什么當它 blit 它在軸外不起作用？ self.background = self.ax.figure.canvas.copy_from_bbox(self.ax.bbox)

我有很多嘗試，但沒有運氣......需要一些建議

下面是一個簡單的例子（我的情節將是一個沉重的情節，我無法在 mousemove 事件上繼續調用 draw() ）我試圖制作一個平滑的十字線光標，並在右軸上進行注釋

import matplotlib.pyplot as plt
import numpy as np

class BlittedCursor:
    """
    A cross hair cursor using blitting for faster redraw.
    """
    def __init__(self, ax):
        self.ax = ax
        self.background = None
        self.horizontal_line = ax.axhline(color='k', lw=0.8, ls='--')
        self.vertical_line = ax.axvline(color='k', lw=0.8, ls='--')
        # text location in axes coordinates
        self.text = ax.text(0.95, 0, '', transform=ax.get_yaxis_transform())
        self._creating_background = False
        ax.figure.canvas.mpl_connect('draw_event', self.on_draw)

    def on_draw(self, event):
        self.create_new_background()

    def set_cross_hair_visible(self, visible):
        need_redraw = self.horizontal_line.get_visible() != visible
        self.horizontal_line.set_visible(visible)
        self.vertical_line.set_visible(visible)
        self.text.set_visible(visible)
        return need_redraw

    def create_new_background(self):
        if self._creating_background:
            # discard calls triggered from within this function
            return
        self._creating_background = True
        self.set_cross_hair_visible(False)
        self.ax.figure.canvas.draw()
        self.background = self.ax.figure.canvas.copy_from_bbox(self.ax.bbox)
        self.set_cross_hair_visible(True)
        self._creating_background = False

    def on_mouse_move(self, event):
        if self.background is None:
            self.create_new_background()
        if not event.inaxes:
            need_redraw = self.set_cross_hair_visible(False)
            if need_redraw:
                self.ax.figure.canvas.restore_region(self.background)
                self.ax.figure.canvas.blit(self.ax.bbox)
        else:
            self.set_cross_hair_visible(True)
            # update the line positions
            x, y = event.xdata, event.ydata
            self.horizontal_line.set_ydata(y)
            self.vertical_line.set_xdata(x)
            self.text.set_text('y=%1.2f' % (y))
            self.text.set_y(y)

            self.ax.figure.canvas.restore_region(self.background)
            self.ax.draw_artist(self.horizontal_line)
            self.ax.draw_artist(self.vertical_line)
            self.ax.draw_artist(self.text)
            self.ax.figure.canvas.blit(self.ax.bbox)


x = np.arange(0, 1, 0.01)
y = np.sin(2 * 2 * np.pi * x)

fig, ax = plt.subplots()
ax.set_title('Blitted cursor')
ax.plot(x, y, 'o')
blitted_cursor = BlittedCursor(ax)
fig.canvas.mpl_connect('motion_notify_event', blitted_cursor.on_mouse_move)
plt.show()

Answer 1

我實際上通過下面的更改解決了問題......但我還是不明白。 任何人都可以進一步解釋嗎？ 我的猜測是ax.get_figure()也會獲取軸外的圖像嗎？ 和ax.clipbox意味着整個數字？

self.background = self.ax.figure.canvas.copy_from_bbox(self.ax.get_figure().bbox)
self.ax.figure.canvas.blit(self.ax.clipbox)