Gtk中的文本视图（GtkTexView Widget）

Gtk中的文本视图（GtkTexView Widget）

在本章的Gtk+程序设计教程中，我们将重点介绍 GtkTexView 构件。
GtkTexView w构件被常常用来显示和编辑多行的文本。正如我们一再提到的， GtkTexBuffer 构件也是给予MVC的设计。GtkTextView 就是显示（view）元素而 GtkTexBuffer 则代表了model 元素。 GtkTexBuffer 常常被用来处理文本数据。GtkTextTag则是一种被用于文本的属性。 GtkTextIter则是代表了两个字符之间的空隙。那么很好理解，文本的排版操作多用iterators。

简单的例子（Simple example）

在我们的第一个例子中，我们将向大家展示GtkTexView 的一些功能。我们还将教大家怎么样去应用各种各样的文本标记（ tags ）。

#include <gtk/gtk.h>


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

  GtkWidget *window;
  GtkWidget *view;
  GtkWidget *vbox;
  
  GtkTextBuffer *buffer;
  GtkTextIter start, end;
  GtkTextIter iter;

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 250, 200);
  gtk_window_set_title(GTK_WINDOW(window), "TextView");
  gtk_container_set_border_width(GTK_CONTAINER(window), 5);
  GTK_WINDOW(window)->allow_shrink = TRUE;

  vbox = gtk_vbox_new(FALSE, 0);
  view = gtk_text_view_new();
  gtk_box_pack_start(GTK_BOX(vbox), view, TRUE, TRUE, 0);

  buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(view));

  gtk_text_buffer_create_tag(buffer, "gap",
        "pixels_above_lines", 30, NULL);

  gtk_text_buffer_create_tag(buffer, "lmarg", 
      "left_margin", 5, NULL);
  gtk_text_buffer_create_tag(buffer, "blue_fg", 
      "foreground", "blue", NULL); 
  gtk_text_buffer_create_tag(buffer, "gray_bg", 
      "background", "gray", NULL); 
  gtk_text_buffer_create_tag(buffer, "italic", 
      "style", PANGO_STYLE_ITALIC, NULL);
  gtk_text_buffer_create_tag(buffer, "bold", 
      "weight", PANGO_WEIGHT_BOLD, NULL);

  gtk_text_buffer_get_iter_at_offset(buffer, &iter, 0);

  gtk_text_buffer_insert(buffer, &iter, "Plain text\n", -1);
  gtk_text_buffer_insert_with_tags_by_name(buffer, &iter, 
        "Colored Text\n", -1, "blue_fg", "lmarg",  NULL);
  gtk_text_buffer_insert_with_tags_by_name (buffer, &iter, 
        "Text with colored background\n", -1, "lmarg", "gray_bg", NULL);

  gtk_text_buffer_insert_with_tags_by_name (buffer, &iter, 
        "Text in italics\n", -1, "italic", "lmarg",  NULL);

  gtk_text_buffer_insert_with_tags_by_name (buffer, &iter, 
        "Bold text\n", -1, "bold", "lmarg",  NULL);

  gtk_container_add(GTK_CONTAINER(window), vbox);

  g_signal_connect_swapped(G_OBJECT(window), "destroy",
        G_CALLBACK(gtk_main_quit), G_OBJECT(window));

  gtk_widget_show_all(window);

  gtk_main();

  return 0;
}

这个例子展示了如何利用各种各样的文本标记（ GtkTextTags）来显示文本。

 view = gtk_text_view_new();

生成一个GtkTextView。

 gtk_text_buffer_create_tag(buffer, "blue_fg", 
     "foreground", "blue", NULL); 

这就是一个运用 GtkTextTag的例子，这个标记改变了文本的颜色。

 gtk_text_buffer_insert_with_tags_by_name(buffer, &iter, 
       "Colored Text\n", -1, "blue_fg", "lmarg",  NULL);

这个代码插入了一些文本，并运用了一个特殊的文本标记blue_fg。

Figure: Simple TextView

行和栏（Lines and Columns）

在接下来的示例中将要显示文本编辑光标目前处于的行数和列数。

#include <gtk/gtk.h>

update_statusbar(GtkTextBuffer *buffer,
    GtkStatusbar  *statusbar)
{
  gchar *msg;
  gint row, col;
  GtkTextIter iter;

  gtk_statusbar_pop(statusbar, 0); 

  gtk_text_buffer_get_iter_at_mark(buffer,
      &iter, gtk_text_buffer_get_insert(buffer));

  row = gtk_text_iter_get_line(&iter);
  col = gtk_text_iter_get_line_offset(&iter);

  msg = g_strdup_printf("Col %d Ln %d", col+1, row+1);

  gtk_statusbar_push(statusbar, 0, msg);

  g_free(msg);
}

static void
mark_set_callback(GtkTextBuffer *buffer,
    const GtkTextIter *new_location, GtkTextMark *mark,
    gpointer data)
{
  update_statusbar(buffer, GTK_STATUSBAR(data));
}


