Python Tkinter : Tree selection

Question

我在 Canvas 中用 idlelib.TreeWidget 创建了 2 棵树，左边和右边。

如果双击，我也可以打印出树节点的名称，但我需要的是双击一个树节点将使某个树节点可见并被选中。

我这里有一个简单的例子。如果双击左侧的“level1”，右侧的“ccc”应该可见并自动选中。你是怎么做到的？

请运行以下代码:

from Tkinter import Tk, Frame, BOTH, Canvas
from xml.dom.minidom import parseString
from idlelib.TreeWidget import TreeItem, TreeNode

class DomTreeItem(TreeItem):
   def __init__(self, node):
      self.node = node
   def GetText(self):
      node = self.node
      if node.nodeType == node.ELEMENT_NODE:
         return node.nodeName
      elif node.nodeType == node.TEXT_NODE:
         return node.nodeValue
   def IsExpandable(self):
      node = self.node
      return node.hasChildNodes()
   def GetSubList(self):
      parent = self.node
      children = parent.childNodes
      prelist = [DomTreeItem(node) for node in children]
      itemlist = [item for item in prelist if item.GetText().strip()]
      return itemlist
   def OnDoubleClick(self):
      print self.node.nodeName

left = '''
<level0>
 <level1/>
</level0>
'''
right = '''
<aaa>
 <bbb> <ccc/> </bbb>
</aaa>
'''
class Application(Frame):

   def __init__(self, parent):
      Frame.__init__(self, parent)
      self.parent = parent
      self.parent.geometry('%dx%d+%d+%d' % (800, 300, 0, 0))
      self.parent.resizable(0, 0)

      dom = parseString(left)
      item = DomTreeItem(dom.documentElement)
      self.canvas = Canvas(self, bg = "cyan")
      self.canvas.grid(column = 0, row = 0, sticky = 'NSWE')
      node = TreeNode(self.canvas, None, item)
      node.update()

      dom2 = parseString(right)
      item2 = DomTreeItem(dom2.documentElement)
      self.canvas2 = Canvas(self, bg = "yellow")
      self.canvas2.grid(column = 1, row = 0, sticky = 'NSWE')
      node2 = TreeNode(self.canvas2, None, item2)
      node2.update()

      self.pack(fill = BOTH, expand = True)

def main():
   root = Tk()
   Application(root)
   root.mainloop()

if __name__ == '__main__':
   main()  

Answer 1

首先，您的双击回调必须知道您的 TreeNode node2(我可以想到全局变量、DomTreeItem 中的属性或跳转到另一个组件)。

然后就可以依赖TreeNode的expand()方法，读取children属性，依次展开，直到需要的元素。请注意，children 属性仅在节点展开后才会填充。

1。快速回答

针对您提供的示例的快速而肮脏的解决方案

class DomTreeItem(TreeItem):
    def OnDoubleClick(self):
        if self.GetText() == "level1":
            node2.expand()
            node2.children[0].expand()
            node2.children[0].children[0].select()

[...]

class Application(Frame):
    def __init__(self, parent):
        global node2

2。通用解决方案

这里有一个更通用的方法来显示树中的任意项。

def reach(node_tree, path):
   tokens = path.split("/")
   current_node = node_tree
   for name in tokens:
      if len(current_node.children) == 0 and current_node.state != "expanded":
         current_node.expand()
      candidates = [child for child in current_node.children if child.item.GetText() == name]
      if len(candidates) == 0:
         print("did not find '{}'".format(name))
         return
      current_node = candidates[0]
   current_node.select()

你可能会这样使用它

if self.GetText() == "level1":
    reach(node2, "bbb/ccc")

3。架构方案

除了扩展项目的选择外，我还通过 DIY 观察器向您推荐一个更简洁的架构。

DIY观察者

(模仿 Tkinter bind 调用，但自 generating event with user data is not properly handled 起不依赖 tkinter 机器)

class DomTreeItem(TreeItem):
   def __init__(self, node, dbl_click_bindings = None):
      self.node = node
      self.dbl_click_bindings = [] if (dbl_click_bindings == None) else dbl_click_bindings

   [...]
   def OnDoubleClick(self):
      self.fireDblClick()

   def bind(self, event, callback):
      '''mimic tkinter bind
      '''
      if (event != "<<TreeDoubleClick>>"):
         print("err...")
      self.dbl_click_bindings.append(callback)
   def fireDblClick(self):
      for callback in self.dbl_click_bindings:
         callback.double_click(self.GetText())

专用组件

依靠上面介绍的 reach 方法。

class TreeExpander:
   def __init__(self, node_tree, matching_items):
       self.node_tree = node_tree
       self.matching_items = matching_items
   def double_click(self, item_name):
      print("double_click ({0})".format(item_name))
      if (item_name in self.matching_items):
         reach(self.node_tree, self.matching_items[item_name])

订阅

class Application(Frame):
   def __init__(self, parent):
      [...]

      expander = TreeExpander(node2, {
         "level1": "bbb/ccc"
         })
      item.bind("<<TreeDoubleClick>>", expander)    

---

我没有找到 idlelib 的文档，在这种情况下，您可以尝试查看代码。以下代码片段可让您找到托管此模块的文件。

import idlelib.TreeWidget
print(idlelib.TreeWidget.__file__)