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中设置变量作为默认值时容易遇到的错误
Apr 03 Python
Django返回json数据用法示例
Sep 18 Python
python 系统调用的实例详解
Jul 11 Python
详解python做UI界面的方法
Feb 27 Python
详解python之heapq模块及排序操作
Apr 04 Python
Python3 requests文件下载 期间显示文件信息和下载进度代码实例
Aug 16 Python
python中的Elasticsearch操作汇总
Oct 30 Python
python框架flask表单实现详解
Nov 04 Python
python实现udp传输图片功能
Mar 20 Python
python变量的作用域是什么
May 26 Python
python实现求纯色彩图像的边框
Apr 08 Python
python中subplot大小的设置步骤
Jun 28 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
PHP base64+gzinflate压缩编码和解码代码
2008/10/03 PHP
PHP校验15位和18位身份证号的类封装
2018/11/07 PHP
基于jquery的一个简单的脚本验证插件
2010/04/05 Javascript
js Array操作的最简短最容易理解方法
2013/12/09 Javascript
js获取select默认选中的Option并不是当前选中值
2014/05/07 Javascript
js使用onmousemove和onmouseout获取鼠标坐标的方法
2015/03/31 Javascript
jquery日历插件datepicker用法分析
2016/01/22 Javascript
jQuery模仿阿里云购买服务器选择购买时间长度的代码
2016/04/29 Javascript
AngularJS 如何在控制台进行错误调试
2016/06/07 Javascript
HTML5 canvas 9绘制图片实例详解
2016/09/06 Javascript
JavaScript遍历Json串浏览器输出的结果不统一问题
2016/11/03 Javascript
jQuery选择器之子元素过滤选择器
2017/09/28 jQuery
vue视频播放插件vue-video-player的具体使用方法
2019/11/08 Javascript
Vue封装全局过滤器Filters的步骤
2020/09/16 Javascript
[01:10]DOTA2次级职业联赛 - U5战队宣传片
2014/12/01 DOTA
python实现查询苹果手机维修进度
2015/03/16 Python
python实现下载文件的三种方法
2017/02/09 Python
Python实现对象转换为xml的方法示例
2017/06/08 Python
python 巧用正则寻找字符串中的特定字符的位置方法
2018/05/02 Python
Pandas:Series和DataFrame删除指定轴上数据的方法
2018/11/10 Python
详解【python】str与json类型转换
2019/04/29 Python
python正则过滤字母、中文、数字及特殊字符方法详解
2020/02/11 Python
Python lambda表达式原理及用法解析
2020/08/18 Python
使用Python操作MySQL的小技巧
2020/09/10 Python
英国经典球衣网站:Classic Football Shirts
2017/05/20 全球购物
Skyscanner加拿大:全球旅行搜索平台
2018/11/19 全球购物
毕业生找工作的自我评价
2013/10/18 职场文书
自动化系在校本科生求职信
2013/10/23 职场文书
函授生自我鉴定
2014/03/25 职场文书
个人贷款承诺书
2014/03/28 职场文书
《夕阳真美》教学反思
2014/04/27 职场文书
装饰工程师岗位职责
2014/06/08 职场文书
档案管理员岗位职责
2015/02/12 职场文书
2015年党风廉政建设目标责任书
2015/05/08 职场文书
房产证明范本
2015/06/19 职场文书
导游词之海南天涯海角
2019/12/05 职场文书