gtkmm4 应用程序使用 CSS 样式

目录

• 前言
• css选择器
• css文件示例
• 源代码
• 效果
• 动态设置css-classes
• 动态设置css属性

前言

• 程序样式和代码逻辑分离开 使代码逻辑更可观

css选择器

• Cambalache提供了两种
• css-classes 相当于css里的类名:class="类名"
• css-name 相当于css里的标签名:spin div p 啥的
  
• 如上我设置了这个按钮控件的类名为testButton
  标签名为myButton
• 它的Xml视图是这样的

  <?xml version='1.0' encoding='UTF-8'?>
  <!-- Created with Cambalache 0.16.0 -->
  <interface>
    <!-- interface-name temp3.ui -->
    <requires lib="gtk" version="4.12"/>
    <object class="GtkButton" id="Button1">
      <property name="css-classes">testButton</property>
      <property name="css-name">myButton</property>
      <property name="focusable">True</property>
      <property name="hexpand">True</property>
      <property name="label">Button1</property>
      <property name="vexpand">True</property>
      <property name="vexpand-set">True</property>
    </object>
  </interface>
  

css文件示例

.testButton{/*类选择器*/
    background-color: blue; /* Green */
    color: greenyellow;
    border: none;
}
myButton {/*标签选择器*/
    background-color: blue; /* Green */
    color: greenyellow;
    border: none;
}

/* 设置按钮在鼠标悬停时的背景色 */
myButton:hover {
    background-color: red;
}

源代码

#include <gtkmm.h>
#include <iostream>
class MainWindow : public Gtk::Window
{
public:
    // Member widgets:

    MainWindow()
    {
        // Set window properties
        set_title("GTKMM4 with CSS Example");
        set_default_size(200, 200);
        auto refBuilder= Gtk::Builder::create_from_file("K:\\VM_Shared\\temp3.ui");
        auto pButton = refBuilder->get_widget<Gtk::Button>("Button1");

        set_child(*pButton);
        pButton->set_visible();

        // Load CSS styles
        load_css();
    }

private:
    void load_css()
    {
        // Check if CSS file exists
        if (Glib::file_test("K:\\VM_Shared\\Style.css", Glib::FileTest::EXISTS))
        {
            // Create CSS provider and load CSS file
            auto css_provider = Gtk::CssProvider::create();
            css_provider->load_from_path("K:\\VM_Shared\\Style.css");
            // Get the default screen and add the CSS provider
            auto screen = Gdk::Display::get_default();
            Gtk::StyleContext::add_provider_for_display(screen, css_provider,GTK_STYLE_PROVIDER_PRIORITY_APPLICATION );
        }
        else
        {
            std::cerr << "Failed to load CSS file: styles.css" << std::endl;
        }
    }
};

int main(int argc, char* argv[])
{
    auto app=Gtk::Application::create("org.HelleCssExample");

    return app->make_window_and_run<MainWindow>(argc, argv);
}

效果

动态设置css-classes

auto button1 = Gtk::make_managed<Gtk::Button>("bottom button");
button1->set_expand();
button1->get_style_context()->add_class("custom_button");

动态设置css属性

// 获取按钮的StyleContext
 auto style_context = button.get_style_context();
// 创建一个CSSProvider
 Gtk::CssProvider css_provider;
// 设置CSS属性
 std::string css = "GtkButton { background-color: red; }"; // 你可以修改这里的CSS属性
 css_provider.load_from_data(css.data(), css.length());
// 将CSSProvider添加到StyleContext中
// 注意：这里使用GTK_STYLE_PROVIDER_PRIORITY_USER来确保我们的样式优先级高于默认样式
style_context->add_provider(css_provider,GTK_STYLE_PROVIDER_PRIORITY_USER);

上面用法无法使css transition属性生效
应该这样用:

void BG_blur() {
    auto controrller = Gtk::EventControllerMotion::create();
    controrller->signal_enter().connect([this](const double &a, const double &b) {
        std::cout << "enter" << std::endl;
        auto style = m_pBG_image->get_style_context();
        style->remove_class("hovered");
    }, true);
    controrller->signal_leave().connect([this]() {
        std::cout << "leave" << std::endl;
        auto style = m_pBG_image->get_style_context();
        style->add_class("hovered");

    }, true);
    m_pmainFrame->add_controller(controrller);
};

上面在鼠标进入和离开时分别增加和移除某个固定classs, 在css文件中可这样写以达到效果:

.custom_Image{
    background-image: url('tai.png');
    background-size: cover;
    transition: all 500ms 0ms ease-in-out;
}
.custom_Image.hovered{
     filter: blur(4px);
}