动态管理Python GTK3应用中的CSS样式：最佳实践指南

#!/usr/bin/env python3
from gi.repository import Gtk, Gdk

# 基础CSS，优先级较低
BASE_CSS = b"""
window {
    background-color: #f0f0f0; /* 默认窗口背景 */
}
entry {
    background-color: green; /* 默认输入框背景 */
    color: white;
    padding: 5px;
}
"""

class DynamicStyleApp(Gtk.Window):
    def __init__(self):
        super().__init__(title="GTK3 Dynamic CSS Demo")
        self.set_default_size(400, 200)
        self.connect("delete-event", Gtk.main_quit)

        # 设置基础CSS提供者
        self.base_provider = Gtk.CssProvider()
        self.base_provider.load_from_data(BASE_CSS)
        Gtk.StyleContext.add_provider_for_screen(
            Gdk.Screen.get_default(),
            self.base_provider,
            Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION
        )

        # 设置用户动态CSS提供者，优先级较高
        self.user_provider = Gtk.CssProvider()
        # 初始时可以加载空数据或一些默认的动态样式
        self.user_provider.load_from_data(b"")
        Gtk.StyleContext.add_provider_for_screen(
            Gdk.Screen.get_default(),
            self.user_provider,
            Gtk.STYLE_PROVIDER_PRIORITY_USER # 用户优先级高于应用优先级
        )

        vbox = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=10)
        self.add(vbox)

        label1 = Gtk.Label(label="Entry 1 (Static Green)")
        entry1 = Gtk.Entry()
        entry1.set_text("This entry is always green.")

        label2 = Gtk.Label(label="Entry 2 (Type 'red' to change background)")
        self.entry2 = Gtk.Entry()
        self.entry2.set_text("Type 'red' here")
        self.entry2.connect("changed", self.on_entry2_changed)

        vbox.pack_start(label1, False, False, 0)
        vbox.pack_start(entry1, False, False, 0)
        vbox.pack_start(label2, False, False, 0)
        vbox.pack_start(self.entry2, False, False, 0)

    def on_entry2_changed(self, entry):
        text = entry.get_text().strip().lower()
        if text == "red":
            # 动态加载新的CSS规则，覆盖原有样式
            new_css = "entry { background-color: red; color: yellow; }"
            self.user_provider.load_from_data(bytes(new_css.encode()))
        else:
            # 恢复到基础样式（通过加载空数据或默认动态样式）
            # 注意：这里加载空数据会使user_provider不再提供任何样式，
            # 从而让base_provider的样式重新生效。
            self.user_provider.load_from_data(b"")

if __name__ == "__main__":
    app = DynamicStyleApp()
    app.show_all()
    Gtk.main()

#!/usr/bin/env python3
from gi.repository import Gtk, Gdk

# 所有CSS规则，包括基础样式和类样式
# 注意：这里只用一个Gtk.CssProvider
APP_CSS = b"""
window {
    background-color: #f0f0f0;
}
entry {
    color: black;
    padding: 5px;
    border: 1px solid #ccc;
}
/* 定义不同的背景色类 */
.entry-green-bg {
    background-color: green;
    color: white;
}
.entry-red-bg {
    background-color: red;
    color: yellow;
}
"""

class ClassBasedDynamicStyleApp(Gtk.Window):
    def __init__(self):
        super().__init__(title="GTK3 Class-Based Dynamic CSS Demo")
        self.set_default_size(400, 200)
        self.connect("delete-event", Gtk.main_quit)

        # 设置一个全局CSS提供者，包含所有基础样式和类样式
        self.style_provider = Gtk.CssProvider()
        self.style_provider.load_from_data(APP_CSS)
        Gtk.StyleContext.add_provider_for_screen(
            Gdk.Screen.get_default(),
            self.style_provider,
            Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION
        )

        vbox = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=10)
        self.add(vbox)

        label1 = Gtk.Label(label="Entry 1 (Static Green)")
        self.entry1 = Gtk.Entry()
        self.entry1.set_text("This entry is always green.")
        # 为entry1添加默认的绿色背景类
        self.entry1.get_style_context().add_class("entry-green-bg")

        label2 = Gtk.Label(label="Entry 2 (Type 'red' to change background)")
        self.entry2 = Gtk.Entry()
        self.entry2.set_text("Type 'red' here")
        # 为entry2添加默认的绿色背景类
        self.entry2.get_style_context().add_class("entry-green-bg")
        self.entry2.connect("changed", self.on_entry2_changed)

        vbox.pack_start(label1, False, False, 0)
        vbox.pack_start(self.entry1, False, False, 0)
        vbox.pack_start(label2, False, False, 0)
        vbox.pack_start(self.entry2, False, False, 0)

    def on_entry2_changed(self, entry):
        text = entry.get_text().strip().lower()
        style_context = entry.get_style_context()

        if text == "red":
            # 如果当前是绿色背景，则移除绿色类，添加红色类
            if style_context.has_class("entry-green-bg"):
                style_context.remove_class("entry-green-bg")
            if not style_context.has_class("entry-red-bg"):
                style_context.add_class("entry-red-bg")
        else:
            # 否则，确保是绿色背景
            if style_context.has_class("entry-red-bg"):
                style_context.remove_class("entry-red-bg")
            if not style_context.has_class("entry-green-bg"):
                style_context.add_class("entry-green-bg")

if __name__ == "__main__":
    app = ClassBasedDynamicStyleApp()
    app.show_all()
    Gtk.main()