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

  GtkWidget *window;
  GtkWidget *vbox;

  GtkWidget *toolbar;
  GtkWidget *view;
  GtkWidget *statusbar;
  GtkToolItem *exit;
  GtkTextBuffer *buffer;

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 250, 200);
  gtk_window_set_title(GTK_WINDOW(window), "lines & cols");

  vbox = gtk_vbox_new(FALSE, 0);
  gtk_container_add(GTK_CONTAINER(window), vbox);

  toolbar = gtk_toolbar_new();
  gtk_toolbar_set_style(GTK_TOOLBAR(toolbar), GTK_TOOLBAR_ICONS);

  exit = gtk_tool_button_new_from_stock(GTK_STOCK_QUIT);
  gtk_toolbar_insert(GTK_TOOLBAR(toolbar), exit, -1);

  gtk_box_pack_start(GTK_BOX(vbox), toolbar, FALSE, FALSE, 5);

  view = gtk_text_view_new();
  gtk_box_pack_start(GTK_BOX(vbox), view, TRUE, TRUE, 0);
  gtk_widget_grab_focus(view);

  buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(view));

  statusbar = gtk_statusbar_new();
  gtk_box_pack_start(GTK_BOX(vbox), statusbar, FALSE, FALSE, 0);

  g_signal_connect(G_OBJECT(exit), "clicked", 
        G_CALLBACK(gtk_main_quit), NULL);

  g_signal_connect(buffer, "changed",
        G_CALLBACK(update_statusbar), statusbar);

  g_signal_connect_object(buffer, "mark_set", 
        G_CALLBACK(mark_set_callback), statusbar, 0);

  g_signal_connect_swapped(G_OBJECT(window), "destroy",
        G_CALLBACK(gtk_main_quit), NULL);

  gtk_widget_show_all(window);

  update_statusbar(buffer, GTK_STATUSBAR (statusbar));

  gtk_main();

  return 0;
}

在上面的代码示例中，我们完成了在状态栏中显示当前文本编辑光标所处于的行和列数。

 view = gtk_text_view_new();

生成一了 GtkTextView构件。

 g_signal_connect(buffer, "changed",
       G_CALLBACK(update_statusbar), statusbar);

如果我们要更改文本，我们只需要调用回调函数 update_statusbar() 就可以了。

 g_signal_connect_object(buffer, "mark_set", 
       G_CALLBACK(mark_set_callback), statusbar, 0);

当光标在移动的时候， mark_set 信号就被发射出去了。

 gtk_statusbar_pop(statusbar, 0); 

这段代码功能是清除了先前的任何一些状态栏中的信息。

 gtk_text_buffer_get_iter_at_mark(buffer,
     &iter, gtk_text_buffer_get_insert(buffer));

 row = gtk_text_iter_get_line(&iter);
 col = gtk_text_iter_get_line_offset(&iter);

显然上面的代码是在获取当前所处于的行号与列号。

 msg = g_strdup_printf("Col %d Ln %d", col+1, row+1);

上面的代码准备好，状态栏中显示出来的行号与列号的内容。

 gtk_statusbar_push(statusbar, 0, msg);

然后，我们就在状态栏上显示文本。

Figure: Lines & Columns

监测& 突显（Search & Highlight）

在接下来的例子中，我们将要在 GtkTextBuffer中做一些监测的工作。我们还将把一些文本的内容进行“突显”处理。

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



gboolean key_pressed(GtkWidget * window,
    GdkEventKey* event, GtkTextBuffer *buffer) {

