Question

我对python很新，我正在尝试使用cairo和wxpython编写一个简单的程序。我习惯使用gtk和C的cairo，但我发现自己很困惑。

我用以下代码构建了一个简单的ui：

import wx

class Frame(wx.Frame):

    def __init__(self, *args, **kwargs):
        super(Frame, self).__init__(*args, **kwargs) 
        self.InitUI()

    def InitUI(self):
        #----------------------------------------------------
        # Build menu bar and submenus   
        menubar = wx.MenuBar()
        # file menu containing quit menu item
        fileMenu = wx.Menu() 
        quit_item = wx.MenuItem(fileMenu, wx.ID_EXIT, '&Quit\tCtrl+W')
        fileMenu.AppendItem(quit_item)
        self.Bind(wx.EVT_MENU, self.OnQuit, quit_item)
        menubar.Append(fileMenu, '&File')      

        # help menu containing about menu item
        helpMenu = wx.Menu() 
        about_item = wx.MenuItem(helpMenu, wx.ID_ABOUT, '&About\tCtrl+A')
        helpMenu.AppendItem(about_item)
        self.Bind(wx.EVT_MENU, self.OnAboutBox, about_item)
        menubar.Append(helpMenu, '&Help')     

        self.SetMenuBar(menubar)

        #----------------------------------------------------
        # Build window layout

        panel = wx.Panel(self)        
        #panel.SetBackgroundColour('yellow')
        vbox = wx.BoxSizer(wx.VERTICAL)
        panel.SetSizer(vbox)        

        midPan = wx.Panel(panel)
        #midPan.SetBackgroundColour('blue')
        hbox = wx.BoxSizer(wx.HORIZONTAL)
        vbox.Add(midPan, 1, wx.EXPAND | wx.ALL, 12)
        midPan.SetSizer(hbox)      

        smallPan = wx.Panel(panel)
        #smallPan.SetBackgroundColour('red')
        hbox2 = wx.BoxSizer(wx.HORIZONTAL)
        vbox.Add(smallPan, 0, wx.ALIGN_RIGHT|wx.LEFT|wx.RIGHT|wx.BOTTOM, 12)
        smallPan.SetSizer(hbox2)   

        #----------------------------------------------------
        # Place buttons in correct box corresponding with panel

        close_button = wx.Button(smallPan, wx.ID_CLOSE)
        self.Bind(wx.EVT_BUTTON, self.OnQuit, close_button)

        hbox2.Add(close_button)
        #----------------------------------------------------
        # Set window properties

        self.SetSize((1600, 1200))
        self.SetTitle('PROGRAM NAME')
        self.Centre()

    def OnQuit(self, e):
        self.Close()

def main():
    ex = wx.App()
    f = Frame(None)
    f.Show(True)  
    ex.MainLoop()  

if __name__ == '__main__':
    main()

我希望能够在名为midPan的面板中绘图。如何添加OnDraw函数并链接信号处理程序？

我非常感谢帮助。

Answer 1

如果你习惯于程序编程那么混乱很自然。 Python是一种OOP语言，在OOP中编码语言是完全不同的。我已经清理并更新了提供的例子。用作绘图区域的面板涂上三个彩色矩形。你没有提供因此，我有OnAboutBox()方法的实现注释掉了这条线。

#!/usr/bin/python

import wx
import wx.lib.wxcairo
import cairo

class DrawingArea(wx.Panel):

    def __init__ (self , *args , **kw):
        super(DrawingArea , self).__init__ (*args , **kw)

        self.SetDoubleBuffered(True)
        self.Bind(wx.EVT_PAINT, self.OnPaint)

    def OnPaint(self, e):

        dc = wx.PaintDC(self)
        cr = wx.lib.wxcairo.ContextFromDC(dc)
        self.DoDrawing(cr)     

    def DoDrawing(self, cr):

        cr.set_source_rgb (0.2 , 0.23 , 0.9)
        cr.rectangle(10 , 15, 90, 60)
        cr.fill()

        cr.set_source_rgb(0.9 , 0.1 , 0.1)
        cr.rectangle(130 , 15, 90, 60)
        cr.fill()

        cr.set_source_rgb(0.4 , 0.9 , 0.4)
        cr.rectangle(250 , 15, 90, 60)       
        cr.fill()     


class Frame(wx.Frame):

    def __init__(self, *args, **kwargs):
        super(Frame, self).__init__(*args, **kwargs) 

        self.InitUI()

    def InitUI(self):
        #----------------------------------------------------
        # Build menu bar and submenus   

        menubar = wx.MenuBar()
        # file menu containing quit menu item
        fileMenu = wx.Menu() 
        quit_item = wx.MenuItem(fileMenu, wx.ID_EXIT, '&Quit\tCtrl+W')
        fileMenu.AppendItem(quit_item)
        self.Bind(wx.EVT_MENU, self.OnQuit, quit_item)
        menubar.Append(fileMenu, '&File')      

