如何检查 GTK3 (C) 中的按键？答案

【问题标题】：How do I Check for the Key Pressed in GTK3 (C)?如何检查 GTK3 (C) 中的按键？
【发布时间】：2024-06-19 03:05:02
【问题描述】：

我们正在尝试使用 glade 过滤 C 中的按键事件中的键。但是我们不知道如何过滤这些键。代码如下：

 // called when key pressed
void on_window_main_key_press_event()
{

}

【问题讨论】：

GdkEventKey keyval 字段
Here you find almost everything you need to know about signals and events

标签： c gtk3 glade

【解决方案1】：

您必须使用GdkEventKey 来处理按键事件。

结构如下所示：

struct GdkEventKey {
  GdkEventType type;  // is it a key-press or key release event
  GdkWindow *window; // the window receiving the event
  gint8 send_event;  // whether the event was sent explicitly. It's TRUE in that case
  guint32 time;    //time of event in ms
  guint state;     //a bit mask representing state of (Ctrl/Alt/Shift)
  guint keyval;   // the key that was pressed
  gint length;    // length of string
  gchar *string;   //the string that may result from this kepress
  guint16 hardware_keycode; //hardware key code
  guint8 group; // keyboard group
  guint is_modifier : 1;  //whether the key is mapped as modifier
};

您可以在此文件中找到所有按键的值：gdkkeysyms.h

这是一个简单的例子：

#include <gtk/gtk.h>
#include <gdk/gdkkeysyms.h>

gboolean
on_window_main_key_press_event (GtkWidget *widget, GdkEventKey *event, gpointer user_data);

int main (int argc, char *argv[])
{
  GtkWidget *window;

  gtk_init (&argc, &argv);

  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

  g_signal_connect (G_OBJECT (window), "key_press_event", G_CALLBACK (on_window_main_key_press_event), NULL);

  gtk_widget_show_all (window);

  gtk_main ();

  return 0;
}

gboolean
on_key_press (GtkWidget *widget, GdkEventKey *event, gpointer user_data)
{
  switch (event->keyval)
  {
    case GDK_Z:
    case GDK_z:
      printf("key pressed: %s\n", "Z");
      break;
    case GDK_S
    case GDK_s:
      if (event->state & GDK_SHIFT_MASK)
      {
        printf("key pressed: %s\n", "shift + s");
      }
      else if (event->state & GDK_CONTROL_MASK)
      {
        printf("key pressed: %s\n", "ctrl + s");
      }
      else
      {
        printf("key pressed: %s\n", "s");
      }
      break;
    default:
      return FALSE; 
  }
  return FALSE; 
}

【讨论】：

【解决方案2】：

按键的回调函数是

on_key_press(GtkWidget *widget, GdkEventKey *key, gpointer user_data)

这里定义了 GdkEventKey 结构 (https://developer.gnome.org/gdk3/stable/gdk3-Event-Structures.html#GdkEventKey) keyval 返回按下的键的值，你可以像这样比较它。

strcmp(gdk_keyval_name(key->keyval), "Return") == 0

【讨论】：

当您可以只比较整数值时，我不会使用键的字符串描述进行检查。

【解决方案3】：

我认为这应该对你有所帮助

void on_window_main_key_press_event(GtkWidget *widget, GdkEventKey *key, gpointer user_data) {
    int TheKeyThatWasPressed = key->keyval; //Incase you need to find out what key got pressed
}

然后在你的主函数中使用它：

g_signal_connect(Window, "key-press-event", G_CALLBACK(KeyPressHandler), NULL);

【讨论】：