GTK3 Python中动态管理CSS样式：多提供器与CSS类方法详解

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

# 基础CSS，通常在应用启动时加载
BASE_CSS = b"""
window {
    background-color: yellow;
}
entry {
    background-color: green;
}
"""

def on_entry_changed(entry_widget, user_css_provider):
    """
    当第二个输入框内容改变时，动态更新输入框样式。
    """
    current_text = entry_widget.get_text()
    print(f"Entry text changed to: {current_text}")

    # 根据某些逻辑决定新样式
    if "red" in current_text.lower():
        new_css_rule = "entry { background-color: red; }"
    elif "blue" in current_text.lower():
        new_css_rule = "entry { background-color: blue; }"
    else:
        # 如果没有特定条件，可以恢复到默认（或清除动态样式）
        new_css_rule = "entry { background-color: orange; }" # 示例：设置为另一种颜色

    # 重新加载用户提供器，覆盖现有样式
    user_css_provider.load_from_data(bytes(new_css_rule.encode('utf-8')))
    print(f"Dynamic CSS applied: {new_css_rule}")


# 初始化GTK构建器并加载UI文件（假设pygtk3test.glade存在）
# 注意：原问题中提到需要一个.glade文件，此处假定其内容包含mainWindow, label2, entry2
# 为简化示例，这里不提供glade文件内容，但代码逻辑依赖其存在
myBuilder = Gtk.Builder()
try:
    myBuilder.add_from_file("pygtk3test.glade")
except Exception as e:
    print(f"Error loading .glade file: {e}. Please ensure 'pygtk3test.glade' is available.")
    # 如果没有glade文件，为了演示CSS，可以手动创建简单UI
    window = Gtk.Window(title="Dynamic CSS Demo")
    box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=6)
    window.add(box)
    label2 = Gtk.Label(label="Enter 'red' or 'blue' to change colors:")
    entry2 = Gtk.Entry()
    box.pack_start(label2, False, False, 0)
    box.pack_start(entry2, False, False, 0)
else:
    window = myBuilder.get_object("mainWindow")
    # label2 = myBuilder.get_object("label2") # 示例中未用到label2，可省略
    entry2 = myBuilder.get_object("entry2")


# 1. 设置全局基础CSS提供器（优先级较低）
base_style_provider = Gtk.CssProvider()
base_style_provider.load_from_data(BASE_CSS)
Gtk.StyleContext.add_provider_for_screen(Gdk.Screen.get_default(), base_style_provider,
                                         Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION)

# 2. 设置用户动态CSS提供器（优先级较高）
user_dynamic_provider = Gtk.CssProvider()
# 初始时可以加载一个空字符串或默认动态样式
user_dynamic_provider.load_from_data(bytes("".encode('utf-8')))
Gtk.StyleContext.add_provider_for_screen(Gdk.Screen.get_default(), user_dynamic_provider,
                                         Gtk.STYLE_PROVIDER_PRIORITY_USER)

# 连接信号，当entry2文本改变时，更新user_dynamic_provider
entry2.connect("changed", on_entry_changed, user_dynamic_provider)

window.connect("delete-event", Gtk.main_quit)
window.show_all()
Gtk.main()

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

# 基础CSS，定义了不同的状态类
CLASS_BASED_CSS = b"""
window {
    background-color: lightgray;
}
entry {
    background-color: white;
    border: 1px solid gray;
}
.entry-error {
    background-color: #ffe0e0; /* 浅红色背景 */
    border: 1px solid red;
}
.entry-success {
    background-color: #e0ffe0; /* 浅绿色背景 */
    border: 1px solid green;
}
"""

def on_entry_class_changed(entry_widget):
    """
    当输入框内容改变时，通过添加/移除CSS类来更新样式。
    """
    current_text = entry_widget.get_text()
    style_context = entry_widget.get_style_context()

    # 先移除所有可能的状态类，确保状态切换的正确性
    style_context.remove_class("entry-error")
    style_context.remove_class("entry-success")

    # 根据文本内容添加相应的类
    if "error" in current_text.lower():
        style_context.add_class("entry-error")
        print("Added class: entry-error")
    elif "success" in current_text.lower():
        style_context.add_class("entry-success")
        print("Added class: entry-success")
    else:
        print("No specific class added.")


# 初始化GTK构建器或手动创建UI
myBuilder = Gtk.Builder()
try:
    myBuilder.add_from_file("pygtk3test.glade")
    window = myBuilder.get_object("mainWindow")
    entry_field = myBuilder.get_object("entry2") # 假设使用entry2作为示例
except Exception:
    print("Could not load .glade file, creating simple UI for demo.")
    window = Gtk.Window(title="Dynamic CSS Class Demo")
    box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=6)
    window.add(box)
    label = Gtk.Label(label="Type 'error' or 'success' to change entry style:")
    entry_field = Gtk.Entry()
    box.pack_start(label, False, False, 0)
    box.pack_start(entry_field, False, False, 0)


# 设置基础CSS提供器
class_style_provider = Gtk.CssProvider()
class_style_provider.load_from_data(CLASS_BASED_CSS)
Gtk.StyleContext.add_provider_for_screen(Gdk.Screen.get_default(), class_style_provider,
                                         Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION)

# 连接信号，当entry_field文本改变时，更新其CSS类
entry_field.connect("changed", on_entry_class_changed)

window.connect("delete-event", Gtk.main_quit)
window.show_all()
Gtk.main()