        # help menu containing about menu item
        helpMenu = wx.Menu() 
        about_item = wx.MenuItem(helpMenu, wx.ID_ABOUT, '&About\tCtrl+A')
        helpMenu.AppendItem(about_item)
        #~ self.Bind(wx.EVT_MENU, self.OnAboutBox, about_item)
        menubar.Append(helpMenu, '&Help')     

        self.SetMenuBar(menubar)

        #----------------------------------------------------
        # Build window layout

        panel = wx.Panel(self)        
        vbox = wx.BoxSizer(wx.VERTICAL)
        panel.SetSizer(vbox)        

        midPan = DrawingArea(panel)
        vbox.Add(midPan, 1, wx.EXPAND | wx.ALL, 12)


        smallPan = wx.Panel(panel)
        hbox2 = wx.BoxSizer(wx.HORIZONTAL)
        vbox.Add(smallPan, 1, wx.EXPAND|wx.ALL, 12)
        smallPan.SetSizer(hbox2)   

        #----------------------------------------------------
        # Place buttons in correct box corresponding with panel

        close_button = wx.Button(smallPan, wx.ID_CLOSE)
        self.Bind(wx.EVT_BUTTON, self.OnQuit, close_button)

        hbox2.Add(close_button)

        #----------------------------------------------------
        # Set window properties

        #~ self.SetSize((1600, 1200))
        self.SetSize((400, 250))
        #~ self.Maximize()
        self.SetTitle('PROGRAM NAME')
        self.Centre()

    def OnQuit(self, e):
        self.Close()

def main():
    ex = wx.App()
    f = Frame(None)
    f.Show(True)  
    ex.MainLoop()  

if __name__ == '__main__':
    main()

为了进行绘图，我们创建了一个自定义类，它将作为一个绘图区。它继承自wx.Panel小部件。

class DrawingArea(wx.Panel):

    def __init__ (self , *args , **kw):
        super(DrawingArea , self).__init__ (*args , **kw)

        self.SetDoubleBuffered(True)
        self.Bind(wx.EVT_PAINT, self.OnPaint)
...

这是我们用于绘图的自定义类。在构造函数中我们将paint事件绑定到OnPaint()方法。

def OnPaint(self, e):

    dc = wx.PaintDC(self)
    cr = wx.lib.wxcairo.ContextFromDC(dc)
    self.DoDrawing(cr)

在OnPaint()方法中，我们创建了一个cairo绘图上下文并将实际绘图代码委托给DoDrawing() 方法

midPan = DrawingArea(panel)
vbox.Add(midPan, 1, wx.EXPAND | wx.ALL, 12)

创建绘图区域并将其添加到垂直框中。

#~ self.SetSize((1600, 1200))
self.SetSize((400, 250))
#~ self.Maximize()

最后注意事项：如果您想要显示最大化的窗口，请致电Maximize() 方法。电脑屏幕尺寸不同。

Example screenshot on Linux

Answer 2

如Very Simple Drawing示例中所述，使用wx.EVT_PAINT;

将OnPaint绑定添加到midPan：

    # (...)
    midPan = wx.Panel(panel)
    #midPan.SetBackgroundColour('blue')
    hbox = wx.BoxSizer(wx.HORIZONTAL)
    vbox.Add(midPan, 1, wx.EXPAND | wx.ALL, 12)
    midPan.SetSizer(hbox)
    # binding here:
    midPan.Bind(wx.EVT_PAINT, self.OnPaint)
    # (...) rest of code

并定义您的OnPaint代码：

   # (...)
   def OnQuit(self, e):
      self.Close()

   # your OnPaint():
   def OnPaint(self,event):
      dc = wx.PaintDC(event.GetEventObject())
      dc.Clear()
      # set up your pen
      dc.SetPen(wx.Pen("BLACK", 4))
      # draw whatever you like
      dc.DrawLine(0, 0, 50, 50)

   # (...) rest of code

在wxpython中用开罗绘图

2 个答案: