杂项构件
标签 Labels
标签(Labels)是 GTK 中最常用的构件，实际上它很简单。因为没有相关联的 X 窗口，标签不能引发信号。如果需要获取或引发信号，可以将它放在一个事件盒中，或放在按钮构件里面。
用以下函数创建一个新标签：
GtkWidget *gtk_label_new( const char *str ); GtkWidget *gtk_label_new_with_mnemonic( const char *str ); |
唯一的参数是要由标签显示的字符串。
创建标签后，要改变标签你的文本，用以下函数：
void gtk_label_set_text( GtkLabel *label,
const char *str ); |
第一参数是前面创建的标签(用 GTK_LABEL() 宏转换)，第二个参数是新的字符串。
如果需要，新字符串需要的空间会做自动调整。在字符串中放置换行符，可以创建多行标签。
用以下函数取得标签的当前文本：
const gchar* gtk_label_get_text( GtkLabel *label ); |
不要释放返回的字符串，因为 GTK 内部要使用它。
标签的文本可以用以下函数设置对齐方式：
void gtk_label_set_justify( GtkLabel *label,
GtkJustification jtype ); |
jtype 的值可以是：
GTK_JUSTIFY_LEFT 左对齐 GTK_JUSTIFY_RIGHT 右对齐 GTK_JUSTIFY_CENTER 居中对齐(默认) GTK_JUSTIFY_FILL 充满 |
标签构件的文本会自动换行。用以下函数激活“自动换行”：
void gtk_label_set_line_wrap (GtkLabel *label,
gboolean wrap); |
wrap参数可取 TRUE 或 FALSE。
如果想要使标签加下划线，可以在标签中设置显示模式：
void gtk_label_set_pattern (GtkLabel *label,
const gchar *pattern); |
pattern 参数指定下划线的外观。它由一串下划线和空格组成。下划线指示标签的相应字符应该加一个下划线。例如,"__ __" 将在标签的第1、第2个字符和第8、第9个字符加下划线。
 | 如果你只是想创建一个用下划线代表快捷键("mnemonic")的标签，你应该用 gtk_label_new_with_mnemonic() 或 gtk_label_set_text_with_mnemonic()，而不是用 gtk_label_set_pattern()。 |
下面是一个说明这些函数的短示例。这个示例用框架构件(Frame widget)能更好地示范标签的风格。现在你不用理会这点,框架构件以后再作介绍。
在 GTK+ 2.0 里，标签文本里能包含改变字体等文本属性的标记,并且标签能设置为可以被选择(用来复制-粘贴)。这些高级特性在这里并不介绍。
#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 (G_OBJECT (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 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 " /* 用一段较长的空白字符来测试空白的自动排列 */\
"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;
} |