使用 glade 和 GTK+ 进行信号处理

Question

出于好奇而尝试学习 Linux 开发，对 C 知之甚少

我正在使用 glade 3.18.3。

我想创建一个应用程序，当按下 button1 时，label1 上的文本将随着 entry1（输入框）中的输入文本而改变。

我不知道如何将所需的参数传递给回调。

这是sample.glade:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.18.3 -->
<interface>
  <requires lib="gtk+" version="3.12"/>
  <object class="GtkWindow" id="window_main">
    <property name="can_focus">False</property>
    <property name="title" translatable="yes">Nishant</property>
    <property name="default_width">440</property>
    <property name="default_height">250</property>
    <signal name="destroy" handler="on_window_main_destroy" swapped="no"/>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkMenuBar" id="menubar1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkMenuItem" id="menuitem1">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_File</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu1">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem1">
                        <property name="label">gtk-new</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem2">
                        <property name="label">gtk-open</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem3">
                        <property name="label">gtk-save</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem4">
                        <property name="label">gtk-save-as</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkSeparatorMenuItem" id="separatormenuitem1">
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem5">
                        <property name="label">gtk-quit</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
            <child>
              <object class="GtkMenuItem" id="menuitem2">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_Edit</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu2">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem6">
                        <property name="label">gtk-cut</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem7">
                        <property name="label">gtk-copy</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem8">
                        <property name="label">gtk-paste</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem9">
                        <property name="label">gtk-delete</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
            <child>
              <object class="GtkMenuItem" id="menuitem3">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_View</property>
                <property name="use_underline">True</property>
              </object>
            </child>
            <child>
              <object class="GtkMenuItem" id="menuitem4">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_Help</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu3">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem10">
                        <property name="label">gtk-about</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">label1</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkEntry" id="entry1">
            <property name="name">entry1</property>
            <property name="visible">True</property>
            <property name="can_focus">True</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
        <child>
          <object class="GtkButton" id="button1">
            <property name="label" translatable="yes">button1</property>
            <property name="name">button1</property>
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <property name="halign">center</property>
            <signal name="activate" handler="on_button1_activate" swapped="no"/>
            <signal name="clicked" handler="on_button1_clicked" swapped="no"/>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">3</property>
          </packing>
        </child>
        <child>
          <object class="GtkStatusbar" id="statusbar1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="margin_left">10</property>
            <property name="margin_right">10</property>
            <property name="margin_start">10</property>
            <property name="margin_end">10</property>
            <property name="margin_top">6</property>
            <property name="margin_bottom">6</property>
            <property name="orientation">vertical</property>
            <property name="spacing">2</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">4</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

...这是 main.c:

//##gcc -o gladewin main.c -Wall pkg-config --cflags --libs gtk+-3.0 -export-dynamic

#include <gtk/gtk.h>
#include <stdio.h>
//gchar *buffer1;   //added
int main(int argc, char *argv[])
{
    GtkBuilder      *builder; 
    GtkWidget       *window;
  // ## gchar BUFF[100];


    gtk_init(&argc, &argv);

    builder = gtk_builder_new();
    gtk_builder_add_from_file (builder, "sample.glade", NULL);

    window = GTK_WIDGET(gtk_builder_get_object(builder, "window_main"));
    gtk_builder_connect_signals(builder, NULL);

    g_object_unref(builder);

    gtk_widget_show(window);                
    gtk_main();

    return 0;
}

// called when window is closed
void on_window_main_destroy()
{
    gtk_main_quit();
}



//called when button1 is clicked
void on_button1_clicked()
{
//buffer1 = gtk_entry_get_buffer (entry);
//gtk_entry_buffer_get_text (buffer1);

g_print("Button1 pressed");

//gtk_button_set_label (button1 ,"Hi");
//gtk_label_set_text(GTK_LABEL(entry1),"hi");   // i think this is correct just need tofigure out what to replace insted of entry1
}

Answer 1

你获取GtkEntry文本的方法很奇怪。您根本不需要玩缓冲区；只是做

const char *text = gtk_entry_get_text(myEntry);

text 返回的缓冲区为您提供了完整的文本，但作为 read-only 字符串，在 GtkEntry 需要时释放。

根据您的需要，可以直接传给gtk_button_set_label()和gtk_label_set_text():

gtk_button_set_label(button, text);
gtk_label_set_text(label, text);

通常，该值在整个信号处理程序中保持有效。

如果您想保留文本供以后使用，您需要使用 g_strdup() 复制它（使用 g_free() 免费）。

另外 gtk_label_set_text() 不适用于 GtkEntry；你需要和它一起使用 GtkLabel。

Answer 2

信号回调接收特定参数，具体取决于捕获的信号类型。每个回调的签名都是官方文档documented

在 glade 中，当定义一个信号时，您可以将一个额外的小部件传递给信号回调。真正的挑战是您只能传递一个小部件，而您需要访问它们（标签和条目）。

在纯 C 中，您会将两个指针填充到一个结构中并使用它来代替，但如果您仍想使用 glade，则必须找到另一种解决方案。一种方法是使用两个回调，例如：

Glade screenshot

那么你的回调可能是：

void read_from_entry(GtkButton *button, gpointer user_data)
{
    GtkEntry *entry = GTK_ENTRY(user_data);

    g_print("read_from_entry\n");

    g_object_set_data(G_OBJECT(button), "text", (gpointer) gtk_entry_get_text(entry));
}

void write_to_label(GtkButton *button, gpointer user_data)
{
    GtkLabel *label = GTK_LABEL(user_data);

    g_print("write_to_label\n");

    gtk_label_set_text(label, g_object_get_data(G_OBJECT(button), "text"));
}

g_object_{set,get}_data 对只是为了避免使用全局变量。以上将可靠地工作，前提是：

保留回调顺序；
不要写入两个回调中或两个回调之间的条目。

使用 glade 和 GTK+ 进行信号处理

Signal handling with glade and GTK+

c

gtk

gtk3

glade