如何在Kivy应用中实现文本片段点击跳转至指定Label的屏幕焦点？

我正在用Kivy和Python开发一款带长滚动文本列表的应用，列表里包含作为标题的Label和承载正文的Label。现在想实现：点击正文中的某段特定文本后，让屏幕滚动聚焦到指定的另一个Label。我已经找到把特定文本超链接到网页的方法，但还没找到在同一应用内实现屏幕焦点跳转的合适方案。

示例代码如下：

<SecondWindow@ScrollView>
    name:"Page"
    canvas.before:
        Color:
            rgba:(1,1,1,1)
        Rectangle:
            pos: self.pos
            size: self.size
            ScrollView:
                GridLayout:
                    cols:1
                    size_hint_y:None
                    size_hint:1,None
                    height:self.minimum_height
                Label:
                    name:"PrefaceL1"
                    canvas.before:
                        Color:
                            rgba:(109/255.0,114/255.0,219/255.0,1)
                        Rectangle:
                            pos:self.pos
                            size:self.size
                    size_hint_y: None
                    height: self.texture_size[1]
                    text_size:self.width,None
                    text:'  Preface'
                    font_size:'52sp'

                Label:
                    name:"PrefaceB1"
                    canvas.before:
                        Color:
                            rgba:(1,1,1,1)
                        Rectangle:
                            pos:self.pos
                            size:self.size
                    size_hint_y: None
                    height: self.texture_size[1]
                    text_size:self.width,None
                    text:"Long [KEY WORD SOMEWHERE IN HERE] Text"  <--------  
                    color: 0,0,0,1
                    font_size:'16sp'
                Label:
                    name:"PrefaceL2" <--------- 想要聚焦的位置
                    canvas.before:
                        Color:
                            rgba:(0,0,0,1)
                        Rectangle:
                            pos:self.pos
                            size:self.size
                    size_hint_y: None
                    height: self.texture_size[1]
                    text_size:self.width,None
                    text:'  Preface'
                    font_size:'52sp'

                    font_size:'16sp'

要实现内部文本点击跳转聚焦的需求，可按以下步骤操作：

1. 自定义支持局部文本点击的Label #

Kivy默认Label不支持局部文本点击，需要自定义Label类，通过检测点击位置判断是否命中目标文本区域：

from kivy.uix.label import Label
from kivy.core.text import Label as CoreLabel

class ClickableLabel(Label):
    def __init__(self, target_widget_name=None, **kwargs):
        super().__init__(**kwargs)
        self.target_widget_name = target_widget_name
        self.keyword = "[KEY WORD SOMEWHERE IN HERE]".strip("[]")
        self._calc_keyword_region()

    def _calc_keyword_region(self):
        # 预计算关键词在文本纹理中的位置范围
        self.core_label = CoreLabel(text=self.text.replace("[", "").replace("]", ""), 
                                    font_size=self.font_size, text_size=self.text_size)
        self.core_label.refresh()
        layout = self.core_label._get_layout()
        text = self.core_label.text
        keyword_start = text.find(self.keyword)
        if keyword_start == -1:
            self.keyword_region = None
            return
        
        current_idx = 0
        y_pos = self.texture_size[1]
        for line in layout.lines:
            line_len = len(line.text)
            if keyword_start < current_idx + line_len:
                # 定位关键词在当前行的字符位置
                char_start = keyword_start - current_idx
                char_end = char_start + len(self.keyword)
                glyphs = line.glyphs[char_start:char_end]
                if glyphs:
                    min_x = min(g.x for g in glyphs)
                    max_x = max(g.x + g.width for g in glyphs)
                    self.keyword_region = (min_x, y_pos - line.height, max_x - min_x, line.height)
                break
            current_idx += line_len
            y_pos -= line.height

    def on_touch_down(self, touch):
        if self.collide_point(*touch.pos) and self.keyword_region and self.target_widget_name:
            # 转换触摸坐标到Label内部纹理坐标系
            local_x = touch.pos[0] - self.pos[0]
            local_y = touch.pos[1] - self.pos[1]
            texture_y = self.texture_size[1] - local_y
            
            kw_x, kw_y, kw_w, kw_h = self.keyword_region
            if kw_x <= local_x <= kw_x + kw_w and kw_y <= texture_y <= kw_y + kw_h:
                # 查找目标Widget并滚动到其位置
                target = self.parent.ids.get(self.target_widget_name)
                if target:
                    self.parent.parent.scroll_to(target)
                return True
        return super().on_touch_down(touch)

2. 修正并更新KV代码 #

原代码存在嵌套ScrollView的错误（SecondWindow本身就是ScrollView，内部无需再嵌套），同时将正文Label替换为自定义的ClickableLabel，指定目标聚焦的Widget名称：

<SecondWindow@ScrollView>
    name:"Page"
    canvas.before:
        Color:
            rgba:(1,1,1,1)
        Rectangle:
            pos: self.pos
            size: self.size
    GridLayout:
        id: main_layout
        cols:1
        size_hint_y:None
        height:self.minimum_height

        Label:
            name:"PrefaceL1"
            canvas.before:
                Color:
                    rgba:(109/255.0,114/255.0,219/255.0,1)
                Rectangle:
                    pos:self.pos
                    size:self.size
            size_hint_y: None
            height: self.texture_size[1]
            text_size:self.width,None
            text:'  Preface'
            font_size:'52sp'

        ClickableLabel:
            name:"PrefaceB1"
            target_widget_name: "PrefaceL2"
            canvas.before:
                Color:
                    rgba:(1,1,1,1)
                Rectangle:
                    pos:self.pos
                    size:self.size
            size_hint_y: None
            height: self.texture_size[1]
            text_size:self.width,None
            text:"Long [KEY WORD SOMEWHERE IN HERE] Text"
            color: 0,0,0,1
            font_size:'16sp'

        Label:
            name:"PrefaceL2"
            canvas.before:
                Color:
                    rgba:(0,0,0,1)
                Rectangle:
                    pos:self.pos
                    size:self.size
            size_hint_y: None
            height: self.texture_size[1]
            text_size:self.width,None
            text:'  Preface'
            font_size:'52sp'

3. 关键说明 #

• 自定义Label中的关键词位置计算为基础版本，若需支持多行复杂文本，可结合kivy.core.text.layout的API进一步优化字符位置检测逻辑。
• 确保目标Widget的name属性正确，且能通过父容器的ids属性获取到（若Widget树结构复杂，可通过遍历树的方式查找目标）。

内容的提问来源于stack exchange，提问作者Luki