  GtkTextIter start_sel, end_sel;
  GtkTextIter start_find, end_find;
  GtkTextIter start_match, end_match;
  gboolean selected;	
  gchar *text;		  
  


  if ((event->type == GDK_KEY_PRESS) && 
     (event->state & GDK_CONTROL_MASK)) {

    switch (event->keyval)
    {
      case GDK_m :
        selected = gtk_text_buffer_get_selection_bounds(buffer, 
            &start_sel, &end_sel);
      if (selected) {
        gtk_text_buffer_get_start_iter(buffer, &start_find);
        gtk_text_buffer_get_end_iter(buffer, &end_find);

        gtk_text_buffer_remove_tag_by_name(buffer, "gray_bg", 
            &start_find, &end_find);  
        text = (char *) gtk_text_buffer_get_text(buffer, &start_sel,
            &end_sel, FALSE);

        while ( gtk_text_iter_forward_search(&start_find, text, 
                GTK_TEXT_SEARCH_TEXT_ONLY | 
                GTK_TEXT_SEARCH_VISIBLE_ONLY, 
                &start_match, &end_match, NULL) ) {

          gtk_text_buffer_apply_tag_by_name(buffer, "gray_bg", 
              &start_match, &end_match);
          int offset = gtk_text_iter_get_offset(&end_match);
          gtk_text_buffer_get_iter_at_offset(buffer, 
              &start_find, offset);
        }

        g_free(text);
      }

      break;

      case GDK_r:
        gtk_text_buffer_get_start_iter(buffer, &start_find);
        gtk_text_buffer_get_end_iter(buffer, &end_find);
      
        gtk_text_buffer_remove_tag_by_name(buffer, "gray_bg", 
            &start_find, &end_find);  
      break;
    }
  }

  return FALSE;
}


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

  GtkWidget *window;
  GtkWidget *view;
  GtkWidget *vbox;
  
  GtkTextBuffer *buffer;
  GtkTextIter start, end;
  GtkTextIter iter;

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 250, 200);
  gtk_window_set_title(GTK_WINDOW(window), "Search & Highlight");
  gtk_container_set_border_width(GTK_CONTAINER(window), 5);
  GTK_WINDOW(window)->allow_shrink = TRUE;

  vbox = gtk_vbox_new(FALSE, 0);
  view = gtk_text_view_new();
  gtk_widget_add_events(view, GDK_BUTTON_PRESS_MASK);
  gtk_box_pack_start(GTK_BOX(vbox), view, TRUE, TRUE, 0);

  buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(view));
  gtk_text_buffer_create_tag(buffer, "gray_bg", 
      "background", "gray", NULL); 
  gtk_container_add(GTK_CONTAINER(window), vbox);

  g_signal_connect_swapped(G_OBJECT(window), "destroy",
        G_CALLBACK(gtk_main_quit), G_OBJECT(window));

  g_signal_connect(G_OBJECT(window), "key-press-event",
        G_CALLBACK(key_pressed), buffer);

  gtk_widget_show_all(window);

  gtk_main();

  return 0;
}

在我们的示例中，我们用到了键盘的快捷键。Ctrl + M 是用来突显我们当前所选取的文本内容。Ctrl + R 则是用来取消上面的操作。

 gtk_text_buffer_create_tag(buffer, "gray_bg", 
     "background", "gray", NULL); 

我们在例子中会再次用到 GtkTextTag 。这个标记可以使文本的背景反白。

 selected = gtk_text_buffer_get_selection_bounds(buffer, 
     &start_sel, &end_sel);

这里我们得到我们选中的文本所具有的起始和终点位置。

 gtk_text_buffer_get_start_iter(buffer, &start_find);
 gtk_text_buffer_get_end_iter(buffer, &end_find);

我们得到了文本缓冲区（text buffer）的起始和终点位置。

 gtk_text_buffer_remove_tag_by_name(buffer, "gray_bg", 
     &start_find, &end_find);  

上面就是，把先前的标记去处。

 text = (char *) gtk_text_buffer_get_text(buffer, &start_sel,
     &end_sel, FALSE);

接着我们得到了所选择的文本内容，我们将要进行监测。

 while ( gtk_text_iter_forward_search(&start_find, text, 
         GTK_TEXT_SEARCH_TEXT_ONLY | 
         GTK_TEXT_SEARCH_VISIBLE_ONLY, 
         &start_match, &end_match, NULL) ) {

   gtk_text_buffer_apply_tag_by_name(buffer, "gray_bg", 
       &start_match, &end_match);
   int offset = gtk_text_iter_get_offset(&end_match);
   gtk_text_buffer_get_iter_at_offset(buffer, 
       &start_find, offset);
 }

这段代码将检测所有我们所选择的文本后的所发生的事件，一旦发现与我们定义的内容有匹配就应用我们设定好的标记。在匹配工作完成之后，单词的尾端将将被成下次监视操作的首端。

Figure: Search & Highlight