使用IronPython和Visual Studio 2010进行GUI开发

Question

我正在教授一门使用Python编程和GUI开发的入门课程，并且发现对于刚开始编程的学生来说，最简单的解决方案是使用Visual Studio进行GUI开发。

虽然c#和VB的GUI开发经验是愉快的，但我找不到用IronPython做同样的方法。我安装了包含Visual Studio工具的IronPython 2.7.1，并创建了一个WPF IronPython项目。

我可以像VB和c#一样使用WPF表单设计器，但是，我找不到一种方便的方法(即，学生可以理解)，可以访问GUI元素。例如，使用VB，您可以根据元素的名称引用元素，然后可以修改其中的属性。我能用IronPython做的最好的事情(我不打算给学生们看)是:

import wpf
from System.Windows import Application, Window
class MyWindow(Window):
    def __init__(self):
        wpf.LoadComponent(self, 'WpfApplication3.xaml')
    def Button_Click(self, sender, e):
        #This is the only way I could find in which I can 
        #access an element and modify its properties
        self.Content.Children[1].Text += 'Hello Worldn'

if __name__ == '__main__':
    Application().Run(MyWindow())

我注意到GUI元素没有名称，每当我试图手动修改XAML来命名元素时，Visual Studio就会崩溃。下面是为一个带有按钮和文本区域的简单框架生成的XAML:

<Window 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Title="WpfApplication3" Height="300" Width="300"> 
    <Grid>
        <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="103,226,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click" />
        <TextBox Height="182" HorizontalAlignment="Left" Margin="24,21,0,0" VerticalAlignment="Top" Width="237" />
    </Grid>
</Window> 

任何帮助，使这对学生来说更容易，将是感激的。我也愿意接受其他关于Python GUI开发的建议，这些建议可以提供类似于Visual Studio的体验。

Answer 1

在IronPython 2.7中LoadComponent方法将连接所有与XAML UI元素同名的属性。如果你正在使用IronPython 2.6，那么你需要使用WombatPM建议的代码。所以在IronPython 2.7中，如果你使用以下XAML:

<Window 
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
       Title="IronPyWpf" Height="300" Width="300">
    <Grid>
        <Button x:Name="button" Content="Button" Height="23" HorizontalAlignment="Left" Margin="103,226,0,0" VerticalAlignment="Top" Width="75"  />
        <TextBox x:Name="textbox" Height="182" HorizontalAlignment="Left" Margin="24,21,0,0" VerticalAlignment="Top" Width="237" />
    </Grid>
</Window> 

然后你可以定义button和textbox两个属性来访问UI元素:

class MyWindow(Window):
    def __init__(self):
        wpf.LoadComponent(self, 'IronPyWpf.xaml')
        self._button.Content = 'My Button'
        self._textbox.Text = 'My Text'
    def get_button(self):
        return self._button
    def set_button(self, value):
        self._button = value
    button = property(get_button, set_button)
    def get_textbox(self):
        return self._textbox
    def set_textbox(self, value):
        self._textbox = value
    textbox = property(get_textbox, set_textbox)

事实上，你似乎可以通过删除属性定义来进一步简化代码:

class MyWindow(Window):
    def __init__(self):
        wpf.LoadComponent(self, 'IronPyWpf.xaml')
        self.button.Content = 'My Button'
        self.textbox.Text = 'My Text'

不幸的是，Visual Studio似乎崩溃了，正如你已经看到的，当你试图编辑XAML并给UI元素一个名字时，null引用异常。

Answer 2

您需要遍历所有对象，并使用如下函数创建更容易理解的引用。

#
# Waddle returns a dictionary of Control types e.g. listbox, Button.
# Each Entry is a dictionary of Control Instance Names i.e.
# controls['Button']['NewSite'] returns the button control named NewSite
# Controls should have Unique names and only those with a Name attrib set
# will be included.
#
def Waddle(c, d):
    s = str(c.__class__)
    if "System.Windows.Controls." in str(c) and hasattr(c,"Name") and c.Name.Length>0:
        ControlType = s[s.find("'")+1:s.rfind("'")]
        if ControlType not in d:
            d[ControlType] = {}
        d[ControlType][c.Name] = c
    if hasattr(c,"Children"):
        for cc in c.Children:
            Waddle(cc, d)
    elif hasattr(c,"Child"):
        Waddle(c.Child, d)
    elif hasattr(c,"Content"):
        Waddle(c.Content, d)
if __name__ == "__main__":
    xr = XmlReader.Create(StringReader(xaml))
    win = XamlReader.Load(xr)
    controls = {}
    Waddle(win, controls)
    #Make all Named buttons do something!
    for butt in controls['Button']:
        controls['Button'][butt].Click += sayhello
    #Make one button do something.
    controls['Button']['NewSite'].Click += sayhello2
    Application().Run(win)

请参阅http://www.ironpython.info/index.php/XAML_GUI_Events_Example查看上述代码和完整示例。