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使用心得之获得github代码库列表
Jun 25 Python
python实现对一个完整url进行分割的方法
Apr 29 Python
Python+MongoDB自增键值的简单实现
Nov 04 Python
Python 基础之字符串string详解及实例
Apr 01 Python
python reduce 函数使用详解
Dec 05 Python
python OpenCV学习笔记实现二维直方图
Feb 08 Python
OpenCV 轮廓检测的实现方法
Jul 03 Python
解决pycharm最左侧Tool Buttons显示不全的问题
Dec 17 Python
python读取raw binary图片并提取统计信息的实例
Jan 09 Python
django序列化时使用外键的真实值操作
Jul 15 Python
树莓派4B安装Tensorflow的方法步骤
Jul 16 Python
解决python3安装pandas出错的问题
May 20 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
PHPMailer 中文使用说明小结
2010/01/22 PHP
DW中链接mysql数据库时,建立字符集中文出现乱码的解决方法
2010/03/27 PHP
详解PHP对象的串行化与反串行化
2016/01/24 PHP
遍历echsop的region表形成缓存的程序实例代码
2016/11/01 PHP
JScript中使用ADODB.Stream判断文件编码的代码
2008/06/09 Javascript
小型js框架veryide.librar源代码
2009/03/05 Javascript
javaScript Array(数组)相关方法简述
2009/07/25 Javascript
jquery+json实现的搜索加分页效果
2010/03/31 Javascript
Javascript实现动态菜单添加的实例代码
2013/07/05 Javascript
JavaScript中的getMilliseconds()方法使用详解
2015/06/10 Javascript
jQuery+PHP星级评分实现方法
2015/10/02 Javascript
JavaScript每天必学之基础知识
2016/09/17 Javascript
footer定位页面底部(代码分享)
2017/03/07 Javascript
jQuery实现的鼠标滚轮控制图片缩放功能实例
2017/10/14 jQuery
AngularJs 最新验证手机号码的实例,成功测试通过
2017/11/26 Javascript
JS字符串去除连续或全部重复字符的实例
2018/03/08 Javascript
使用svg实现动态时钟效果
2018/07/17 Javascript
详解如何给React-Router添加路由页面切换时的过渡动画
2019/04/25 Javascript
基于vue的tab-list类目切换商品列表组件的示例代码
2020/02/14 Javascript
[38:51]2014 DOTA2国际邀请赛中国区预选赛 Orenda VS LGD-CDEC
2014/05/22 DOTA
[33:17]OG vs VGJ.T 2018国际邀请赛小组赛BO2 第二场 8.18
2018/08/19 DOTA
Django实现CAS+OAuth2的方法示例
2019/10/30 Python
Python面向对象程序设计之继承、多态原理与用法详解
2020/03/23 Python
css3背景图片透明叠加属性cross-fade简介及用法实例
2013/01/08 HTML / CSS
CSS3动画:5种预载动画效果实例
2017/04/05 HTML / CSS
HTML5网页录音和上传到服务器支持PC、Android,支持IOS微信功能
2019/04/26 HTML / CSS
大学生入党自我鉴定
2013/10/31 职场文书
水电维修专业推荐信
2014/09/06 职场文书
技术员岗位职责
2015/02/04 职场文书
自主招生英文自荐信
2015/03/25 职场文书
同意转租证明
2015/06/24 职场文书
青年联谊会致辞
2015/07/31 职场文书
PyQt5 显示超清高分辨率图片的方法
2021/04/11 Python
Flask搭建一个API服务器的步骤
2021/05/28 Python
oracle删除超过N天数据脚本的方法
2022/02/28 Oracle
SQL Server中T-SQL标识符介绍与无排序生成序号的方法
2022/05/25 SQL Server