matplotlib绘制鼠标的十字光标的实现(自定义方式,官方实例)


Posted in Python onJanuary 10, 2021

matplotlib在widgets模块提供Cursor类用于支持十字光标的生成。另外官方还提供了自定义十字光标的实例。

widgets模块Cursor类源码

class Cursor(AxesWidget):
  """
  A crosshair cursor that spans the axes and moves with mouse cursor.

  For the cursor to remain responsive you must keep a reference to it.

  Parameters
  ----------
  ax : `matplotlib.axes.Axes`
    The `~.axes.Axes` to attach the cursor to.
  horizOn : bool, default: True
    Whether to draw the horizontal line.
  vertOn : bool, default: True
    Whether to draw the vertical line.
  useblit : bool, default: False
    Use blitting for faster drawing if supported by the backend.

  Other Parameters
  ----------------
  **lineprops
    `.Line2D` properties that control the appearance of the lines.
    See also `~.Axes.axhline`.

  Examples
  --------
  See :doc:`/gallery/widgets/cursor`.
  """

  def __init__(self, ax, horizOn=True, vertOn=True, useblit=False,
         **lineprops):
    AxesWidget.__init__(self, ax)

    self.connect_event('motion_notify_event', self.onmove)
    self.connect_event('draw_event', self.clear)

    self.visible = True
    self.horizOn = horizOn
    self.vertOn = vertOn
    self.useblit = useblit and self.canvas.supports_blit

    if self.useblit:
      lineprops['animated'] = True
    self.lineh = ax.axhline(ax.get_ybound()[0], visible=False, **lineprops)
    self.linev = ax.axvline(ax.get_xbound()[0], visible=False, **lineprops)

    self.background = None
    self.needclear = False

  def clear(self, event):
    """Internal event handler to clear the cursor."""
    if self.ignore(event):
      return
    if self.useblit:
      self.background = self.canvas.copy_from_bbox(self.ax.bbox)
    self.linev.set_visible(False)
    self.lineh.set_visible(False)
    
  def onmove(self, event):
    """Internal event handler to draw the cursor when the mouse moves."""
    if self.ignore(event):
      return
    if not self.canvas.widgetlock.available(self):
      return
    if event.inaxes != self.ax:
      self.linev.set_visible(False)
      self.lineh.set_visible(False)

      if self.needclear:
        self.canvas.draw()
        self.needclear = False
      return
    self.needclear = True
    if not self.visible:
      return
    self.linev.set_xdata((event.xdata, event.xdata))

    self.lineh.set_ydata((event.ydata, event.ydata))
    self.linev.set_visible(self.visible and self.vertOn)
    self.lineh.set_visible(self.visible and self.horizOn)

    self._update()

  def _update(self):
    if self.useblit:
      if self.background is not None:
        self.canvas.restore_region(self.background)
      self.ax.draw_artist(self.linev)
      self.ax.draw_artist(self.lineh)
      self.canvas.blit(self.ax.bbox)
    else:
      self.canvas.draw_idle()
    return False

自定义十字光标实现

简易十字光标实现

首先在 Cursor类的构造方法__init__中,构造了十字光标的横线、竖线和坐标显示;然后在on_mouse_move方法中,根据事件数据更新横竖线和坐标显示,最后在调用时,通过mpl_connect方法绑定on_mouse_move方法和鼠标移动事件'motion_notify_event'。

import matplotlib.pyplot as plt
import numpy as np


class Cursor:
  """
  A cross hair cursor.
  """
  def __init__(self, ax):
    self.ax = ax
    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(0.72, 0.9, '', transform=ax.transAxes)

  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 on_mouse_move(self, event):
    if not event.inaxes:
      need_redraw = self.set_cross_hair_visible(False)
      if need_redraw:
        self.ax.figure.canvas.draw()
    else:
      self.set_cross_hair_visible(True)
      x, y = event.xdata, event.ydata
      # update the line positions
      self.horizontal_line.set_ydata(y)
      self.vertical_line.set_xdata(x)
      self.text.set_text('x=%1.2f, y=%1.2f' % (x, y))
      self.ax.figure.canvas.draw()


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

fig, ax = plt.subplots()
ax.set_title('Simple cursor')
ax.plot(x, y, 'o')
cursor = Cursor(ax)
#关键部分,绑定鼠标移动事件处理
fig.canvas.mpl_connect('motion_notify_event', cursor.on_mouse_move)
plt.show()

优化十字光标实现

在简易实现中,每次鼠标移动时,都会重绘整个图像,这样效率比较低。
在优化实现中,每次鼠标移动时,只重绘光标和坐标显示,背景图像不再重绘。

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(0.72, 0.9, '', transform=ax.transAxes)
    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('x=%1.2f, y=%1.2f' % (x, 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()

捕捉数据十字光标实现

在前面的两种实现中,鼠标十字光标可以随意移动。在本实现中,十字光标只会出现在离鼠标x坐标最近的数据点上。

import matplotlib.pyplot as plt
import numpy as np


class SnappingCursor:
  """
  A cross hair cursor that snaps to the data point of a line, which is
  closest to the *x* position of the cursor.

