Cairo 图形指南(10) —— 文本

Cairo 图形指南 (10) —— 文本 本篇讲述如何处理文本。

灵魂伙伴第一个示例是在 GTK+ 窗口中显示《灵魂伙伴》的部分歌词。

?1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 #include <cairo.h>#include <gtk/gtk.h>static gbooleanon_expose_event(GtkWidget *widget,GdkEventExpose *event,gpointer data){cairo_t *cr;cr = gdk_cairo_create(widget->window);cairo_set_source_rgb(cr, 0.1, 0.1, 0.1);cairo_select_font_face(cr, "Purisa",CAIRO_FONT_SLANT_NORMAL,CAIRO_FONT_WEIGHT_BOLD);cairo_set_font_size(cr, 13);cairo_move_to(cr, 20, 30);cairo_show_text(cr, "Most relationships seem so transitory"); cairo_move_to(cr, 20, 60);cairo_show_text(cr, "They're all good but not the permanent one");cairo_move_to(cr, 20, 120);cairo_show_text(cr, "Who doesn't long for someone to hold");cairo_move_to(cr, 20, 150);cairo_show_text(cr, "Who knows how to love you without being told"); cairo_move_to(cr, 20, 180);cairo_show_text(cr, "Somebody tell me why I'm on my own"); cairo_move_to(cr, 20, 210);35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 cairo_show_text(cr, "If there's a soulmate for everyone");cairo_destroy(cr);return FALSE;}int main (int argc, char *argv[]){GtkWidget *window;gtk_init(&argc, &argv);window = gtk_window_new(GTK_WINDOW_TOPLEVEL);g_signal_connect(window, "expose-event",G_CALLBACK(on_expose_event), NULL);g_signal_connect(window, "destroy",G_CALLBACK(gtk_main_quit), NULL);gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER); gtk_window_set_default_size(GTK_WINDOW(window), 420, 250); gtk_window_set_title(GTK_WINDOW(window), "Soulmate");gtk_widget_set_app_paintable(window, TRUE);gtk_widget_show_all(window);gtk_main();return 0;}在这个示例中，显示了 Natasha Bedingfield 的《灵魂伙伴》的部分歌词。

（在这里，可以听这首歌，很美妙） ?1 2 3 cairo_select_font_face(cr, "Purisa",CAIRO_FONT_SLANT_NORMAL,CAIRO_FONT_WEIGHT_BOLD);这里设置字体。

这个函数接受了三个字体参数的传入，字体的名称、样式与轻重。

1 c airo_set_font_size(cr, 13);这里设定字号。

1 2 cairo_move_to(cr, 20, 30);cairo_show_text(cr, "Most relationships seem so transitory"); 通过在窗口中指定位置并调用 cairo_show_text() 函数显示文本。

一个字接一个字……这种效果就是一个字一个字的显示，这些字的绘制存有时间差。

1 2 3 4 5 6 7 8 9 10 11 #include <cairo.h>#include <gtk/gtk.h>gpointer text[7] = { "Z", "e", "t", "C", "o", "d", "e" };gboolean timer = TRUE;static gbooleanon_expose_event(GtkWidget *widget,GdkEventExpose *event,gpointer data)12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 {cairo_t *cr;cairo_text_extents_t extents;static gint count = 0;cr = gdk_cairo_create(widget->window);cairo_select_font_face(cr, "Courier",CAIRO_FONT_SLANT_NORMAL,CAIRO_FONT_WEIGHT_BOLD);cairo_set_font_size(cr, 35);cairo_set_source_rgb(cr, 0.2, 0.2, 0.2);gint i;gint x = 0;for (i = 0; i < count; i++) {cairo_text_extents(cr, text[i], &extents);x += extents.width + 2;cairo_move_to(cr, x + 30, 50);cairo_show_text(cr, text[i]);}count++;if (count == 8) {timer = FALSE;count = 0;}cairo_destroy(cr);return FALSE;}static gbooleantime_handler (GtkWidget *widget){if (widget->window == NULL) return FALSE;if (!timer) return FALSE;gtk_widget_queue_draw(widget);56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 return TRUE;}int main (int argc, char *argv[]){GtkWidget *window;gtk_init(&argc, &argv);window = gtk_window_new(GTK_WINDOW_TOPLEVEL);g_signal_connect(window, "expose-event",G_CALLBACK(on_expose_event), NULL);g_signal_connect(window, "destroy",G_CALLBACK(gtk_main_quit), NULL);gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER); gtk_window_set_default_size(GTK_WINDOW(window), 300, 90); gtk_window_set_title(GTK_WINDOW(window), "ZetCode");gtk_widget_set_app_paintable(window, TRUE);g_timeout_add(1000, (GSourceFunc) time_handler, (gpointer) window);gtk_widget_show_all(window);gtk_main();return 0;}在这个示例中，我们在 GTK+ 窗口中画了“ZetCode”这个字串，并让逐个字母伴随一定的时间差逐一显示。

1 g pointer text[7] = { "Z", "e", "t", "C", "o", "d", "e" };构造一个字符数组。

1 2 3 cairo_select_font_face(cr, "Courier",CAIRO_FONT_SLANT_NORMAL,CAIRO_FONT_WEIGHT_BOLD);将字体设置为 Courier 。