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GTK+ 2.0 教學-雜項元件

標籤

標籤(Labels)是 中最常用的元件,實際上它很簡單。因為沒有相關聯的 X 視窗,標籤不能引發信號。如果需要獲取或引發信號,可以將它放在一個事件盒中,或放在按鈕元件裡面。

用以下函式創建一個新標籤:

GtkWidget *gtk_label_new( const char *str );

GtkWidget *gtk_label_new_with_mnemonic( const char *str );

唯一的參數是要由標籤顯示的字串。

創建標籤後,要改變標籤你的文字,用以下函式:

void gtk_label_set_text( GtkLabel   *label,
                         const char *str );

第一參數是前面創建的標籤(用 GTK_LABEL() 巨集轉換),第二個參數是新的字串。

如果需要,新字串需要的空間會做自動調整。在字串中放置換行字元,可以創建多行標籤。

用以下函式取得標籤的當前文字:

const gchar* gtk_label_get_text( GtkLabel  *label );

不要釋放返回的字串,因為 GTK 內部要使用它。

標籤的文字可以用以下函式設置對齊方式:

void gtk_label_set_justify( GtkLabel         *label,
                            GtkJustification  jtype );

jtype 的值可以是:

  GTK_JUSTIFY_LEFT  左對齊
  GTK_JUSTIFY_RIGHT  右對齊
  GTK_JUSTIFY_CENTER  居中對齊(預設)
  GTK_JUSTIFY_FILL  充滿

標籤元件的文字會自動換行。用以下函式來啟用「自動換行」:

void gtk_label_set_line_wrap (GtkLabel *label,
                              gboolean  wrap);

wrap參數可取 TRUE 或 FALSE。

如果想要使標籤加下劃線,可以在標籤中設置顯示模式:

void       gtk_label_set_pattern   (GtkLabel          *label,
                                    const gchar       *pattern);

pattern 參數指定下劃線的外觀。它由一串下劃線和空格組成。下劃線指示標籤的相應字元應該加一個下劃線。例如,"__ __" 將在標籤的第1、第2個字元和第8、第9個字元加下劃線。

Note 如果你只是想創建一個用下劃線代表快捷鍵(“mnemonic”)的標籤,你應該用 gtk_label_new_with_mnemonic() 或 gtk_label_set_text_with_mnemonic(),而不是用 gtk_label_set_pattern()。

下面是一個說明這些函式的簡短範例。這個範例用框架元件(Frame widget)能更好地示範標籤的風格。現在你不用理會這點,框架元件以後再作介紹。

在 GTK+ 2.0 裡,標籤文字裡能包含改變字型等文字屬性的標記 ,並且標籤能設置為可以被選擇(用來複製-貼上)。這些進階特性在這裡並不介紹。

#include <gtk/gtk.h>

int main( int   argc,
          char *argv[] )
{
  static GtkWidget * = NULL;
  GtkWidget *hbox;
  GtkWidget *vbox;
  GtkWidget *frame;
  GtkWidget *label;

  /* 初始化 */
  gtk_init (&argc, &argv);

   = gtk__new (GTK__TOPLEVEL);
  g_signal_connect (, "destroy",
		    G_CALLBACK (gtk_main_quit),
		    NULL);

  gtk__set_title (GTK_ (), "Label");
  vbox = gtk_vbox_new (FALSE, 5);
  hbox = gtk_hbox_new (FALSE, 5);
  gtk_container_add (GTK_CONTAINER (), hbox);
  gtk_box_pack_start (GTK_BOX (hbox), vbox, FALSE, FALSE, 0);
  gtk_container_set_border_width (GTK_CONTAINER (), 5);

  frame = gtk_frame_new ("Normal Label");
  label = gtk_label_new ("This is a Normal label");
  gtk_container_add (GTK_CONTAINER (frame), label);
  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);

  frame = gtk_frame_new ("Multi-line Label");
  label = gtk_label_new ("This is a Multi-line label.\nSecond line\n" \
			 "Third line");
  gtk_container_add (GTK_CONTAINER (frame), label);
  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);

  frame = gtk_frame_new ("Left Justified Label");
  label = gtk_label_new ("This is a Left-Justified\n" \
			 "Multi-line label.\nThird      line");
  gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_LEFT);
  gtk_container_add (GTK_CONTAINER (frame), label);
  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);

  frame = gtk_frame_new ("Right Justified Label");
  label = gtk_label_new ("This is a Right-Justified\nMulti-line label.\n" \
			 "Fourth line, (j/k)");
  gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_RIGHT);
  gtk_container_add (GTK_CONTAINER (frame), label);
  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);

  vbox = gtk_vbox_new (FALSE, 5);
  gtk_box_pack_start (GTK_BOX (hbox), vbox, FALSE, FALSE, 0);
  frame = gtk_frame_new ("Line wrapped label");
  label = gtk_label_new ("This is an example of a line-wrapped label.  It " \
			 "should not be taking up the entire             " /* 用一段較長的空白字元來測試空白的自動排列 */\
			 "width allocated to it, but automatically " \
			 "wraps the words to fit.  " \
			 "The time has come, for all good men, to come to " \
			 "the aid of their party.  " \
			 "The sixth sheik's six sheep's sick.\n" \
			 "     It supports multiple paragraphs correctly, " \
			 "and  correctly   adds "\
			 "many          extra  spaces. ");
  gtk_label_set_line_wrap (GTK_LABEL (label), TRUE);
  gtk_container_add (GTK_CONTAINER (frame), label);
  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);

  frame = gtk_frame_new ("Filled, wrapped label");
  label = gtk_label_new ("This is an example of a line-wrapped, filled label.  " \
			 "It should be taking "\
			 "up the entire              width allocated to it.  " \
			 "Here is a sentence to prove "\
			 "my point.  Here is another sentence. "\
			 "Here comes the sun, do de do de do.\n"\
			 "    This is a new paragraph.\n"\
			 "    This is another newer, longer, better " \
			 "paragraph.  It is coming to an end, "\
			 "unfortunately.");
  gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_FILL);
  gtk_label_set_line_wrap (GTK_LABEL (label), TRUE);
  gtk_container_add (GTK_CONTAINER (frame), label);
  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);

  frame = gtk_frame_new ("Underlined label");
  label = gtk_label_new ("This label is underlined!\n"
			 "This one is underlined in quite a funky fashion");
  gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_LEFT);
  gtk_label_set_pattern (GTK_LABEL (label),
			 "_________________________ _ _________ _ ______     __ _______ ___");
  gtk_container_add (GTK_CONTAINER (frame), label);
  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);

  gtk_widget_show_all ();

  gtk_main ();

  return 0;
}
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