  For simplicity, this assumes that *x* values of the data are sorted.
  """
  def __init__(self, ax, line):
    self.ax = ax
    self.horizontal_line = ax.axhline(color='k', lw=0.8, ls='--')
    self.vertical_line = ax.axvline(color='k', lw=0.8, ls='--')
    self.x, self.y = line.get_data()
    self._last_index = None
    # text location in axes coords
    self.text = ax.text(0.72, 0.9, '', transform=ax.transAxes)

  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 on_mouse_move(self, event):
    if not event.inaxes:
      self._last_index = None
      need_redraw = self.set_cross_hair_visible(False)
      if need_redraw:
        self.ax.figure.canvas.draw()
    else:
      self.set_cross_hair_visible(True)
      x, y = event.xdata, event.ydata
      index = min(np.searchsorted(self.x, x), len(self.x) - 1)
      if index == self._last_index:
        return # still on the same data point. Nothing to do.
      self._last_index = index
      x = self.x[index]
      y = self.y[index]
      # update the line positions
      self.horizontal_line.set_ydata(y)
      self.vertical_line.set_xdata(x)
      self.text.set_text('x=%1.2f, y=%1.2f' % (x, y))
      self.ax.figure.canvas.draw()


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

fig, ax = plt.subplots()
ax.set_title('Snapping cursor')
line, = ax.plot(x, y, 'o')
snap_cursor = SnappingCursor(ax, line)
fig.canvas.mpl_connect('motion_notify_event', snap_cursor.on_mouse_move)
plt.show()

参考资料

https://www.matplotlib.org.cn/gallery/misc/cursor_demo_sgskip.html

到此这篇关于matplotlib绘制鼠标的十字光标的实现(自定义方式,官方实例)的文章就介绍到这了,更多相关matplotlib鼠标十字光标 内容请搜索三水点靠木以前的文章或继续浏览下面的相关文章希望大家以后多多支持三水点靠木!

Python 相关文章推荐
python之wxPython菜单使用详解
Sep 28 Python
在linux下实现 python 监控usb设备信号
Jul 03 Python
完美解决python3.7 pip升级 拒绝访问问题
Jul 12 Python
Python 获取windows桌面路径的5种方法小结
Jul 15 Python
Python 实例方法、类方法、静态方法的区别与作用
Aug 14 Python
使用tensorflow显示pb模型的所有网络结点方式
Jan 23 Python
Python while循环使用else语句代码实例
Feb 07 Python
Python pip安装模块提示错误解决方案
May 22 Python
keras自定义回调函数查看训练的loss和accuracy方式
May 23 Python
python关于倒排列的知识点总结
Oct 13 Python
python drf各类组件的用法和作用
Jan 12 Python
Python上下文管理器Content Manager
Jun 26 Python
解决selenium+Headless Chrome实现不弹出浏览器自动化登录的问题
Jan 09 #Python
用Python自动清理电脑内重复文件,只要10行代码(自动脚本)
Jan 09 #Python
selenium+headless chrome爬虫的实现示例
Jan 08 #Python
plt.figure()参数使用详解及运行演示
Jan 08 #Python
matplotlib绘制多子图共享鼠标光标的方法示例
Jan 08 #Python
利用python查看数组中的所有元素是否相同
Jan 08 #Python
Python爬虫自动化获取华图和粉笔网站的错题(推荐)
Jan 08 #Python
You might like
Search Engine Friendly的URL设计
2006/10/09 PHP
PHP 单引号与双引号的区别
2009/11/24 PHP
PHP 引用是个坏习惯
2010/03/12 PHP
PHP采集类Snoopy抓取图片实例
2014/06/19 PHP
PHP数组排序之sort、asort与ksort用法实例
2014/09/08 PHP
Thinkphp5.0框架的Db操作实例分析【连接、增删改查、链式操作等】
2019/10/11 PHP
javascript入门·动态的时钟,显示完整的一些方法,新年倒计时
2007/10/01 Javascript
jquery mobile changepage的三种传参方法介绍
2013/09/13 Javascript
JQuery实现动态适时改变字体颜色的方法
2015/03/10 Javascript
node.js实现快速截图
2016/08/27 Javascript
vue自定义指令实现v-tap插件
2016/11/03 Javascript
Async Validator 异步验证使用说明
2017/07/03 Javascript
解决AjaxFileupload 上传时会出现连接重置的问题
2017/07/07 Javascript
AngularJS模态框模板ngDialog的使用详解
2018/05/11 Javascript
使用p5.js临摹动态图片
2019/11/04 Javascript
jQuery实现获取多选框的值示例
2020/02/07 jQuery
[51:06]DOTA2-DPC中国联赛 正赛 Elephant vs Aster BO3 第二场 1月26日
2021/03/11 DOTA
Python pass详细介绍及实例代码
2016/11/24 Python
Python排序搜索基本算法之堆排序实例详解
2017/12/08 Python
解决Django的request.POST获取不到内容的问题
2018/05/28 Python
python中的tcp示例详解
2018/12/09 Python
对Python 简单串口收发GUI界面的实例详解
2019/06/12 Python
在Django的View中使用asyncio的方法
2019/07/12 Python
Python的条件锁与事件共享详解
2019/09/12 Python
Python hashlib模块加密过程解析
2019/11/05 Python
基于TensorFlow的CNN实现Mnist手写数字识别
2020/06/17 Python
python使用smtplib模块发送邮件
2020/12/17 Python
canvas 阴影和图形变换的示例代码
2018/01/02 HTML / CSS
舞会礼服和舞会鞋:PromGirl
2019/04/22 全球购物
圣诞树世界:Christmas Tree World
2019/12/10 全球购物
100%法国制造的游戏和玩具:Les Jouets Français
2021/03/02 全球购物
司机的工作范围及职责
2013/11/13 职场文书
企业法人授权委托书
2014/04/03 职场文书
2015年纪委工作总结
2015/05/13 职场文书
2015年酒店销售部工作总结
2015/07/24 职场文书
Java实现经典游戏泡泡堂的示例代码
2022/04/04 Java/Android