標籤 Labels
標籤(Labels)是 GTK 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 );
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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);
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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);
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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。
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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 *window = NULL;
GtkWidget *hbox;
GtkWidget *vbox;
GtkWidget *frame;
GtkWidget *label;
/* 初始化 */
gtk_init (&argc, &argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
g_signal_connect (window, "destroy",
G_CALLBACK (gtk_main_quit),
NULL);
gtk_window_set_title (GTK_WINDOW (window), "Label");
vbox = gtk_vbox_new (FALSE, 5);
hbox = gtk_hbox_new (FALSE, 5);
gtk_container_add (GTK_CONTAINER (window), hbox);
gtk_box_pack_start (GTK_BOX (hbox), vbox, FALSE, FALSE, 0);
gtk_container_set_border_width (GTK_CONTAINER (window), 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 linen"
"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-Justifiedn"
"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-JustifiednMulti-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 (window);
gtk_main ();
return 0;
}
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