为Thonny开发插件：TreeView文本适配视图宽度自动换行问题

我正在为Thonny开发一款插件，构建TreeView时遇到了问题——这个TreeView只有一列，部分行文本过长，希望实现文本根据视图宽度自动截断并换行，且视图大小变化时能响应式调整换行。当前代码如下：

class TestTreeView(ttk.Frame):    
    def __init__(self, master):
        ttk.Frame.__init__(self, master)
        self._init_widgets()

    def _init_widgets(self):
        # init and place scrollbar
        self.vert_scrollbar = SafeScrollbar(self, orient=tk.VERTICAL)
        self.vert_scrollbar.grid(row=0, column=1, sticky=tk.NSEW)

        self.horz_scrollbar = SafeScrollbar(self, orient=tk.HORIZONTAL)
        self.horz_scrollbar.grid(row=1, column=0, sticky=tk.NSEW)
        
        self.tree = ttk.Treeview(self)
        
        # scrollbars
        self.vert_scrollbar["command"] = self.tree.yview
        self.horz_scrollbar["command"] = self.tree.xview
        
        self.tree.grid(row=0, column=0, sticky=tk.NSEW)
        
        # configure the scroll bars on the tree view
        self.tree.configure(yscrollcommand=self.vert_scrollbar.set, xscrollcommand=self.horz_scrollbar.set) 
        
        # set single-cell frame
        self.columnconfigure(0, weight=1)
        self.rowconfigure(0, weight=1)

        # init tree events
        self.tree.bind("<<TreeviewSelect>>", self._on_select, True)

        # configure the only tree column
        self.tree.column("#0", anchor=tk.W, stretch=True, width=1000, minwidth=1000)
        self.tree["show"] = ("tree",)

        self.tree.tag_configure('orange', foreground='orange')
        self.tree.tag_configure('red', foreground='red')
        self.tree.tag_configure('green', foreground='darkgreen')

        ttk.Style().configure('Treeview', rowheight=40, rowwidth=40)

ttk TreeView本身不支持原生自动换行，但可以通过以下方式实现需求：

• 移除固定列宽，绑定视图resize事件
  删掉self.tree.column("#0")里的固定width和minwidth参数，让列随容器自适应宽度。然后给TreeView绑定<Configure>事件，在窗口或TreeView大小变化时重新处理文本换行。

• 动态计算文本换行与行高
  编写文本换行函数，利用tkinter.font.Font计算文本宽度，把长文本拆分成多行；同时根据换行后的行数动态设置每行的高度，避免内容被截断。

修改后的完整代码示例：

import tkinter as tk
from tkinter import ttk
import tkinter.font as tkfont

class TestTreeView(ttk.Frame):    
    def __init__(self, master):
        ttk.Frame.__init__(self, master)
        self._init_widgets()
        # 绑定视图大小变化事件
        self.tree.bind("<Configure>", self._on_tree_resize)
        # 初始化字体对象，用于计算文本宽度
        self.text_font = tkfont.Font(font=ttk.Style().lookup('Treeview', 'font'))

    def _init_widgets(self):
        # 滚动条初始化（如果SafeScrollbar是Thonny自定义组件，保留原引用即可）
        self.vert_scrollbar = SafeScrollbar(self, orient=tk.VERTICAL)
        self.vert_scrollbar.grid(row=0, column=1, sticky=tk.NSEW)

        self.horz_scrollbar = SafeScrollbar(self, orient=tk.HORIZONTAL)
        self.horz_scrollbar.grid(row=1, column=0, sticky=tk.NSEW)
        
        self.tree = ttk.Treeview(self)
        
        self.vert_scrollbar["command"] = self.tree.yview
        self.horz_scrollbar["command"] = self.tree.xview
        
        self.tree.grid(row=0, column=0, sticky=tk.NSEW)
        
        self.tree.configure(yscrollcommand=self.vert_scrollbar.set, xscrollcommand=self.horz_scrollbar.set) 
        
        self.columnconfigure(0, weight=1)
        self.rowconfigure(0, weight=1)

        self.tree.bind("<<TreeviewSelect>>", self._on_select, True)

        # 修改列配置，去掉固定宽度，让列自适应
        self.tree.column("#0", anchor=tk.W, stretch=True)
        self.tree["show"] = ("tree",)

        self.tree.tag_configure('orange', foreground='orange')
        self.tree.tag_configure('red', foreground='red')
        self.tree.tag_configure('green', foreground='darkgreen')

        # 添加测试数据
        self._add_sample_items()

    def _add_sample_items(self):
        self.tree.insert("", tk.END, text="Short test item")
        self.tree.insert("", tk.END, text="Tests Run: 2, Failures: 0, Errors: 0, Skipped: 0, Expected Failures: 0, Unexpected Successes: 0")

    def _on_tree_resize(self, event):
        # 获取当前列的可用宽度（减去TreeView内边距，避免文本贴边）
        column_width = self.tree.winfo_width() - 20
        if column_width <= 0:
            return
        
        # 遍历所有条目，重新处理文本换行
        for item_id in self.tree.get_children():
            original_text = self.tree.item(item_id, "text")
            wrapped_text = self._wrap_text(original_text, column_width)
            self.tree.item(item_id, text=wrapped_text)
            # 根据换行行数设置行高
            line_count = wrapped_text.count('\n') + 1
            tag_name = f"row_{line_count}"
            self.tree.item(item_id, tags=(tag_name,))
            # 配置对应tag的行高（单行基础高度可根据字体调整）
            ttk.Style().configure(f"{tag_name}.Treeview", rowheight=line_count * 20)

    def _wrap_text(self, text, max_width):
        # 按单词分割文本，逐行拼接直到超过宽度
        words = text.split()
        if not words:
            return ""
        
        lines = []
        current_line = words[0]
        for word in words[1:]:
            test_line = f"{current_line} {word}"
            if self.text_font.measure(test_line) <= max_width:
                current_line = test_line
            else:
                lines.append(current_line)
                current_line = word
        lines.append(current_line)
        return '\n'.join(lines)

    def _on_select(self, event):
        # 保留原选择逻辑
        pass

• 优化建议
  如果频繁调整窗口大小出现卡顿，可以给_on_tree_resize添加延迟处理，比如用self.after(100, self._handle_resize, column_width)，避免短时间内重复计算。

内容的提问来源于stack exchange，提问作者Réda