如何让 GtkLayout 滚动？答案

【问题标题】：How to make GtkLayout scroll?如何让 GtkLayout 滚动？
【发布时间】：2021-03-04 11:48:34
【问题描述】：

我的问题与 GtkLayout 有关，我读过它负责使用小部件创建无限可滚动区域。我使用以下代码创建了一个：

    GtkWidget *window;
    GtkWidget *button1;
    GtkWidget *button2;
    GtkWidget *layout;

    window = gtk_application_window_new (app);
    gtk_window_set_title (GTK_WINDOW (window), "Window wowowwow");
    gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);



    layout = gtk_layout_new(NULL, NULL);
    gtk_container_add (GTK_CONTAINER (window), layout);

    button1 = gtk_button_new_with_label ("Hello World");
    g_signal_connect (button1, "clicked", G_CALLBACK (print_hello), NULL);
    g_signal_connect_swapped (button1, "clicked", G_CALLBACK (gtk_widget_destroy), window);
    gtk_layout_put(GTK_LAYOUT(layout), button1, 20,20);

    button2 = gtk_button_new_with_label ("Button 2");
    g_signal_connect_swapped (button2, "clicked", G_CALLBACK (gtk_widget_destroy), button2);
    gtk_layout_put(GTK_LAYOUT(layout), button2, 200,200);
    
    GtkAdjustment *hadjustment = gtk_adjustment_new(0, 0, 1000, 1, 1, 20);
    gtk_layout_set_size(GTK_LAYOUT(layout), 1000,1000);
    gtk_scrollable_set_hadjustment(GTK_SCROLLABLE(layout), hadjustment);

    gtk_widget_show_all (window);

这显示了一个如下所示的窗口：

Window initial

.. 调整大小时：

Window resized

问题是，我希望 GtkLayout 的内容可以滚动。我认为问题出在我必须配置的调整对象上，但我不知道参数的确切含义，而且关于此的文档非常稀缺。所以，我期待在这里寻求帮助。

【问题讨论】：

标签： user-interface gtk

【解决方案1】：

为了使它工作，我必须将 GtkLayout 放在 GtkScrolledWindow 中并覆盖布局的默认尺寸。有效的代码如下所示：

#include <gtk/gtk.h>

static void
print_hello (GtkWidget *widget,
             gpointer   data)
{
  g_print ("Hello World\n");
}

static void
activate (GtkApplication *app,
          gpointer        user_data)
{
    GtkWidget *window;
    GtkWidget *scrolled_window;
    GtkWidget *layout;

    window = gtk_application_window_new (app);
    gtk_window_set_title (GTK_WINDOW (window), "Window");
    gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);

    scrolled_window = gtk_scrolled_window_new(NULL, NULL);
    gtk_container_add (GTK_CONTAINER (window), scrolled_window);

    layout = gtk_layout_new(NULL, NULL);
    gtk_container_add(GTK_CONTAINER(scrolled_window), layout);

    int i = 0;

    while (i < 10) {
        GtkWidget *a_button;
        a_button = gtk_button_new_with_label("Button");
        gtk_layout_put(GTK_LAYOUT(layout), a_button, 10, 10 + 40 * i);
        i += 1;
    }

    gtk_layout_set_size(GTK_LAYOUT(layout), 1000,1000);

    gtk_widget_show_all (window);
}

int
main (int    argc,
      char **argv)
{
      GtkApplication *app;
      int status;

      app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
      g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
      status = g_application_run (G_APPLICATION (app), argc, argv);
      g_object_unref (app);

      return status;
}

【讨论】：